Population Distribution of Land Birds in Temperate Rainforest of Southern New Zealand
Jiro Kikkawa
By
Department of Zoology, University of Otago*
[Received by the Editor, 6 October 1964.]
CONTENTS
Abstract Introduction Areas and Methods Results
A. General Survey
1. Fiordland 2. Stewart Island 3. Inland Nelson 4. East coast 5. Relative abundance in other areas
B. Detailed study at Botanic Gardens, Dunedin
1. Area 2. Size of breeding populations 3. Seasonal changes in total population size 4. Selection of nest-sites 5. Nesting success and productivity 6. Food and feeding habits
Discussion
1. Limitations of the results 2. Ecological distribution 3. Population distribution 4. Exploitation of new habitats 5. Stability and instability of populations.
Acknowledgments
Apppendices
Literature Cited
Abstract
A survey of bird populations was made in three breeding seasons 1958—61 in various forest habitats of the South Island of New Zealand. Detailed accounts of observations are recorded for the less known areas. There was a difference in the species composition and breeding population density of birds between the warm-temperate podocarp-dominant forest and the cool-temperate Nothofagus-dom'ma.nt forest. Among indigenous species of birds, honeyeaters, the Fantail and the Grey Warbler prefered the former habitat and the Rifleman the latter habitat. Total population density was highest in low hardwood forest (175—600 pairs per 100 acres), and lowest in Nothofagus forest (70-175 pairs per 100 acres). An intensive study of bird populations in a modified habitat revealed nesting success, productivity, mortality factors and seasonal population changes of some common species with wide ecological distribution and whose diet changed seasonally. Naturalized species in indigenous habitats and indigenous species in modified habitats seem to have modified their breeding and feeding habits only slightly. Present interaction among the existing species, both indigenous and naturalized, is probably not great enough to cause interspecific competition in indigenous habitats. An attempt has been made to explain the commonness and rarity of indigenous species from two aspects of their preadaptive conditions: habitat selection and breeding capacity. An examination of the known facts and evidence obtained in the present study support the hypotheses that (a) the highly specialized species, the populations of which are stable only in limited environmental conditions, have small reproductive capacity and have decreased in number since European settlement, and (b) the species with wide ecological distribution generally have greater reproductive capacity and have been less affected by introduced influences. For the understanding of the long-term effects of environmental changes, it is necessary to know the distribution and stability of populations in relation to vegetation and reproductive capacity. Since such aspects of ecological study are still scanty in New Zealand, further studies along these lines are needed before conservation of indigenous birds can be carried out on sound principles.
Introduction
To date the majority of ecological studies of birds have been carried out in northern temperate regions where the description of communities and classification of habitats have been made and theories concerning population dynamics, habitat selection and competition among closely related species have been developed. New Zealand, composed of oceanic islands in a southern temperate region, has received little attention from avian ecologists in the past. The opportunity that New Zealand offers for the study of ecological relationships of birds is nonetheless unique. The uniqueness of the avifauna in New Zealand may be illustrated by comparing it with that of the mainland of Japan, which is similar to New Zealand in size and in latitude range but is in the Palaearctic Region and lies close to the continent (Table I). In New Zealand, apart from a few species of archaic elements, characteristic of this zoogeographical subregion, there is a striking paucity of land birds. This is in contrast with a profusion of oceanic birds, most of which breed on the New Zealand coast or subantarctic islands. The regular migratory species which spend part of their life outside the New Zealand area are almost exclusively waders and sea birds. Among the land birds only two species in Cuculiformes and none in Passeriformes migrate. The indigenous species of passerines which at present breed in New Zealand are only 18 in number (72 species in Japan) and these are closely or distantly related to birds of the western Pacific Islands and eastern Australia (Mayr, 1939; Falla, 1953). The element of naturalized species is conspicuous, forming 47% (16 species) among the passerines. Most of the introduced species are Palaearctic and British in origin.
Elton (1958) has shown how drastic are the changes that are taking place in the present world fauna, apparently resulting in the modification of community structure and establishment of new food chains. The environmental changes that the introduced species met in the different zoogeographical regions were not gradual and time so far has not permitted their morphological adaptation. The successful
species in the new environment must have physiological and ecological advantages over the indigenous species which had evolved to form the original community. Forest species of birds in New Zealand thus provide a suitable subject for the study of this dynamic process in the species network which is at present undergoing a change to a new state of dynamic balance. Thus in this paper an “ avian community ” is used for describing a combination of various species of birds living in the same habitat in the selected sample areas and is not meant to imply functions of a discrete entity. Throughout the paper an emphasis is placed on the numbers present rather than presence or absence of species. In discussing the distribution, the total populations provide a basis for comparison of productivity between habitats while the density of each species discloses adaptiveness of that species in different habitats. “ Population distribution ” is used for convenience in the discussion of such aspects of ecological distribution.
In the North Island the natural forest has been destroyed to a great extent and relatively undisturbed populations of indigenous birds are now confined to restricted areas and some of the offshore islands which have been set aside as bird sanctuaries. Although comparatively large offshore islands seem to support an avian community close to that of the mainland in pre-European days (Turbott, 1961; Kikkawa, 1964), their isolation prevents us from making useful comparisons with the community in modified habitats of the North Island. In the present study a survey of bird populations was carried out in the South Island where the preEuropean vegetation is better preserved (Fig. 1). The purpose of the survey was (1) to describe the pattern of present ecological distribution of land birds in both indigenous and modified habitats, and (2) to assess various forest habitats of New Zealand in relation to the population density of birds. In the modified habitat more detailed observations were possible and an attempt was made to determine the broad food niches occupied by the constituent species of the avian community and to assess the stability of the population.
Areas and Methods
For the population survey in relatively undisturbed areas expeditions were made to the following places (Fig. 1).
Fiordland: Lake McKerrow-Martins Bay (1) 17-29 January 1959. Lake Manapouri—Doubtful Sound (2) 12-24 February 1959. Lake Monk-Long Sound (3) 16-28 January 1960.
Stewart Island (4) 13-24 November 1959.
Inland Nelson: Lake Rotoroa (6) 29 January-5 February 1961.
For these less known areas full accounts of birds were given in relation to the environment. Population counts were also made in the following areas (Fig. 1).
East Coast: Hook Bush (7, Waimate), 26-28 December 1958, 24-26 October 1959, 27 December 1960. Papatowai (5, Gatlins), 10-12 February 1961. Sullivan Dam (8, Dunedin), July 1958-February 1961. Botanic Gardens (8, Dunedin), July 1958-February 1961.
In all the above areas avian habitats were classified according to the vegetation type and in each habitat the breeding bird populations were estimated by censuses in sample areas. In selecting the census area physiognomic uniformity of the vegetation was the most important criterion used, but steep slopes were avoided. Prior to the census a map of the area was made, indicating conspicuous features to facilitate the plotting of birds. In order to minimize observational errors due to the different conspicuousness of birds according to species, light intensity, density of vegetation, and their activity which may be affected by the time of day, weather, etc., in most areas field observations on the breeding population density were made on early morning counts in fair weather. However, as the weather was not always favourable, some counts had to be made in rain in the morning or late in the afternoon. In each count all portions of the area were visited and all individuals seen or heard were plotted on the map together with records of their activities (e.g., singing, feeding, nest building). Whenever possible the count was repeated in the same area at different times of the day. Most naturalized species stop singing in January (late in the breeding season), and some become very inconspicuous (e.g., Song Thrush). In such species, if the counts were made later than January, the number of breeding birds was estimated from the count of the adults and the number of nests found in the area. In the present report all census results are given bv the standard expression of the number of pairs per 100 acres (40 hectares).
Fortunately the number of forest species in New Zealand is very limited and field marks of both indigenous and naturalized species are very distinct, even juveniles being readily distinguishable by either plumage or call notes. In addition, most species have fairly uniform distribution in each habitat and have relatively small territories during the breeding season. Thus estimation of the density was possible from small sample areas of various sizes and the short period of time spent in most areas, sometimes under the trying conditions of bad weather during the expedition. Inclusion or exclusion of birds recorded at the border of the census area influences the estimation of the density according to the size of the area selected. If the nest was found within the area or if such birds were recorded more frequently within the area than outside, the birds were included in the final count. In order to obtain a sufficient number of pairs in each sample, if not many birds were encountered in the initial mapping survey, a larger area was selected wherever the habitat was uniform. The result is that many larger areas sampled support smaller densities than smaller areas sampled.
In each census area small samples of invertebrates were collected from forest litter (30cm x 30cm), foliage (50 sweeps), and bark (30cm x 30cm), where birds were seen to search for food. A very sketchy description of the components of the habitat thus obtained was compared with actual food taken by birds (wherever such data were available). The specimens of invertebrates were preserved in the Otago Museum for taxonomic studies. Earthworms in the surface layer of soil were collected from 1m 2 with 4gms of potassium permanganate dissolved in 4 litres of water.
The relative abundance of each species of birds was estimated in various habitats for comparison. For this estimation all the birds seen or heard along any route taken during the expedition were recorded, care being taken to avoid repeated recording of the same individuals. The results are given with an approximate distance covered in each count and the relative abundance of species is indicated by the percentage of the total number of individuals recorded. Because of the different conspicuousness the results will not show the true relative abundance but only serve comparative purposes in discussing differences between different areas or habitats. General observations of birds, and counts to show relative abundance were also made in the following localities (Fig. 1): Arthurs Pass (9), Ashley (13, plantation) and Enys (10) in Canterbury; Trotter’s Gorge (11), Evansdale (11), Flagstaff (8), Silverstream (8, plantation), Maungatua (12), and Henley (12) in Otago.
In the course of the study special attention was paid to the feeding habits of birds in the field and stomach contents of some naturalized birds collected from various localities were examined. The indigenous species are strictly protected so that the records available are those based on field observations of the feeding habits and food items.
At the Botanic Gardens in Dunedin a detailed study was made of bird populations between September 1958 and February 1961, covering three breeding seasons. A total of 223 visits was made to this area to record numbers, nesting and feeding activities and to band nestlings and adults of the key species. A summary of the first year’s work has been published (Kikkawa, 1960 a). From the end of August 1960 the early-morning count of the total populations was reduced from weekly to monthly. The breeding population density was determined by means of territory mapping (Williams, 1936). In order to avoid the disclosure of nests to rats, the nests were not touched until the nestlings were large enough to be banded, and the examination of nests was made by a mirror attached to the end of a pole. For banding young in nests situated in inaccessible places, such as near the end of a branch, a “ chick lift ” was used to remove nestlings without injury. This is a pair of spring tongs with plastic foam to seize the chick, and is attached under the mirror at the end of a pole. It was manipulated from the ground with a piece of string while holding the pole. Nestlings of Blackbirds and Song Thrushes, about 7 to 9 days old, could be successfully lifted from a height of 15ft. A few individuals of naturalized species were collected not far from the study area to examine the stomach contents. The birds which met accidental deaths in or near the study area were also examined. For some nestlings of naturalized species food samples were collected by forcible regurgitation. A small piece of cotton wool was attached to a thread and suspended in the oesophagus from the beak, and as soon as the young were fed the food material was collected.
General observations of birds and records of breeding were also kept in an adjacent area (2.5 acres in size) where the relatively uniform habitat of regenerating native forest with Leptospermum canopy supported somewhat different populations of birds. Similar records were kept for the wooded parts of the Woodhaugh Gardens and the Town Belt of Dunedin,
Nomenclature of native plants follows Allan (1961), and Cheeseman (1925) for monocotyledons.
Results
A. General Survey
1. Fiordland
Three regions were visited in Fiordland: Lake McKerrow—Martins Bay, 17—29 January 1959; Lake Manapouri-Doubtful Sound, 12-24 February 1959; Lake Monk-Long Sound, 16-28 January 1960,
Lake McKerrow lies at the northern end of Fiordland, where deeply dissected upland consisting of diorite gneiss is replaced by the southern end of the Southern Alps (Mt Tutoko, 9,042 ft, as a prominent peak) and the glacial erosion ceases to reach the coast. The lower Hollyford River runs out from Lake McKerrow to the northern end of Martins Bay. The climate is mild and wet, the precipitation being one of the highest in New Zealand, exceeding 250 inches a year (though the number of raindays is less than that in the southern part of Fiordland). The vegetation differs from the rest of Fiordland in that the podocarp element in Nothofagus forest is conspicuous and the coastal vegetation of Dacrydium cupressinum/Metrosideros umbellata/Weinmannia racemosa stands forms a wide belt occupying the flat area from Martins Bay to the north-eastern side of Lake McKerrow as far inland as the Hokuri Creek. The delta which has developed at the head of Lake McKerrow supports Nothofagus/Weinmannia forest but the Nothofagus forest on the alluvium in the Hollyford Valley contains strong elements of Dacrydium cupressinum, Podocarpus spicatus and P. dacrydioides. Patches of podocarp forest also grow on the sunny side of the slopes above Lake McKerrow. Two areas were selected on the alluvium of the Hollyford River for the census of breeding bird populations. Area 1 is on the delta which developed where the Hollyford River enters Lake McKerrow. The total area is about 150 acres in size, but about one-third of the area is occupied by a swamp and patches of pure tree fern stands. The rest has a canopy of Nothofagus spp. mixed with only a few trees of Weinmannia racemosa and Podocarpus spp. Nothofagus is of various sizes and smaller ones are about the same height as Griselinia littoralis and Carpodetus serratus which form the secondary layer of the forest. Tree ferns and Ripogonum scandens are numerous in wetter parts of the area and most of the trees are covered with moss. Pseudowintera colorata, Coprosma spp., Pennantia corymbosa, etc., form the shrub layer which is dense on the forest edge along the river bank and lake shore, as well as around the swamp. Along the lake shore and river bed, patches of Phormium tenax and Cortaderia are common. Behind these are found some scattered Sophora microphylla and Cordyline. Three population counts were made in this area before 7 a.m., after which the noise of extremely abundant cicadas made an accurate count impossible. Area 2 was selected from the Nothofagus forest with a strong element of Podocarpus on the Hollyford Valley floor near the Pyke Junction. It is 17 acres in area and covered with Nothofagus spp. of various sizes and scattered Weinmannia racemosa, Podocarpus spicatus, and Dacrydium cupressinum. The last two are sometimes over 80ft in height. Fuchsia excorticata, Griselinia littoralis, Aristotelia serrata, Neopanax spp., and Carpodetus serratus are common in the secondary layer and Pseudowintera colorata, Neomyrtus pedunculata, Coprosma, tree ferns, etc., form the shrub layer. As in Area 1 the ground is covered with moss or ferns and there is no humus under the thin litter of Nothofagus leaves. Two counts of birds were made in this area.
The region of Lake Manapouri-Doubtful Sound has typical Fiordland topography and vegetation. Indentations of the fiord are largest in this region, the narrow sea stretching 25 miles inland from the west coastline. Nothofagus forest with some podocarp species extends from sea level to 2,700-3,300 ft in altitude and extends eastwards to the arms of deep, cold lakes. To the west of Wilmot Pass
(2,100 ft) where patches of Hoheria glabrata mark the end of the open eastern valley with bogs and Nothofagus cliffortioides forest, the west coast vegetation appears, as the composition of the Nothofagus forest changes to include tree ferns (Cyathea spp.) and Ripogonum scandens with abundant bryophytes and epiphytes. Weinmannia racemosa increases near the head of the sound and tall Dacrydium cupressinum and Metrosideros umbellata also appear. Patches of small Metrosideros were also found on ridges near Lake Manapouri. Two census areas were taken, one at the mouth of the Spey River (Area 3, Plate la) to the West Arm of Lake Manapouri (600 ft in altitude) and one at the mouth of the Lyvia River in Deep Cove, the head of Malaspina Sound (Area 4, sea level). Area 3 is 50 acres in size, being connected to a patch of Leptospermum scoparium on one side and marked by the lake shore, foothills of mountains and the Spey River. Nothofagus menziesii and N. cliff ortioides form the canopy about 50-60 ft high and the secondary layer is sparsely occupied by Carpodetus serratus, Griselinia littoralis, Elaeocarpus hookerianus, Fuchsia excorticata and Neopanax spp. The shrub layer includes Pseudowintera colorata, Neomyrtus pedunculata, Coprosma spp. and Myrsine divaricate. It is boggy in places and tree trunks and the ground with decaying logs are covered with moss and ferns. Three counts were made in this area. Area 4 is also 50 acres in size and triangular in shape, surrounded by the head of the sound, the Lyvia River and foothills of mountains. It contains some scattered tall specimens of Dacrydium cupressinum and Nothofagus menziesii above the normal canopy (about 60ft) of Weinmannia racemosa and Nothofagus. The secondary layer include Fuchsia excorticata, Aristotelia serrata, Griselinia littoralis, Neopanax spp., and Schefflera digitate; the shrub layer contains Cyathea sp., Pseudowintera colorata, and other species. Ripogonum scandens and Rubus spp. are also common. Two population counts were made in this area.
The region of Lake Monk-Long Sound lies in the southern part of Fiordland where mountain ranges are low with only few peaks exceeding 4,000 ft, though deep glaciated valleys run in various directions complicating the topography. Upland Nothofagus forest covers valley floors and slopes of mountains up to 2,700-3,000 ft. At the head of Lake Monk (2,200 ft) this forest forms a narrow belt bordered by the lake shore and bogs at the bottom, and the alpine meadow and subalpine scrub at the low timber line. On the slope a few old slips support Nothofagus stands of different ages. In parts of the valley and at high altitudes where there is a strong seepage, Dacrydium biforme and other scrub grow densely in stunted Nothofagus cliff ortioides forest. In such conditions if the slope is gentle scattered Nothofagus forms a parkland, sometimes with a radiating drainage pattern of streams. Towards Long Sound along the Jeanie Burn, Weimannia racemosa, Metrosideros umbellata and Coprosma increase with the decrease in altitude, developing a typical west coast rainforest near the sound, with abundant tree ferns and Ripogonum scandens. In the autumn of 1957 an expedition team spent 11 days in the Lake Monk area, and a report on the relationship of the naturalized Red Deer ( Cervus elaphus) and birds to the vegetation has been published (Riney, et al., 1959). In the present work two census areas were selected; one at the head of Lake Monk (Area 5, 2,200 ft in altitude) and one in the Jeanie Burn Valley (Area 6,1,500 ft in altitude). Area 5 of about 20 acres is covered with mature Nothofagus menziesii forest and patches of bog with scrub in between. The secondary layer of this forest is sparsely occupied by Griselinia littoralis, Neopanax spp., and Senecio bennettii at the foot of old slips. The shrub layer is formed by Pseudowintera colorata and Myrsine divaricata; the latter is often dense in the edge of the forest where Dacrydium biforme also grows on the bog. This area represents a rather unique habitat of upland Nothofagus forest between lakes and mountain tops, where there is no extensive unbroken forest due to streams, bogs, slips and the damage by deer. It is not a typical forest habitat but nevertheless common in this part of Fiordland. Area
6 of 18 acres has a similar composition of the forest to that of Area 5. However, except for a small bog opening, the canopy is higher and denser with over-matured Nothofagus menziesii and scattered Weinmannia racemosa. The ground and decaying logs are covered with a thick carpet of moss. These conditions are similar to those of Area 3 (Lake Manapouri). In both areas the census was made twice.
The census results for the areas 1-6 are summarized in Table 11. In Area 1 birds in the forest edge were excluded, but the edge effect was still apparent in the numbers of Silvereyes, Redpolls, Chaffinches and Hedge Sparrows, as these species were breeding in the forest interior as well. One Kaka and one Tui were recorded from Area 1 but were apparently visitors to the area. Area 2 supported a greater density of birds than Area 1 with abundant Tui, Blackbirds and Yellowbreasted Tits, though it lacked edge species.
