Some farmers are using bats to control nighttime flying insects such as moths, stinkbugs and naval orangeworm. Farmers encourage bats to establish residency on farms by building bat boxes. About 200 bats can pack themselves into a one square-foot space. Bats from a single colony can consume millions of insect pests each growing season. Vineyard and orchard owners are also using barn owls to keep rodent populations in check.
Farmers provide nests for owls on the perimeter of their property.
During the night and early morning hours, owls swoop down to feed on burrowing squirrels and gophers. Napa Valley grape growers have used predatory birds to control flocks of grape-eating starlings, finches and robins that move into vineyards when the fruit ripens. As grapes reach 15 percent sugar, the birds start to cause damage, but because wineries may not pick the grapes until more sugar develops, farmers need an effective way to control crop damage. Many growers use kestrels, also known as sparrow hawks, to keep unwanted birds away. Boxes built for kestrels, Western Bluebirds and red-tailed hawks help keep these vineyard sentinels on the job.