Farmers provide homes for owls that control gophers
By Steve Adler
California Farm Bureau Federation
Mark Browning, left, of the Pittsburgh Zoo, is doing barn owl research in a 100-acre chardonnay vineyard near Sloughhouse. Vino Farms viticulturalist Chris Storm, right, said the field being studied has had problems with gophers. While most people are fast asleep in their beds, barn owls take to the air on their graveyard-shift patrol of farm fields in search of rodents, primarily pocket gophers in California’s agricultural areas.
The idea of utilizing barn owls for rodent control really took off in Israel in the 1950s, when farmers there installed owl boxes adjacent to their alfalfa fields. The concept is slowly catching on in the United States, thanks to researchers such as Mark Browning of the Pittsburgh Zoo.
Browning is a field researcher who currently has a project at Vino Farms, a winegrape operation with headquarters in Lodi. Working with Vino Farms viticulturalist Chris Storm, Browning and a group of University of California, Davis, students have erected 20 barn owl boxes along the perimeter of a 100-acre vineyard of young chardonnay grapes near Sloughhouse.
“We surrounded this field on three sides with nesting boxes spread 200 feet apart,” Browning said. “Within two weeks, we had signs of visitation in 19 out of 20 boxes: dirty claw marks around the entrance holes and the mulch scooted around. Two of the boxes had occupancy within the first two weeks, and we fully expect to get a good bit of occupancy this year and hopefully increase each spring until we get very high occupancy.”
The project is being supported by the Lodi Winegrape Commission and Pacific Gas & Electric Co., which has provided a $25,000 grant to provide free barn owl boxes to interested farmers. There are a limited number of free boxes available and priority is being given to replacing boxes currently installed on power poles.
The barn owl boxes, which were designed by Browning, are lightweight but very durable, and capable of withstanding adverse weather ranging from bitter cold to triple-digit temperatures.
Barn owls readily move into nesting boxes designed by Browning.
Browning shared his ideas with a group of Lodi-area winegrape growers last week at a meeting at the Lodi Grape Festival Grounds. After hearing his presentation, those in attendance received vouchers for the owl boxes.
Vino Farms, Storm said, supports research projects such as the one being carried out by Browning because the projects can benefit everyone, from the farmer to the consumer.
“The vineyard we are using is certified green through the Lodi Rules program, so putting up owl boxes and raptor perches made a lot of sense,” he said. “This was an ideal spot because we had barn owls already living in our nearby barn. So we thought this would be a good spot for the barn owls to begin moving into the field and start taking care of the gopher population that is really out of control.”
Browning noted that while the Lodi program involves winegrapes, the barn owl boxes would be effective in any farming operation—such as alfalfa or processing tomatoes—that has trouble with gophers.
“In warm weather, a barn owl adult will eat two rodents per night and in cold weather that increases to three or four per night. The babies eat a high number, anywhere from one per night when the chicks are just hatched to up to six per night when the young are about ready to fledge,” he said.
Browning noted that barn owls can hunt up to two miles from their nest, but that is extremely rare. They prefer to hunt as close as possible to their nesting box in order to conserve energy.
Barn owl nesting boxes line three sides of this 100-acre vineyard of chardonnay winegrapes near Sloughhouse. Owls started moving into the boxes within days of their installation.
“Barn owls are really unique; they aren’t like very many other raptors and each of these traits lends barn owls to integrated pest management,” he said. “For one, they tolerate the presence of other barn owls. Most other raptors are very territorial and they chase each other away all day long. Barn owls won’t bother each other and if indeed the food source goes down, one or more pairs will leave the area. Second, these birds can be attracted to nesting boxes, which other raptors won’t do.”
Another plus is that barn owls tolerate human activity.
Of all the owl species in the world, barn owls probably have the best hearing, Browning said, noting that the birds can actually hear gophers chewing on roots under the ground.
“Researchers have placed barn owls in a completely dark room with leaves on the ground and the barn owls were able to catch mice moving through the leaves nearly 100 percent of the time in total darkness,” he said.
Mike Best, PG&E avian protection program manager, said the utility supported the research because it provides a good opportunity for farmers to move forward in implementation of integrated pest management practices. At the same time, the utility company benefits by having previously-installed owl boxes removed from power poles.
“We have been working on this program for a few years,” Best said. “This is very unique and PG&E is one of the only utilities nationwide that is providing a service like this to growers. We are testing it out here to see how it works and hopefully we can implement this in other areas of our service territory.”
For more information on owl boxes, Browning maintains the following website: www.barnowlbox.com.
(Steve Adler is associate editor of Ag Alert. He may be contacted at [email protected].)
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