In Area 3 the scarcity of fruit-bearing trees is reflected in the populations of Pigeons, Bellbirds and Silvereyes. Juvenile Bellbirds were concentrated in the Leptospermum patch just outside Area 3. There were more insect-spider eaters (especially Grey Warblers, Brown Creepers and Yellowheads) and seed eaters (Redpolls and Chaffinches) in Area 3 than in Area 4. Both in the number of species and in the total number of individuals Area 3 supported more birds than Area 4.
The following birds recorded in the Areas 5 and 6 were excluded from the table as their range was not confined to the area concerned; 1 pair of Kea which had a breeding territory, 1 Long-tailed Cuckoo, and 1 juvenile Fantail which was not accompanied by adults, in Area 5; 1 Long-tailed Cuckoo and 1 Kaka in Area 6. The population density in Area 5 was high compared with those obtained
in other areas in Fiordland, but the area included much of the forest edge habitat where naturalized species were common. In fact 57% of the total population was made up of naturalized species, of which the Chaffinch and Redpoll were as common as the commonest indigenous species (Yellow-breasted Tit) in the area. The density and composition of the species in Area 6 approaches that of a typical Fiordland Nothofagus forest, but the scarcity of fruit-bearing trees is still reflected in the small number of Bellbirds and total absence of Pigeons.
Table 111 summarizes the counts for relative abundance made in the three regions. In northern Fiordland the count was made along the eastern shore of Lake McKerrow from the head of the lake to the Hokuri Creek {Nothofagus/Weinmannia forest along an undulating route across many small ridges and gullies and lake shore), from the Hokuri Creek to Martins Bay ( Dacrydium cupressinum/ Metrosideros umbellatafWeinmannia racemosa stands with dense secondary cover and an open paddock on the flat), and along the Hollyford River from the head of Lake McKerrow to the Pyke Junction ( Nothofagus forest with strong podocarp elements on the alluvium, eastern side of the river, and podocarp forest on the west bank). These counts were made while walking at about one mile per hour, in exceptionally good weather conditions. A few Long-tailed Cuckoos, Parakeets and Morepork were present, but the records are incomplete. Suspected call notes of Riflemen and Yellowheads were excluded from the counts, but they were not common along the shore of Lake McKerrow. The Yellow-breasted Tit was the commonest species in the forest habitat and was very evenly distributed. The Bellbird was also common and evenly distributed, while the Tui was found more commonly in podocarp dominant forest or Nothofagus forest with a strong element of podocarp, than in Weinmannia dominant forest. The Tui was almost absent from NothofagusjWeinmannia forest (e.g., Area 1). The number of Pigeons and Blackbirds followed a similar tendency. No Kaka was recorded along the coast though inland they sometimes formed flocks flying high, to and from the apparent feeding areas. On one early morning (19 January) 38 of them were counted in a flock forming a long row and flying high over the Hollyford Valley. Fantails and Grey Warblers were not very common, and out of 15 Fantails recorded only one (juvenile) was the black form. Many Blackbirds, Song Thrushes, Chaffinches, Yellow Hammers and Redpolls were found in a paddock near Davey Gunn Hut towards Martins Bay, but few only were recorded in or over the forest.
In central Fiordland the counts were made along the track from the mouth of the Spey River to Deep Cove of Doubtful Sound (divided into two parts: the Spey River mouth to Wilmot Pass Hut, 6 miles; and Deep Cove to Wilmot Pass Hut, 5.5 miles), from the Spey River mouth towards Mt Grey (600-3,400 ft in altitude), and from Deep Cove towards Mt Plaisted (50-4,000 ft in altitude). These counts were made on sunny mornings while walking uphill. A comparison of the count between the east (4) and the west (5) of Wilmot Pass Hut reveals a difference between the two sides of the mountain range, indicating that the tendency of population distribution as obtained in census areas (3 and 4) is generally held. The slopes of Mt Plaisted and Mt Grey are steep and cliff faces are exposed in places. The vegetation of Mt Grey is more open than that of Mt Plaisted and has an irregular timber line which is formed by the alpine scrub and stunted Nothofagus cliffortioides, while the slope of Mt Plaisted supports a dense forest of Nothofagus up to 3,300 ft where it abruptly gives way to tussock. The difference was reflected in the results of the bird counts. More forest species were recorded from the Mt Plaisted count than from Mt Grey. Kaka were recorded below 1,700 ft; Riflemen, Yellow-breasted Tits and Bellbirds up to the timber line; a Blackbird, a Song Thrush and several flocks of Silvereyes from the lowland forest; Kea above 3,000 ft; and Rock Wrens among rocks and on hanging cliffs with alpine tussock above 4,000 ft. At Mt Grey, Redpolls were heard over the forest on the slope and
were breeding near the timber line about 2,700 ft; Chaffinches were recorded on steep ridges sparsely covered with Dacrydium cupressinum and Weinmannia racemosa about 1,000 ft; and Kea were found above 2,300 ft. Of 39 Fantails observed 2 only were the black form.
An estimation of relative abundance of land birds on Secretary Island, which lies at the mouth of Doubtful Sound, was made by a member of the expedition, James Watt. According to him the common species in the forest from Blanket Bay to the timber line (3,000 ft) of Mt Grono (3,922 ft) were the Yellow-breasted Tit, Bellbird and Silvereye, less common were the Grey Warbler and Fan tail. A few Pigeons, Weka, Kaka, Brown Creepers (1 record) and Rifleman (1 record) were also recorded. Above and about the timber line, Redpolls, N.Z. Pipits and Kea were noted. The birds on the island were not particularly numerous compared with those in the shore areas of the mainland. As Secretary Island supports none of the mammal populations that are often alleged to be the cause of the scarcity of many forest birds on the mainland, the tendency of the population distribution found in the Doubtful Sound area must be understood as general and the factors influencing it should be sought along lines other than predation.
In southern Fiordland the counts were made along the Jeanie Burn from the upper basin near Lake Monk to sea level on the shore of Long Sound, at the upper end of the Big River from the saddle between the Jeanie Burn to the level of 1,200 ft and up to 3,200 ft towards Lake Monk, and around the northern end of Lake Monk over the east and west saddles. These counts were made in rainy conditions at normal hiking speed. The results are probably much affected by weather. However, they show a conspicuous change in the bird distribution with a change in vegetation as Long Sound is approached about 17 miles inland from the west coastline. Kaka were found below 2,000 ft, Parakeets below 1,500 ft, and Pigeons below 900 ft in altitude. The number of Riflemen and Bellbirds increased while
Blackbirds, Brown Creepers and Yellowheads decreased. Blackbirds were seen only in Hoheria glabrata and Senecio bennettii patches. Hedge Sparrows and Song Thrushes were not recorded along the Jeanie Burn, but the time spent was too short to prove their absence. One Rock Wren not in Table 111 was recorded at the north end saddle of Lake Monk. Redpolls and Silvereyes were common both at the timber line and in the openings of the valley floor. Fantails were scarce throughout regardless of the forest edge conditions.
To compare relative abundance with that obtained by the previous expedition, Turbott’s method of counting in “observation periods” (Turbott & Bull, 1954) was used along one of the lines previously covered (line “ a ” in Riney et al, 1959). These counts were made in almost identical conditions to those in 1957; (1) 10.45 to 12.0 a.m. on 17 January, high gusty winds, showers becoming heavy rain; (2) 3.15 to 4.30 p.m. on 19 January, gusty winds, persistent rain and (3) 3.15 to 4.30 p.m. on 20 January, windy, moderate rain. The results are summarized in Table IV, together with the sum of three counts made by Turbott in 1957. Observational errors due to weather conditions and the times of day at which the counts were made may be lessened by summing the three counts. This comparison with the autumn counts in 1957 reveals some interesting facts. The abundance of some indigenous forest species such as the Rifleman, Yellow-breasted Tit and Grey Warbler remained more or less the same. The Fantail, Brown Creeper and Bellbird were absent, though they were recorded in small numbers not far away from this line in both expeditions. These facts seem to indicate stability of these species in this area. On the other hand, the total absence of the Yellowhead in 1957 from the Lake Monk area suggests either a possible seasonal movement in autumn or a change in distribution since 1957. In the present survey this species showed a scattered distribution of breeding populations and outside this area was found only around Area 6 in the Jeanie Burn. The Blackbird and Chaffinch showed a slight increase in this area, but the high juvenile counts of these species in the present survey may indicate a seasonal increase which might be checked in a relatively short period of time. Juvenile Silvereyes were not encountered in these counts. A flock of 40 was recorded in this area on 17 January. The order of abundance obtained in these counts generally agrees with that in the total breeding density measured in the same area. This may indicate that the relative abundance obtained by Turbott represented the true relative abundance in the area, not dependent on the conspicuousness of the species. However, the common species which showed agreement in relative abundance were all equally conspicuous in this area.
The detailed accounts of breeding and feeding habits recorded in Fiordland are given in Appendix 11.
2. Stewart Island
Stewart Island, which lies 20 miles off the southern coast of the South Island, is about 45 miles long and 25 miles wide, marked by the intricate coastline. Paterson Inlet, with the wide Freshwater River basin, divides the upland of the island into two parts. The highest peak of the island, Mt Anglem, 3,214 ft, stands in the northern section. The South-west Arm of the Inlet receives the Rakeahua River, which isolates Mt Rakeahua (2,217 ft) from the southern upland. Dominance of Podocarpus is the characteristic of the Stewart Island forest from which Nothofagus is absent.
Population counts were made between 13 and 24 November 1959 in four small areas of the lowland forest: one at the Scenic Reserve of the township of Oban (Area 7) one on Ulva Island in Paterson Inlet (Area 8), one at the foot of the
Thomson Ridge by the Freshwater River (Area 9) and one at the foot of Mt Rakeahua by the Rakeahua River ( Area 10). Area 7is 18 acres in size and supports a dense stand of Weinmannia racemosa mixed with Podocarpus jerrugineus and Dacrydium cupressinum. Fuchsia excorticata, tree ferns, Coprosma, Ripogonum scandens, Neopanax and Schefflera digitata are also abundant under the canopy, making the traverse difficult. In this area the count was made only once on a rainy morning, and except for the Tui probably fewer individuals were counted than were actually present. Area 8 is 12 acres in area and supports a mixed forest of Dacrydium cupressinumjWeinmannia racemosa/Podocarpus hallii[Podocarpus jerrugineus with the secondary and shrub layers of Coprosma, Neomyrtus, Neopanax, Pseudopanax, tree ferns, etc. Few epiphytes and climbers are present and bryophytes are not common on tree trunks. In this area one early morning count was made in fine weather. Area 9 is 12 acres in area and supports a mixed forest of Podocarpus hallii/Dacrydium cupressinum /Weinmannia racemosa with a very sparse secondary layer consisting of Griselinia littoralis and Carpodetus sarratus. The shrub layer consisting of Coprosma foetidissima and Pseudowintera colorata is also sparse, but the ground is densely covered with Blechnum. Two counts were made in this area. Area 10 is 11 acres in area and supports a mixed forest of Dacrydium cupressinum/Metrosideros umbellata/Weinmannia racemosa/Podocarpus hallii/Podocarpus jerrugineus with Neomyrtus and Coprosma spp. as the shrub layer. The ground is covered with Blechnum and occasional decaying logs. Only one early morning count was made in cloudy weather.
The census results given in Table V show a concentration of Tui in Area 7, a high population count of Brown Creepers in Area 8, and a similarity of the species composition and population size between Areas 9 and 10. Robins were found in the Leptospermum scrub and the forest edge on both sides of the wide Freshwater River Basin and also in Leptospermum scrub in the Rakeahua Basin, though none occurred in the census areas. Brown Creepers were also recorded in the Leptospermum scrub in the Rakeahua Basin but were commoner on Ulva.
The counts for relative abundance were made near Golden Bay near the township of Oban, the south side of the Freshwater River, Thomson Ridge and Mt Rakeahua. As the areas covered in each count were small (in the last two areas it was less than an hour before the timber line was reached) and as only few juveniles had entered the population at the time of counting, and some adults may have been incubating, the results shown in Table VI are inconclusive. Neverthe-
less they indicate a concentration of Tui on Fuchsia flowers near the township, and a relatively even distribution of Yellow-breasted Tits, Fantails and Grey Warblers in indigenous forest. Redpolls were found both on the flat (flocks on the Freshwater River Basin) and above the timber line (2,100 ft at Mt Rakeahua) and 1 Blackbird was noted in the subalpine scrub at Mt Rakeahua. Besides those species already mentioned or listed in the tables, the following species were noted: 1 Shining Cuckoo on the shore and several Greenfinches in a few planted trees on Ulva, 1 Long-tailed Cuckoo, 1 Kingfisher and 2 Silvereyes at the Freshwater River, Starlings and Pipits at the Freshwater Basin, 1 pair of Starlings in planted Cupressus macrocarpa by the Rakeahua Hut, and Stewart Island Kiwi at the Rakeahua. The presence of the Kiwi at the Freshwater River area was indicated by the feathers found in a recently-built Grey Warbler’s nest. No Rifleman was recorded. Detailed accounts of field observations are recorded in Appendix 11.
3. Inland Nelson
Lake Rotoroa was visited between 29 January and 5 February 1960. It lies about 50 miles south-west of Nelson. The head of the lake where the present survey was made receives two wide rivers, the Sabine and the D’Urville, which originate in Spencer Mountains (several peaks over 7,000 ft high) in the northern part of the Southern Alps. The sedimentary rock of hard greywacke supports Nothofagus forest up to the high timber line, about 4,000-5,000 ft. N. menziesii and N. cliffortioides occur at higher and N. fusca at lower altitudes. Damage by wind and frost is apparent in a few places where dead trees stand. In these patches and on old slips young Nothofagus is regenerating with or without passing through Leptospermum sere in succession. However, on the delta of the two rivers where the water table is high, podocarp forest is developed with associated dense scrub.
Two census areas were selected; one in Nothofagus forest at the mouth of the Sabine River (Area 11, 1,480 ft in altitude, Plate lb) and one in podocarp forest on the delta of the D’Urville River (Area 12, 1,470 ft in altitude). Area 11, which is 54 acres in area and triangular in shape, surrounded by the lake shore, the river bank and foothills, supports Nothofagus fusca of various ages with the canopy 80-100 ft high. A very sparse shrub layer is formed by Pseudowinter a colorata, Lophomyrtus spp. and Coprosma spp. The ground, with decaying logs is covered with moss or Blechnum, and Nothofagus leaf litter is visible in places. Near the lake and the river bank Neopanax anomalum, Myrsine australis, Carpodetus serratus, Cyathodes fasciculata, Rubus, Fuchsia excorticata, Neomyrtus and Coprosma provide the edge conditions. Most of it was excluded from the census area. In this area one early morning count was made in fine weather. Area 12 is 16 acres in area and is bordered by the lake shore, the bed of the D’Urville River, a stream in the delta and a track. The canopy of the forest (50ft-70ft) is sparsely occupied by Podocarpus ferruginous, P. dacrydioides, and P. spicatus mixed with scattered Nothofagus fusca. Carpodetus serratus, Fuchsia excorticata, Griselinia littoralis, Aristotelia serrata and Rubus occupy the secondary layer above a very dense shrub layer formed by Pseudowinter a colorata, Myrsine divaricata, Lophomyrtus obcordata, Coprosma spp. Near the lake shore Sophora microphylla grows above Phormium tenax. There are many dead stands and decaying logs in this area. The ground is covered with moss and patches of the grass Microlaena avenacea. The count was made on one cloudy afternoon with some difficulty experienced in traversing the almost impenetrable shrub layer in wet conditions and plotting the position of the birds on the map.
The counts for relative abundance were made in podocarp forest on the delta and along the Tiraumea Track which included Nothofagus/Podocarpus forest on the river bank, Nothofagus/Weinmannia forest on the slope and pure Nothofagus forest about Tiraumea Saddle (2,160 ft). Both counts were made in rainy conditions. The results of both the census and other counts which are summarised in
Table VII show a marked difference in the population between the Nothofagus dominant and Podocarpus dominant forests. Species which favour the latter habitat are the Pigeon, Song Thrush, Blackbird, Tui, Silvereye, while the Rifleman is the only species which favours the former habitat. As a result the population density in the podocarp dominant forest is much higher than that in the Nothofagus dominant forest. This is probably due to the thick secondary shrub layer which provides more nest sites and food for nectar and fruit feeders in the podocarp forest. The Parakeet, Fantail, Yellow-breasted Tit, Robin, Grey Warbler, Bellbird and Chaffinch were more or less evenly distributed. Detailed accounts of field observations are recorded in Appendix 11.
4. East Coast
Three areas were studied on the east coast: Gatlins Forest (10-12 February 1961), Waimate (26-28 December 1958, 24-26 October 1959, 27 December 1960), Dunedin (July 1958-February 1961).
Lying at the south-east corner of the South Island, Gatlins supports the only large remnant of the east coast forest in the South Island. Gentle hills consisting of Jurassic sediments are covered with forest from the coast to hill tops (Mt Pye, 2,361 ft, being the highest), except for a few farming communities. Stands of Nothofagus menziesii and Podocarpus/Metrosideros occupy the hillside, while Weinmannia racemosa is replacing podocarp forest on the coast. The census area of 15 acres (Area 13) was taken on the coastal terrace at Papatowai, where the rainforest is composed of dense Weinmannia racemosa/Podocarpus hallii stands (30—50 ft high) with scattered tall trees of Dacrydium cupressinum and Podocarpus spicatus (60-70 ft high). The secondary layer of the forest is sparsely occupied by Neopanax simplex, Carpodetus serratus, Griselinia littoralis, etc., while the shrub layer is dense with Coprosma foetidissima, C. rotundifolia, Myrsine australis, Pseudopanax crassifolium, tree ferns, etc. The ground is covered with moss and ferns. A similar forest but with less podocarp and more Weinmannia racemose (1) and another coastal forest at Mahaka (2) were covered about a mile in distance for the estimation of relative abundance of birds. In the latter area the vegetation is very dense with Weinmannia racemosa (dominant) and Dacrydium cupressinum and Podocarpus spicatus (scattered). In the forest tree ferns and climbers ( Ripogonum scandens, Ruhus, and others) are abundant, making the forest interior dark (Plate 2a). Metrosideros diffusa occurs along the coastline but is rare in the forest interior. The census was made on one cloudy morning. The results of the census and the counts for relative abundance are given in Table VIII.
Pigeons were seen feeding on fruits of Neopanax and Coprosma. One Morepork was heard at the camp site in Area 13. Riflemen were not common and besides one pair in Area 13 only two flocks were seen. Fan tails were commoner in the young forest (in 1) than in the dark forest (2), and all recorded were the pied form. The Yellow-breasted Tit and Grey Warbler were evenly distributed in the forest, while the Brown Creeper had patchy distribution and moved in flocks. Song Thrushes were very inconspicuous in dense forest, and only two were seen eating fruits of Fuchsia excorticata. Only one pair and one juvenile Blackbird were recorded inside the forest. One Hedge Sparrow was recorded at the edge of the forest (2) and two others in the dense scrub in Papatowai forest. Bellbirds were very common throughout the area and made a chorus for 15 minutes at dawn in Area 13. The Tui was only seen on tall Podocarpus and Dacrydium cupressinum. The flowering season of Metrosideros diffusa was over and Tui were no longer concentrating on them. Silvereyes were seen in the forest interior as well as the edge. Two pairs recorded in Area 13 came down to the shrub under dense canopy. They
were common along the forest edge and open country in the vicinity. Redpolls, Goldfinches, Greenfinches, Hedge Sparrows and Skylarks were also common just outside the forest near the farmland. Redpolls occasionally flew over the forest but were not included in the counts.
