Art. XXIII.—The Geographic Relationships of the Birds of Lord Howe, Norfolk, and the Kermadec Islands.

Transactions and Proceedings of the Royal Society of New Zealand, Volume 44, 1911, Page 214

Art. XXIII.—The Geographic Relationships of the Birds of Lord Howe, Norfolk, and the Kermadec Islands. By W. R. B. Oliver. [Read before the Auckland Institute, 28th November, 1911.] Whether the main islands of New Zealand, together with certain outlying islands, be considered entitled to the full rank of biological “region,” or only that of “subregion,” will not affect the contention which the evidence assembled in this paper is held to support—namely, that the three groups of islands lying to the north of New Zealand (Lord Howe, Norfolk, and the Kermadecs) should be included within that region. It can be said that conclusions drawn from the study of one class of animals may not be trustworthy, and should be checked by conclusions deduced from a consideration of other classes. There can be no questioning the truth of this statement, and I would go even further, and say that the claims of a district on the border-line of two biological regions to be included in any one of such regions should be decided upon an examination of the whole of the fauna and flora of the district in question, together with a consideration of its geological history. In most cases this is not practicable, and in this paper I will deal principally with the avifauna of Lord Howe, Norfolk, and the Kermadec Islands, only referring incidentally to other sections of the fauna or to the flora, and endeavour to point out its true relationship to those of the adjacent biological regions. In treating of islands, the real test for deciding to which region they should be attached is to consider the evidence in favour of a land connection with a part of the region within the bounds of which it is claimed they should be included. If the probabilities are that the islands have never been actually joined to a land-mass, then the character of the fauna and flora must decide. But here certain life-forms, such as pelagic species, need not be taken into account, except as characterizing a province or subregion. Again, the presence of such a group as “accidental visitors” may be due merely to climatic conditions, and cannot be held to ally one fauna to another any more than the occasional occurrence of a stray royal spoonbill or pelican in New Zealand allies the avifauna of that country to that of Australia, for species of birds cannot often be dispersed by such accidents. From a geographical standpoint, the birds of a district may be arranged according to their life-forms or manner of occurrence into groups. The ecological groups into which I have divided the birds of Lord Howe, Norfolk, and the Kermadec Islands, and whose numerical strength in these islands is shown in the following table, would not necessarily be the most useful to adopt when treating the avifauna of a large area, but are, I think, the most convenient for the purpose of this paper. Ecological Group. Lord Howe. Norfolk. Kermadecs. Resident land-birds—Breeding 15 19 6 Sea-birds—Breeding 8 11 12 Visitors—Sea-birds 6 5 10 Migrants 11 7 8 Occasional 13 6 4 Accidental 8 5 3 Totals 61 53 43

Resident land-birds are the most important from a geographical point of view, as they alone include species whose presence can only be accounted for by a former land connection. The group sea-birds includes forms which habitually frequent the open sea, but does not include coastal genera, such as Larus and Phalacrocorax. Those breeding in the islands are chiefly circumtropical species, and of no value in determining the geographic relationships of the avifauna, as their presence depends mainly on the latitude of the place. Migrants, especially if occurring regularly and in large numbers, are important as indicating the line of a former land connection.* Hutton, Trans. N.Z. Inst., vol. 5, p. 235. Occasional visitors are those which regularly visit the islands, or have frequently been recorded. They probably belong to species which are in the habit of wandering far from their ordinary breeding-places, and possibly frequently cross and recross the Tasman Sea. Most of them are fairly widely distributed; ranging from the Malay Archipelago through Australia to New Zealand. Accidental visitors are stragglers (and I have included doubtful records under this heading). I wish here to acknowledge my indebtedness to Mr. Basset Hull's valuable paper on the “Birds of Lord Howe and Norfolk Islands,”† Proc. Linn. Soc. N.S.W., vol. 34, p. 636. from which, mainly, the list of birds inhabiting those islands, together with other information, have been taken. By searching through the British Museum “Catalogue of Birds” I have added a number of other records, and the lists have been added to from other sources. In the list of birds of the Kermadec Islands there appear the names of six species not hitherto recorded from the group—Prion desolatus, Sterna bergii, Tringa canutus, Oestrelata macroptera, Sula leucogaster, Phalacrocorax sulcirostris. For three of these I have to thank Mr. T. F. Cheeseman, F.L.S., who kindly supplied me with a list of the skins in the Auckland Museum collected by Mr. R. S. Bell on Sunday Island. Of the fourth—Oestrelata macroptera—dead specimens were found by myself in 1908 washed up on the beach in Denham Bay, Sunday Island. A dead specimen of Sula leucogaster was found on the beach in Denham Bay by Mr. R. S. Bell previous to my visit, and the same observer states that a small number of Phalacrocorax sulcirostris once made their abode on Sunday and Macaulay Islands, staying for some years. They, however, failed to establish themselves. Lord Howe Island. Of fifteen species of resident land-birds breeding in the island, twelve (including Aplonis fuscus, which occurs also on Norfolk Island) are endemic. The affinities of the peculiar forms are mainly with New Zealand and New Caledonia. Species related to New Zealand forms are Nesolimnas sylvestris, Notornis alba and Cyanorhamphus subflavescens; those related to New Caledonian forms are Turdus vinitincta and Aplonis fuscus. The two species of Gerygone are allied to forms in New Zealand and New Caledonia, while the Lord Howe and Norfolk Island species of Zosterops belong to a group occurring in New Zealand, New Caledonia and adjacent islands, and Australia. The remaining three endemic species—Ninox albaria, Rhipidura cervina, Pachycephala contempta—are probably related to Australian forms. Numerically the Australian, New Zealand, and New Caledonian elements in the endemic birds of Lord Howe Island are about equal, or overwhelmingly in favour of a New

