Feeding Ecology of Snowy Owls ( Nyctea scandiaca) Wintering in Southern Alberta

Abstract

Food habits, habitat selection, arid hunting behavior of snowy owls (Nyctea scandiaca) wintering near Calgary, Alberta were investigated during the winters of 1976-77 and 1977-78. The owls preyed extensively upon rodents. Gray partridge (Perdix perdix) were an important prey only in one winter. Dietary differences between years seem to be related to differences in weather. Male snowy owls preyed almost exclusively upon mice, whereas females utilized a wider range of prey, including much larger species. The owls appeared to respond to variation in habitat quality by selecting those habitats with the highest availability of prey. Snowy owls were successful in 43% of 51 attempts to capture prey. The success rate of attempts to capture birds, was lower than for small mammals. Juvenile females had lower success rates and longer prey-handling times than did adult females.