Waimate, which lies in the South Canterbury plain about six miles inland from the east coast, has a few patches of remnant forest in the vicinity. Sedimentary rocks of comparatively recent origin in this area were once covered with forest of immense Podocarpus totara trees when the climate was presumably milder and wetter. Before European settlement much of it had been destroyed by fire and invasion of tussock occurred, presumably in association with the climatic change. The remaining forest in the plains was estimated in 1849 to be 19,500 acres (Gillespie, 1958), of which 3,000—4,000 acres at Waimate consisted of Podocarpus totara, P. spicatus, P. dacrydioides, P. ferruginous and some Dacrydium cupressinum. The associated species in the forest were Myrsine australis, Melicytus ramiflorus. Fuchsia excorticata, Cyathodes juniperina (?), Plagianthus, Myoporum laetum, Pittosporum eugenioides, and climbers ( Rubus, Convolvulus, Ripogonum ), Studholme, 1954), which are still common in wooded areas. Timber (P. dacrydioides, P. totara, P. spicatus, Dacrydium cupressinum and Nothofagus solandri (?)) was milled in early days of settlement. Four sawmills were still at work in the Waimate forest in 1878 when fire destroyed the remaining forest except for a few patches along streams. Farmland was developed in the burnt area as well as in dry and wet grassland. The birds once common in forest, such as Robins, Parakeets, Tui, Kaka, Weka and Laughing Owls (last specimen in 1916), and in the grassland and marsh such as Quails and Fernbirds gradually disappeared (Studholme, 1954). On the other hand, the birds introduced from England (Blackbird, Song Thrush, Skylark, Chaffinch, Redpoll, Yellow Hammer, House Sparrow, Starling, etc.) and Australia (White-backed Magpie) between 1861 and 1874 by Acclimatisation Societies and local people were soon naturalized and increased so rapidly in a short period of time that the Small Bird Nuisance Act was passed in 1882 and the Levels County Council, for example, bought 3,694 dozen eggs and 881 dozen heads of young birds in 1883 (Gillespie, 1958). These naturalized birds form the main population in the farmland today. For example, Blackbirds, Song Thrushes, Goldfinches, Redpolls, Chaffinches, Yellow Hammers, Hedge Sparrows, Skylarks and Magpies breed in farms and grassland where introduced trees and shrubs provide an English country habitat. House sparrows, Starlings and Rock Pigeons nest on limestone cliffs and buildings as well. Only a few indigenous species such as Bellbirds, Fantails, Grey Warblers, Shining Cuckoos, Pigeons and Harriers occur in the open country.
About 450 acres of Hook Bush where some Podocarpus spicatus and P. totara remained was taken over by the State in 1898. For the census of breeding bird populations a small area (Area 14) was selected on the riparian terrace covered with induced forest of hardwood. The canopy is about 30ft high and composed of Elaeocarpus hookerianus, Carpodetus serratus, Hoheria angustifolia, Griselinia littoralis, Fuchsia excorticata, Pittosporum eugenioides, P. tenuifolium, Myrsine australis, Pseudopanax, etc., many parts covered with Rubus. The shrub layer is sparse and mostly occupied by Pseudowintera colorata (unpalatable species for grazing animals), but in the edge Neomyrtus pedunculata, Coprosma spp., Melicope simplex, Leptospermum, etc., are present under isolated trees of Sophora microphylla, Cordyline australis and Podocarpus totara. The forest floor is bare as a result of heavy grazing by sheep and naturalized Scrub Wallaby {Wallabia rujogrisea). In 1958 the census was made in 6 acres of this forest, but in 1959 and 1960 the area covered (8 acres) included patches of grassland and scrub where naturalized rabbits ( Oryctolagus cuniculus) had added grazing pressure.
The results given in Table VIII show a consistent dominance over three breeding seasons of Brown Creepers, Blackbirds, Song Thrushes and Bellbirds. In these years no violent fluctuation of numbers was noted. Shining Cuckoos, Greenfinches, Magpies and Harriers were also recorded in this area, but as their breeding in the area was doubtful they were excluded from the Table. Redpolls were numerous in the tussock grassland above this area, and most of them seemed to breed in nearby Leptospermum scrub. The breeding season apparently started in September at least for Bellbirds and Brown Creepers whose fledglings were found on 24 October 1959. No fledglings of other species were noted on the same day. The nest for a second brood of Bellbirds had already been made by at least one pair. Blackbirds, Song Thrushes and Silvereyes were either building nests or incubating while Chaffinches were just building in October. These and other naturalized species were still laying towards the end of December (1958 and 1960). The fledglings of the first broods of Bellbirds fed on nectar from Fuchsia. Territorial fighting of Bellbirds was often seen on Fuchsia trees which were visited by birds from neighbouring territories. A pair of Brown Creepers collecting food for young moved together while the male continually sang and once chased a Fantail near the nest.
Sullivan Dam, at Dunedin, lies at about 950 ft in altitude in the upper catchment of the Leith River and receives high precipitation during summer. It was once covered with coastal podocarp forest of Dacrydium cupressinum and Podocarpus ferrugineus. Timber has been either milled or burned in this area where at present hardwood forest of small trees remains under dead stands of Dacrydium cupressinum and two small patches of plantation ( Pinus radiata and Pseudotsuga taxifolia ) cover the gentle slope of the catchment. In an adjacent forest, widely spaced trees of Dacrydium cupressinum still exist, emerging above a continuous canopy of broadleaf forest, but their regeneration rate is generally inadequate (Wardle & Mark, 1956). In the study area along about three-quarters of a mile of the reservoir shore, the hardwood forest has a canopy of 15-25 ft, formed by Griselinia littoralis, Leptospermum scoparium, Neopanax, Schefflera digitata, Olearia, Fuchsia , with abundant Ruhus cissoides, and in places Coprosma, Neomyrtus, Myrsine, Cyathodes, Cassinia, etc., form a dense shrub layer. A very small patch of naturalized Acer pseudo-platanus is the only open woodland where grass grows on the ground. Otherwise the ground with decaying logs is always humid and in places is covered with moss. Along one side of the reservoir is a narrow belt of lawn, most of which is kept short. In the two patches of plantation it is dark and no plant grows on the thick layer of slowly decaying pine leaves on the ground. Fifteen visits were made to this area between July 1958 and February 1961. The breeding population density of birds for three seasons was determined in 12 acres (Area 15).
Both patches of plantation were occupied by Bellbirds throughout the year. Other species recorded in the plantation were Blackbirds, Song Thrushes, Chaffinches, Yellow-breasted Tits and Hedge Sparrows. The last two were often seen in the edge of the plantation, which was also visited by Fan tails, Brown Creepers, Silvereyes and Redpolls. Fantails occurred in autumn and winter in 1959 and 1960, suggesting their breeding in the vicinity in the first two years of the study. Song Thrushes and Blackbirds were sometimes seen feeding on earthworms and emerging Tipulids on the lawn, but they also fed their young with beetles collected on the forest floor. Flocking Silvereyes, up to 25, were seen in autumn feeding on Schefflera, naturalized Leycesteria formosa, and other fruits. The breeding started early (fledglings of the first brood were out before November) in Bellbirds, Silvereyes, Yellow-breasted Tits and Song Thrushes, but late in Blackbirds, Chaffinches and Hedge Sparrows, Both Song Thrushes and Blackbirds were very shy in this area
and inconspicuous. Other species of land birds recorded were Greenfinches, Goldfinches, Redpolls, which fed on grass seeds in autumn, Starlings (flocks up to 9 at a time) which fed on the lawn, Pigeons in scrub, a Harrier, which was mobbed by Blackbirds and Bellbirds in the plantation (29 December, 1959), and single Kingfishers.
5. Relative abundance in other areas.
The results of bird counts made in the following areas are given in Table IX.
Mt Bealey ( Nothofagus forest) along the track from Arthur’s Pass. Birds were recorded in two hours in Nothofagus forest and subalpine scrubland. The numbers of Yellow-breasted Tits and Hedge Sparrows represent singing males only, while the numbers of Riflemen, Brown Creepers, Redpolls and Silvereyes represent the number of individuals in 4,3, 1 and 3 flocks respectively; hence the Yellow-breasted Tit was the commonest species.
Enys State forest, in Central Canterbury, is a pure forest of Nothofagus which under extremely dry conditions is regenerating and contains dead as well as live stands of various age groups under the canopy. The results of the count made in two hours represent the number of adult males in Bellbirds, Grey Warblers and Hedge Sparrows. All birds were nesting on Nothofagus. The species recorded only outside the forests were Magpies, Yellow Hammers and Starlings.
Evansdale, north of Dunedin, is a gorge covered with regenerating scrubland and patches of grassland along a stream. The count was made at the beginning of the breeding season. An abundance of Grey Warblers (the number represents singing males only) should be noted. Some of them were laying in September.
Trotter’s Gorge, near Palmerston South, is partly covered with low hardwood forest in which the winter population was counted in two hours. An abundance of Bellbirds and Fantails should be noted. In the vicinity where the farmland had patches of Leptospermum along streams the Chaffinch was abundant. Blackbirds, Silvereyes and Chaffinches fed on naturalized Leycesteria formosa while Bellbirds fed on fruits of Coprosma.
Henley, south of Dunedin, represents an area where the land is heavily grazed by sheep, and at the same time the scrub is allowed to regenerate. The area supports scattered Leptospermum stands on one side of the hill which is connected to an extensive farmland, and dense Leptospermum scrub with patches of low hardwood forest on the other side. The count was made in two hours in autumn. On the open side Goldfinches bred in Leptospermum stands while on the other side of the hill Yellow-breasted Tits, Brown Creepers, Grey Warblers were recorded.
Flagstaff (2,186 ft) in Dunedin District, has a belt of low hardwood forest and patches of plantation below the tussock grassland. The count was made from the scrub forest to the top in 2.5 hours. In the plantation Bellbirds and Yellow-breasted Tits were noted. Redpolls and Goldfinches were breeding at the upper limit of the scrub where Leptospermum and naturalized gorse ( Ulex europaeus ) grow very densely. In the low hardwood forest Blackbirds and Song Thrushes must be common as a number of their nests (made mainly of moss) were found, but they were shy and only few were recorded.
Maungatua (2,944 ft), west of Taieri Plain, has Nothofagus and Podocarpus forests at its foot, Nothofagus menziesii reaching 2,400 ft on the seaward face (Baylis, 1959), its main ridges being covered with tussock grassland with Leptospermum scrub and bracken fern at lower altitudes. The count was made in four
hours in autumn along the northern ridge through tussock grassland, Leptospermum scrub, and a few Nothofagus- covered gullies. Skylarks had wide altitudinal distribution, while Pipits occurred only near the top. In Nothofagus forest Fantails, Yellowbreasted Tits, Grey Warblers, Blackbirds, Hedge Sparrows, Bellbirds, Silvereyes and Chaffinches were recorded. Goldfinches were common in lower parts, while Redpolls were common in higher parts of the slope. These two species and Silvereyes were flocking. A flock of Starlings was seen in lowland. Brown Creepers were seen in Leptospermum scrub where the Hedge Sparrow was also common. In this area Silvereyes, Chaffinches and Song Thrushes were feeding on naturalized Leycesteria formosa. Blackbirds were not plentiful, but on another trip made during the breeding season they were seen in the gully up to near the top.
The Dunedin City Council plantation at Silverstream supports some indigenous species of birds, but unfortunately the count was made only once in a small portion of Pinus radiata forest at the end of the breeding season. It only shows the occurrence of certain species in this plantation. Another plantation was visited at Ashley, in Canterbury, where the count was made in the breeding season in Pinus radiata forest (planted in 1939). The main part of the breeding population was composed of naturalized species (Greenfinches being the commonest), but Fantails, Bellbirds (especially near the edge), Silvereyes and Yellow-breasted Tits were also recorded.
Generally speaking, both naturalized species and indigenous species occur in suburban areas, but there is a tendency for the former to become dominant (some species attained higher densities than in their native land) in farmland areas, and the latter species to remain in less modified habitats. The species which occur in plantations probably vary from place to place according to the population density in the neighbouring areas. The problems of colonization of exotic forest by indigenous species are not yet fully understood (Gibb, 1961).
B. Detailed Study at Botanic Gardens, Dunedin.
1. Area
The upper part of the Botanic Gardens in Dunedin (12 acres) contains regenerating low hardwood forest which forms part of the Town Belt reserved on the hillside of Dunedin. Patches of planted exotic trees, flower gardens and lawn occupy the rest of the area (Fig. 2).
2. Size of Breeding Populations
Territory mapping in three breeding seasons revealed a slight fluctuation of the size of the breeding populations (Table X). In five common species, however, the order of abundance remained unchanged, and the average breeding density of three years was 567 pairs per 100 acres, which was the highest density obtained in the present study.
3. Seasonal Changes in Total Population Size
The two years’ results of weekly counts of the total populations (excluding the House Sparrow) in the study area are shown in Fig. 3. The total population reached its highest in spring and lowest in winter in both years. Although these counts were made in early mornings when the birds were most active, not all birds could be recorded as some were at the nest during the breeding season and many birds were inconspicuous during the moulting season. Thus the number of individuals which bred in the area, determined by means of territory mapping and counts of singing males, was greater than the number recorded in any one count during the breeding season. The most obvious species responsible for the change in total numbers was the Silvereye, which showed a definite seasonal change in population and since it moved in flocks, fluctuated in number more violently than any other species (Kikkawa, 1961).
In the Blackbird, Song Thrush and Chaffinch population size was highest in spring when territorial fighting was most frequently observed. In these species the number actually breeding in the area was smaller than the number obtained in the spring counts. Also because of low breeding success and dispersal of the young these species did not show any significant increase due to the additions of juveniles to the population. The increase in Blackbirds took place later in the season when their food distribution changed and juveniles from other areas moved in. Song Thrushes were inconspicuous in autumn and the count probably did not indicate the true number present.
The species which showed an increase due to breeding were the Silvereye, Brown Creeper, Grey Warbler, Bellbird and Fantail. However, in the Silvereye the fledglings did not remain in the same area so that the gradual accumulation of individuals was not observable. Juveniles of Grey Warblers and Bellbirds stayed longer in the area, but the population dropped again before winter. Juvenile Fantails born outside the area came in soon after they fledged, sometimes accompanied by parent birds. They soon became independent but remained in the area throughout the winter.
Some of the less common species in the area are listed in Table XI. Pigeons, though recorded in every month of the year, did not breed in the area. One pair of Mallards ( Anas platyrhynchos platyrhynchos) nested successfully in one year, and one pair of Brown Creepers and one pair of Redpolls bred for two years. Shining Cuckoos were heard every year but no fledglings appeared in the area. Yellow-breasted Tits (mostly juveniles) visited the area after the breeding season, but did not remain in the area, whereas Fantails did, as described above. The Tui is a winter visitor to the Dunedin area, and a few came to the study area in spring before leaving for the breeding grounds. Greenfinches, Goldfinches and Redpolls were summer visitors to this area, but a few were seen through the winter. These species formed flocks in winter and fed in farmland or patches of grass in wasteland. In the study area a flock of 30 Greenfinches was once recorded in September. Greenfinches bred more commonly in the Leptospermum stand near the study area. Other finches preferred more open habitat for nesting, such as stands of naturalized Acer pseudo-platanus, Aesculus hippocastanum and sparsely planted Nothofagus spp. near the study area.
Most House Sparrows in the area nested on planted Eucalyptus and Pinus radiata, but some on Leptospermum ericoides, Myoporum laetum and Melicytus ramiflorus. Later in the breeding season juveniles formed flocks and fed in regenerating forest and on the lawn. Only a few Starlings nested on Pinus radiata in the area, though in late summer large flocks appeared near the study area and fed on the lawn.
4. Selection of Nest-sites
For three common species (Blackbird, Song Thrush and Silvereye) the height of the nest was examined in relation to the height of the tree selected for nesting. The data for this analysis were obtained from Dunedin District. The height of the nest varied from 2ft to 40ft, but most of the nests were built in higher parts of the trees selected for nesting (Fig. 4). This tendency was more marked in the Silvereye, which nested in dense foliage in the canopy or the end of branches. The nest-sites of Blackbirds and Song Thrushes were similarly situated, but a slightly greater proportion of the Blackbird’s nests (20%) were built lower than half the height of the tree selected, than the Song Thrush’s (15.5%). Among
these low-ratio nests, forks of tall trees were more often used by Blackbirds than by Song Thrushes, and a few tree hollows were selected by Blackbirds, while the end of low branches was more favoured by Song Thrushes.
For further analysis of nest-site selection, an intense search for nests was made in the Leptospermum stand (Plate 2b) near the study area and the nest-sites of Blackbirds (40 nests), Song Thrushes (42 nests), and Silvereyes (58 nests) were examined to see whether they were chosen at random in this area in respect to the species and the height of the tree. Distribution of trees according to the species and height (Table XII) was obtained by a belt transect covering about one-third of the area. The test comparing the four classes (5.5-10 ft, 10.5-15 ft, 15.5-20 ft, 20.5 ft +) of heights of trees sampled with those of trees with nests showed that the birds selected trees with certain heights (x 2 10.24 with 3 d.f., P < 0.02 for the Blackbird; x 2 15.10 with 3 d.f., P < 0.01 for the Song Thrush; x 2 = 17.75 with 3 d.f., P < 0.001 for the Silvereye). There was a tendency for Blackbirds and Song Thrushes to avoid shrubs lower than 10ft. (Song Thrushes chose trees between 15.5 ft and 20ft in height more than expected), while Silvereyes preferred shrubs between 10.5 ft and 15ft in height. There was no significant difference, however, in the selection of tree heights between the Blackbird and the Song Thrush (x 2 = 1.55 with 2 d.f., P > 0.30). A similar
analysis was made for the species of trees selected for nesting. For this test the species of trees were grouped into four categories: Leptospermum, Melicytus, Myrsine, and the rest. In Blackbirds there was no significant deviation from random expectation (x 2 = 1.51 with 3 d.f., P > 0.60), but in Song Thrushes significantly more nests were built in Melicytus (x 2 = 11.43 with 3 d.f., P < 0.01) and in Silvereyes significantly more nests were built in Myrsine (x 2 = 17.20 with 3 d.f,, P < 0.001). A comparison between Blackbirds and Song Thrushes showed that preference of Melicytus by Song Thrushes was not a result of significantly different nest-site selection between the two species (x 2 4.27 with 2 d.f., P > 0.10). Blackbirds made nests with climbers more than expected by chance (x 2 c = 4.89, P < 0.05), while Song Thrushes did not (x 2 c = 0.30, P > 0.50). In this respect the difference in selection between the two species was significant (x 2 c = 6.85, P < 0.01). Silvereyes also selected trees with climbers more than by chance (x 2 c = 9.89, P < 0.01).
5. Nesting Success and Productivity
The nesting success and productivity of common species in the study area are summarized in Table XIII. The nests deserted before laying were omitted. Although most nests of territory-holding birds were found, the discovery of the nests was not complete and some pairs also made nests outside the study area, thus the average number of nests per pair in the table is probably lower than the true average. In SilvereyeS there may have been a few more nests built later in the breeding season at which time visits to the area were not frequent enough to make complete observations of every pair. Most Bellbirds nested in canopy or tall pine trees, and not all the unsuccessful nests could be found. However, the number of fledged young in the area could be counted fairly accurately as fledglings were conspicuous while they were fed by parent birds outside the nests.
