Election Section

In Defense of the Sometimes Annoying Barn Owl By JOE EATON Special to the Planet

Tuesday October 25, 2005

I don’t usually do advocacy; sitting back and watching things go to hell is more my style. But with Halloween approaching, it seems like an auspicious time to make a pitch for the barn owls of Berkeley. 

All owls are somewhat uncanny, and barn owls, with their ghostly heart-shaped faces and rasping cries, are more so than most. Having one fly into your headlights on a back road in south Texas can be an unsettling experience, one that both the owl and I survived. 

Particularly in England, a lot of odd notions have accrued around the barn owl: familiar of witches, harbinger of death, forecaster of hailstorms. It shows up as a bird of ill omen in Shakespeare, Milton, Byron, and Keats. There is also the old belief, current in the Ozarks until fairly recently, that owl eggs are an infallible cure for alcoholism. 

The real bird behind the myths is a pretty neat creature, and I’ve touched on some of its attributes in an earlier column. The placement of its ears and its neural architecture allow it to hunt in total darkness by triangulating on high-frequency sounds. For years, barn owls brought in to a wildlife rehab program in Fresno that were too badly injured to be released were sent to Stanford for acoustical research, ultimately leading to the development of the human cochlear implant. 

Barn owls, unusually for birds of prey, don’t seem put off by the human presence. Cavity-nesters in the wild, they’ll use man-made structures or ornamental street trees. They seem to have a particular liking for palms, nesting up inside the fronds. According to Cathy Garner, who runs that Fresno program, the scarcity of barns and dead trees has prompted more and more barn owls, rural and urban, to switch to palms. Several of the Berkeley nest sites I’m aware of are in palm trees, usually of the Canary Island date variety. 

Unfortunately for the owls, some Berkeley property owners have decided they don’t want them in the neighborhood. This year alone, two palms that historically hosted owl nests have been felled—one near Bancroft and Edwards, another on Curtis—and there may be more that I haven’t heard about. Some of the responsible parties have claimed liability concerns, but I suspect the real reason is the noise: young owls can make quite a racket when begging for food, and keep it up most of the night. 

Why should anyone tolerate such a nuisance? I would submit that the barn owl’s services as a predator—a rodent control agent—far outweigh the short-term annoyance factor. Barn owls specialize in small rodents, of the field mouse size class; they’ll also take shrews (which are not strictly speaking rodents), young rabbits, and the occasional bird or reptile. Unlike great horned owls, they would be unlikely to go after a house cat. Proportions of prey species vary from habitat to habitat, but a Louisiana study reported that house mice made up 15 per cent of the diet of the local owls, with non-native rats accounting for another 5 percent. 

You can tell what a barn owl has been eating by teasing apart the pellets it coughs up and going through the skeletal remains. It’s harder to quantify the bird’s appetite. I’ve read that a Lord Lilford—not a Harry Potter character but a real British peer—had a tame barn owl that would take mice from his hand. He once fed the bird nine mice at one sitting, then, after a three-hour breather, four more. That may still stand as the individual mouse-eating record.  

Consumption peaks when a barn owl pair is raising its family. An owlet can eat its weight in mice in one night—and before it fledges, its weight will have overshot the typical one-pound bulk of an adult. The only calculation I’ve been able to find of how this would translate into rodents was done by Bruce Colvin, based on his field work in Ohio and New Jersey: a brood of six (not unusual for these prolific birds) can consume 600 field mice in the 10 weeks it takes them to become independent and begin hunting on their own. 

Without knowing the barn owl population of Berkeley, it’s hard to extrapolate further. But I have a feeling there are more than enough mice and rats to go around. Brown and black rats thrive in beds of ivy. A couple of years ago, an ivy-removal project I was involved with on the west side of town prompted complaints from neighbors about a rat invasion. They didn’t invade; they had just been rendered visible. And as for mice—the mice that once ate all the labels off my wine bottles, the mice that twice have bedded down inside my stove—well, don’t get me started. If you bake a lot, you don’t want stove mice. You think moose turd pie is unappetizing? Try mouse pee pie. And my associate Matt the Cat is an abject failure as a mouser. He’ll go as far as pointing them, but he leaves the dirty work up to me. 

So we do need those owls. And I’m happy to report that Lisa Owens Viani, Berkeley writer/editor/naturalist, is launching a pro-owl organization called Keep Barn Owls in Berkeley. Her goal is to educate palm-tree owners about the benefits of having owls as neighbors. (Nest boxes are actually safer than palm trees, which the nestlings have a tendency to fall out of; we’d like to see more of the boxes that went up at Cesar Chavez Park some time back). If you’re interested in helping, e-mail Lisa: lowensvi@earthlink.net. Or contact me via the Daily Planet. ›