IN TOUCH WITH NATURE

Otago Daily Times, Issue 14465, 6 March 1909, Page 4

IN TOUCH WITH NATURE

ANIMAL MICIKATIONS. (By .Tajiks l)m'jisio.\n, F.T,.,5„ F.Z.S.)

The notes cm (hi! migrations of eels supplicd Ijy Messrs Bruce unci Perry .Smith lmvi! attracted a great, deal of attention Irom and investigators in many parts of New Zealand, and iri'-di information in regard to Ihe habits of pels him lici'ii brought forth. Mr \\. W. Smth, of New Plymouth, states that when he was curator of the. Pubic Oartlens in A.-hhurtim he. noted every year the migrations of the indigenous spirirs of eels, which passed through the lakes in the gardens on their way from the 'llnknmii, or north branch of the Aslibiirton Tiiver, to Ih« sea. He says that the litigatory or seaward movements down tho rivers and streams of Canterbury usually begin about tlie middle of April and continue until the end of .Tune. Al(lkiiijjli Mr iSmilli made a careful and detailed examination of the female eels, ho saw no signs of ova in any stage, and there was nothing to lead to a supposition (hat the fish were about, to spawn. They were all abnormally/ fat, and in most eases the stomach was empty, a condition usually attained by oilier species of fresh-water lish before suawjn'ng. Mr Smith found thai, the swamp eels, as well as the river eels, were also very fat and (lid not have any signs tin:l, they would spawn. lie says that eels sometimes remain fsr an indefinite period in lagoons, lakes, and rivers before migrating to sea to spawn. Ifc suggests thai thin is due to the nature of the seasons and to the. (piantily and nature of the food in respect to stimulating the breeding instinct.

"Wo know," Mr Smilh says, "that these strange lish frequently attain enormous size in lakes and lagoons that have safe and easy egress to large rivers and the sea ; but we cannot say whether or not tiny of llicsu monsters urn already sea-run fish. In regard to large eels observed migrating seawards in the autumn or winter, iL would bo an interesting experiment In have them captured and tail.ringed, or otherwise indelibly marked niltl liberated, in order lo enable observers to ascertain If they ever return to their old haunts, or if they are captured in other lakes or streams. Those who have opportunities for observation and experiment!! of this nature should undertake them, as the results would be of great .scientific interest and value. It would be an excellent experiment to capture a large number of eels in binakis, or eel basket-, during the summer months —especially in the deeper cel-frcquentcd inland streams.—and have them duly, hill: not cruelly, marked and carefully libcra'ed. When eels ascend or descend streams they usually keep close to the edge, and are therefore easily drawn into w.'ilcr nices or mill streams. If a series of these experiments were undertaken in some, streams or lakes different ' brands' would be required lo enable the eel, captors in future, years lo ascertain their originnl homes. Persons who have, small ponds of dear water could add largely to our knowledge o[ the habits of eels by experimenting in feeding them and observing their rate of growth and longevity. l''ow lish are more interesting, or afford a better subject for original work, than eels; and they are not- by any means the repulsive creatures they are generally believed to be."

Mr W. M. D. Homes, of Albany, writes that bis observation!! show that eels do not always go lo Ihe sea to spawn. In pools in tho solid rock some distance above a waterfall there is a slimy water-weed, and from it small fry, about as Jong as an ordinary pin, and no thicker, can bo squeezed out villi the hand. The fry are miniature counli'i'pai'ls of full-grown eels. How, he asks, can such small fry climb falls 18ft or 20ft high? Shortly before he wrote his letter, on February 7, ho tested the pools, and in five niinutes lie disturbed a dozen or more of these fry. Ho lias caught largo :els at' different seasons of the year, and has never known a dearth of them, and therefore concludes (hat they do not migrate. Mr A. M'Kechnie, of .Ifcnloul street, Wellington, slates that when lie resided in the Tokomairiro district, in Otago, some 50 years ago he and his brother often went on tho Tokomairiro Diver to spear flounders. One day when they were eight miles up the river from the sea, they found in the sand, which was covered by shallow water, large numbers of young eels. The eels were from an inch and a-half to 4in lon«, and there seemed lo bo three sizes of them,

Mr W. Yv'. Smith points out, that eels on these seaward journeys are not impelled by Iho snme instinct that sends birds and insects in flocks and swarms to different parts of the country in search of food. There have been some extraordinary migrations of- New Zealand birds, uosides the movements of the godwit, tho cuckoos, and other annual migrants. Several irruptions of parrakeets have been noted. The last, as far as records show, occurred in 1888, 'when large numbers of these birds visited the towns and villages of tho West Coast of the South Islam", and also some of the settled parts of Canterbury, Mr 'Smith, .who made observations 'at the time, attributes (his disturbance in Nature to a- partial or total failure of the food supplies of the specie.-, affected. .This theory is supported by the miser'ably lean and starving condition of the birds when they first arrived at any district, and by the poor condition of their plumage, and the presence of many parasites on their bodies. There was nil alisence of berries in the birds' original districts, and they went, further afield to 'find other supplies. Insectivorous birds are affected by the same cause. A season of scanty blooms produces a scarcity of insects, and the birds' supplies of insect, food decrease. The kaka, the tui, and the bell-bird, which arc honey-suckers, also suffer when their houcy-hearing dowers in the spring and summer fail llicm.

Mr Percy Smith states that he recorded a strange migration in New Plymouth of a moth, ilelanolora composita, at to lipgimiing of March of last year. The, summer was a very hot one in the district, with a severe drought in Taranaki until the middle of February. Heavy rains I hen set in, and they moistened the .stu-baked soil and enabled the moths to emerge from their prolonged term in the chrysalis staec. "About "the beginning of March," .Mr Percy Smith says, "while sitting at a window in uiy stndy at 2 p.m., I noticed an extraordinary flight of moths coming from the west and Hying against a gentle easterly wind. I estimated that there was one modi to each 10 cubic feet of air, and the flight was at least 40ft deep and 100 yds wide. They spread out as fains I t'oiikl s;e thrin, in fact, Tho flight continued the whole afternoon tip to 6 o'clock. The numbers, therefore, must have been prodigious. For some weeks previously there bad been a great abundance of these moths, so much so that they were quite a nuisance, setting in at the open windows and Hying about the lamps. About the same time I noticed in town that the light of the arc-light lamps was to a certain extent obscured by great numbers of the same, species of moth, which continued to circulate around (he lamps to a width of 20fi- or more."