Sexes usually form separate flocks in winter. In Massachusetts, predation exerted greatest influence on productivity; in Minnesota, winter conditions and resulting pre-breeding female condition were important factor in productivity (Vander Haegen et al. 1988). In southeastern Oklahoma, mean seasonal home range sizes for adult females were 225 ha (winter), 865 ha (spring), 780 ha (summer), and 459 ha (fall) (Bidwell et al. 1989). Home range in Montana was 260 to 520 hectares (Jonas 1966). In Colorado, adult males moved an average distance of 5.3 km from winter ranges to spring breeding areas; subadult males moved an average distance of 8.7 km; in spring males moved about 1000 m between morning and evening roosts used on the same day (Hoffman 1991). In north, deep snow restrict movements.