Great horned owl USFWS photo by Gary M. Stolz. Mountain bluebird USFWS photo by Dave Menke. Great horned owls hunt rabbits and rodents on canyon rims at night. Their prey eat nuts, seeds and berries – of pinyon, juniper, and Gambel oak trees and serviceberry and other shrubs prevalent on canyon rims. Its disc-shaped face channels sound waves to the owl’s ears – slits at the side of its head, not those feathers atop it. Great horned owls are year-round residents because rabbits and rodents stay active in winter.