Male greater sac-winged bats (Saccopteryx bilineata) use one song to attract females and another to defend their territory. They also vocalize to find food, bouncing sound waves off insects as they fly, a behavior known as echolocation. Researchers wondered if those sounds might also communicate social information, the way you can often tell the sex of another person by their voice—even if he or she is just ordering a double tall skim latte with sugar-free vanilla syrup. The scientists caught bats in mist nets, measured their forearms, determined their sex, and put tiny plastic bands on them. Then, they let them go and recorded their calls. The echolocation calls of females were slightly higher and shorter than those of males that lived nearby , even though the bodies of female bats are bigger. Bats from different places sounded different, too, the team reports online today in the Proceedings of the Royal Society B. The researchers also released single male and female bats near a colony where the males had already returned for the day. When a male flew in, the other males barked and sang territorial songs. When it was a female, the males erupted in courtship song.
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