Great Basin Naturalist


Productivity and food habits of the Barn Owl (Tyto alba) utilizing nest boxes in Juab, Utah, and Salt Lake counties, Utah, During 1979–1984 were examined. Average clutch size was 5.8 eggs for the 6-yr period; mean number fledged was 3.9 young per successful nest. While severe weather during the 1981–82 winter did not result in significant decrease in productivity during the 1982 breeding season, it may have resulted in a significant overproduction of female young. Barn Owls in north central Utah fed almost exclusively on mammalian species, particularly Microtus spp. Difference in clutch size between areas and years may be a response to availability as well as abundance of prey.