"Sex can be a risky business if you're a fly," reports the Great Lakes Advocate of New South Wales, Australia. The newspaper says scientists have demonstrated that Natterer's myotis locate and attack mating flies by listening for a buzzing sound made by the males. The result is a supersized meal for the bats.
|Hibernating Natterer’s myotis. © Jeroen van der Kooij
German researchers led by Bjorn Siemers of the Max Planck Institute for Ornithology filmed the flies (of a species common in Europe) and bats in a cowshed in central Germany. About a fourth of the mating flies were attacked by bats – and mostly eaten –during four years of observations, reporter Nicky Phillips wrote. Meanwhile, the bats ignored flies that were simply walking on the shed ceiling.
Siemers, a bat biologist, told the newspaper that the bats succeeded in catching the insects almost 60 percent of the time. "Keying in on copulating flies typically afforded the bats with a double meal,'' he said. In addition to revealing themselves, the flies seem to pay less attention to their surroundings while mating, so they are likely to be easier targets from predators.
Most bats hunt at night using a biological sonar system called echolocation. They emit high-frequency sounds into their path and analyze the echoes that bounce back from insects or obstacles. But, the researchers said, bats have a hard time spotting an insect resting on vegetation or a wall because the fly's faint echo is masked by a much stronger and broader background echo.
But when two flies began mating, with the buzzing noise that entails, bats can use their hearing rather than echolocation to spot them. "When the scientists played a recording of the fly's mating sounds, it triggered multiple bat attacks," the Advocate said.
The research was published in the journal Current Biology.