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Hummingbird Tongues Are Pumps, Not Straws

A tiny, quick pump mechanism lets birds slurp up nectar at a rate of 14 licks per second

smithsonian.com

Hummingbirds have long tongues inside their beaks — tongues that allow them to eat up to three times their body weight in nectar and bugs every day. Now, writes Science’s Sid Perkins, scientists have revealed something they never knew about those tiny tongues: they act as nectar-sucking pumps.

The discovery overturns the long-held theory that hummingbird tongues act more like straws, reports Perkins. The old hypothesis was supported by observations that birds seem to use capillary action, which draws liquid into cramped spaces against gravity, to suck up nectar.

Now, a years-long study of hummingbirds in the wild has proved that theory wrong. When scientists studied 18 hummingbird species over five years, they learned that instead, hummingbird tongues act more like miniature pumps. With the help of slow-motion video, researchers discovered that hummingbird tongues open their flat tips when they reach nectar. That action creates a pump-like effect that draws nectar into a reservoir at the tip of the tongue, then squeezes the sweet stuff into the bird.

The entire process takes less than a tenth of a second, says lead researcher Alejandro Rico-Guevara in a release. Though hummingbirds apparently can use capillary action to feed, writes Perkins, they get far more nectar from the pump-like method — researchers tell Perkins that if hummingbirds relied on capillary action alone, they’d only get a third as much juice.

So why study hummingbird tongues in the first place? Guevara points out that the research is just the beginning. Now that they understand the process, the team says in the release, they can use mathematics to figure out just how much nectar hummingbirds eat. That will help scientists learn even more about how hummingbirds make decisions about food, develop foraging habits and impact the world around them.

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