From: Nature News, SciDevNet, More from this Affiliate
Published September 6, 2013 11:13 AM

Small birds save big money for Costa Rica's farmers

The yellow warbler may not pull a perfect latte, but it turns out it's a friend to coffee drinkers all the same. Research in Costa Rica shows that hungry warblers and other birds significantly reduce damage by a devastating coffee pest, the coffee berry borer beetle.

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A study found that insectivorous birds cut infestations by the beetle Hypothenemus hampei by about half, saving a medium-sized coffee farm up to US$9,400 over a year’s harvest — roughly equal to Costa Rica’s average per-capita income. The results, published in Ecology Letters1, not only offer hope to farmers battling the beetle, but also provide an incentive to protect wildlife habitat: the more forest grew on and near a coffee farm, the more birds the farm had, and the lower its infestation rates were.

"Based on this study, we know that native wildlife can provide you with a pretty significant benefit," says Daniel Karp, a conservation biologist at Stanford University in California, who led the study. "Incorporating their conservation into your management of pests is absolutely something you should do."

Beetle busters
The borer beetle is originally from Africa, but has spread to nearly every coffee-producing region. The insect is invulnerable to most pesticides, and can cost farmers up to 75% of their crop. To learn whether birds can mitigate the problem, Karp and his colleagues covered coffee bushes on two Costa Rican plantations with mesh fine enough to keep out birds.
They found that avian predators did indeed pick off a lot of beetles: in the rainy season — peak time for beetle activity — borer infestation almost doubled when birds were excluded from foraging on coffee shrubs, rising from 4.6% to 8.5%. By analysing bird faeces for beetle DNA, the team identified the yellow warbler (Setophaga petechia) and four other species as beetle eaters.

Next, the researchers combined data about bird abundance, forest cover and beetle populations from six coffee plantations. They found that beetle-eating birds were most common at sites with lots of stretches of forest nearby, and that beetle infestations were slightly more severe at sites that were not surrounded by abundant forest. Furthermore, many of the avian exterminators were living in small scraps of unprotected woodland, rather than in big nature reserves.

Read more at SciDevNet.

Yellow warbler image via Shutterstock.

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