Caledonia — New Zealand migration as against an Australian immigration. The two flightless rails turn the balance in favour of New Zealand. The distribution of the three resident land-birds not peculiar to Lord Howe Island shows but a slight excess of Australian immigrants over others. Strepera graculina extends to Australia, Halcyon vagans to New Zealand, while Chalcophaps chrysochlora (perhaps introduced) is found in Australia and New Caledonia. Eleven migrants have been recorded from Lord Howe Island, some of which occur regularly in considerable numbers. Two are cuckoos, the rest Charadriiformes; all have been recorded in New Zealand, and all except Eudynamys taitensis in Australia. It is evident that the island is in the line taken by these species on their migration to and from New Zealand, and thus probably on an old land-line stretching northwards from New Zealand. Of the thirteen occasional visitors which have been recorded in Lord Howe Island, all are found in Australia, ten extend to New Zealand, and eleven to New Caledonia or Malaya. The proximity of the Australian Continent to Lord Howe Island and the direction of the prevailing winds (westerly) in the south-west Pacific is sufficient to account for the preponderance of Australian forms in the accidental visitors to the island. Of the eight recorded, only two extend to New Zealand. The large proportion of endemic forms in the resident land-birds of Lord Howe Island points to the long period the island has been an isolated spot. The existence of two brevipinnate rails belonging to genera found elsewhere only in New Zealand is sufficient proof of a former land connection with that country. That there was also land connection to the north, whence these birds probably came, is indicated by the large proportion of endemic Lord Howe Island land-birds which are allied to New Caledonian forms. Corroborative evidence of a land bridge between New Caledonia and New Zealand is furnished by the presence in Lord Howe Island of the large land-mollusc Placostylus.* Hedley, Proc. Linn. Soc N.S.W., vol. 7 (1892), p. 335.. It would be over this bridge that the large portion of the New Zealand fauna and flora showing Malayan affinities migrated. As the two flightless rails mentioned above are closely allied to New Zealand forms, it is probable that the land bridge was severed in the north before the connection with New Zealand was broken. Lord Howe Island would therefore properly belong to the New Zealand biological region. Australia can have no claim whatever to include Lord Howe Island within its regional limits, as a permanent ocean-basin separates the island and continent, and what birds of Australian origin are found in Lord Howe Island have crossed the intervening tract of ocean, yet in spite of the proximity of the continent have not outnumbered the New Caledonian and New Zealand forms except in those groups which I have designated occasional and accidental visitors. Norfolk Island. There are twelve endemic species of land-birds (including Aplonis fuscus). Of these, four—Hemiphaga spadicea, Nestor productus, Cyanorhamphus cooki, Gerygone modesta—are related to New Zealand species; two—Rhipidura pelzelni, Pachycephala xanthoprocta — to Australian species; four—Petroica multicolor, Diaphoropterus leucopygius, Turdus fuliginosus, Aplonis fuscus—to New Caledonian species; and there are two species of Zosterops. Numerically the New Caledonian element predominates,

