Studies on the Behavior of Wintering Geese

Abstract

(1) White-fronted (numbered 6, 000 in 1978) and Bean geese (numbered 1, 500 in 1978) winter in Lake Izunuma in Miyagi Prefecture. Lake Izunuma is now the only roosting place of geese on the Pacific coast of Japan. The authors studied the distribution of feeding area of the geese wintering at Lake Izumuna for eight years from 1971 to 1978. These geese feed chiefly in harvested paddy fields. This feeding habit is in contrast to that in England or other European countries where geese feed in arable lands and grasslands. (2) In ordinary years the feeding areas of the geese at Lake Izunuma is limited to the alluvial plains in northern half of Miyagi Prefecture. In years of heavy snow, however, they move to the areas with light snow for feeding, south to the southern part of Miyagi Pref. and the northern part of Fukushima Pref., sometimes reaching to the Kanto Plain which is three hundred kilometers south of Lake Izunuma. (3) The past history of decrease of the geese populations in Japan accounts for the present situation of the geese whose feeding areas are restricted to the Senpoku Plain in northern Miyagi Prefecture. Due to heavy hunting and gradual worsening of environments since the Imperial Restoration of Meiji, geese in Japan have lost their wintering grounds one by one from Kyushu to Kanto, namely from the south to the north, and today the Senpoku Plain has left as the last remained wintering place of geese on the Pacific coast of Japan. (4) The Feeding areas of White-fronted Geese and those of Bean Geese in the Senpoku Plain are separated topographically with each other. The feeding areas of White-fronted Geese are situated in the northern and the western parts of the Senpoku Plain and they are distributed along the middle to the upper reaches of the Hazama and the Naruse rivers. Bean Geese feed in the eastern and the southern parts of the Senpoku Plain, in which the feeding areas are located along the middle and the lower reaches of the Hazama, Naruse and Yoshida rivers. The two species were occasionally seen feeding together in the same field in a few districts, but such is rather rare.However, in the years of heavy snow and when the geese migrated to the south, they were more frequently observed to feed in mixed flocks. (5) The spatial separation of feeding areas of the two species may be due to their former habitats in their history, that is a habitual attachment for the former feeding sites ('traditional attachment'). The feeding areas of Bean Geese before the reclaim for fields are presumed to have been a vast marsh area, where the Been Geese could obtain water-chestnuts (Tarapa Linn.) and other aquatic plants. Water-chestnuts are growing over in marshes and must be a 'traditional diet' of Bean Geese in Japan.The reclaimed paddy fields supply a fairly good amount of paddy gleans for geese so that they still hold the habitual attachment to the places of the former feeding areas. In the case of White-fronted Geese, the 'traditional attachment' is also the main factor for separation of feeding areas from Bean Geese and the aquatic plant Makomo (Zizania Linn.) is supposed to be one of their 'traditional diet' in Japan.