Hazel Grouse Bonasa bonasia group sizes and sex rations in Japan and Sweden

Abstract

The social behavior of Hazel Grouse (Bovasa bonasia) has been reported to vary geographically ; they form flocks in autumn and winter in Asia, but overwinter as pairs or singly in Europe. We compared seasonal group sizes and population structure in Japan and Sweden. Group size was statistically similar in both areas during all seasons except autumn, when it was smaller in Japan. Our results suggest a similar social organization in both areas, with loosely bound pairs and a male-biased sex ratio.