and, as with Lord Howe Island, the species of this and the New Zealand element together far outnumber those of the Australian section; but again the presence of such important genera as Nestor and Hemiphaga turns the scale in favour of New Zealand. Of the seven resident land-birds not peculiar to the island, one—Halcyon vagans—extends to New Zealand; two—Platycercus elegans (perhaps introduced), Ninox boobook—to Australia; while the remaining four are found in both these countries. Australian forms are thus scarcely in excess of others. The migrants recorded include the same two species of cuckoo as occur in Lord Howe Island, and five Charadriiformes, two of which are said to be plentiful at certain seasons of the year. Here again an old land-line is indicated. All the occasional visitors to Norfolk Island occur in both Australia and New Zealand. Of the five accidental visitors, all are Australian forms, of which three have been recorded from New Zealand as stragglers, and one—Herodias timoriensis—is resident there. There are no species of birds in Norfolk Island whose presence demands that the island should at one time have been connected with a large land-area; nor, as far as I am aware, are there any other members of the indigenous fauna or flora of the island whose presence cannot reasonably be attributed to dispersal by their own means or by accident across a narrow sea. At the same time, as the avifauna shows similar characteristics to that of Lord Howe Island—namely, by its large proportion of endemic land-birds and strong New Caledonian — New Zealand affinities — it is evident that both islands received their first land-birds about the same time and by the same route. It seems most probable that at the time Lord Howe Island was actually part of the land bridge stretching northwards from New Zealand, Norfolk Island was a detached islet lying off the east coast of the land, and thus received its fauna and flora across a narrow strait. The present contour of the ocean-floor lends support to this view, as Norfolk Island is completely surrounded by deep water—over 1,000 fathoms—while Lord Howe Island lies in comparatively shallow water on the western edge of a submarine ridge stretching from New Zealand to New Caledonia. For reasons of like origin and characteristics the avifaunas of Lord Howe and Norfolk Islands proclaim that both islands must be included in the same biological region, and their relationships as detailed above decide this to be the New Zealand region. Kermadec Islands. The conspicuous feature of the avifauna of the Kermadecs is its paucity of land-birds, and what few occur there are of a decided New Zealand character. There is practically no Australian element represented. The migrants include the two cuckoos mentioned above as occurring in Lord Howe and Norfolk Islands, and six Charadriiformes. None occur in any great numbers; thus their presence affords but little indication of the island lying in an ancient land-line. If a large area of land ever existed in this direction, it disappeared before the present islands came into existence.* Trans. N.Z. Inst., vol. 20, p. 161; vol. 43, p. 531. The occasional and accidental visitors are all common New Zealand species, and all except Anthus novae-zealandiae occur also in Australia. The Kermadec Islands are of a typical oceanic character—that is, they were formed by volcanic action in mid-ocean, and have been populated

entirely by trans-oceanic migration. The land avifauna and flora are unmistakably closely allied to those of New Zealand, so that the islands fall. naturally within the New Zealand biological region. The marine fauna has affinities with that of Polynesia. An explanation of this meeting of New Zealand land species and Polynesian marine species may lie in the fact that during the winter months, which cover the period when plant-seeds are being dispersed, the prevailing winds in the Kermadecs are from the south-west, while during the summer months, when the free-swimming larval forms of marine animals are abundant, the prevailing winds are from the north-east. The Lord Howe — Norfolk Island Province and the Kermadec Islands Province. Having shown by an analysis of their avifaunas that Lord Howe, Norfolk, and the Kermadec Islands fall within the limits of the New Zealand biological region, it remains only to consider whether they form one or more provinces or subregions of that region. The avifaunas of Lord Howe and Norfolk Islands are undoubtedly closely allied. Of the resident land-birds two species are common, to which must be added the endemic species of four genera — Gerygone, Cyanorhamphus, Turdus, Zosterops—having representative forms in each island. Most of the sea - birds (breeding), migrants, and occasional visitors are common to the two islands, but, from the manner of their occurrence, this is not the case with the accidental visitors and the sea-birds (visitors). With regard to the six resident land-birds of the Kermadec Islands, all except Prosthemadera novae-zealandiae are identical with or closely allied to species in Norfolk Island or Lord Howe Island. But of resident land-birds in Lord Howe or Norfolk Islands found also in the Kermadecs the proportion is very low, so that the fact that five-sixths of the Kermadec land-birds are related to species found in Lord Howe and Norfolk Islands merely shows that in all probability, as with the plants, some of the species in the Kermadecs which occur in both New Zealand and Norfolk Island have arrived from Norfolk Island direct. The sea-birds (breeding) and migrants chiefly belong to the same species as occur in Lord Howe and Norfolk Islands. The occasional and accidental visitors, like the resident land-birds, are very' few, a fact which can be explained by the isolated position of the islands. The three islands therefore fall naturally into two biological provinces. One includes Lord Howe and Norfolk Islands, and is characterized by an avifauna containing four main elements: (1) an original element which includes the species which came by the ancient New Caledonia - New Zealand land bridge (majority of resident land-birds); (2) Australian and New Zealand species arrived subsequently by trans - oceanic migration (some of the resident land-birds and all the visitors except migrants); (3) circumtropical species (sea-birds, breeding); (4) migrants. The Kermadec province contains only — (1) New Zealand (and Norfolk Island) species arrived by trans-oceanic migration; (2) circumtropical species (sea-birds, breeding); (3) migrants. Although the important and characteristic element circumtropical species is common to the three islands, and, in the case of plants, formed the basis of my subtropical islands province,* Trans. N.Z., Inst., vol. 42, p. 155. I think now, on a consideration of the avifauna, that a more

