Farmers Enlist Barn Owl in War on Gophers

From the perspective of a pitiful pocket gopher, the barn owl must seem like the perfect killing machine.

Consider:

The owls see prey in the dark from several hundred feet away.

They can hear a mouse munching on a seed or pushing through dirt from a similar distance.

Their bones are hollow and their feathers light, allowing them to soar in total silence.

“It’s like a ghost owl flying by,” said Tom Hoffman, who grows wine grapes in Lodi. “That’s until they let out a screech that jars your nerves.”

Hoffman is one of many people in the San Joaquin Valley who in recent years have learned the value of the raptors in fighting public enemy No. 1 for the region’s growers, the pocket gopher.

While gophers certainly play an important role in native ecosystems, they’re tough on a farm. Of their many crimes, the two worst are gnawing holes in irrigation lines and killing trees and crops by chewing on their roots. Both can lead to costly losses.

Farmers have long relied on several strategies to exterminate gophers, including the flooding of fields, trapping and the use of poisons called rodenticides. All are expensive and time-consuming, and the use of poisons is frowned upon by conservationists and many farmers.

Weary of the never-ending war on the gophers, several growers in the late 1980s decided to use nature as a weapon.

Enter the barn owl.

Native to much of the United States, the owls nest in cavities of dead trees, cliffs and buildings--thus the species’ name. Because the owls have no fear of people, farmers have learned that erecting a suitable nesting box is a sure way to attract the birds.

Before long, area farmers were finding impressive piles of gopher bones, skulls and fur near the nesting boxes, the indigestible material that owls cough up in pellets. Word of mouth about this new form of pest control spread quickly.

Today, nobody knows precisely how many valley farms have owl boxes, but the consensus is that there are many. And there is no shortage of testimonials from growers.

Ed Rocha, an almond grower in Newman, said: “As soon as it starts getting dark out, they start leaving their boxes. I take my grandkids out to watch them.”

Hal Carlton, an almond grower and dairy farmer in Hughson, said: “We have four lagoons, where the waste water goes from the dairy cows. We put an owl box near each one, because if a gopher digs a hole in the side of the lagoon, we’ve got a big-time mess.”

Justin Pareira, who grows alfalfa, oats and corn in Merced said that “I had someone come over to bale my hay and he said, ‘Your fields sure are clean. There’s no gopher holes.’ I said, ‘It’s the owls.’ ”

The owls have become so popular that an owl box building boom is underway. Hoffman, the Lodi grape grower, is building more than 500 of them each year and said he can barely keep up with orders.

The undisputed champion of owl boxes, however, is Steve Simmons, a shop teacher at Merced High School. In the last five years, Simmons’ students have made and sold more than 7,000 boxes to area farmers, most of them constructed from scrap wood.

Money from the sales goes to a scholarship fund students can use for college or vocational school. Overall, $125,000 in profit has been generated from the boxes.

Simmons, by his own admission, is a “wannabe wildlife biologist” and spends a good chunk of his time catching and banding barn owls, which allows him to track how young owls disperse in the valley and colonize new boxes.

“One of the things in California and across the nation is that, when a tree dies, people cut it down,” Simmons said. “These birds are desperate for places to nest. If you increase the number of nest sites, the food base is there.”

Barn owl numbers have plummeted in many parts of the country, including the Midwest. The cause is twofold. The rodent population has fallen due to annual plowing of fields for crops such as corn and soybeans, and many old structures preferred by the owls have been razed.

In the San Joaquin Valley, though, the boom in owl boxes has resulted in more barn owls than ever.

Which brings us to the question: Will the owls eat all the gophers?

Probably not.

Predators rarely eat their prey into extinction. When prey numbers get low, predators often move elsewhere or switch to another food.

There are also more gophers than ever, as year-round irrigation in the fields provides the little beasts with constant grass to chomp. More food means more offspring, and a female gopher can produce 20 young in a year. Most are doomed to a premature and grisly death by predators, but the few that survive reproduce on a scale that would impress even a rabbit.

Just how effective, then, are the owls at gopher patrol? Studies have shown owls can certainly eat a lot of rodents--there’s evidence that an owl family can easily dispatch 1,000 gophers in a year, plus assorted voles, mice, shrews and moles.

Still, there’s no scientific proof that owls can completely control a farmer’s rodent problem, said Dirk Van Vuren, a professor of wildlife biology at UC Davis. He thinks the owls are a step in the right direction, but will probably have to be used in combination with other tactics, including limited use of poisons.

“Personally, I think what makes the whole thing worthwhile is that farmers are providing habitat for wildlife,” Van Vuren said. “And I like the fact that the use of the boxes was initiated by the growers. They weren’t forced to do it by a judge or the law.”

There is another reason that barn owls are not always the perfect solution.

In the oaks and willows that fringe San Joaquin Valley fields, there lurks another killer waiting for the cloak of darkness.

When a barn owl leaves its box for its own nightly escapades, all it takes is one moment of carelessness for a great horned owl to swoop down, its talons slamming shut in a show of who’s really in charge.