Quick! If I asked you to name the most abundant bird of prey in
the greater San Francisco Bay area, what would you reply?
You probably didn’t say Western Screech Owl. In fact, you’ve
probably never seen one, but they’ve most certainly seen you,
haunting the woods, fields and neighborhoods across the West each
night.
Quick! If I asked you to name the most abundant bird of prey in the greater San Francisco Bay area, what would you reply?
You probably didn’t say Western Screech Owl. In fact, you’ve probably never seen one, but they’ve most certainly seen you, haunting the woods, fields and neighborhoods across the West each night.
Western Screech Owls are one of several owl species that are common to our area. The one most people think of when they think “owl” is the Barn Owl, a pale, large bird that, true to its name, is comfortable in the company of people and their dwellings. Barn owls are frequent sights in the night sky, pale ghosts passing silently overhead. Their common call is a screech that sounds like steel plates being torn apart, a chilling eulogy for the rodents that make up much of their diet.
Most of our other owls are overlooked by nearly everyone, a consequence of their nocturnal habits, cryptic coloring and quiet nature.
Screech owls, for example, usually don’t screech. Their call is a quiet, almost musical tremolo rendered in a quickening tempo that’s been likened to the way a ping-pong ball dropped onto a table bounces. That, combined with their tendency to spend the day in a tree cavity, or on a branch napping next to a tree trunk, where they look far more like a chip of bark than a bird, means that most people will never encounter one.
But owls are worth seeking out. They’re fascinating both for their great diversity and for a variety of adaptations that make them the undisputed masters of the night sky. Owls nest in tree hollows or nest boxes, on the ground, or in unused hawk nests. Some migrate, and some are present in an area year-round.
They range in size from hawk-like to downright tiny (Another reason they’re overlooked by most people, who think “big”, when they think “owl.”). The Western Screech Owl is about as long as a Red-winged Blackbird, and another of our local owls, the Northern Pygmy-Owl, is even smaller, about the same size as the White-crowned Sparrows visiting local feeders now.
The Northern Pygmy is stuffed-animal cute, a tiny predator active during daylight hours in wooded areas. An indication that one may be nearby is the excited chattering of songbirds, which will sometimes “mob” this little owl to alert other birds of its presence. The fuss is justified, as these little owls will readily take prey much larger than themselves – birds as large as California Quail may be on the menu.
The feathers of owls are soft, the better to silence the wind as they fly. Their eyes are structured to permit vision in near dark, but their eyes are not even necessary during the hunt. A Barn Owl’s ears are located asymmetrically, giving it better binocular hearing. The heart-shaped facial disk of feathers acts like a satellite dish, catching and concentrating the faintest murmurs. Even with their vision obscured, Barn Owls can locate mice scurrying in a field.
The owl’s appetite for the small mammals that we commonly regard as pests is another reason to appreciate them. The large wooden boxes mounted on poles around several local farms are growers’ pesticide-free solution to gophers. At regular Barn Owl roosts in Hollister, there’s further mute evidence to their effectiveness at ridding us of mice, rats and gophers. Owls swallow their food whole. About six hours after eating, they regurgitate a neat pellet of indigestible material – fur and bones, mostly. If you can overcome your initial squeamishness, these pellets can be picked apart to reveal exactly what was on the menu.
If you’re interested enough to go out looking for owls on your own, there are better ways to increase your chances of success than just stumbling around in the dark. A bit of advance work is a good idea. Read a field guide to get an idea of the kind of habitat owls favor. Visit some likely spots, stop, and listen. Most owl calls are uncannily hard to locate. It can help to have a friend or two along, so you can triangulate toward the call. A flashlight, probing in the direction of the sound, will eventually reveal its source.
Tapes of birdcalls are widely available. Listening to the owl calls on one is useful in helping you determine what may be an owl, as opposed to something else going bump in the night. Many of those who regularly go out “owling” use taped calls to prompt a response from nearby owls. Tapes should be used judiciously, since the calls are a way of making a territorial claim, and their overuse is probably stressful to the genuine owls calling in your neck of the woods.
If all that sounds like a lot of trouble, one of our resident owls is still willing to oblige. The Burrowing Owl, a long-legged, modest sized owl of open areas, is frequently spotted perching near its underground home during daylight hours. Numbers of these birds continue to decline as their habitat disappears. Look for them wherever grass is cropped short and burrows abound. They tend to form colonies, so when you spot one, others are likely to turn up. Perched near the mouths of their burrows, they might be overlooked since they resemble ground squirrels with bad posture at a glance.
With luck, and more careful observation, Burrowing Owls will emerge, tawny streaked birds with dancer’s legs and the most unforgettable stare through pairs of large, brilliant yellow eyes.
Mark Paxton lives in Hollister and works in Morgan Hill. His e-mail address is [email protected].