natural arrangement is to keep the Kermadec Islands separate from Lord Howe and Norfolk Islands. The two avifaunas (and floras) will thus be grouped naturally according to their origin and characteristics. The following is a list of species of birds arranged in groups according to their manner of occurrence:— Lord Howe. Island. Resident Land-birds—Breeding. Chalcophaps chrysochlora. Nesolimnas sylvestris. Notornis alba. Ninox albaria. Cyanorhamphus subflavescens. Halcyon vagans. Gerygone thorpei. G insularis. Rhipidura cervina. Turdus vinitincta. Pachycephala contempta. Zosterops tephropleura. Z. strenua. Aplonis fuscus. Strepera graculina. Sea-birds—Breeding. Puffinus sphenurus. P carneipes. Oestrelata montana. Sterna fuliginosa. Procelsterna cinerea. Anous stolidus. Sula cyanops. Phaethon rubricanda. Visitors—Sea-birds. Majaqueus aequinoctialis. Prion desolatus. Anous leucocapillus. Fregata ariel. Phaethon lepturus. Sula leucogaster. Visitors—Migrants. Arenaria interpres. Charadrius dominicus. Numenius variegatus. N. cyanopus. Erolia aurita. E. ferruginea. Limosa novae-zealandiae. Tringa canutus. Gallinago australis. Chalcococcyx lucidus. Eudynamya taitensis. Visitors—Occasional. Porphyrio melanonotus. Charadrius bicinctus. Notophoyx novae-hollandiae. Nycticorax caledonicus. Anas superciliosa. Phalacrocorax sulcirostris. P. melanoleucas. Circus gouldi. Eurystomus pacificus. Cuculus inornatus. Cacomantis rufulus. Coracina robusta. Grallina picata. Visitors—Accidental. Phaps elegans. Himantopus leucocephalus Herodias timoriensis. Ardetta pusilla. Astur novae-hollandiae. Haliaetus leucogaster. Haliastur sphenurus. Chelidon neoxena.

Norfolk Island. Resident Land-birds—Breeding. Hemiphaga spadicea. Hypotaenidia philippensis. Porzana plumbea. Porphyrio melanonotus. Ninox boobook. Nestor productus. Platycercus elegans. Cyanorhamphus cooki. Halcyon vagans. Petroica multicolor. Gerygone modesta. Rhipidura pelzelni. Diaphoropterus leucopygius. Turdus fuliginosus. Pachycephala xanthoprocta. Zosteropa caerulescens. Z. albigularis. Z. tenuirostris. Aplonis fuscus. Sea-birds—Breeding Puffinus sphenurus. P. assimilis. P. griseus. Oestrelata philippi. Sterna fuliginosa. Procelsterna cincrea. Anous stolidus. A. leucocephalus. Gygis alba. Sula cyanops. Phaethon rubricauda. Visitors—Sea-birds. Oestrelata macroptera. Puffinus cerneipes. Megalestris antarctica. Sterna albistriata. Ossifraga gigantea. Visitors—Migrants. Arenaria interpres. Charadrius dominicus. Numenius variegatus. Glottis nebularius. Limosa novae-zealandiae. Chalcococcyx lucidus. Eudynamys taitensis. Visitors—Occasional. Charadrius bicinctus. Notophoyx novae-hollandiae. Anas superciliosa. Phalacrocorax sulcirostris Euryatomus pacificus. Circus gouldi. Visitors—Accidental. Himantopus leucocephalus Platalea regia. Herodias timoriensis. Larus novae-hollandiae. Astur approximans. Kermadec Islands. Resident Land-birds—Breeding. Prosthemadera novae-zealandiae. Halcyon vagans. Cyanorhamphus cyanurus. Anas superciliosa. Porzana plumbea. ? Hemiphaga novae-zealandiae.

Sea-birds—Breeding. Sterna fuliginosa Gygis alba. Anous leucocapillus. Procelsterna cinerea. Phaethon rubricauda. Sula cyanops. Puffinus sphenurus. P. assimilis. Oestrelata cervicalis O. neglecta. O. nigripennis. Visitors—Sea-birds. Daption capensis. Diomedea exulans. D. melanophrys. Phoebetria fuliginosa. Pelagodroma marina. Sula leucogaster. Puffinus tenuirostris. Fregata aquila. Prion desolatus. Oestrelata macropteras. Sterna bergii. Visitors—Migrants. Charadrius dominicus. C. veredus. Tringa canutus. Numenius variegatus. Erolia aurita. Limosa novac-zealandiae. Chalcococcyx lucidus. Eudynamys taitensis. Visitors—Occasional. Circus gouldi. Zosterops caerulescens. Anthus novae-zealandiae. Phalacrocorax sulcirostris. Visitors—Accidental. Hypotaenidia philippensis. Porphyrio melanonotus. Demiegretta sacra.