How Farmers Can Use Birds To Control Pests

With the right kind of landscaping, farmers can turn birds from foes into friends.

Western Bluebird, photo by Mick Thompson

By Sierra Dawn McClain
Published in the Capital Press

Across the West, farmers and researchers are learning to design habitats around crop fields that attract beneficial bird species while reducing crop damage and food safety risks.

“We don’t grow produce in an enclosed, hospital-like setting. You’re going to have species on the farm. Birds will be there. But if you maintain the right kind of habitat, that’s going to influence the kinds of species you find in the field … species of higher conservation concern, that damage crops less often and are less likely to carry food-borne diseases,” said Daniel Karp, associate professor of wildlife, fish and conservation biology at the University of California-Davis.

Studies show farms with natural habitats experience the most benefits from birds, while farms that remove non-crop vegetation face higher levels of crop damage and foodborne pathogens.

Swainson's Thrush eating elderberry, photo by Mick Thompson

Primarily insect-eating bird species often need natural habitats nearby to survive, said Karp, while invasive species that travel in large flocks and gobble up crops can thrive on mono-cropped landscapes without habitat.

Insect-eating birds that forage in canopies are also less likely to carry foodborne pathogens and come into direct contact with produce, while invasive species that flourish in open spaces, such as blackbirds and starlings, are more likely to transmit pathogens.

Jo Ann Baumgartner, executive director of Wild Farm Alliance, a nonprofit promoting farm biodiversity, said farms with habitats also give birds more food options.

“Birds are just looking for something to eat,” she said. “If you have nothing out there but the crop, birds will eat that.”

This was confirmed in a 2022 study by UC-Davis conducted across 21 strawberry fields, which found that birds ate more berries on farms without natural habitats.

Models from another study, published by the Ecological Society of America in 2020, indicated that adding natural habitat can decrease a farm’s crop damage costs by 23%, while removing natural habitat can increase costs up to 76%.

Trying to attract beneficial birds might seem to contradict best practices for food safety, but experts say that is not the case.

In 2006, officials traced a high-profile outbreak of E. coli in bagged spinach to wildlife along California’s Central Coast. Produce buyers subsequently pressured growers to minimize wildlife intrusion on their farms, including by removing habitats.

More recently, Karp and other researchers have found that birds are less responsible for spreading foodborne pathogens than once thought.

One study, involving 11,000 bacteria tests of wild bird feces, found pathogenic E. coli and Salmonella in only 0.5% of samples.

A third pathogen, Campylobacter, can be more conclusively traced to birds, as the bacteria was present in 8% of samples.

However, Karp said it is not clear if this strain can make people sick.

Research has also found that the presence of pathogens in feces depends on the bird species, with the risk being higher in invasive species that flock near livestock.

Baumgartner and Karp said farmers may still need to protect crops during harvest from birds by using sound boxes, scarecrows and netting, but Karp said the key message is that strategic habitat creation can be “a win-win for birds and farmers.”