Lesser White-fronted Goose Anser erythropus at Sarobetsu in northern Hokkaido, Japan: a preliminary report on numbers in autumn

抄録

Lesser White-fronted Goose Anser erythropus is recognized as a globally threatened species. Very small numbers stage and winter in Japan, mostly individually, as families or sometimes in small flocks. Since beginning to observe this species in 2001 at Sarobetsu, northern Hokkaido, Japan, we have noted increasing numbers. The increase, from a few individuals (2001–2004) to flocks (2005–2007), is of interest, given the threatened status of this species. Lesser White-fronted Goose now regularly migrates through Sarobetsu, giving us opportunities to observe this relatively rare winter visitor to Japan. In order to help clarify the status of this threatened species in Japan, we describe and discuss the change in numbers, the proportion of juveniles in flocks, family size and length of stay.