Planet Earth

In the Light of a Streetlamp, Young Blue Tits Get More Action

DiscoblogBy Jennifer WelshSep 16, 2010 8:46 PM

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It can be hard to sleep with a light shining in your window, but for the male blue tit, this night-lighting gives him a sexual advantage. Researchers have found that male tits that live near streetlights wake up and start to sing on average three minutes earlier than the rest of the gang. These birds are more likely to be chosen as mates because under normal conditions, early risers are the strongest fully grown birds. When adventurous lady-birds go looking for extramarital affairs in the morning light they are attracted to early risers because they assume they are the macho, macho men of the group. As a result, any male blue tit--even a young and scrawny fellow--that lives within 50 feet of a streetlight gets about twice as much extramarital action, and has more offspring than male tits that live in other parts of the neighborhood. Study author Bart Kempenaers told Science News that they don't know what effect this might have on the population:

From an otherwise unattractive male’s point of view, streetlights must be great. But Kempenaers says he doesn’t have data on the consequences for the blue tit population as a whole if artificial light inspires many females to mate with males that they would normally shun.

The study found that male blue tits weren't the only ones influenced by artificial mood-lighting. The females were also affected: They started laying their eggs about 1.5 days earlier than the females that nested further from the lights. Kempenaers says that light pollution is usually ignored in favor of other, more obvious pollution. But, he says, it's plenty disruptive for mating behavior in these birds, and for many other behaviors in many other species. As biogeographer Travis Longcore told Science News

:

The new paper “deals with things that aren’t as obvious as dead bodies on the ground but are no less profound,” he says.

There may soon be bad news for these blue tits masquerading as studs: Companies are currently working to develop and test street lights that are less ecologically disturbing. I guess those poor birds will have to find some other way to pull the wool over the eyes of their potential mates. Related content: 80beats: Bird Sex Round-up: Why Monogamous Birds Cooperate, Why Finches Cheat

80beats: Finch Mothers Can Subconsciously Control the Gender of Their Little Ones

20 Things: 20 Things You Didn't Know About... Sex

Not Exactly Rocket Science: Male bowerbirds create forced perspective illusions that only females see

Image: Flickr / Ben Fredrickson (xjrlokix)

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