Fig. 5 shows, for the three breeding seasons 1958-61, the clutch size (according to the month in which laying was completed), the brood size (according to the month in which hatching was completed), and the number of young leaving nest (according to the month in which young left nest). As not all the nests were found before the eggs hatched, and less than half of these reached fledging stage, the data are not all from the same population. The Song Thrush made a
larger number of nests per pair and showed higher mean values of clutch size, brood size, and the number fledging than the Blackbird, accounting for its greater productivity. For both species these mean values were lower and partial failure was higher than in England (Snow, 1955). The Silvereyes had the highest reproductive rate in this area, the low mean value for the number of young leaving the nest (2.1) being due to the low mean clutch size (2.8 for the 18 nests examined before the young hatched). In Blackbirds and Song Thrushes, breeding seemed to be affected by the variable rainfall in the area (Fig. 6). The greater breeding activity in 1959 was associated with high rainfall, while drought seemed to delay nest-building in 1958. In 1958 no nests were built in September, while 13.1% of the nests in 1959 and 32.2% of the nests in 1960 were built in September. Earthworms which formed a majority of food for nestlings (see later) were not readily available in dry weather. No winter laying (Bull, 1946; McKenzie, 1950) was recorded in Dunedin (see also Gurr, 1954).
Out of the 81 nests of Blackbirds and the 152 nests of Song Thrushes for which the fate was known the nesting success was calculated in three classes of the height of the nest (up to 10ft, 10.5ft-15ft, 15.5 ft and higher), and three classes of the ratio, the height of nest per height of tree used (up to 0.50, 0.51-0.75, 0.76 and greater). In Blackbirds no particular nest-sites gave more successful breeding (x 2 = 2.30 with 2 d.f., P > 0.30 for the nest height, and x 2 0-29 with 2 d.f., P > 0.80 for the height ratio). In Song Thrushes no particular height was more favourable than others (x 2 = 0.50 with 2 d.f., P > 0.70), but there was a slight tendency for the nests of low height ratios (< 0.50) to have higher nesting success. However, this tendency was not significant in the contingency x 2 test (x 2 = 3.67 with 2 d.f., P > 0.10). These results show that in both species the higher nest-sites were no more protected than the lower nestsites.
Blackbirds and Song Thrushes had common mortality factors in the study area though the Song Thrush suffered a slightly greater mortality than the Blackbirds. The partial failure in breeding—i.e., the loss of eggs and young in successful nests, seems to be caused by bad weather, especially by a cold spell and prolonged rain or drought. The local fluctuation of temperature from day to day was so great during the breeding season that developing eggs and small nestlings would perhaps require more protection than in the northern hemisphere. Another cause of partial failure of Blackbirds in England (Snow, 1958) is competition among the nestlings for the food that parent birds bring to the nest, especially when the efficiency of food collecting by parent birds drops, as it does in drought. However, the separation of causes of the partial failure was not always possible. Mortality factors in the total loss of eggs or young are summarized in Table XIV. Predation (mostly by rats and mice) was greater in the Song Thrush than in the Blackbird, and the predation of young in the Blackbird was rare (one case only by a rat). Two cases of predation of Song Thrush nestlings were suspected to be due to Starlings. Desertion of young was not frequent, but commoner in the Blackbird than in the Song Thrush and, as with desertion
of eggs, was likely to be caused by drought and disturbance (construction work near the nest or persistent passing of people near the nest over fine weekends, after nest-building and incubating along the paths normally quiet on weekdays and wet weekends). Desertion of nests in both species occurred more frequently towards the end of the breeding season. Among miscellaneous factors, the destruction of nests by wind and rain, by children (twice), and by the weight of own nestlings (once in Song Thrush) were included. In two cases movements of an opossum were suspected as the cause of destruction. Post-fledging mortality was hard to estimate as the young did not remain in the neighbourhood of the nest. The ring recoveries showed that the young scattered within a radius of f mile in the Blackbird, and half a mile in the Song Thrush within 2 to 4 weeks of leaving the nest. Mortality at this stage is presumably high as these species feed on the ground. In fact, most recoveries of rings resulted from predation by cats. At this time of the year stray cats were often seen hunting fledglings in the study area. One-year-old birds which entered the breeding population in the area were mostly born outside the area.
Silvereyes and Bellbirds had a long breeding season from August to March. The earliest laying records in the study area are 2 September for the Bellbird and 20 September for the Silvereye, the last dates of fledging 14 February for the Bellbird and 4 March for the Silvereye, Both species made nests in dense foliage, but Bellbirds nested mostly in the canopy (the height of 9 nests ranged from 14.4 ft to 51ft), while Silvereyes nested either in the canopy of trees or on thin branches of shrubs. Of 46 nests of Silvereyes whose fate was known 37 (80.4%) were successful and predation of eggs or young by rats was negligible. The Bellbird’s nests were very coarsely constructed in the canopy, and were easily blown off by strong winds (three were found in the area). Both species raised two to three broods in a year and fledglings were fed normally for 10 days or longer. They do not come near the ground and their mortality due to predation is probably low. However, the winter mortality of Silvereyes which fed in urban areas seemed high, likely causes being starvation, disease and predation by cats (Kikkawa, 1962).
Chaffinches were numerous at the beginning of the breeding season, though the actual number that bred was small. They suffered high mortality by predation during the breeding season as their nests were almost invariably placed at a fork or in contact with the main trunk of a tree where rats and mice had easy access. Sometimes parent birds were also attacked in the nest. Hedge Sparrows built nests in thickets, in suckers of large trees, and on fallen branches near the ground. Predation of eggs was not so high as in other naturalized species, but the predation of fledglings was considered high. Both Grey Warblers and Brown Creepers had a long breeding season from September to February, but only one or two broods were raised each year. The period of parental care lasted longer than in most other species. However, in the small sample studied the partial failure was rather high, only 50-60 % of the eggs reaching fledging stage. Although none was parasitized by the Shining Cuckoo, at least three cases of desertion of
second broods of Grey Warblers may have been caused by interference of the cuckoo. Fantails which bred just outside the study area raised two to three broods in a long breeding season (September-February) and three to four young left each nest. A few Goldfinches, Redpolls and Greenfinches bred in the area and from the successful nests 4-5, 2-4, and 2-3 young fledged respectively. The numbers of these birds were too small to allow examination of mortality factors.
6. Food and Feeding Habits
Most of the seasonal movements of birds in the area were associated with the distribution of food, especially of plant food of honey-eaters and berry-eaters. Fig. 7 summarizes the types of food and feeding habits of 18 species observed in the study area. Seasonal changes of a supply of plant food are summarized in Fig. 8 together with the occurrences of consumer species.
Most of the indigenous species of plants in the area were evergreen and supported active insect populations throughout the winter. Fantails were seen to catch flies and moths on the wing from ground level to canopy, while Grey Warblers in the air often collected insects off leaves. Brown Creepers and Bellbirds fed more frequently from branches than from leaves, while Silvereyes fed less selectively though many flocks fed on insects obtained particularly from Plagianthus hetulinus, Hoheria angustifolia and Fuchsia excorticata (deciduous).
As shown in Fig. 9 (a), caterpillars occurred most frequently in the stomachs of Silvereyes examined, followed by beetles, spiders, Hemiptera, moths, small snails, small flies and wetas. They consumed nectar in spring and fruits of shrubs and trees throughout the year. Nestlings after five days began to receive some plant food. The bark, especially of Fuchsia and Leptospermum, was searched intensively by Brown Creepers, Silvereyes and Bellbirds (particularly those feeding young).
Blackbirds, Song Thrushes, Hedge Sparrows and occasional Chaffinches fed from the forest floor. The first two species mainly collected larger arthropods (mostly Carabid beetles but some Elaterid and Staphilinid beetles, Psammocharid wasps, moths, wetas, earwigs, millipedes, centipedes, amphipods and spiders), but some small flies, snails, and mites were also found in stomachs examined. The last two species collected seeds of herbs and grass and very small insects, including Hymenoptera, Coleoptera, Lepidoptera, Diptera, Hemiptera, and Collembola and earthworm. Earthworms and snails in litter and surface layer of forest floor were all very small and rather scarce (less than 4 individuals in 1 m 2 ). Blackbirds and Song Thrushes fed more frequently on open paths and lawns where besides ground insects earthworms were numerous (up to 37 in 1 m 2 ). These earthworms belonged to a common introduced species {Lumhricus ruhellus ) and formed the major item of food for the nestlings. Nematoceran larvae and Hepialid larvae in lawns were also shared by Starlings and House Sparrows in summer. In late summer Blackbirds and Song Thrushes fed more commonly in trees, picking fruits of native as well as introduced trees. In a patch of lawn adjacent to the study area, the number of Blackbirds and Song Thrushes appearing during the peak feeding period of morning was counted 28 times in 1960 to find out if there was any difference in the number feeding on the lawn between the prebreeding and the post-breeding periods. Between January and May (post-breeding to wintering) the mean of the numbers recorded for Blackbirds and Song Thrushes was 2.6 and 1.3 respectively, while between June and November (wintering to breeding) it was 6.5 and 6.0. Combining the data for the two species the difference of the mean values between the seasons was tested. The result was significant (t = 3.2, d.f. = 26, P < 0.01). From January to May (specially in February and March) some counts recorded no individuals, while in mid-winter (June and July) some birds always fed on the lawn if the ground was damp and not covered with frost or snow.
The supply of plant food was markedly seasonal and also changed from year to year. For example, Sophora microphylla had a longer flowering season in 1959 than in 1960. In the latter year more Silvereyes fed on nectar from Fuchsia while a few Tui remained on planted Eucalyptus. In 1959 Melicytus had a good crop of fruits, but in 1960 it was poor and few flocks of Silvereyes were seen on them (the total number in the area did not increase as much as in 1959; Fig. 3). In this season feeding on other plants such as Muehlenheckia was more pronounced. It is important to note that these plant species form low hardwood forest and sometimes grow in the secondary or shrub layer, as well as along the edge, of Podocarpus and some Nothofagus forests.
In the study area finches fed on grass seeds (e.g., Anthoxanthum odoratum) wherever grass was left uncut between December and February.
As described above and shown in Figs. 7 and 8, Blackbirds and Song Thrushes appeared to feed on the same food in the same area. A further analysis was made in Fig. 9 (b and c), showing the frequency of food items in the samples of stomach contents and forcibly regurgitated food of nestlings (45 samples of Blackbirds and 40 samples of Song Thrushes). Testing frequency distribution of beetles, caterpillars, earthworms, and the rest, a remarkably good agreement of the preference of food items between the Blackbird and Song Thrush was obtained (x 2 = 0.634, d.f. = 3, P > 0.80), indicating that these two species share the majority of food given to young in the same area.
Discussion
1. Limitations of the Results
The present survey was carried out in three years and the breeding population size in most areas was estimated in a short period of one season only. Therefore, comparison of populations between different areas where the estimations
were made in different years is, strictly speaking, not possible. However, in these three years in at least one habitat (low hardwood forest, Areas 14-16) the breeding population size and the order of abundance among common species remained much the same. Thus the following discussions are based on the assumption that the general population level in the areas studied did not change significantly over the period of the study.
There are also some errors to be considered in the estimation. The breeding season differs slightly from species to species, especially among the naturalized birds. Judging from the detailed study in Area 16 it is possible that in some areas a count in the early part of the breeding season tends to over-estimate the population sizes of the Blackbird, Song Thrush and Chaffinch, and underestimate that of the Redpoll, while a count made late in the breeding season tends to underestimate the sizes of Song Thrush and Hedge Sparrow populations. The latter applies to the estimations made in Fiordland, Lake Rotoroa and Gatlins, where the field studies were made in January and February.
Selection of the areas in Fiordland and Stewart Island was limited for practical purposes of mapping and early morning counting under unfavourable weather conditions, and the area selected may not have been typical of the region. This could be checked to some extent against the counts made for relative abundance. A few indigenous species were not uniformly distributed in one habitat (e.g., Yellowheads at Lake Manapouri and Lake Monk areas, Brown Creepers and Robins on Stewart Island), so that the species composition found in the census areas was not always representative of the habitat. This fact will be referred to later. The inclusion of forest edges in some census areas resulted in higher counts of naturalized species. However, in many parts of the South Island such habitats were more typical than unbroken dense forest, and in the forest the population density of some forest edge species could be considered as an indicator of the instability of the habitat. Observational errors due to the large size of the census area probably caused somewhat low estimation of the density in Area 1, while in the standard expression of the density (number of pairs per 100 acres or 40 hectares) statistical errors caused by the small size of census areas were probably greater for species with wide-ranging individuals (e.g., non-passerine species on Stewart Island). For these reasons the discussion of population distribution is mostly limited to the common passerine birds, more than one pair of which were represented in one census area. The abundance of other species is indicated, where necessary, in relative terms.
The conclusions based on the present results of population distribution may not apply to North Island habitats where the species composition and the environmental conditions are different (cf. Caughley, 1962).
2. Ecological Distribution
Before proceeding to the discussion of population distribution, it is necessary to give a picture of general ecological distribution of common land birds in New
Zealand. Since the distribution of these species in various forest types is only little known, the classification of habitats used in Table XV is necessarily very broad, yet it shows a wide ecological distribution of common woodland species of both indigenous and naturalized birds, suggesting that these species occupy a variety of habitats with widely overlapping ranges. Percentage occurrences of woodland birds in three major forest habitats studied are given in Fig. 10. This shows a wide distribution of common woodland species within forest habitats. In a schematized arrangement an altitudinal distribution of some of these and other forest species in a Fiordland area (Fig. 11) also shows much overlap.
On the other hand, the feeding habitats of some of these species as tabulated for the Lake Monk area by Riney et al. (1959) show that many species utilize only a small fragmment of the total environment in an area. We have seen this for the birds in the Dunedin Botanic Gardens also (Fig. 7). These facts indicate that in normal conditions there is little competition for food between these species. The nest-sites of common species summarized in Table XVI also suggest little competition for nest-sites among them, especially as the sites commonly used ’ by different species, such as shrubs, under rocks or tree holes, are numerous in the habitat.
Generally speaking, the fact that many habitats are covered by successful species and competition for food or for nest-sites between species is limited seems to be due to the paucity of the fauna, indicating very little interaction between land birds in New Zealand (cf. Kikkawa, 1960 b).
3. Population Distribution
Densities of total breeding populations of passerine species estimated in various forest habitats of the South Island are shown in Fig. 12. It is obvious from this diagram that there is a tendency for a decrease in the total density from low hardwood forest —to Podocarpus dominant forest—to Nothofagus dominant forest.
This is particularly true with the population of indigenous species. Consideration of different habitats at each locality visited makes this tendency more obvious. For example, at Sullivan Dam, Dunedin (Area 15), where the density was lower than in other low hardwood forests, the forest was at an early serai stage with a very low canopy, and included patches of conifer plantation in which the population density was low. In the podocarp dominant forest, if the secondary or shrub layer was only sparsely occupied as at the Freshwater River of Stewart Island (Area 9) the total density of indigenous species was low though still higher than the average density in the Nothofagus dominant forest. In the Nothofagus dominant forest if the podocarp element was very strong, as at the Pyke Junction in the Hollyford Valley (Area 2), the total density approached that in the podocarp dominant forest. The density of naturalized species is much affected by the presence of forest edges. Lake shore, wide riverbeds, forest clearings, land-slips, etc., in the indigenous habitat attracted naturalized species which in the past 50 years or so successfully colonized Fiordland. Lake Monk (Area 5) is a good example of the high density achieved by naturalized species in such conditions. In the low hardwood forest which is developing in farming districts along the east coast of the South Island, the naturalized species maintain high densities (Hook Bush, Sullivan Dam, and Botanic Gardens, Areas 14-16).
The total breeding density varied from 70 pairs to 600 pairs per 100 acres (40 hectares). In the Nearctic temperate region, deciduous forest generally supports a greater density (about 200 pairs per 100 acres) than coniferous forest (Keideigh, 1961). However, a greater density (319 -j- pairs per 100 acres) was recorded in boreal forest of Canada during a spruce budworm outbreak (Kendeigh, 1947). The present results show that the densities in cool-temperate Nothofagus forest and warm-temperate podocarp forest are comparable to, or slightly lower than, those in northern climax forests (Kendeigh, 1944). In low hardwood forest and garden habitats of suburban districts, where naturalized species maintain high densities, the total density is much greater than in any natural community except some offshore islands (e.g., Kapiti).
In order to assess similarities between the communities in three types of forest, all counts of 17 passerine species (including 7 naturalized species) made during the breeding season were grouped under Nothofagus dominant forest (1,343 individuals), Podocarpus dominant forest (560 individuals), and low hardwood forest (484 individuals), assuming that variations between samples were not too great and conspicuousness of each passerine species was similar between different counts in different forest habitats. The index of similarity was obtained, using Morisita’s (1959) G\ (see Appendix I). The result, expressed in Fig. 13, shows a decrease
of the similarity in the following order: Nothofagus dominant forest —Podocarpus dominant forest, Podocarpus dominant forest—low hardwood forest, low hardwood forest— Nothofagus dominant forest. Since low hardwood forest is a maninduced forest, the order reflects a less discontinuous distribution of common indigenous species in less disturbed habitats and greater differences in the density of some naturalized species between low hardwood forest and other forests. It also indicates a closer similarity of low hardwood forest to Podocarpus dominant forest, reflecting a similar structure of the vegetation.
For the explanation of differences in the population density between different forest habitats, we must further examine the density of constituent species in each habitat. Table XVII summarizes the population density of each species estimated in three forest habitats. Since the estimation of the number of breeding pairs per 100 acres was obtained from the count made in areas of different sizes and since the distribution of some species was not uniform over a large area, the significance of the differences between the mean density values obtained in different habitats
cannot be tested statistically. Nevertheless, an examination of the densities and relative abundance of some species shows that such differences are not likely to result from random distribution.
