A Great Horned Owl appeared yesterday during the San Andreas Fault Tour. Craig, the guide on that tour, had the video camera ready as it took flight. Great Horned Owls are some of the earliest-breeding birds in North America. They breed in late January or early February and are often heard calling to each other in the fall, starting in October. They choose a mate by December and are often heard duetting before this time. For owls found in more tropical climates, the dates of the breeding season are somewhat undefined. They often take over a nest used by some other large bird, sometimes adding feathers to line the nest but usually not much more. Old crow and raven (Corvus), Red-tailed Hawk (Buteo jamaicensis) or large squirrel nests are often favored in North America. However, they are far from dependent on the old nests of others and may use cavities in trees and snags, cliffs, deserted buildings, and artificial platforms.

Great Horned Owl eggs, nestlings and fledgings may be preyed on by foxes, coyotes, or wild or feral cats. There are almost no predators of adults, but they may be killed in confrontations with eagles, Snowy Owls and, mostly, other Great Horned Owls.