Some Avifaunal Observations in the Vicinity of Hanasaki Harbor, Eastern Hokkaido

Abstract

Four trips to the easternmost part of Hokkaido for avifaunal observation were made in the vicinity of Hanasaki Harbor during three periods in summer and once in winter, i. e. 11-13th of June, 1964, 21st of July and 10-11th of August, 1965, and 11th of January, 1966. A total of 56 species of birds were recorded.Among them, Gavia arctica viridigularis, G. stellata, Melanitta nigra americana, Histrionicus histrionicus pacificus, Rissa tridactyla pollicaris, Larus hyperboreus pallidissimus and Uria lomvia arra, which had been reported as winter birds in Japan, were actually observed during summer time in the above area. One individual (sex unidentified) of Aethia psittaculus, hitherto recorded as stray birds in Japan, was also observed on the sea south of Moyururi Island.Though we had had no breeding record of Phalacrocorax urile in our country, excepting on the Islands of Yururi and Moyururi, two nests of this species with eggs were found each year on the coast of Hanasaki Bay. The nesting sites of Phalacrocorax pelagicus and Uria salge inornata were newly found in our survey area, i. e. on the Pacific coasts, although their breeding had been previously recorded only on the coasts of Japan Sea.On Kamoiwa Island the nesting sites of the birds belonging even to the same family were found fairly apart from one another and under quite different environmental conditions as follows: On the other hand, the birds of some different families, Larus schistisagus, Phalacrocorax capillatus and Uria salge inornata made a common, peaceful colony on top of the island.The number of sea-birds found around Moyururi Island appears to have steadily increased year after year during the past seven years.Brief discussions on some species, other than those mentioned above, were also made from zoogeographical and ecological points of view.