The Rifleman was recorded from all Nothofagus forests examined (except locally at Lake McKerrow, Area 1). The counts for relative abundance in the Lake Rotoroa area also indicated its common occurrence in Nothofagus forest and scarcity in podocarp forest. This species has been recorded from Stewart Island (Oliver, 1926) where Nothofagus does not grow, but the density appears to have been low, none being recorded in the present study. There is an indication in the data that in Nothofagus forest the Rifleman prefers drier parts, and the density becomes low as the west coast is approached. It also breeds in low hardwood forest if the area is extensive and not near urban areas. The Fantail is widely distributed but never abundant in any Nothofagus forest examined, and more commonly recorded from low hardwood forests. It seems to tolerate suburban conditions more than the Rifleman. The Yellow-breasted Tit also has a wide ecological distribution, but with a slight tendency to prefer Nothofagus forest. It also occurs in low hardwood forest and to some extent tolerates suburban conditions. The Robin showed a patchy distribution. However, it breeds in both Nothofagus and podocarp forests. It is not known to breed in low hardwood forest (except on Stewart Island) and in most parts of Fiordland in recent years (Fleming, 1948). The Brown Creeper also has a patchy distribution, though it was recorded from all three habitats. In breeding areas it is always represented by more than one pair, being abundant in some low hardwood forests. It is scarce in the west coast forest at sea level. The Yellowhead is also represented by more than one pair wherever breeding, but only in Nothofagus forest, excluding the west coast vegetation at sea level. The Grey Warbler has a wide distribution, covering all three habitats and suburban districts, but is less common in Nothofaugs forest. The Bellbird was recorded from all regions surveyed, but locally it was not found in Area 5, Lake Monk. It shows a definite trend of increase from
Nothofagus dominant forest —to podocarp dominant forest—to low hardwood forest, and in the South Island it is one of the commonest indigenous species in suburban districts. The only Nothofagus forest in which the Bellbird was a dominant element was at the Tiraumea Saddle, Lake Rotoroa, where the tree trunks were covered with black honey fungi attracting Bellbirds. The tui shows a more marked pattern of distribution. It is common in podocarp forest, sometimes breeding in concentration, and visits low hardwood forest and suburban areas in winter. It was once a common species throughout the forest along the east coast of the South Island, now mostly confined to the Gatlins forest. It is also common from inland Nelson to west Nelson, along the west coast forest down to the Hollyford Valley, where the podocarp dominant forest gradually disappears. The Tui is not known to breed south of Milford Sound until the lower part of the Waiau Valley is reached (Dunckley & Todd, 1949) where podocarp dominant forest reappears (Holloway, 1954). In the present study the Tui was not recorded from Nothofagus forest, except in Area 2 (Hollyford Valley) where the strong element of Podocarpus was the characteristic of the forest. Therefore it is reasonable to conclude that the breeding population of the Tui occurs in association with podocarp forest, and possibly in some low hardwood forests and Nothofagus/Podocarpus forests near the centre of the distribution. The Silvereye occurred in all forest habitats and suburban districts. It is commoner in the forest edge regardless of the type of the forest, breeding in high concentration, particularly in the open low hardwood forest.
Most of the naturalized species which occur in indigenous forests follow the example of the Silvereye, being more common in the forest edge. Their population densities are much higher in the low hardwood forest, particularly near the settled areas, than in other forests. An interesting fact obtained in the present study is that in Fiordland the Lesser Redpoll with variable plumage breeds in both lower and higher limits of Nothofagus forest (see Appendix II). There have been a few records of the occurrences of the Goldfinch (Bull & Falla, 1951; Riney et ai, 1959) and Yellow Hammer (Riney et al., 1959) from Fiordland, but in the present study none of them was recorded from the forest habitats in Fiordland.
In summary, those species which tend to have higher densities in podocarp dominant forest are the Fan tail, Grey Warbler, Bellbird and Tui, while those which tend to have higher densities in Nothofagus forest are the Rifleman, Yellowbreasted Tit and Yellowhead. The Robin and Brown Creeper occur in both types of forest and their present population distribution is not explicable in terms of vegetation. The Bellbird and Silvereye attained the highest density in low hardwood forest of suburban districts. The naturalized species which occur in indigenous habitats at present have low densities in major forests but maintain high densities in suburban districts, including some low hardwood forests.
Except for the Brown Creeper, which had patchy distribution, the birds exclusively feeding on invertebrates did not show concentration in any area studied, while honey-eaters and berry-eaters showed great variation in the population density. In Podocarpus dominant forest the associated plants include many flowering and fruit-bearing species which in other places form low hardwood forest by themselves. As already seen the food distribution (Fig. 8) accounts for the abundance of honey-eaters and berry-eaters in low hardwood forests and hence in the podocarp dominant forest also. Among the insect-eaters the Rifleman has a higher density in Nothofagus forest, but its feeding habitat is peculiar. It does not utilize much of the edge habitat, which is provided also under canopy of Podocarpus dominant forest, where Fantails and Grey Warblers are common.
A brief survey was made in this study of invertebrates which were considered to form potential sources of food for many insect-eaters and opportunistic feeders. The methods used to collect invertebrate samples are very crude and inadequate
for assessing the amount of potential food in the habitat. The following discussions based on the invertebrate samples (Appendix III) are therefore largely speculative.
Among foliage feeders, caged Silvereyes presented with foliage invertebrates devoured every form but Hymenoptera, and this was consistent with stomach contents examined (Fig. 9). If this is true with other foliage feeders, food supply is much the same in all types of forest studied. Podocarp forest has slightly lower density of food organisms per sample, but the amount of foliage per unit area is greater than in Nothofagus forest, providing more components of insectspider habitats and making the density of food animals higher. There are also more flowering plants in podocarp forest. The figure does not include samples taken from flowering trees, but separate samples from flowering trees contained three to five times more Diptera and Coleoptera per sample. These facts may account for greater densities of some insect-eaters in podocarp forest and low hardwood forest.
Relative abundance of litter animals in low hardwood forest and podocarp forest was very similar, though the density was greater in low hardwood forest. The most abundant form, Amphipoda {Orchestia) , was very little utilized by naturalized ground-feeding birds (e.g., Blackbirds and Song Thrushes in Fig. 9). The composition of litter animals in Nothofagus forest was somewhat different, Coleoptera being the most abundant. However, there was no significant different in the population density of Blackbirds and Song Thrushes between podocarp forest and Nothofagus forest. The high densities of these species in low hardwood forest are largely due to the fact that these forests have developed in settled areas where the birds have access to pastures and gardens in which earthworms are abundant, providing much food during the breeding season.
In low hardwood forest bark samples were taken from Fuchsia and Leptospermum, while in podocarp forest and Nothofagus forest most samples were taken from moss on the trunks of canopy forming species. Many species of invertebrates in this habitat are either unpalatable or protected under cover during the day. Some spiders are probably the only significant sources of food for birds. However, Riflemen, Brown Creepers and Yellowheads in Nothofagus forest must take small insects from the bark, but no samples of birds were taken to find out major food items.
The scarcity of passerine populations in Nothofagus forest was pronounced in Fiordland, where the climatic factors probably give added pressure. Robertson (1951) summarized the few data available on the climate of Fiordland. The prevailing north-westerly winds reach their maximum velocity (often attaining gale force) in the breeding season of passerine birds. The rainfall at sea level at Milford averages 23 inches with 18 raindays per month during summer. The number of raindays in the southern part averages over 20 days per month. Temperature in summer is persistently low for the temperate region, fluctuating only little (mean daily minimum, 29° F. (September) to 50° F. (January) ; mean daily maximum 54° F. (September)-64° F. (January)). The population density of birds which are not specially adapted to such conditions has probably been low since their distribution to the area. There is indication in Reischek’s notes (1884) that very few passerine species were numerous even before predators could have influenced the bird population in Fiordland. An interesting fact is that those indigenous species that maintain greater densities in high rainfall areas of Fiordland today (Weka, Kaka, Kea, Parakeets, Morepork, Rifleman, Rock Wren, Yellow-breasted Tit, Yellowhead) all nest in sheltered sites, e.g., tree hollows, under bark, and rock crevices. Such nesting habits must have adaptive significance in wet environment. It may be significant that (1) Acanthisittidae (Rifleman, Rock Wren, Bush Wren), endemic to New Zealand, occur in high rainfall
areas and build nests under cover; (2) species of Petroica in Australia do not normally use tree hollows for nesting but usually do in New Zealand; (3) the Yellowhead utilizes tree hollows, unlike the North Island subspecies, the Whitehead, which usually nests in a fork of a shrub.
4. Exploitation of New Habitats
In New Zealand, as a consequence of European settlement, with extensive dairy farming and introduction of exotic species of birds and mammals, two types of exploitation by birds have been recently initiated: exploitation of indigenous habitat by naturalized species and exploitation of exotic habitat by indigenous species. The species involved were listed by Turbott (1957) and with more recent information indicated in Table XV.
Exploitation in the process of colonization of indigenous habitat by naturalized species (first type) may be analysed according to the breeding and feeding habits of the species concerned (for details see Appendix II). For the purpose of the discussion the area to be considered will be largely limited to Fiordland, where extensive Nothofagus dominant forests with various forest edge conditions are least modified by human activities. In this area the breeding season of naturalized species (Song Thrush, Blackbird, Hedge Sparrow, Redpoll, Chaffinch) so far as is known is the same as that in the rest of the South Island, the season corresponding to that in Britain. The breeding habitat is mostly the forest edge, but Song Thrushes and Blackbirds breed also in the forest interior. Other species also occur in the forest interior, especially where the canopy has a small opening, either the open ground being well lit or densely covered with low scrub. Although shrubs and trees used as nest-sites are necessarily different, the nesting heights and positions for tree nesting birds are similar to those in Britain. Shrubs and trees forming the edge or secondary layer of the forest are generally used, though nests are occasionally built on branches and forks of canopy forming trees (e.g., Nothofagus) . As already seen their selection of nest-sites in the low hardwood forest of suburban areas is very wide and they utilize indigenous plants to a great extent. There was no indication in the present study that these naturalized species utilized sheltered nest-sites, such as tree hollows, in wet environment. The nesting materials of Blackbirds and Song Thrushes largely consist of moss instead of usual leaf litter, which is scarce in Nothofagus forest. Sometimes mud is lacking from Blackbirds’ nests, while rotten wood chips, which are available in all forests, are always present in Song Thrushes’ nests. The Hedge Sparrow is known to use much moss for nest construction in Britain (Witherby et al., 1943) and moss is abundant everywhere in Fiordland. The lining of Hedge Sparrows’ nests consists of feathers, grass and filmy fern ( Mecodium spp.), instead of hair or wool. The Chaffinch utilizes much moss and lichen, with grass and filmy fern as lining. Redpolls’ nests also contain much moss and filmy fern besides grass and twigs, with lichen, flowers and seeds of herbs as lining. Thus nesting habits of exotic birds in indigenous habitats show that there is only slight modification in their nesting habits from their original habits in Britain and that shortage of nest-sites or nesting materials of these species whose requirements are normally flexible is not likely to occur in indigenous habitats.
Food and feeding requirements of these species are flexible in their original country (Witherby et al., 1943) and, as already discussed, in a modified New Zealand habitat (Figs. 7 and 8). In Fiordland, though invertebrate forms are abundant on the forest floor, earthworms are rather scarce in the surface layer and food collecting by Blackbirds and Song Thrushes may not be as efficient as in grassland or gardens in suburban districts. This might be partly responsible for the comparative scarcity of these species in forested areas of Fiordland. The
Chaffinch, Redpoll and Hedge Sparrow eat varied food items in Fiordland, probably with considerable seasonal changes. They occur in forest edges and open forests where they have access to both forest and open country. Chaffinches feed on insects from forest floor and foliage, seeds from grassland and on the mast of Nothofagus, while Redpolls feed on caterpillars and other insects from foliage and open ground, seeds from marsh and dry grassland, and also on the mast of Nothofagus (Riney et ah, 1959). Hedge Sparrows feed on small insects and seeds from the ground both inside and outside the forest. In conclusion, those exotic species which have colonized Fiordland are opportunistic feeders and utilize a wide variety of resources, and their seasonal adjustment in feeding habits would probably follow a similar pattern to that in their original habitat.
Although evidence presented in the present paper is not conclusive, the indication is that there is no decisive factor which may hinder the distribution of introduced species into indigenous habitats once the breeding population has been established under similar climatic conditions and dispersal has begun. Geographical barriers are apparently negligible in these species, which have successfully colonized outlying islands. Among other naturalized species that have wide distribution in settled areas, the House Sparrow breeds in low hardwood forest of suburban districts (e.g., Botanic Gardens, Dunedin, Area 16) and has successfully colonized uninhabited islands (Wodzicki, 1956). Also, flocks of Starlings were observed in the Freshwater River Basin, and one nest was found in the Rakeahua River Hut in the uninhabited part of Stewart Island which is seldom visited by people. However, these species and the feral Rock Pigeon are not likely to spread very far into the indigenous forest. The Skylark, Greenfinch, Goldfinch, and Yellow Hammer may find high barren mountains a barrier. These birds may establish themselves in some parts of Fiordland if they find their way in. In fact, as mentioned earlier, a few Goldfinches and Yellow Hammers were recently recorded from parts of Fiordland.
The process of colonization of settled areas by indigenous species (second type) may be analyzed according to the requirements of these species. Apart from the species commonly found in open country such as the Harrier and Pipit, the indigenous species which are found in settled areas of the South Island are the N.Z. Pigeon, Morepork, passerine species of insect-eaters and honey /berry/ insect-eaters. Early records show that these and other indigenous species became very scarce in the settled areas through destruction of the habitat. However, the Fantail, Grey Warbler, Silvereye, a contemporary arrival from Australia (Thomson, 1922), and Bellbird in the South Island remained in small numbers and have apparently increased since. As already seen in the section on population distribution, these species maintain high densities in low hardwood forest and podocarp dominant forest. In fact the densities of these species recorded in low hardwood forest and podocarp dominant forest were greater than in indigenous Nothofagus dominant forest. These facts show that many of them require edge conditions and that the modified habitats with patches of indigenous shrubs require no special adaptation on their part. Their distribution and abundance in settled areas are probably determined by the degree of their tolerance to human activities and of their breeding success against supposedly increased predation. In Dunedin District they nest in relatively undisturbed wooded areas (Town Belt, public gardens, and farmland), and appear in small private gardens after breeding. Their exploitation of new habitats is rather limited. Except for Pinus radiata used by a pair of Bellbirds, the nest-sites of these species were the same as those in indigenous habitats, exotic shrubs and trees being seldom used. Nesting materials also showed little modification from their original ones: wool and cotton wool used by Brown Creepers and Grey Warblers, and feathers of domestic fowl used by Bellbirds were the only additions found. Although Silvereyes fed on nectar and
berries from exotic trees as well as from native trees, very few Bellbirds were seen to feed on exotic plants. In plantations and farmland they no doubt will feed on naturalized insects too, but such records are still scanty. The Pigeon is the only species which in some areas feeds to a significant extent from introduced trees, especially on flowers and leaves of fruit trees.
Generally speaking, the above mentioned species require practically no special adaptation to survive, other than to escape from predators, in settled areas in which the elements they require are still present.
Other indigenous species which have wide ecological distribution (Table XV) are the Shining Cuckoo, Rifleman, Yellow-breasted Tit, Brown Creeper and Tui. They all occur in some settled areas at some seasons (cf. Moncrieff, 1929). The Shining Cuckoo breeds also in settled districts where the Grey Warbler, the host species, is common. The Rifleman, though a species of forest interior, especially in Nothofagus dominant forest, appears in some plantations and near the town if the forest is extensive. Exploitation of the new habitat may be seen in their selection of nest-sites, which now include human artefacts. The Yellow-breasted Tit in settled areas often feeds in the open as it does in indigenous habitats. However, its requirements for nest-sites are scarcely fulfilled in settled areas as it sometimes nests on buildings. In these areas it normally appears after breeding. The Brown Creeper occurs commonly in low hardwood forest of settled areas, but does not seem to appear in private gardens or patches of exotic trees except conifer plantations. In Dunedin it breeds in Leptospermum ericoides forest and in low hardwood forest of the Town Belt. The pattern of its exploitation of the new habitat is not exactly known, but its nesting materials include wool and other introduced items. The Tui, together with other podocarp forest inhabitants, has disappeared from most of the east coast of the South Island as the forest has been destroyed, but in winter it still visits some settled areas, not far from its breeding grounds. The Tui is one of the two species of Meliphagidae which occur in the South Island, and its feeding habits are not so variable as the other species (Bellbird) . This occurrence in settled districts corresponds to the flowering season of some indigenous trees, though some stay through winter and visit honey-water pots put out by people (Kikkawa, 1962).
Other indigenous land birds such as Weka, Kaka, and the Parakeets have limited ecological distribution and have disappeared completely from the settled districts as their habitat was destroyed. Tree holes, which are common nest-sites of these species, are as yet scarce in settled areas, and their exploitation of the new habitat, if it is to occur, will involve their adaptation in both feeding and nesting habits.
The above examination suggests that those indigenous species which now occur in settled areas have not undergone any decisive change in their habits, that other indigenous species which disappeared from the settled areas could not survive in settled areas without much change in their habits, and that exploitation of the man-made habitat by the indigenous species is still limited.
Naturalized species in settled areas also meet new situations and in some areas they may find environment more favourable than in their original country. Thus Redpolls, for example, maintain high densities in some fruit growing districts, and apparently have developed a new habit of attacking blossoms (Stenhouse, 1962).
5. Stability and Instability of Populations
In the mainland of New Zealand, all endemic passerine genera except Xenicus are represented by single species, races of some species being separated geographically and a few having developed into different species on outlying islands. Among
non-endemic, indigenous, passerine genera, Rhipidura and Anthus are represented by single species in New Zealand. Petroica has two species on the mainland, but different arrivals of the ancestral forms indicate no contemporary differentiation of the two species (Fleming, 1950). Among Psittaciformes the endemic genus Strigops is represented by one species while non-endemic (though distribution limited) Nestor is represented by two and Cyanoramphus by three species on the mainland. Among Ratites of New Zealand, there are three species of Apteryx still surviving and at least 20 species belonging to 6 genera of Dinornithiform.es, now extinct, differentiated before the Pliocene (Archey, 1941). These facts suggest that in both new and old elements of the land avifauna of New Zealand there was no effective isolation of populations during the Pleistocene that resulted in speciation of closely related species on the mainland. The ancestors of “young Australian elements” (Mayr, 1939) such as Petroica macrocephala probably arrived in New Zealand in early Pleistocene, and their subsequent subspeciation through geographical isolation in the New Zealand region has occurred only in the Recent era (cf. Fleming, 1950).
Thus, highly endemic passerine species which form older elements of the fauna must have undergone specialization at an earlier time in New Zealand with no predation pressure from mammals, and in most passerine birds such specialization has not involved radiation of the group. The deduction that such species are vulnerable to modification of the habitat stems from their disappearance from settled areas at an early stage and has led Myers (1923) to generalize that “the tendency of a species to disappear under the combined influence of introduced conditions is directly proportional to the degree of specific endemism which it exhibits ”.
Quite contrary to the statements made by early workers, the present results show that some endemic species can survive and maintain even higher population densities in settled areas than in unmodified habitats.
Among introduced influences on indigenous birds, possibilities of competition with naturalized species were discussed by Turbott (1961), but so far such competition has not been demonstrated. As we have seen the broad spectrum of feeding habitats and nest-sites used by common species suggests that these are in most cases not limiting the population size. Therefore competition resulting from the utilization of common resources is unlikely. Two closely related naturalized species, the Blackbird and Song Thrush, share the same food and the same nestsites, and yet they maintain high densities in low hardwood forest of settled areas. They have nesting territories and common feeding grounds in which only individual distance is maintained, sometimes developing into a feeding territory. In Botanic Gardens, Dunedin (Area 16), there was no part of the wooded areas where both species did not occupy territories. This suggests that the breeding density of one species is not affected by that of the other. In other words their breeding densities are not resource-limited though competition may occur in winter. Territorial behaviour within the species is the only factor likely to determine the density of breeding populations. However, some functions of territoriality (and other social behaviour) liable to natural selection in their original habitat may have been lost or modified in the new habitat in which the density level or controlling factors of population differ. The greater breeding capacity of the Song Thrush was offset by greater predation upon them and the two species had about the same rate of recruitment each year. In the indigenous habitats studied, the densities of these two species were nowhere as high as in low hardwood forest of settled areas and, although they may still be increasing in number, territories were not contiguous where they occurred and there were vast, apparently suitable areas in which they still did not occur. Apart from Kiwi and Weka, the only possible
indigenous species that may feed on the same food is the South Island Piopio (the native thrush) which, however, is very rare and restricted in distribution. It is hard to imagine that competition should occur between the native and naturalized thrushes in low density areas of indigenous forest, especially as two naturalized species of thrushes can coexist in high densities in settled areas where they utilize the same resources. Other naturalized species (e.g., Hedge Sparrow, Chaffinch) are also opportunistic feeders and not likely to “ eat out ” one type of food. They occur in large numbers in settled areas where some insect-eating indigenous species also maintain high densities.
