The great horned owls are super predators. They are the single most successful predator on the planet Earth and can live as long as 28 years. Their talons are the dangerous thing, with five hundred pounds per square inch of pressure that they can exert on their prey; similar to a golden eagle, or to that of a German shepherd’s bite. The great horned owl is a genuine avian apex predator, which hunts and kills at least five hundred known species of creatures. They have the most varied diet of all North American raptors, they will hunt; voles, moles, shrews, mice, rats, gophers, chipmunks, squirrels, woodchucks, marmots, prairie dogs, bats, skunks, house cats, porcupines, ducks, loons, mergansers, grebes, rails, owls, hawks, crows, ravens, doves, starlings, reptiles, insects, fish, invertebrates, and sometimes coyotes and other raptors (other owls). The great horned owl can kill and fly off with prey more than twice its own body weight, and even were the victim is too big for the owl to fly off with, it will get a bellyful on the ground. The only time that this raptor is in real danger is when it is feasting on the ground. These monogamous birds start courting in October, make decisions by December, and then are mated for life.
http://www.delta-optimist.com/opinion/blogs/blog-the-super-predator-the-great-horned-owl-1.2351353