After its half a century activity at Shibuya, Tokyo, the Yamashina Institute for Ornithology has been opened on 1 December 1984 at its new site near lake Tega, Abiko City, Chiba Prefecture. The lake Tega had been one of the four marshy lakes, Imba, Wada, Ushiku and Tega, which provided the most important winterquarters for waterfowl in central Honshu. Geese, the Bean and White-fronted, concentrated at lake Wada and ducks preferred Tega where joint duck-netting grounds existed since old tims. A pair of ducks caught were annually presented to Toyotomi and then Tokugawa Shogunates. The pochard, Aythya ferina was characteristic wintering species of the lake and many rare and accidental species of waterfowl had been obtained and observed, including Snow Goose, Canada Goose, Canvasback, Long-tailed Duck, Rudy Shelduck, etc. After the world war II, ducks were persecuted by indiscriminate gun-hunters and traditional netting came to the end. Moreover, main area of waterfowl resort was reclaimed for rice fields. However, remaining water surface is now protected from hunting and is still visited and inhabited by ducks, coots, moorhens and reed buntings, etc. The water pollution of lake Tega has been reputed as worst of lakes, but measures of water purification are being advanced. We saw and heard a green pheasant, an Ural owl and other birds in back-hill wood of new institute site, and it would be a tempting idea to have, in future, a waterfowl laboratory somewhere along the lake coast.
1973年7月10～24日の間アナディール湾とその周辺海域において行った海鳥目視観察から,アナディール湾におけるウミガラス類の生息数は357054羽(ウミガラス:302068羽,ハシブトウミガラス:54986羽)と推定した。また,上記海域で行なわれた14回のサケマス流し網試験操業時に混獲されたウミガラス425羽の胃内容物解析から食性を明らかにした。すべてのウミガラスの胃内容物重量組成は端脚類44.6%,オキアミ類31.3%,魚類18.3%,消化物5.5%,エビ類0.2%,イカ類0.07%,クラゲ類0.004%であった。端脚類はほとんどすべてがParathemisto libellulaであった。Ogi and Hamanaka(1982)により報告された同一海域におけるハシブトウミガラスの胃内容物組成を使用し,本報告で明らかにされたウミガラスの食性と比較した。因子分析結果から,ウミガラスはオキアミ類と魚類を多く捕食する傾向があった。一方ハシブトウミガラスは端脚類を多く捕食していた。しかし,索餌域に端脚類が卓越する場合には両種共端脚類を専食していた。