Predation by naturalized predatory mammals must have affected populations of indigenous species, but this could not be the single factor responsible for the rarity of certain species at present. Marshall (1963) concluded from an extensive survey of mustelids in New Zealand that the effect of mustelids on native birds appears to have been of relatively small significance.
As discussed in the preceding section, there does not appear to be a drastic change in the habits of birds in modified conditions, showing positive adaptation. Why, then, can indigenous species in man-induced habitats and naturalized species in indigenous forest maintain themselves? We may be able to explain their commonness and rarity in changed environment by considering two aspects of their pre-adaptive conditions. Firstly, the habitat selection of indigenous species which are now common in settled districts was essentially the same before and after European settlement. Some modified habitats contain corresponding or identical
components of the original habitat in which the specialization of these species has taken place (food, nesting requirements, etc.). Secondly, the breeding capacity of these species has been kept high for some reason and does not now succumb to added mortality factors. This should also apply to the habitat modified only by the activities of naturalized predatory mammals.
Some evidence for the first aspect was obtained in the present study, but the second aspect requires evidence obtainable only in the past. However, certain deduction is possible from the early records (cf. Buller, 1870, 1873; Potts, 1869, 1870, 1873; Reischek, 1884, 1887; Henry, 1903; Guthrie-Smith, 1910) that the forest birds now rare or nearly extinct had smaller breeding capacity and were either restricted in distribution or at least not as numerous as the species that survived introduced influences. Examples from the passerine species may be seen in Table XVIII.
New Zealand has undergone climatic changes in recent geological times, and especially during Pleistocene glaciation and the post-glacial period the birds that survived until the present must have been affected by climatic instability. Those species which maintained a high reproductive capacity probably responded more successfully to the expansion and shrinkage of forest under the influence of climatic change. Other species whose specialization was not favourable for survival in the subsequent period of changed climate probably became extinct, and this was perhaps accelerated in the most recent climatic change at which time human activities became influential in New Zealand (e.g., Moa-hunters). When the distribution of mortality factors changes suddenly as a result of the introduction of new factors either by man or by relatively fast natural changes in environment, the species that normally has a high mortality rate (hence having a high reproductive capacity in a stable population) is less likely to suffer a greater mortality than the species that normally has a low mortality rate (hence having a low reproductive capacity in a stable population). For the added pressure on the former species may only take a portion of the population which is normally eliminated by other mortality factors. The species, such as the Fantail and Grey Warbler, which have wide distribution with different densities in different habitats, and which maintain a high reproductive rate, probably have a constant struggle to colonize or increase in less favourable habitats and the surplus individuals are more readily eliminated. On the other hand, the species such as the Kokako and Piopio, which were specialized in one habitat, or maintained the population under very little predatory pressure in the past, have a low reproductive rate and do not produce many surplus individuals. In the latter species, a new factor may replace an old one in greater proportion than in the case of the former species and it may eliminate more individuals which are not surplus. What we see today is the result of such a dynamic change which is probably still in progress in many parts of New Zealand, and therefore we are not dealing with the populations whose birth-rate and death-rate have been in balance for many years under comparatively stable conditions.
Anomalies observed in soil formation (Raeside, 1948) and distribution of vegetation (Speight, 1910; Holloway, 1954) in the South Island have been interpreted to mean that slight but significant climatic changes took place in the post-glacial period in New Zealand (cf. Fleming, 1963). The distribution of birds may only reflect the present pattern of vegetation. If so, the stabilized populations of birds in podocarp forest in the past may be beginning to disappear today with retreating podocarp forest, especially when the destruction of the forest is aided by man. At the same time, the species with wide ecological distribution and a high reproductive capacity will probably survive the modified conditions, even after disease or predation has had serious effects on local populations.
The hypotheses presented here are not supported by substantial evidence, and also do not exclude the possibilities of extinction by causes already suggested by previous workers. However, it should be noted that the long-term effects of environmental changes caused either by human activities or by natural agents cannot be predicted from the examination of the immediate causes of damage alone.
Acknowledgments
I am indebted to a number of people, those mentioned below and others, for their willing help in both official and private capacities.
Mr J. W. Ramsay, Otago Catchment Board, Miss M. A. Chapman and other members of the University of Otago Biological Society assisted me in the strenuous field work in Fiordland. The following people kindly arranged field trips for me and gave me valuable local information: Mr G. R. Watters and Mr P. A. Watters (Waimate) ; Mr E. G. Turbott, Canterbury Museum (Enys and Ashley) ; Mr J. R. Jackson (Arthur’s Pass) ; Miss M. Simpson, Botany Division, D.S.I.R. (Lake Rotoroa) ; Mr J. Peterson, Owaka Rabbit Board, and Mr J. W. Ramsay (Gatlins); and Dr M. N. Watt and Mr R. Traill (Stewart Island). In the course of the study I received helpful suggestions from Dr R. A. Falla, Dominion Museum; Mr E. G. Turbott, Canterbury Museum, and Professor B. J. Marples, Department of Zoology, University of Otago; and useful criticisms on parts of the manuscript from Dr B. I. Brewin, Department of Zoology, University of Otago; Dr A, F. Mark, Department of Botany, University of Otago, and Mr J. W. Ramsay. Drs C. A. Fleming and J. A. Gibb gave further helpful comments on the manuscript. Miss M. Simpson identified, in the field, some plants and plant materials used in bird nests in Fiordland and the Lake Rotoroa area, and also examined stomach contents of some introduced birds for me. Professor Baylis and staff of the Department of Botany, University of Otago, identified some plant specimens, and Dr R. R. Forster, Otago Museum, helped with identification of some insects and spiders. Mr K. Calvert helped with field equipment. Thanks are also due to the Botanic Gardens authority, Dunedin City Corporation, who allowed me to work in the upper part of the Gardens and supplied rainfall data. The field trips were partly supported by the Hutton Fund from the Royal Society of New Zealand and by a University of New Zealand Research Grant.
APPENDICES
Appendix I.The Index of Similarity.
The index of similarity, G*, proposed by Morisita (1959) is based on Simpson’s equation of the index of diversity:
q 2ni(n,— 1) i = 1 X = N (N—l)
where N is the total number of individuals consisting of q species in a sample and n, is the number of individuals of ith species. Calculating the value of \ for each community sampled, the index of similarity between two communities is obtained by the equation
rj —: 2 S n n n 2l X (Ai +A 9) N, N 2 *
where the values obtained from the communities 1 and 2 are indicated by the subscripts 1 and 2 respectively.
Appendix 11. Detailed Accounts of Birds in Less Known Areas.
A. Fiordland.
(i) Breeding. As the visits were made towards the end of the breeding season, many juveniles were independent in all areas studied. At Lake Monk about 50% of Blackbirds, Hedge Sparrows, Chaffinches, Redpolls recorded were juveniles. Young Silvereyes and Redpolls fed in flocks (Lake McKerrow, Lake Monk) when some adults were still breeding. Seven Redpolls collected at Lake McKerrow all belonged to the subspecies Carduelis flammea cabaret in measurements; 5 were adults and in breeding condition. The plumage showed much variation, some adult males with large testes having very little red colour on crest and breast. In January all but the Shining Cuckoo were still singing (Lake McKerrow, 1959, and Lake Monk, 1960), but in February only one Blackbird and a few Chaffinches were heard early in the morning (Lake Manapouri, 1959). A chorus of Bellbirds was heard at 5 a.m. below the west saddle of Lake Monk in January 1960. Records of nesting in these periods are: Lesser Redpoll (4 eggs in 1 nest hatching on 25 January 1959, Lake McKerrow; 4 eggs (12.5 x 7mm) in 1 nest being incubated on 14 February 1959 at the timber line (2,750 ft) of Mt Grey; 5 nestlings about 10 days old on 24 February 1959 at the Spey River Mouth (600 ft); 1 nest at Lake Monk (2,200 ft) and 1 nest at the Jeanie Burn (1,300 ft) being constructed on 25 January 1960), Bellbird (2 nestlings in 1 nest about 10 days old on 16 February 1959, at Doubtful Sound), Grey Warbler (2 young leaving nest on 20 January 1960, at Lake Monk), and Kea (a nesting territory in Nothofagus forest at the West Arm of Lake Manapouri in January 1959). The following species fed fledglings; in northern Fiordland in January 1959, Song Thrush (3 young) and Bellbird (2 young); in central Fiordland in February 1959, Rifleman, Yellow-breasted Tit, Brown Creeper, Bellbird, and Western Weka (black cock and brown hen with 2 black and 1 brown chick about 4 weeks old at Wilmot Pass); in southern Fiordland, in January 1960, Yellowbreasted Tit and Grey Warbler. The following nests were examined: Western Weka, 2 nests at Wilmot Pass (in hollows at the base of Nothofagus cliff ortioide si outer diameter 30cm, inner diameter 18cm, depth Bcm, made of moss, Astelia nervosa leaves, Rumohra t adiantiformis, Uncinia and Mecodium) ; Pigeon, 2 nests at Lake McKerrow (6ft on Coprosma rotundifolia, 18ft on Nothofagus menziesii); Fantail, 1 successful nest at Doubtful Sound (20ft on W einmannia racemosa, made of moss and scales of the tree fern Cyathea smithii) ; Grey Warbler, 1 successful nest at Lake Manapouri (6.5 ft on Myrsine divaricata, made of moss and feathers of Blackbird, Song Thrush, Redpoll, Pigeon, Kea, Yellowhead); Song Thrush, 1 nest at Lake McKerrow (lift on Pennantia corymbosa), 4 unsuccessful nests at Lake Manapouri (15ft on Griselinia littoralis and 15ft on Phyllocladus alpinus, in the secondary layer of the forest interior, 7ft on Neomyrtus pedunculata in forest edge, Bft on Neomyrtus pedunculata in Leptospermum stand), 3 nests on Myrsine divaricata in the secondary layer of the forest at Lake Monk (5.5, 6,6,5 ft); Blackbird, 5 nests at Lake McKerrow (10ft on Weinmannia racemosa, 6ft on Nothofagus menziesii, 12ft on Carpodetus serratus, 20ft on Pennantia corymbosa, Bft on dead shrub) 3 nests at the edge of Leptospermum stand at Lake Manapouri (9ft on Pseudopanax crassifolium, 6.5 ft on Myrsine divaricata, 7ft on Neomyrtus pedunculata), 3 nests at Lake Monk (10ft on small stand, 12ft on Griselinia littoralis, 6ft on Myrsine divaricata); Bellbird, 1 successful nest at Doubtful Sound (lift on Weinmannia racemosa, made of filmy fern and liverwort (outer layer), Deyeuxia forsteri and Dacrydium cupressinum leaves (middle layer), and the lining of feathers of Weka and Kea, Silvereye, 3 nests in the forest edge at Lake McKerrow (4.5 ft on Coprosma parviflora, 10ft on C. rotundifolia, 10ft on C. linariifolia), 1 nest in forest edge at Doubtful Sound (sft on Neomyrtus pedunculata); Redpolls, 2 nests at Lake McKerrow (6ft on Coprosma parviflora, sft on C. linariifolia), 2 nests at Lake Manapouri (10ft on Leptospermum scoparium, 5.5 ft on stunted Nothofagus cliff or tioides), 2 nests at Lake Monk (10ft on Nothofagus menziesii, 4.5 ft on Coprosma sp.); Chaffinch, 1 nest at Lake McKerrow (lift on Coprosma linariifolia), 2 nests in Leptospermum stand at Lake Manapouri (9ft on Myrsine divaricata, 5.5 ft on Neomyrtus pedunculata) . Nests of Blackbirds and Song Thrushes had much moss in place of litter, and one nest of Blackbird was made almost entirely of moss and lichen with only a little mud. Another nest of Blackbird had Leptospermum bark and dry leaves for the main bulk and contained sand instead of mud under the grass lining. A Song Thrush’s nest contained twigs, dry grass and wood chips as lining besides a bulk of moss. One nest of Redpoll had dry grass, moss, filmy fern, small twigs, feathers, cobweb, and grass seeds (lining). Another nest had the outer layer of Leptospermum twigs, the middle layer of Nothofagus leaves and Poa annua, and the lining of thistle seeds, moss and rhizome. Nests of Chaffinches were made of moss, Leptospermum twigs, filmy fern, grass and lichen.
(ii) Feeding. The following observations were made on feeding habits and food of land birds in Fiordland. Pigeons fed on fruits of Aristotelia serrata (northern and central Fiordland) and of Coprosma rotundifolia (field observations and examination of droppings at Lake McKerrow). Kea frequented the area below the timber line as well as above at
Lake Manapouri, but the dropping remains found in Nothofagus forest at Lake Monk consisted largely of Coprosma seeds which could be obtained only in the alpine meadow. Kaka and New Zealand Parakeets were seen in the canopy, but remains of beetles on the cliff face scratched by Kaka at Mt Plaisted suggested its feeding on the ground as well. Riflemen were confined to the forest interior, feeding in all strata of the forest but specially on bark of Nothofagus (central and southern Fiordland). Fantails frequented the forest edge, tracks and river banks in central Fiordland. Yellow-breasted Tits had a variety of feeding habitat, including the forest edge (Lake Monk), shrubs and ground (central Fiordland), but were normally found in the canopy and the secondary layer of the forest (all areas). Brown Creepers were seen to feed among the foliage, on trunks of Nothofagus and in Leptospermum stands (central Fiordland), but at Lake Monk they were mostly restricted to open stunted Nothofagus stands and scrubland, Yellowheads, moving in flocks, fed at various heights of Nothofagus, searching branches and trunks and often pulling away the moss from the bark (central and southern Fiordland). They also came out to the edge of the forest where they fed in the foliage of isolated Nothofagus trees (Lake Monk). Grey Warblers fed in the canopy of the forest interior as well as on the edge (central Fiordland), but more were recorded in low stands of Nothofagus along the river bank than in dense forest (southern Fiordland). Song Thrushes and Blackbirds at this time of year fed on fruits where available ( Coprosma rotundifolia and other berries at Lake McKerrow and Doubtful Sound), but also fed on the ground, especially in the areas that lacked berrybearing shrubs and trees (all records are from the ground at Lake Manapouri and Lake Monk, feeding on beetles and caterpillars). At Lake McKerrow some juvenile Blackbirds and Chaffinches were seen to take abundant cicadas. Chaffinches and Redpolls often fed in the same place. At Lake Monk Chaffinches fed mainly on caterpillars, but small beetles and seeds of Scirpus and composites in the bog were shared by the two species. At Lake Manapouri they were seen to feed on the bank of the Spey River. Redpoll fledglings were fed with seeds of Scirpus, Danthonia and Agrostis as well as small beetles and spiders, while juvenile Chaffinches fed on Pratia angulata, Viola, Scirpus, Deyeuxia forsteri, Danthonia, etc. Three juvenile Chaffinches were found freshly dead in this area. Their gizzards were empty. On the bank and bed of the Spey River open ground with grass and herbs attracting Chaffinches was scanty at this time of year. Stomach contents of adult Redpolls contained seeds of Plantago, Cardamine, Cortaderia, etc., those of juveniles had small beetles, spiders and pupae besides seeds of Danthonia, Carex, Trifolium (naturalized plant), Cardamine and moss capsules; and those of nestlings 3 days old were fed mainly with seeds of Cortaderia richardii, Collembola (Sminthuridae) and some small spiders, aphids, monocotyledon seeds and moss. Hedge Sparrows searched the forest floor (Lake McKerrow) and fed on small beetles and seeds from the peaty ground in forest edge or scrubland at Lake Monk. Tui were recorded only from podocarp forest in northern Fiordland where they fed on berries of Aristotelia serrata and Coprosma rotundifolia. Bellbirds in this region also ate these berries, but in central Fiordland they fed on insects in the Leptospermum stand also. Bark was searched by some of them which were feeding young. Silvereyes at Lake McKerrow were seen on Phormium tenax and Coriaria, and at Doubtful Sound on Schefflera digitata, while at Lake Monk they seemed to be searching for insects and spiders as berries were lacking where they were seen.
(iii) Other Records. Some interesting records were obtained during the expeditions to Fiordland. In northern Fiordland Paradise Ducks ( Tadorna variegata) occurred in single pairs at the Pyke Junction and the mouth of the Hokuri Greek, and in a flock of 115 near the mouth of the lower Hollyford River towards Martins Bay. One pair of N.Z. Scaup ( Athya novaeseelandiae ) had 7 chicks along the eastern shore of Lake McKerrow in January 1959; another pair had 5 downy chicks about 7 days old on Lake Monk on 23 January 1960. Blue Ducks ( Hymenolaimus malacorhynchos) were recorded from the Spey River and Wilmot Pass in central Fiordland, A total of 36 Black Swans ( Cygnus atratus) was counted along the lower Hollyford River from Lake McKerrow to Martins Bay. In central Fiordland no proof was obtained of the occurrence of the Hedge Sparrow though single call notes were doubtfully recorded near the mouth of the Spey River. No Robin was recorded in the areas covered except on the open floor of Nothofagus forest at Manapouri township. In southern Fiordland the Pigeon which was reported only from the Big River Basin during the previous expedition (Riney et al., 1959) was found in the Lake Monk Valley as well as in the Jeanie Burn. However, it was very scarce, and apart from one sight record in a Senecio patch at the north end of the Lake Monk Valley the only evidence of its presence in the vicinity was the feathers found in a Grey Warbler’s nest in Area 5. Yellowheads were recorded for the first time from the Lake Monk area in the present expedition. The species previously recorded but not seen in the present trip to this area are the Kiwi, Goldfinch and Yellow Hammer.
B. Stewart Island.
(i) Breeding. The trip was made at the height of the breeding season, and songs of most species were heard for a long period of daylight. On Ulva on a lightly overcast morning (15 November) Tui began singing first at 3.45 a.m,, followed by Yellow-breasted Tits at
4.30 a.m., Brown Creepers at 4.45 a.m., and Parakeets, Fantails and Grey Warblers at 4.50 a.m. At the Freshwater River on a cloudy morning a Long-tailed Cuckoo stopped singing for a while at 3.40 a.m., Tui began singing at 4.10 a.m., followed by Robins at 4.15 a.m., Blackbirds, Bellbirds and Yellow-breasted Tits at 4.25 a.m., Grey Warblers at 4.35 a.m., Redpolls and Chaffinches at 4.40 a.m. At the Rakeahua River on a cloudy morning a Robin started singing at 4.05 a.m., followed by Tui at 4.10 a.m. On Ulva fledglings of Hedge Sparrows and Brown Creepers and small chicks of Weka were seen (14 November) indicating the early October laying of these species. On a planted Cupressus macrocarpa at the landing place on Ulva a pair of Yellow-breasted Tits fed nestlings. One nest of Pigeons (12ft on Podocarpus hallii on Ulva), 2 nests of Fantails (7ft on Weinmannia racemosa on Ulva and 6ft on Coprosma foetidissima at Mt Rakeahua), 4 nests of Song Thrushes (1 at 9ft on Neomyrtus and 3 between 6ft and 10ft on Griselinia littoralis at the Freshwater River) and 4 nests of Tui (3 between 9 and 14ft on Coprosma and 1 at 14ft on Podocarpus hallii, at the Freshwater and Rakeahua Rivers) were nests of previous years. No nests of Tui were found in Fuchsia patches near Oban where they were concentrated, suggesting that they had not started nesting at the time of investigation. However, they apparently had breeding territories in podocarp forest. A Blackbird’s nest found at the Freshwater River (Bft on Griselinia littoralis) had 3 eggs under incubation (19 November) and 1 Song Thrush’s nest found on the south side of the Freshwater River Basin (7ft on Coprosma and Rubus) contained 2 abandoned eggs. One Grey Warbler’s nest found in the Leptospermum stand at the Freshwater River (5.5 ft on Leptospermum) had just been completed (20 November), while another found in the forest on the south side of the Freshwater River Basin (Bft on Coprosma) contained 4 nestlings about 5 days old (19 November). A nest of Starlings found on the roof of the Rakeahua River Hut had 5 eggs under incubation (21 November). A Pipit’s nest found in the open ground near the Freshwater River Hut had 4 nestlings about 6 days old (20 November).
