Spacing Pattern, Habitat Use and Survival of Capercaillie in a Fragmented Winter Habitat

Abstract

Habitat, spacing pattern and survival of Capercaillie Tetrao urogallus were studied in southeast Norway during the winters 1981-87 using 65 radio-marked birds. Adult males (>3.5 yr) preferred old, pine-dominated forests close to their lekking grounds. Subadult males (0.5, 1.5, 2.5 yr) and females (>0.5 yr) were distributed more independently of leks and utilized middle-aged (>7 m) pine plantations besides older, natural forest. Spruce-dominated forests and younger plantations were avoided by all sex/age groups. Home range size of subadult males (98.4 ha) was significantly larger than that of adults (63.5 ha) which was significantly larger than that of females (26.8 ha). During late winter (1 Mar 15 Apr), adult males concentrated within 400 m of leks, subadult males occupied the peripheral zone between 400 and 800 m of leks, and most females stayed further than 800 m away from leks. When leks were only attended by subadult males, such males concentrated within 400 m of lek centres, thus further suggesting that adult males exclude subadults from the vicinity of leks in late winter. Hens retreated to interlek regions with low male density, possibly to avoid male courting interference. Males in highly fragmented habitats stayed farther away from their lekking grounds than males in less fragmented areas during midwinter. Birds living in highly fragmented habitats had larger home ranges and lower survival than other birds.