Falcons help keep bird poop off your delicious cherries
Nobody wants poop on their cherries. Northern Michigan farmers could get help on this fecal matter from some feathered allies. Small hawks called American kestrels help deter small birds that like to munch on the fruit as it grows. By chasing cherry-pecking birds, these birds of prey prevent them from contaminating crops with their droppings. The results are detailed in a study published on November 27 in the Journal of Applied Ecology.
American kestrels are the smallest species of hawk at only nine inches from head to tail. They live throughout North and South America. During their flight, they hover in the air while scanning the ground for insects, mice, and small birds to eat. Eating these little birds could help keep crops clean of excess bird droppings, which can contaminate fruit with pathogens that make people sick.
“It’s difficult to keep birds away from crops,” Olivia Smith, study co-author and agroecologist at Michigan State University, said in a statement.
Other methods of keeping unwanted birds away from crops include scarecrows, sprays, nests and noisy devices. These approaches can be expensive and do not always produce excellent results. According to the team, even with control measures in place, sweet cherry growers in Michigan, Washington, California and Oregon can lose between five and 30 percent of their crops each year to contamination.
In this new study, the team was curious if encouraging these predators to patrol orchards could help reduce risks. They installed nest boxes in eight cherry orchards in northern Michigan. Kestrels use tree cavities and other small spaces to raise their chicks and were quick to take up residence in orchards. They then took note of all the bird species they could see and hear as harvest time approached in July.
When kestrels flew nearby, blackbirds, grackles and starlings were much less likely to visit orchards and eat fruit. By scaring away these visitors, kestrels have increased the risk of damage to cherries more than tenfold.
When it came to other birds’ droppings, the team found fewer signs that they were doing their business on the cherry trees. Kestrels have been linked to a three-fold reduction in droppings spotted on tree branches.
The team noted that, of course, kestrels also poop, but the number of fruit-eating birds they keep away from an orchard makes up for that. The team found that cherry trees closer to kestrel nest boxes were less likely to contain droppings.
Olivia Smith/Michigan State University.
DNA analysis revealed that 10 percent of the feces contained Campylobacter. These bacteria commonly cause foodborne illnesses. However, the team says none of the foodborne illness outbreaks caused by Campylobacter have been linked to cherries and it may be too early to blame contaminated crops entirely on birds. Only one home was assigned to the birds. In 2008, a Campylobacter an outbreak linked to migratory cranes has been reported in pea fields in Alaska.
The study still suggests that kestrels could be a way to improve the food security of other crops associated with disease outbreaks, such as leafy greens.
“They are really good at reducing the amount of poop,” Smith said. “This means less opportunity for transmission.
Smith added that this won’t solve all the bird problems farmers face, namely that kestrels are more likely to stay in some areas than others. However, it could still help keep these crops clear and healthy.
“Certainly kestrels poop too,” said Catherine Lindell, study co-author and integrative biologist. “But it’s an inexpensive, low-maintenance tool that growers can use in their bird management toolbox.”
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