Barn Owls Throw Shade

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Arterra/Universal Images Group, via Getty Images

Thank you, as always, Mr. Gorman:

White Barn Owls Thrive When Hunting in Bright Moonlight

Something about the light from a full moon shining on the frightening face of a barn owl makes voles freeze a bit too long.

When the moon hits your eye like a big pizza pie, it may not be amore at all, but a ghostly white barn owl about to kill and eat you.

If you’re a vole, that is.

Voles are a favorite meal for barn owls, which come in two shades, reddish brown and white. When the moon is new, both have equal success hunting for their young, snagging about five voles in a night. But when the moon is full and bright, the reddish owls do poorly, dropping to three a night.

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Education Images/Universal Images Group, via Getty Images

Barn owls with white faces and breasts do as well as ever, however, even though they should be more easily spotted than their reddish relatives when the lunar light reflects off their feathers.

They may well be more easily seen, but it doesn’t matter because of the behavior of their prey. Voles have two responses to owl sightings. They freeze, and hope the owl doesn’t see them. Or they run. But when they see a white owl in bright moonlight, the terrified rodents act like deer caught in headlights and freeze up to five seconds longer than they do for a reddish brown barn owl.

This is not what Luis M. San-Jose and Alexandre Roulin, both of the University of Lausanne in Switzerland, expected. They and other scientists reported in Nature Ecology and Evolution on Monday that they expected the white owls to do worse.

“The study is a fascinating new look at an old question: How does moonlight affect the plumage of nocturnal predators?” said Richard Prum, an evolutionary biologist and ornithologist at Yale University, who has studied how coloration evolved in birds.

He added that authors used “a remarkable array of technologies and methods” to investigate the effect of the variation…

Read the whole article here.

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