Blackbirds aiming to feast on rice crops could perhaps be kept off with a blast of caffeine, according to research presented here.

Redwing blackbirds (Agelaius phoeniceus) are no friends to rice farmers. They soon grow blasé over scarecrows, and swoop in to devour rice seeds. In Asia, farmers typically hire a corps of workers with slingshots to keep them away. In the United States, people are looking for a more practical, chemical solution.

A team at the USDA’s National Wildlife Research Center (NWRC) in Fort Collins, Colorado, hit on what they thought was the perfect compound: caffeine. It’s cheap at $3 a kilogram (thanks to all the decaf coffee generating a surplus of the stuff). And the birds don’t like it: in trials it reduced the number of seeds lost to hungry pecking by up to 76% (see https://www.aphis.usda.gov/ws/nwrc/is/05pubs/avery051.pdf).

But they needed a chemist to make the idea fly. Caffeine doesn’t enter into solution very well at room temperature, so it was clogging up the spray hoses on the aircraft that were trying to blast it onto test fields.

Jerry Hurley at the NWRC found a solution: he mixed the caffeine with equal parts sodium benzoate, a product sometimes used as a preservative, and solved the problem. He reported the work at the American Chemical Society meeting in San Francisco on Thursday (see https://oasys2.confex.com/acs/232nm/techprogram/P1011525.HTM).

The new mix was tested on blackbird caught in mist nets. After four days of being offered it at 10,000 parts per million in a choice test, they ignored it completely in favour of the plain rice.

And the rice doesn’t seem to suffer: germination tests showed no effect of the mix on the seeds.

But before it can go into regular use, it still must be shown that the caffeine sticks around. And the effect of the caffeine on the birds still has to be tested: no one knows if it gives them the shakes.

But what if birds, like humans, come to like and even depend on the pick-me-up of a morning jolt of caffeine? Hurley laughs. “Birds don’t have the same bad habits we do,” he replies.

With 90% of the world’s rice grown and consumed in Asia, where they seem to already have a viable solution, the caffeine spray is likely to remain a niche product – at least for now.

[posted on behalf of Emma Marris]

Blackbirds aiming to feast on rice crops could perhaps be kept off with a blast of caffeine, according to research presented here.

Redwing blackbirds (Agelaius phoeniceus) are no friends to rice farmers. They soon grow blasé over scarecrows, and swoop in to devour rice seeds. In Asia, farmers typically hire a corps of workers with slingshots to keep them away. In the United States, people are looking for a more practical, chemical solution.

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