(ii) Feeding. On Ulva, several Weka were seen feeding in the tidal zone at low tide and both New Zealand and Yellow-crowned Parakeets were found together near the ground as well as in canopy. The habitat of Stewart Island Robin as observed in the present study was confined to the forest edge of Leptospermum scrub where they fed mostly on the ground. The distribution of Brown Creepers was puzzling in that on the mainland of Stewart Island they were found only in Leptospermum scrub at the Rakeahua River, while on Ulva they were very common in the forest. Yellow-breasted Tits, Grey Warblers, Bellbirds and Chaffinches were evenly distributed, feeding in the forest interior as well as in the edge habitat. Song Thrushes, Blackbirds and Hedge Sparrows fed on the ground. Silvereyes were not numerous except near the township of Oban, where they were seen feeding on Fuchsia nectar. Some Redpolls were feeding in flocks at the Freshwater River Basin. Around Oban a concentration of Tui on Fuchsia was remarkable, but on Ulva they were scattered and some, together with Bellbirds, were seen on planted Fuchsia and Dracophyllum longifolium near the landing. Fruits of Podocarpus when they ripen will be eaten by Tui, Kaka and Parakeets, but no such evidence could be obtained in the spring. In very dense scrub with Leptospermum canopy which developed on the bog along the Freshwater River, Grey Warblers, Bellbirds, Silvereyes and Blackbirds were found. Bellbirds in this area often searched Leptospermum bark for insect food which apparently was taken to nestlings.
(iii) Other Records. One pair of Black-backed Gulls (Larus dominicanus) on top of Mt. Rakeahua had a nest with two eggs under incubation beside a pond above the timber line. Naturalized mammals including opossums (Trichosurus vulpecula ) were common in the forest. In the forest south of the Freshwater River several of them were driven out of hollows under trees in the daytime and in the Rakeahua Basin they were heard continually during the night. Rats (Rattus sp.) on Ulva were seen feeding by the beach at low tide.
C. Inland Nelson.
(i) Breeding. The field trip was made at the end of a long drought period which probably affected breeding of many species, especially Blackbirds and Song Thrushes. All naturalized species had stopped singing and no chorus of Bellbirds could be heard in early mornings. Chaffinches, Redpolls and Silvereyes were flocking and most fledglings of indigenous species were independent, though 3 Riflemen, 3 Grey Warblers, 1 Silvereye and 3 Bellbirds were still feeding young. One old nest of Pigeons at 15ft on Myrsine australis and one old nest of Chaffinches at 5.5 ft on Pseudowinter a colorata (successful but with 1 unhatched egg) were located in Area 12. Out of the 16 nests of Song Thrushes found (5-15 ft on Myrsine divaricata (1), Nothofagus menziesii (1), Coprosma rotundifolia (3), Coprosma sp. (1), Lophomyrtus obcordata (3), Neomyrtus pedunculata (2), Pseudowinter a colorata (3), P. colorata + Rubus (1), and P. colorata + Muehlenbeckia (1), 6 were of previous seasons, 8 were unsuccessful (mostly predation of eggs by mice or rats and 1 case of predation of 3 nestlings by rats, evidence being their droppings in the nests) and
only 2 were successful. All the 5 nests of Blackbirds found (6ft on Coprosma , sp., 7ft on Coprosma rotundifolia, Bft on Myrsine divaricata, lift on Lophomyrtus obcordata and 20ft on Nothofagus fusca ) were unsuccessful (predation or desertion of eggs). Some Robins were singing high on trees as well as on the ground and some were moulting.
(ii) Feeding. Fruit of Coprosma rotundifolia in podocarp forest attracted Song Thrushes, Blackbirds, Bellbirds and Silvereyes. Song Thrushes and Blackbirds were also seen feeding on fruits of Fuchsia, and only few were flushed from the ground. Tui were mostly on podocarp trees, but some juveniles were also seen feeding on fruits of Aristotelia serrata and Fuchsia excotticata. One adult Tui was seen on the ground (possibly searching for food for nestlings). Pigeons were mostly seen on fruits, though one was seen eating leaves of Sophora microphylla near the lake shore. Silvereyes were numerous, feeding in flocks along the forest edge, including the lake shore and by the stream as well as in the canopy of podocarp. Some Fan tails were seen catching moths on the wing. Out of 15 Fantails recorded 2 were the black form. In the pure Nothofagus forest about the Tiraumea Saddle, the Bellbird was the commonest species, many of them feeding on honey water from the bark fungus on Nothofagus. In this forest the Rifleman was the next commonest, followed by the Yellow-breasted Tit, Robin and Grey Warbler in order of abundance. They were all feeding on insects and spiders. No Fantail was found in this forest. Chaffinches fed in flocks (up to 40 in a flock) in the forest edge, clearings of the forest, and the river bed. A few Redpolls visited Leptospermum stands near the lake shore but were not seen on the river bed. Parakeets which fed in canopy and flew over the forest were not identified as to species. Juvenile Shining Cuckoos were seen along the lake shore and about the clearings, up to 3 at a time and one was seen feeding in an isolated Sophora microphylla tree near the lake.
(iii) Other Records. Other species recorded on this trip were 1 Kea and 1 Weka, which were heard from the direction of Mt Hutton, 1 Weka seen near the D’Urville Hut, 1 Long-tailed Cuckoo and 1 Morepork heard in the D’Urville Valley, and 1 Kingfisher beside the mouth of the D’Urville River. Except for one doubtful record of distant call notes the Brown Creeper was not recorded on this trip. Yellowheads and Hedge Sparrows were not seen in the area covered. (A flock of about 30 Yellowheads was recorded at Lake Rotoroa by Grimmett in January, 1922 (Moncrieff, 1929)). Rats and mice were common in the forest, but no signs of opossums were found. Deer and wild pig ( Sus scrofa, naturalized) were present but not common in podocarp forest. One stoat was seen near the Sabine Hut and squeals were heard during the night, possibly of mice being hunted.
D. East Coast.
At Gatlins two unoccupied nests of Pigeons were found: one at 14ft on young Podocarpus hallii, and one at 15ft on Coprosma foetidissima. Rats and mice were known to be common in the area, and one of the Pigeon’s nests had a pile of pulpy cases of Podocarpus ferrugineus fruit presumably gathered by a rat ( Rattus rattus). Opossums were common in the forest (1) where the damage to Neopanax was obvious. At Hook Bush, Waimate, a nest of Brown Creepers was located at 28.5 ft in the canopy of old Myrsine australis, containing 3 fully fledged nestlings on 25 October 1959. It had a lining of grass and sheep’s wool in a cup made of moss, lichen and bark tissue of Cordyline australis. One of the early breeding records of Grey Warblers was obtained at Evansdale, north of Dunedin; a nest at 6.5 ft on Leptospermum scoparium was nearly completed on 17 September 1960.
Appendix lll.— Comparison of the Components of Feeding Habitats of Birds Between Three Types of Forest.
The size of the circle area represents the relative size of biomass per sample.
Appendix IV. —List of the Bird Species.
Apterygidae South Island Kiwi Apteryx australis australis Stewart Island Kiwi Apteryx australis lawryi Accipitridae Australasian Harrier Circus approximans gouldi Falgonidae New Zealand Falcon Falco novaeseelandiae Phasxanidae New Zealand Quail Coturnix novaezealandiae zealandiae Rallidae Western Weka Galliralius australis australis Stewart Island Weka Gallir alius australis scotti CoLUMBIDAE New Zealand Pigeon Hemiphaga novaeseelandiae novaeseelandiae *Rock Pigeon Columba livia P S ITT ACIDAE Kakapo Strigops habroptilus South Island Kaka Nestor meridionalis meridionalis Kea Nestor notabilis New Zealand Parakeet Cyanoramphus novaezelandiae novaezelandiae Yellow-crowned Parakeet Cyanoramphus auriceps auriceps Gugulidae Shining Cuckoo Chalcites lucidus lucidus Long-tailed Cuckoo Eudynamis taitensis Strigidae Morepork Ninox novaeseelandiae novaeseelandiae Laughing Owl Sceloglaux albifacies albifacies Alcedinidae New Zealand Kingfisher Halcyon sancta vagans Aganthisittidae South Island Rifleman Acanthisitta chloris chloris South Island Bush Wren Xenicus longipes longipes Rock Wren Xenicus gilviventris Alaudidae * Skylark Alauda arvensis Musgicapinae South Island Fantail Rhipidura fuliginosa fuliginosa Yellow-breasted Tit Petroica macrocephala macrocephala South Island Robin Petroica (Miro) australis australis Stewart Island Robin Petroica (Miro) australis rakiura Sylviinae South Island Fernbird Bowdleria punctata punctata Malurinae Brown Creeper Finschia novaeseelandiae Whitehead Mohoua ochrocephala albicilla Yellowhead Mohoua ochrocephala ochrocephala Grey Warbler Gerygone igata Turdinae *Song Thrush Turdus ericetorum *Blackbird Turdus merula Prunellidae *Hedge Sparrow Prunella modularis occidentalis Motagillidae New Zealand Pipit Anthus novaeseelandiae novaeseelandiae Meliphagidae Bellbird Anthornis melanura melanura Tui Prosthemadera novaeseelandiae novaeseelandiae ZoSTEROPIDAE Silvereye Zosterops lateralis
Fringillidae ♦Greenfinch Chloris chloris ♦Goldfinch Carduelis carduelis britannica ♦Lesser Redpoll Carduellis flammea cabaret ♦Chaffinch Fringilla coelebs gengleri ♦Yellowhammer Emberiza citrinella citrinella Plogeddae ♦House Sparrow Passer domesticus Sturnidae ♦Starling Sturnus vulgaris Gracticidae ♦White-backed Magpie Gymnorhina hypoleuca Callaeidae South Island Saddleback Philesturnus carunculatus carunculatus South Island Kokako Callaeas cinerea cinerea Turnagridae South Island Piopio Turnagra capensis capensis
* Introduced species.
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♦ Naturalized species. The same applies to the rest of the tables.
f Presence was indicated by calls but no count was made.
f The number of observation periods with no species recorded.
* Other species include Pseudopanax crassifolium , Carpodetus serratus, Paratrophis microphylla, Pseudowintera colorata, Fuchsia excorticata, Neopanax sp.
* The Tui in Nothofagus dominant forest was recorded in one area only where the Podocarpus element in the forest was very strong.
* The Robin was once an abundant species in most localities and is still common in restricted areas. Its highly sedentary habits and relatively low reproductive rate may account for the retardation of re-distribution into areas from which they have disappeared, whatever the cause may be.
f The Bellbird in the North Island once disappeared from north of Auckland (disease being the likely cause), but is now spreading again (Turbott, 1953).
* Introduced species.
Order New Zealand Indigenous Naturalized Species Species Japan Indigenous Species Naturalized Species Apterygiformes 3(3) — 0 — Sphenisciformes 7(4) — 0 — Podicipitiformes 2(2) — 5(1) — Colymbiformes 0 — 3(0) — Procellariiformes 47(13) — 20(3) — Pelicaniformes 14(7) — 9(3) — Ciconiiformes 13(5) — 21(13) — Anseriformes 10(7) 5 37(3) — Falconiformes 3(2) — 23(10) — Galliformes 0 6 4(4) 2 Gruiformes 9(6) — 12(3) — Charadriiformes 52(16) — 93(13) — Golumbiformes 1(1) 2 5(3) 1 Psittaciformes 6(6) 2 0 — Guculiformes 5(2) — 4(4) — Strigiformes 3(2) 1 7(5) — Apodiformes 2(0) — 2(2) — Gaprimulgiformes 0 — 1(1) — Coraciiformes 2(1) 1 4(3) — Piciformes 0 — 6(3) — Passeriformes 22(18) 16 125(72) — Total 201(95) 33 381(146) 3
Table I. Comparison of the avifauna between the mainland of New Zealand (the North and South Islands) and the mainland of Japan (Honshu). The number of breeding indigenous species is given in parentheses and the number of naturalized species includes only those that breed at present. The information is based on the Ornithological Society of New Zealand, 1953, and the Ornithological Society of Japan, 1958. Subspecies are excluded.
Number of Pairs Area 1 Area 2 Area 3 Area 4 Area 5 Area 6 Species (100 acres) (17 acres) (50 acres) (50 acres) (20 acres) (18 acres) Western Weka — — 2 2 N.Z. Pigeon 8 3 1 3 — — S.I. Kaka — 1 — 1 — ■ — N.Z. Parakeet — — 2 — — — Long-tailed Cuckoo — — — 1 — — Morepork — — 1 — — — S.I. Rifleman — 2 11 9 1 4 S.I. Fantail 3 — 3 2 — — Yellow-breasted Tit 7 5 15 12 7 4 Brown Creeper — — 6 — — 1 Yellowhead — — 4 .—. 2 3 Grey Warbler 4 1 8 3 3 1 ♦Song Thrush 2 1 2 — 2 — ♦Blackbird 7 4 2 1 4 — ♦Hedge Sparrow 4 — — — 1 — Bellbird 6 3 5 7 — 2 Tux — 6 — — — — Silvereye 14 2 — 4 2 2 ♦Redpoll 7 — 5 — 6 — ♦Chaffinch 8 — 5 1 7 2 Total 70 28 72 46 35 19 (11 spp.) (10 spp.) (15 spp.) (12 spp.) (10 spp.) (8 spp.) No. of pairs per 100 acres 70 164 144 96 175 105
Table 11. Breeding population density of birds on the delta at the head of Lake McKerrow (Area 1), in the Hollyford Valley at Pyke Junction (Area 2), at the Spey River mouth (Area 3), at Deep Cove (Area 4), at Lake Monk (Area 5), and at the Jeanie Burn (Area 6).
Species (1) (2) (3) (4) (5) (6) (7) (8) 9 . (10) miles 8 5 4.5 6 5.5 1.5 miles 5.5 miles 2 miles 600-3, 50-4,000ft 1,200altitude 50-4,000ft altitude 3,000ft 0ft 3,200ft altitude 1.5 miles 2,2003,000ft 5.5 miles 2,400Oft 2 miles 1,2003,200ft Australasian 1(0.6) N.Z.Falcon 1(0.6) WekaWestern 2(1.0) 1(0.7) Pigeon 6(3.6) 12(6.9) 18(14.0) 1(0.5) 6(3.9) 1(3.1 3(1.7) Kaka 6(3.6) 5(3.9) 2(1.3) 4(2.8) 10(5.6) Kea 3(1.5) 4(2.6) 4(12.5) 6(8.7) 1(1.8) 1(0.6) 5(11.4) Parakeet t t 1(0.7) 4(2.3) Cuckoo 1(0.8) Long-tailed t t 5(7.2) 1(1.8) 4(2.3) 1(2.3) Morepork t 1(1.8) 86(42.6) 1(1.8) Rifleman 8(4.7) 7(5.4) 67(44.1) 7(10.1) 2(3.6) 59(33.3) 10(22.7) 86(42.6) 67(44.1) 7(10.1) 2(3.6) 59(33.3) 10(22.7) Rock Wren Fantail TitYellow-breasted Creeper Yellowhead 12(7.1) 49(29.0) 2(1.1) 30(17.2) 1(0.8) 21(16.3) 2(1.6) 18(8.9) 41(20.3) 5(2.5) 2(1-0) 9(5.9) 34(22.4) 2(1.3) 1(3.1) 8(25.0) 4(5.8) 1(1.4) 16(23.2) 1(1.8) 1(1.8) 6(10.9) 7(12.7) 6(10.9) 3(5.5) 3(1.7) 32(18.1) 3(1.7) 2(1.1) 9(5.1) 8(18.2) Grey Thrush* Song 7(4.1) 7(4.0) 1(0.6) 2(1.6) 1(0.8) 8(4.0) 7(4.6) 4(12.5) 2(2.9) 1(1.4) 1(1.4) 4(5.8) 1(2.3) Blackbird* Hedge Pipit Bellbird Tui 6(3.6) 1(0.6) 34(20.1) 21(12.4) 8(4.6) 21(12.1) 36(20.7) 11(8.5) 1(0.8) 15(11.6) 34(26.4) 19(9.4) 10(6.6) 4(12.5) 8(14.5) 2(3.6) 1(1.8) 3(1.7) 18(10.2) 1(2.3) 5(11.4) Silvereye 17(10.1) 50(28.7) / 4(4.7) 2(1.0) C 9(5.9) 17(24.6) 3(5.5) 15(8.5) Redpoll* Chaffinch* Yellow 1(0.6) 1(0.6) 3(1.7) 2(1.1) 4(3.1) 7(3.5) 8(4.0) 5(15.6) 5(15.6) 1(1.4) 11(20.0) 1(1.8) 8(4.5) 3(1.7) 11(25.0) 2(4.5) Total 169 174 202 129 152 32 69 55 177 44 202 152 32 69 55 177 44
Table 111 The number of birds recorded along the eastern shore of Lake McKerrow (1), the northern end of Lake McKerrow to Martins Bay (2), the Hollyford Valley (3), the Spey River to Wilmot Pass Hut (4), Deep Cove to Wilmot Pass Hut (5), Mt Grey (6), Mt Plaisted (7), the head of Lake Monk (8), the Jeanie Burn (9), and Jeanie Burn-Upper Big River Basin-Lake Monk West Saddle (10). Relative abundance is indicated as a percentage in parentheses.
Birds recorded in 10 observation periods in each count. (Birds recorded between periods in each count are in brackets.) Frequency of occurrence of species in 10 observation periods in each count. 1 2 3 Total A 1 2 3 Total . A S.I. Rifleman 1 1(1) 2(1) 2 1 1 2 2 Yellow-breasted Tit 7 4(1) 1 12(1) 20 6 4 1 11 20 Yellowhead 1(5) 2(1) 0(2) 3(8) 0 1 1 2 0 Grey Warbler 5 3(1) 8(1) 7 2 3 5 6 Song Thrush* 1(1) 1(1) 0 1 1 0 Blackbird* 6(5) 2(4) 3(4) 11(13) 3 4 1 2 7 3 Hedge Sparrow* 1 0(1) 1(1) 0 1 1 0 Silvereye 0 36 0 11 Redpoll* 2 1 5 8(0) 3 1 1 3 5 2 Chaffinch* 6(5) 4(4) 3(1) 13(10) 3 3 4 3 10 3 Total 23 (15) 19 (10) 17 (11) 59 (36) 74 (1) Grand Total 38 29 28 95 75 t3 t3 tl t7 t7
Table IV. Relative abundance of birds at the head of Lake Monk in January 1960, as obtained in three counts (1, 2,3) along a transect (approx. ¼ mile) in Nothofagus forest. Birds seen or heard were recorded during and between 10 observation periods of 5 minutes along the transect in each count. The frequency of occurrences was obtained from the number of periods in which the species was recorded. The sum of three counts made along the same transect in 1957 (April) by Turbott (Riney et al., 1959) is shown under A for comparison.
