Nestling barn owls can eat their weight in food every night. Young leave the nest at 9-12 weeks, after flight feathers develop. Barn owls hunt open fields, flying low over the ground in search of prey. Other studies have confimmed mice and shrews as this owl's main prey items. Small birds, insects, flying squirrels and rabbits occasionally are taken.
Females are slightly larger than males.
These owls hoot to stake out territory and as part of the species' mating activity, which in Pennsylvania takes place in December or early January. Great horned owls are believed to mate for life. They nest in crow, heron or hawk nests, tree cavities or hollow stumps and are the earliest nesters of all owls. A mated pair cleans debris from an appropriated nest, and the female then partly lines a central hollow with feathers. She lays two or three eggs at several-day intervals, usually in February, and may temporarily get covered with snow while incubating.