Great horned owls feed primarily on small- to medium-sized mammals, birds, reptiles and amphibians. Rabbits and hares are statistically the great horned owl's most frequent prey. Rodents, rats, squirrels, mice, lemmings and voles are also devoured regularly.
Studies have shown that nocturnal creatures are preferred by great horned owls, as the birds are also primarily nocturnal. The great horned owl is capable of preying on creatures two to three times heavier than itself. According to About.com, they are the only animal that regularly feeds on skunks, although not exclusively.
Great horned owls often feed on adult and nestling American crows. For this reason, they are often attacked by crows as a preventative measure. Peregrine falcon and osprey nestlings are also eaten by great horned owls. It is common for the great horned owl to pluck birds before eating them, which involves tearing off and discarding portions of their wings and legs.
The great horned owl supplements its diet with fish, crustaceans, insects, centipedes, earthworms and scorpions. Domesticated animals, such as small dogs and cats, are also targeted by great horned owls. Because the great horned owl is a natural predator to so many creatures, it is common to see plastic replicas of them in areas where there is troublesome wildlife.