Number of Pairs Species Area 7 Area 8 Area 9 Area 10 (18 acres) (12 acres) (12 acres) (11 acres) Stewart Island Weka 3 N.Z. Pigeon 1 1 S.I. Kaka 1 1 New Zealand Parakeet 1 1 1 Yellow-crowned Parakeet 2 Long-tailed Cuckoo 1 1 Morepork 1 1 S.I. Fantail 2 1 2 Yellow-breasted Tit 1 2 3 3 Brown Creeper 7 Grey Warbler 2 2 3 3 Song Thrush* 1 Blackbird* 2 2 1 Hedge Sparrow* 1 1 Bellbird 3 1 4 2 Tux 15 5 1 3 Silvereye 2 1 Chaffinch* 1 1 2 2 Total 28 (9 spp.) 30 (14 spp.) 21 (12 spp.) 19(10spp.) spp.) 19 (10 spp.) No. pairs, 100 acres 156 150 175 173
Table V, Breeding population density of land birds at the Scenic Reserve of Oban (Area 7), on Ulva Island (Area 8), at the Freshwater River (Area 9) and at the Rakeahua River (Area 10), Stewart Island.
Species (1) Number of Individuals (2) (3) (4) Stewart Island Weka 1(4.0) N.Z. Pigeon 2(8.0) 1(5.6) 1(6.3) S.I. Kaka 1(4.0) 1(4.0) Parakeet 2(12.5) 2(8.0) S.I. Fantail 3(16.7) 2(12.5) 1(4.0) Yellow-breasted Tit 4(22.2) 5(31.3) 3(12.0) Stewart Island Robin 1(5.6) Grey Warbler 1(4.0) 4(22.2) 3(18.8) 4(16.0) Song Thrush* 1(5.6) 1(4.0) Blackbird* 2(8.0) 1(6.3) 1(4.0) Bellbird 1(4.0) 1(5.6) 2(12.5) 5(20.0) T ui 15(60.0) 2(11.1) 5(20.0) Silvereye 2(8.0) Redpoll* 2(8.0) Chaffinch* 1(5.6) Total 25 18 16 25
Table VI. The number of land birds recorded at Golden Bay (1), south side of the Freshwater River (2), Thomson Ridge (3) and Mt Rakeahua (4), Stewart Island. Relative abundance is indicated as a percentage in parentheses.
Number of Pairs Number of Individuals Species Area 11 Area 12 (54 acres) (17 acres) Area 12 (17 acres)(1) (1)(2) (2) Australasian Harrier N.Z. Pigeon 1 2 2(2.1) 7(6.5) Parakeet 2 1 4(4.2) 3(2.8) Shining Cuckoo 1 2(2.1) 1(0.9) Long-tailed Cuckoo S.I. Rifleman 4 23(24.0) 1(0.9) 2(1.9) S.I. Fantail 4 1 2(2.1) 2(1.9) Yellow-breasted Tit 9 3 7(7.3) 11(10.2) S.I. Robin 5 2 7(7.3) 8(7.4) Grey Warbler 5 2 8(8.3) 6(5.6) Song Thrush* 3 3 2(1.9) Blackbird* 4 3 2(2.1) 6(5.6) Bellbird 9 5 22(22.9) 9(8.3) Tui 2 1(1.0) 9(8.3) Silvereye 7 4 8(8.3) 39(36.1) Chaffinch* 5 2 8(8.3) 2(1.9) Total 59(13 spp. 30(12 spp.) ) 30(12 spp.)96 96108 108 No. pairs, 100 acres 109 188
Table VII. Breeding population density and relative abundance of birds in Lake Rotoroa area. Census at the mouth of the Sabine River (Area 12) and on the delta of the D’Urville River (Area 13), other counts in Nothofagus dominant forest along the Tiraumea Saddle Track (1) and podocarp dominant forest on delta (2). Relative abundance is indicated as a percentage in parentheses.
Number of Individuals Area 14 Area 15 (12 acres) Number (1) (2) 1958 1959 1960 1958-59 1959-60 1960-61 Species Area 13 (15 acres) Number of Individuals (1.) (2) 1 mile 2 counts in 1 mile 1958 (6 acres) { Area 14 1959 1960 (8 acres) (8 acres) Area 15(12 acres) 1958-59 1959-60 1960-61 Species N.Z. Pigeon 13(15 Area acres) 2 mile 22(5.1) in counts 6(8.3) 1 (6 acres) (8 acres) (8 acres) N.Z, PigeonMorepork 2 1 2(5.1) 6(8.3) 1 Morepork 1 1 1 Shining Rifleman 1 1 1 3(7.7) 2(2.8) 2 1 3 Rifleman Fantail 12 3(7.7)5(12.8) 2(2.8)2(2.8) 22 12 32 1 Fantail Tit 23 5(12.8) 13(18.1) 22 21 2 1 1 2 2 2 Yellow-breasted Brown Creeper 3 1 5(12.8) 13(18.1) 26 17 16 21 21 21 Brown Creeper Warbler Grey 13 3(7.7) 8(11.1)6(8.3) 61 71 6 1 12 12 11 Warbler Grey 2(2.8) 3 7 6 1 2 2 3 3(7.7) 6(8.3) 1 1 1 2 2 1 Thrush* Song Blackbird* 2(2.8) 3 7 6 1 2 2 1 1(2.6) 4 6 4 3 3 3 Blackbird*Hedge 11 1(2.6) 4 6 4 3 3 3 1(1.4) 1 1 1 2 1 Hedge Bellbird 15 1(2.6)13(33.3) 1(1.4)19(26.4) 1 1 1 2 1 3 5 4 6 5 5 BellbirdTui 5 1 1(2.6) 19(26.4) 3 5 4 6 5 5 Silvereye 2 2(5.1) 8(11.1) 2 4 3 1 3 1 Goldfinch* 1 1 Redpoll* 1 2 3 Chaffinch* 1 3 2 4 4 3 Total 23 (12 spp.) 39 72 27 (11 spp.) 41 (13 spp.) 38 (14 spp.) 21 (9 spp.) 25 (10 spp.) 21 (11 spp.) No. pairs, 100 acres 153 450 512 475 175 208 175 1 1(2.6) 5(6.9) TuiSilvereye 2(5.1) 8(11.1) 2 4 3 1 3 1 2 1 1 Goldfinch*Redpoll* 2 3 1 1 3 2 4 4 3 Chaffinch* Total 39 72 27 41 38 21 25 21 23(12 (13 spp.) (14 spp.) (9 spp.) (10 spp.) (11 spp.) (11 spp.) 153 450 512 475 175 208 175 No. pairs, 100 acres
Table VIII. Breeding population density and relative abundance of birds in Catlins forest (census at Papatowai, Area 13) and other counts at (1) Papatowai and (2) Mahaka, at Waimate (Hook Bush, Area 14), and at Dunedin (Sullivan Dam, Area 15). Relative abundance is indicated as a percentage in parentheses.
Species Mt 20/8/60 Enys 1/12/59 Evansdale 17/9/60 Trotter’s Gorge 18/4/59 Henley 8/3/59 Flagstaff 11/1/59 Maungatua 5/4/59 Silverstream 25/2/60 Ashley 2/12/59 Pigeon 1(2.9) 3(1.5) Kea 2(4.0) Rifleman 8(16.0) 3(7.5) 3(5.6) 3(12.5) Skylark* 2(5.7) 24(12.1) Fan 4(11.8) 8(14.8) 2(5.7) 2(1.0) 4(7.7) Tit 5(10.0) 1(2.5) 1(2.9) 1(1.9) 3(5.6) 3(8.6) 3(1.5) 3(5.8) Brown 8(16.0) 2(5.0) 4(7.4) 5(9.3) 3(1.5) 5(20.8) Grey 1(2.0) 5(12.5) 7(20.6) 2(3.7) 1(1.9) 4(2.0) 2(8.3) 2(3.8) Song 4(10.0) 1(2.9) 7(13.0) 3(5.6) 2(5.7) 2(1.0) 2(3.8) Blackbird* 4(10.0) 7(20.6) 4(7.4) 2(3.7) 2(5.7) 2(1.0) 1(4.2) 6(11.5) Hedge Sparrow* 2(4.0) 2(5.0) 3(5.6) 3(5.6) 16(8.1) 1(4.2) 2(3.8) Pipit 2(5.7) 6(3.0) Bellbird 5(10.0) 6(15.0) 4(11.8) 11(20.4) 3(5.6) 3(8.6) 10(5.1) 2(8.3) 3(5.8) Silvereye 8(16.0) 7(13.0) 2(3.7) 4(11.4) 53(26.9) 4(16.7) 8(15.4) Greenfinch* 6(11.1) 11(21.2) Goldfinch* 20(37.0) 4(11.4) 35(17.8) 4(16.7) 4(7.7) Redpoll* 7(14.0) 4(10.0) 10(28.6) 12(6.1) 2(8.3) 3(5.8) Chaffinch* 4(8.0) 9(22.5) 5(14.7) 7(13.0) 1(2.9) 7(3.6) 4(7.7) Hammer* Yellow 3(5.6) House Sparrow* 4(11.8) Starling* 15(7.6) Total 50 40 34 54 54 35 197 24 52
Table IX. Results of bird counts in various places in Canterbury and Otago. Relative abundance is indicated as a percentage in parentheses. Number of Individuals
Species 1958-59 Number of Pairs 1959-60 1960-61 Mallard* 0 (1) U Brown Creeper 0 1 1 Grey Warbler 2 3 4 Song Thrush* 16 18 19 Blackbird* 15 18 15 Hedge Sparrow* 5 5 4 Bellbird 6 5 6 Silvereye 12 13 13 Greenfinch* 1 2 1 Goldfinch* 3 2 2 Redpoll* 1 1 0 Chaffinch* 2 4 4 House Sparrow* t (17) t Starling* t (2) t Total 63 (10 spp.) 72 (11 spp.) 69 (10 spp.) No. pairs, 100 acres 525 600 575
Table X. Breeding population density of birds at the Botanic Gardens (Area 16, 12 acres), Dunedin. Mallard, House Sparrow and Starling are excluded from the total and the standard expression of the density.
Species Sept. Oct. Nov. Dec. Jan. Feb. Jan. Feb. Mar. April May June July Aug. Mar. April May June July Aug. Australasian Harrier x(l) N.Z. Pigeon XXX XXX XX XX X XXX XX XX X X XX XX Mallard* XX XXX XX Shining Cuckoo X XXX X N.Z. Kingfisher x(l) S.I. Rifleman x(l) S.I. Fantail X X X XX XXX XXX XX XX XX XX XX XX Yellow-breasted Tit XX X, x(l) x(l) Brown Creeper XXX XX XX X X XX XX X XX XX X Tui XX XXX X x(l) X X XX Greenfinch* XXX XX XX XXX XXX XX XX X X X XX Goldfinch* XX XX XX XXX XX X X XX X XX X Redpoll* X XXX XX XX XX X X X X
Table XI. Seasonal occurrences of less common birds in the upper part of the Botanic Gardens, Dunedin. x, xx, xxx indicate the occurrence of the species in the month for one, two, three years respectively; x(l) denotes one accidental occurrence of one individual. The area was visited 4—lß times a month each year for three years in the months September-February and for two years in the months March-August.
Height of Tree Species 5-10ft 10-15ft 15-20ft 20ft+ Leptospermum ericoides 0 0 2 59(4) Melicytus ramiflorus 26(2) 36(9) 51(6) 17(2) Myrsine australis 51(1) 43(10) 15(2) 2 Coprosma spp. 8 4 0 0 Pittosporum spp. 0 4(1) 2 5 Schefflera digitata 1 3(1) 0 2 Other Species* 7 2(1) 0 6
Table XII. Vegetation of a Leptospermum stand in the upper part of Botanic Gardens, Dunedin, which supported a large breeding population of Silvereyes, Blackbirds, Song Thrushes, and Greenfinches, and a few Chaffinches, Hedge Sparrows, Fantails, Grey Warblers, Bellbirds (in order of abundance). Figures indicate the number of trees in a belt transect (covering about one-third of the area) according to the species and the height. Trees with climbers are shown in parentheses.
Total BreedingNests Year(per pair) IViiTnhpr nf BreedingNumber of YearPairs Bred Total Number ofNests Pairs Bred(per pair) Number of Nests Found Successful Unsuccessful Number of Young Fledged (% of Adults) Song Thrush 1958-59 16 39(2.4) 13(32.8%) 26(67.2%) 36(112%) 1959-60 18 49(2.7) 20(40.8%) 29(59.2%) 60(167%) 1960-61 19 45(2.4) 19(42.2%) 26(57.8%) 57(150%) Blackbird 1958-59 15 24(1.6) 10(41.7%) 14(58.3%) 23(77%) 1959-6043(119%) 1959-6018 1837(2.1) 37(2.1)18(48.6%) 18(48.6%)19(51.4%) 19(51.4%)43(119%) 1960-61 15 27(1.8) 13(48.2%) 14(51.8%) 32(107%) Silvereye 1958-59 12 22 19(86.4%) 3(13.6%) 51(212%) 1959-6048(185%) 1959-6013 1322 2221(95.5%) 21(95.5%)1(4.5%) 1(4.5%)48(185%) 1960-61 13 24 22(91.7%) 2(8.3%) 50(192%) Bellbird 1958-59 6 8 5 3 12(100%) 1959-60 5 — 6 — 12(120%) 1960-61 6 — 6 — 13(108%)
Table XIII. Nesting success and productivity of common birds in the Botanic Gardens, Dunedin.
Blackbird Song Thrush Predation (eggs) 22(46.8%) 48(59.2%) Predation (nestlings) 1(2.1%) 8(9.9%) Desertion (eggs) 12(25.5%) 21(25.9%) Desertion (nestlings) 4(8.5%) 2(2.5%) Miscellaneous 8(17.1%) 2(2.5%) Total 47 81
Table XIV. Mortality factors in the total loss of eggs and young of the Blackbird and Song Thrush at the Botanic Gardens (1958-61).
Species Coastal Grassland and Rocks Habitats Urban Conifer District Farmland Plantation Habitats Subalpine Scrub and Alpine ConiferNative Meadow Farmland PlantationForest and Rocks Subalpine Scrub and Alpine Native Meadow Forest and Rocks Kiwi (3 spp.) X X Australasian Harrier X (x) X X X X N.Z. Falcon X Western Weka X N.Z. Pigeon (X) X X X Rock Pigeon* X X X S.I. Kaka X Kea X X N.Z. Parakeet X Yellow-crowned Parakeet X X Shining Cuckoo X X Long-tailed Cuckoo X Morepork X X S.I. Rifleman X X Rock Wren X Skylark* X X X X S.I. Fantail (X) X X X Yellow-breasted Tit (x) X X S.I. Robin X Brown Creeper (X) X X Yellowhead X Grey Warbler (x) X X X Song Thrush* X X X X X Blackbird* X X X X X Hedge Sparrow* X X X X X N.Z. Pipit X X X Bellbird (x) X X X Tui (x) (x) X Silvereye X (X) X X X Greenfinch* X X X X X Goldfinch* X X X X X Redpoll* X X X X X Chaffinch* X X X X X Yellow Hammer* X X X X House Sparrow* X X X X Starling* X X X X
Table XV. Habitats of common land birds in the South Island of New Zealand, x indicates general habitat, (x) winter appearances only.
Species Ground Tree Hollow, Under Rock Surface Log Shrubs & Small Trees Trees Trunk Canopy and and Main End of Branch Branch Hole Epiphyte and Under Exposed Bark Root Parasitic Kiwi (3 spp.) X Australasian Harrier X X N.Z. Falcon X X X X Western Weka X N.Z. Pigeon X X S.I. Kaka X Kea X X Parakeet (2 spp.) X Shining Cuckoo X Long-tailed Cuckoo X Morepork X X S.I. Rifleman X X X X Rock Wren X Skylark* X S.I. Fantail X Yellow-breasted Tit X X X X X S.I. Robin X X X X X Brown Creeper X X X Yellowhead X Grey Warbler X X Song Thrush* X X X Blackbird* X X Hedge Sparrow* X X X N.Z. Pipit X Bellbird X X X Tui X X Silvereye X X Greenfinch* X X X Goldfinch* X X Redpoll* X X X Chaffinch* X X Yellow Hammer* X X House Sparrow* X X X X Starling* X X X
Table XVI. Nest-sites of common land birds in indigenous habitats of New Zealand. Nest-sites
Nothofagus Dominant Forest Podocarpus Dominant Forest Low Hardwood Forest Indigenous Species Mean Range Mean Range Mean Range S.I. Rifleman 13.5 0-22 — (0-7) — (0-27) S.I. Fantail 2.9 0-7 10.3 0-18 — (0-27) Yellow-breasted Tit 23.3 7-35 18.7 5-27 — (0-18) S.I. Robin — (0-9) — (0-12) 0 Brown Creeper — (0-12) — (0-58) — (0-85) Yellowhead — (0-16) 0 — 0 — Grey Warbler 9.1 6-16 18.7 11-27 17.7 14-25 Bellbird 10.7 0-18 22.8 8-33 49.0 45-54 Tui — 0-35* 29.5 8-82 0 — Silvereye Naturalized Species 9.7 0-14 9.3 0-24 53.3 14-106 Song Thrush 3.9 0-10 4.5 0-18 78.0 14-148 Blackbird 9.0 0-23 10.3 0-18 74.0 25-134 Hedge Sparrow — (0-5) — (0-7) 19.7 9-39 Redpoll 6.7 0-30 0 — 11.0 0-27 Chaffinch 10.7 0-35 10.2 0-18 28.7 27-31
Table XVII. Breeding population densities of passerine birds (number of pairs per 100 acres) in three major forest habitats examined in the South Island. No means were calculated for the species that showed sporadic occurrences.
Species Clutch Size Laying Season Habitat Selection Rare or Near Extinct Species Saddleback 2-3 Oct.-Dec. Podocarp forest ? Kokako 2-3 Dec.-Jan. Podocarp forest (irregular) Piopio 2 Dec.- ? Podocarp forest ? of valleys (local) Species With Irregular Occurrences Brown Creeper 2-4 Oct.-Jan. Wide, but irregular Robin*Wide, now irregular Robin*2-3(4) 2-3(4)Oct.-Dec. Oct.-Dec.Wide, now irregular Yellowhead 3-4 Nov.-Dee. Nothofagus forest, irregular Common Species Grey Warbler 4(5,6) Aug.-Jan. Wide Fan 3-4 Sept.-Jan. Wide Yellow-breasted Tit 3-4(5) Sept.-Dee. Wide Silvereye 2-4(5) Sept.-Feb. Wide, forest edge Bellbirdf 3-5 Sept.-Jan. Wide Tui 3-4 Oct.-Jan. Podocarp forest Rifleman 4(5) Aug.-Dee. Nothofagus forest
Table XVIII. Comparison of breeding capacity and habitat selection between rare, irregular, and common species of passerines in the South Island of New Zealand (modified from Oliver, 1955, with the results of Potts, Buller, Fleming, and the present work).
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Transactions of the Royal Society of New Zealand : Zoology, Volume 7, Issue 17, 26 January 1966, Page 215
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28,294Population Distribution of Land Birds in Temperate Rainforest of Southern New Zealand Transactions of the Royal Society of New Zealand : Zoology, Volume 7, Issue 17, 26 January 1966, Page 215
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