When a hummingbird sips nectar from a flower, it’s drinking more than just sweet stuff – there’s a drop of the hard stuff in there, too.
Nectar, like overripe fruit, is prone to fermentation, producing alcohol.
Happily, new research suggests that the birds might know when they’ve had enough.
Biologists at the University of California Berkeley have tested the preferences of Anna’s hummingbirds to different concentrations of alcohol in sugar solutions provided at artificial feeders.
They found that the birds are as happy swigging on a solution containing one per cent alcohol as they are on an alcohol-free tipple.
But when presented with an alcohol content of two per cent, they only drink half as much.
“Because they’re drinking half the volume, the dosage of alcohol is about the same,” says Julia Choi, lead author of the study published in Royal Society Open Science. “They seem to know how to pace themselves.”
Which is probably just as well. Because the precise coordination required for their gymnastic hovering flight might be expected to be impaired considerably when under the influence.
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“I think that would be very dangerous in terms of their survival,” says Choi. But routinely drinking even just a one per cent alcohol solution could still have ramifications for an animal that quaffs so much.
“They’re drinking about 80 per cent of their body weight per day in nectar,” says Choi, “so even low concentrations could add up to a decent amount of alcohol.”
Indeed, at one per cent, their alcohol intake would be equivalent to an 80kg human drinking 28 pints (16 litres) of beer containing four per cent alcohol.
Choi stresses, though, that very little is known about the alcohol content of nectar in real flowers, which might be significantly lower than in her experiments.
Main image: Anna's hummingbirds like a drop of the hard stuff. © Devonyu/Getty