As dusk descends on the Anza Valley, insistent “whhooo, whooos!” can be heard echoing through the still air. These are the haunting calls of the male Great Horned Owl.
According to the Audubon Society, “The Great Horned Owl is in many ways the quintessential owl. Picture an owl in your head, and you’ve probably imagined the Great Horned. It is a large, thick-bodied bird with large eyes and two distinct tufts on its head. It is relatively common throughout California and North America. You can find this owl in all kinds of habitat – deserts, forests, meadows, wetlands, grasslands, even backyards. It is equally capable of attacking larger birds and mammals, as it is of smaller prey, such as mice or insects.”
The Great Horned Owl, Bubo virginianus, is the Valley’s most common year-round owl resident. It lives in all types of woodland and in any open scrublands, and Anza provides good habitat.
These interesting birds are among the earliest nesting birds in North America. The courtship and territorial establishment runs from October to December, and mates are chosen by December to January.
The owls do not build their own nests, but make it their mission to commandeer the abandoned nests of other large birds, such as common raven and red-tailed and red-shouldered hawks – in trees, cliff ledges or even buildings or bridges.
Great Horned Owls begin nesting in midwinter – as early as late January, occasionally even earlier – enabling them to get a head start over other species that might want to reuse the nests. Their courting and territory-defending hoots can be heard at all hours of the night until dawn.
Local owl expert and educator Dominique Rauton said, “Great Horned Owls are mostly nocturnal hunters, but will also hunt during the day in winter. They are strictly carnivorous animals and will eat any creature that moves. They cannot lift more than their body weight, therefore a four-pound animal is the maximum they can lift. Their wingspan can be up to 5 feet.
“The females are larger than the males. They mate for life, and while the female sits on the eggs, the male will bring food to her and protect them from other predators,” Rauton said.
The chicks are born virtually naked and completely helpless and are tended to by their parents until they fledge and learn to fly.
“Owls are large birds,” Matthew L. Miller said in his science blog, “The Hooting Season: Enjoying Great Horned Owls.”
“It takes them longer to grow and mature than, say, a songbird,” he said. “Young great horned owls must also master complex hunting maneuvers. They are equipped with superb senses – researchers have found that a great horned owl can hear a mouse rustling at 900 feet – but hunting still involves learning, trial and error.
“Early hatching means they’re ready to practice their flying and hunting skills when the weather is mild and prey is abundant,” Miller said.
Owls of any species are valuable controllers of rodents, from squirrels and rats to mice and gophers. The use of rodent poisons are detrimental to these birds, as the poison is transferred from prey to the end predator. Dead birds are reported every year as a result of eating prey that has been poisoned.
Like other nocturnal birds, the owls are more apt than diurnal or daytime species to be struck by cars, so increasing traffic threatens them. Otherwise, their numbers appear to be thriving.
Enjoy the hooting, and know these interesting birds are on patrol helping control damaging pests, as they prepare for another season raising chicks.
Diane Sieker can be reached by email at dsieker@reedermedia.