2000 Volume 48 Issue 3 Pages 219-232
Inter-annual variability of the numbers of Anser fabalis middendorffii (AFM) in northern Shiga Prefecture was investigated during 1982-97 in relation to the temperature, snow-depth and water level of Lake Biwa.Statistical analysis showed: 1) a strong negative correlation between the numbers and winter temperature in northern Shiga Prefecture, in which the temperature represented the average temperature and snow cover extension in Japan; 2) a negative correlation between the numbers and water level; and 3) abnormal heavy snow fall in Shiga Prefecture, such as in 1983/84, caused a decrease of the numbers. The results indicate that nation-wide cold winter with extensive snow cover induced southward migration of AFM to increase their numbers in Shiga Prefecture. Besides, due to poor feeding conditions, the AFM moved to the neighboring inland areas in case the water level of Lake Biwa increased.