Thomas Edison probably never saw this coming. Staring at an electric light all day can mess up your biological clock. In birds, it can screw up their sex lives. Researchers have found that male blue tits living on the edge of a Viennese forest near lighted streets begin their morning songs 3 to 10 minutes earlier than those that live in the forest interior. Females looking for extramarital liaisons—a common custom for birds—find early singers macho, because they tend to be strong and fully-grown. This can make hooking up tough for immature yearlings. Thanks to the lights, however, they have twice as much extramarital mating success as their counterparts in the forest interior, the researchers report today in Current Biology.
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