Why cherry growers are turning to a tiny predator for help

Cherry season is months away in northern Michigan, but some growers are already rooting for a spring comeback – with the help of a raptor barely bigger than a blue jay. 

American kestrels, the smallest falcons in the U.S., have long been welcomed as aerial bouncers that shoo fruit-raiding birds out of orchards.

New research from Michigan State University (MSU) suggests they do something else, too: they cut down the mess those raiders leave behind, with potential benefits for food safety.

Birds steal a lot of cherries

Kestrels are cavity nesters that thrive in open country, fence lines, and, as it turns out, cherry blocks – particularly when growers provide nest boxes. 

When kestrels are on patrol, fruit-eating birds think twice about dropping in. “They’re cool to watch in flight,” said lead author Olivia Smith, an assistant professor of horticulture at MSU.

The birds hover in place, scanning for insects, mice, and small birds, then rocket down to strike. That presence matters in a business where birds are a stubborn, costly problem.

“It’s hard to keep birds out of crops,” Smith said. Growers usually try many solutions, including netting, noisemakers, scarecrows, or repellents.

Yet across major cherry states like Michigan, Washington, California, and Oregon, birds still claim up to 30% of the crop in a typical year.

Nest boxes, counts, and DNA

To test whether predators could do more than reduce peck damage, the team worked in eight sweet cherry orchards in northern Michigan that had kestrel nest boxes. 

Kestrels, which prefer existing hollows to excavating their own, moved in quickly.

As harvest approached, the researchers conducted systematic bird surveys to log which species were visiting and when, and they inspected branches for fresh droppings.

The team also collected samples for DNA analysis to check for pathogens commonly associated with foodborne illness.

The results point to a double dividend: kestrels not only kept robins, grackles, and starlings off the fruit, they also lowered the overall load of bird feces on trees.

Cleaner cherry trees with less damage

When kestrels were nesting nearby, fruit-eating species were far less likely to visit and feed.

The team estimated a more than tenfold reduction in the likelihood of cherry damage compared with sites without active kestrel nests.

Moreover, orchards with kestrels saw a threefold drop in visible droppings on branches, with the cleanest canopies closest to active nest boxes.

“Certainly, kestrels poop too,” said senior author Catherine Lindell, an associate professor emerita of integrative biology. But because kestrels displace large numbers of fruit-eating birds, the net effect was cleaner trees.

Fewer droppings on the trees

To understand risk, the researchers tested droppings for Campylobacter, a leading bacterial cause of foodborne illness characterized by diarrhea, fever, and stomach cramps. 

DNA analysis showed about 10% of samples were positive. No outbreaks have been linked to cherries, and only one U.S. outbreak – Campylobacter in Alaskan peas in 2008 – has been traced to birds.

Even so, fewer bird visits mean fewer droppings on the trees, cutting down opportunities for contamination.

“They’re really good at keeping the amount of poop down,” Smith said. “That means fewer opportunities for transmission.”

A simple, low-cost strategy

Nest boxes are cheap to build, simple to maintain, and, in many landscapes, quickly occupied.

They also integrate easily with other bird management tactics without adding noise or labor during the busy pre-harvest window. 

The catch? Kestrel occupancy varies by region and habitat, and boxes aren’t a silver bullet. “This won’t solve all the bird problems farmers face,” Smith noted.

Even so, the balance of effort and benefit looks promising for many growers. According to Lindell, it is “a low-cost, low maintenance tool for growers to use in their bird management toolbox.”

Food safety beyond cherries

The food safety connection in this study – less fecal deposition where predators are nesting – could matter even more in crops with a history of contamination concerns, such as leafy greens grown near wetlands or flyways. 

While causation between birds and specific outbreaks remains rare and hard to prove, the logic is straightforward: fewer visits, fewer droppings, lower risk.

That opens the door to proactive, habitat-based strategies that align conservation and compliance.

Protecting cherries from birds

For growers intrigued by the approach, the playbook is straightforward: install and maintain nest boxes at recommended heights and spacings, put them in places with good visibility and nearby perches, and keep adjacent habitat friendly to kestrels.

In return, expect fewer pecked fruits, less mess on canopies, and a little more peace of mind about what’s landing on your crop.

As the study shows, a palm-sized falcon can punch above its weight – saving fruit, tidying trees, and reminding us that sometimes the most elegant farm innovations are feathered, not fabricated.

The study is published in the Journal of Applied Ecology.

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