On the migration course of geese wintering at Lake Izunuma

Abstract

The total number of wild geese migrating to Japan in recent years is estimated as about 6, 000-7, 000 and about two-thirds of them used to winter at Lake Izunuma, situated in the northern part of Miyagi Prefecture, Honshu.In January 1973. our bird census at Lake Izunuma revealed a flock of 3, 000 White-fronted Geese (Anser albifrons), 230 Bean Geese (Anser fabalis) and 3 Aleutian Canada Geese (Branta canadensis leucopareia (Brandt)). The majority of them had started from there to northward flight late in February. The junior author and Akio Watanabe observed early in March on paddy field at Hachirogata, about 2, 000 White-fronted Geese, 155 Bean Geese and 2 Aleutian Canada Geese. Hachirogata is located at the north-western part of Akita Prefecture, Tohoku district of Honshu, having an area of 22, 000 ha, and had been known as wildfowl resort since ancient days. Fifteen years ago, Hachirogata became reclaimed by drainage and now changed into large paddy fields.Our attention was directed to the appearance of Aleutian Canada Geese at Hachirogata. Since, the Aleutian Canada Goose is a rare bird, we concluded that the flocks of wild geese accompanied by 3 Aleutian Canada Geese had migrated from Lake Izunuma to Hachirogata on the way of north ward migration.Next year in 1974 we noticed the same phenomena, as listed below:Observed at Lake Izunuma Jan. Mar. 1974 (Most abundant number) White-fronted Goose … 4, 493 birds Bean Goose … 307 Aleutian Canada Goose … 2 Lesser Snow Goose … 1 Observed at Hachirogata Mar. Apr. 1974 (Most abundant number) … 3, 600 birds … 550 … 2 … 1The Lesser Snow Goose (Anser caerulescens caerulescens (L.)) is also a rare bird and one wintering individual of this bird was recorded at Lake Izunuma during winter of 1974. It disappeared from Lake Izunuma on 24th of March and found at Hachirogata on 28th of the same month.The straight distance from Lake Izunuma to Hachirogata is about 170km and between the two places there are Oh-u mountain range and Mt. Kurikoma (1, 628m above the sea). In order to veryfy our presumption that wild geese fly along this straight line crossing over Oh-u mountain range to Hachirogata, we tried to obtain the informations by questionnaire to the villagers, farmers and hunters living beneath this flyway, whether they had seen wild geese passing high overhead on their way. We have collected 20 evidences that have witnessed passing wild geese within a period from autumn 1973 to spring 1974, and 29 persons answered that they had sighted during last sixty years passing flocks of wild geese high up in the sky.The migration course of wild geese has been hitherto supposed to be: (1) from Hokkaido southwards to Honshu, (2) across the Japan Sea to coastal prefectures in Japan, (3) along the Korean Peninsula to western Japan. Among them the first route, namely from Hokkaido to Honshu, is divided into two ways at Tohoku district (North-East District of Honshu), one way of which goes southward along the Pacific Ocean coast, and the other along Japan Sea coast, thus the the two ways run parallel and never meeting each other.But, we have added a crossing flyway from Pacific coast resort at Lake Izunuma to Hachirogata on Japan Sea coast, passing over Oh-u mountain range lying between them.