Characteristics of hazel grouse Bonasa bonasia distribution in southern Korea

During October 1998 ‐ May 1999, we studied the distribution of hazel grouse Bonasa bonasia and the structure of their habitats in southern Korea. Hazel grouse were censused from the responses to calls imitated using a Scandinavian metal hunter's whistle in winter and spring along line transects. Hazel grouse were distributed in most of the high mountain forest areas in southern Korea. The frequency of occurrence varied with altitude within the range of 300–1,200 m a.s.l., with the highest density at 600–900 m a.s.l. Altitudinal distribution differed between seasons, however, and hazel grouse were observed at lower altitudes more often in winter than in spring. They occurred in mixed, deciduous and coniferous forest areas, but the use of forest types varied by season. Particularly many individuals were observed in planted Japanese larch Larix leptolepis forests. The coverage and density of understory vegetation was more developed where hazel grouse were observed, but coverage more than 2 m above ground did not seem to be important in explaining hazel grouse presence. The occurrence of hazel grouse was related to the development of understory vegetation more than to forest type. Seasonal use of forest types may have been related to the combined availability of food and cover in understory vegetation.