Bonasa umbellus

Dense forest with some deciduous trees, in both wet and relatively dry situations from boreal forest (especially early seral stages dominated by aspen) and northern hardwood ecotone to eastern deciduous forest and oak-savanna woodland (AOU 1983). Young forest provides optimum conditions. See Crawford (1986) for additional information on habitat and cover requirements. Nests in forests or woodlands with some deciduous trees. Nest usually at base of tree, bush or stump. Drumming areas and broods usually in areas with high density of woody stems. Broods select habitats with abundant ground cover. In Wisconsin, females nested in areas in which they wintered following natal dispersal (Small and Rusch 1989).

Population densities may fluctuate dramatically. Some populations exhibit an approximately 10-year cycle of abundance. Spring density generally about 2-10/40ha; fall density up to 20-55/ha; densities highest in boreal forest region (Crawford 1986). Good habitats support densities better than 1 breeding male per 8 ha (Atwater and Schnell 1989).

Home range of brood about 6-19 ha, averages about 16 ha (40 acres). In Missouri, mean home range of adult males was 104 ha in fall-winter, 67 ha in spring-summer (Thompson and Fritzell 1989); Crawford 1986 reported examples of male and female home ranges that ranged from 2-12 ha. Mature and some immature males may defend a territory.

In Wisconsin, juvenile females in fall dispersed average of 4.8 km to winter range, males 2.1 km; in other areas dispersal distance often less than 2 km; juvenile males may wander extensively in spring (Small and Rusch 1989).

Usually roosts in small groups in winter. Fox predation often is an important cause of nesting failure. Other important predators include great horned owl and, in north, goshawk. In Alberta, predation by great horned owl declined when snowshoe hares were abundant (Rusch and Keith 1971). Shallow snow cover or icy crust on snow may reduce survival in winter by precluding access to subnivean shelter.

Drumming and mating peak in mid-March in Missouri, early April in Indiana, and late April in Minnesota, early May in far north. The first eggs are laid in April or May, depending on the location (latitude). Clutch size is 4-19 (generally 9-12). Incubation, by female, lasts 23-24 days. Nestlings are precocial, downy; can fly in 10-12 days. Young are tended by female. Broods break up in fall when young about 84 days old; young disperse (Terres 1980), at about 120-125 days in Wisconsin (Small and Rusch 1989). In Alberta, about 50% of young survived from fall to spring (Rusch and Keith 1971). Single-brooded, but females may renest of first nesting attempt is unsuccessful. Sexually mature in one year; uncommonly lives more than 5 years. Cold wet weather in May/June may cause high losses among broods.