Researchers identify bird species that pose a risk to crop food security


DAVIS. California – Concerns about foodborne risk to birds may not be as serious as farmers once thought, according to a study from the University of California, Davis, which found low cases of E.coli and Salmonella prevalence.

Although research has found that the risk is often low, it varies by species. Birds such as starlings that flock in large numbers and feed on the ground near livestock are more likely to spread disease-causing bacteria to crops such as lettuce, spinach and broccoli, according to the health risk study. food safety and bird pathogens. In contrast, insectivorous species were less likely to carry pathogens.

The results, published in the journal Ecological applications, suggest that the current practice of removing bird habitats around the farms of agricultural producers, because the animals could introduce foodborne pathogens to their fields, may not solve the problem.

“Farmers are increasingly concerned that birds are spreading foodborne diseases to their crops,” said Daniel Karp, the study’s lead author and assistant professor in the Department of Wildlife, Fish and Conservation. from UC Davis. “Yet not all bird species pose the same risk.”

Only one outbreak of foodborne illness in products has been conclusively attributed to birds: an Campylobacter pea outbreak in Alaska, UC Davis said. Although the bacteria can cause diarrhea and other foodborne illnesses in humans, it is of less concern to growers than E.coli and Salmonella, which have been responsible for several outbreaks across the country.

In this study, researchers compiled more than 11,000 bacterial tests on wild bird droppings and found that Campylobacter was detected in 8% of the samples. But pathogenic E.coli and Salmonella were found only in very rare cases (less than 0.5%).

In addition to bacterial testing, the researchers conducted about 1,500 bird surveys in 350 fresh produce fields in the western states and collected more than 1,200 fecal samples from the fields. They then modeled the prevalence of pathogens in feces, interactions with crops, and the likelihood of different species of birds defecating on crops to determine risk.

Insectivorous birds pose a lower risk

According to the data, insectivorous birds, such as swallows, pose a lower risk, while birds that flock near livestock, such as blackbirds and starlings, are more likely to transmit pathogens.

The data can help the agriculture industry identify risks and take action, such as separating food crops from livestock land. They also don’t need to treat all birds the same.

“Perhaps farmers don’t need to be so concerned about all types of birds,” Karp said. “Our data suggests that some of the bird pests that can really benefit agricultural production may not be so risky from a food security perspective.”

Habitat removal can backfire

This study and the authors’ previous work indicate that habitat removal around farms may actually benefit species that pose the greatest risk and harm beneficial pest species that pose less risk to food security. Indeed, many prolific insect eaters may visit cultivated fields to eat pests, but need nearby natural habitats to survive. In contrast, many species of birds that most often carry foodborne pathogens easily thrive on cattle farms and produce farms with no nearby natural habitat.

Insectivorous birds that forage in the tree canopy pose a minimal threat because they are less likely to carry foodborne pathogens and come into direct contact with produce. They can also be valuable parts of the ecosystem, especially if they eat pests that can harm crops. Installing birdhouses could attract pest eaters, as well as help with conservation efforts.

“We didn’t know which birds were the problem,” said lead author Olivia Smith, a postdoctoral fellow at Michigan State University, who was at the University of Georgia when the article was written. “I think it’s a good step forward for the pitch.”

Other co-authoring institutions include James Cook University, UC Berkeley, UC Riverside, University of Kentucky, University of Texas, Virginia Polytechnic Institute and State University, the Washington State University, BioEpAr, The Nature Conservancy and the Van Andel Institute.

The research was funded by the Department of Agriculture and the National Science Foundation.


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