Now that December is here, those of us who treasure all things wild witness a decided downturn in our local Sky Islands biodiversity. Fewer butterflies, and invertebrates in general, are around, and the majority of bats and neotropical bird migrants have traveled to warmer climes or, in the case of the former, are in hibernation. Where, then, to turn our curious naturalist gaze this month?
Well, December is prime time to observe and (more importantly) listen to the handful of owl species wintering in the Sky Islands.
The first owl I ever saw—and perhaps still my favorite species—is the great horned owl. It began my love affair with owls, prompting me to serve as a spotted owl researcher in three states. With a range stretching from Alaska to Tierra del Fuego, the great horned owl—our largest Arizona species—is familiar to most people. If you’ve seen or heard only one owl species, it is likely this ubiquitous “hoot owl.”
There may be no better month than December to stalk this nocturnal assassin. The leaves have fallen from most deciduous trees, making a sighting of at least the silhouette of this hefty owl more probable. Perhaps more importantly, this month sees great horns in courtship mode. The species is the earliest breeding bird in North America. The timing makes sense. By laying eggs in early winter, great horned owls ensure that their voracious young are born during a time of plenty in spring. Food abounds just when it is urgently needed.
Exhibiting what is termed “reversed sexual dimorphism,” great horned owl females are on average much bigger than males. Though weights vary greatly by geographic region and diet, females can average 3.5 pounds and males 3.0 pounds. Regardless of gender, these weights make the species the heftiest owl in the Sky Islands.
It also opens up a veritable feast for them in terms of prey. Though small mammals such as mice and wood rats tend to be staples, these powerful owls can tackle surprisingly large prey items. Squirrels of various species are a step up in prey size, but even an unwary common gray fox, ringtail, and other small predators—including other owl species—had better take heed when great horns are on the hunt.
Still not impressed? How about 20-plus pound Mexican wild turkeys dispatched on their roosts? Add in the very rare slaying of perched diurnal raptors, such as red-tailed hawks, and you begin to fathom the predatory prowess of these masters of the night sky.
One more unlikely prey item: various skunk species! Given the owl’s poor olfactory capacity, it seems these odiferous and seemingly impregnable carnivores have met their match.
Lest you think them invulnerable, great horned owls have evolved their namesake feather tufts—they are just that, and not ears or horns, which are located on either side of the head—in part to hide from predators by day. The same raptors they occasionally kill at dusk and at night are now a decided threat to their own lives in daylight. I’ve even found a bobcat-killed great horned owl at Raven’s Nest Nature Sanctuary—a case of an avian predator being one-upped by a feline one. Hence, all the better to break up your bodily outline via the so-called horns, as well as superbly cryptic plumage.
Another locally common species is the western screech owl, which resembles a severely shrunken version of a great horned owl. It too has “ear tufts” or “horns” for the same aforementioned survival purposes. Likewise, it exhibits reversed sexual dimorphism, with local females averaging about 5.1 ounces and males 4.2 ounces. Of course the prey of these diminutive owls is correspondingly small. Like their behemoth cousins, great horned owls, western screech owls will consume any plausible prey item small enough to overpower. Small mammals, small birds, and insects are all staples. They can even take down mallards and adult cottontails—again demonstrating the power of talons and beak to unwary, often dozing prey.
There are other owls a-wing in December. Barn owls using old buildings and caves as refuge. Wintering long-eared owls roosting sometimes by the dozens in evergreen trees and oaks. Whiskered screech owls barely breaking the international border into various U.S. Sky Island ranges. Northern pygmy owls hunting by day and dusk. Mexican spotted owls lurking in canyons or dense forests. Truly we host an impressive winter lineup of these “masters of the night.”
To enjoy various owl species, venture out about half an hour before dusk into prey-rich habitat. Sit quietly, in camouflaged clothing. Riparian areas, such as along Sonoita Creek, are prime owl-hunting grounds. Tote a pair of binoculars to try to tell owl from broken branch. Listen intently for the hooo-hoo-hoo-hooo of great horned owls, the plaintive toots of western screech owls, or the blood-curdling screeches of barn owls among others. Even if you fail to see or hear an owl, a sky strewn with stars and the quiet chill of a December night may well be compensation enough.
Vince Pinto and his wife, Claudia, run RAVENS-WAY WILD JOURNEYS, their Nature Adventure & Conservation organization devoted to protecting and promoting the unique biodiversity of the Sky Islands region. RWWJ offers a wide variety of private, custom-made courses, birding and biodiversity tours. Visit ravensnatureschool.org