Bats work in teams! Findings from the Bat Lab
The flying mammals forage by following the sounds of others hunting nearby.
Bats have been deemed "ecologically indispensable" due to their valuable contributions to the environment. Many types of bats eat their weight in insects every day, significantly cutting down on the need for pesticides for farmers (and reducing uncomfortable bug bites for the rest of us). Other nectar-sucking bats do the important work of pollinating popular crops like bananas and mangoes.
Now it appears one type of bat can tell us more about how mammals work together to find food and resources in the wild. The greater mouse-tailed bat, which is native to Israel, recently was the subject of a study by Dr. Yossi Yovel, founder of The Bat Lab and a professor of neuroscience at Tel Aviv University. He and Dr. Noam Cvikel glued tiny microphone-GPS units to these bats – which later fell off and were collected by their team – to get a "bat's-ear view" of how they use their sonar, and each other, to find their next meal.
Bats make different sonar calls depending on the activity they are engaged in – the sounds made while hunting for prey and attacking insects sound different – so importantly, the researchers could both locate the animals and determine what they were doing. Usually it's difficult to get both pieces of information in wild populations of animals.
The greater mouse-tailed bat was an ideal candidate for a study of this kind, since it masses in groups of several hundred animals and is highly social. "Bats are great animal models, and some bats are extremely social. And they are mammals, so if you want to look at mammal behavior, you have to look at bats," Yovel told From The Grapevine.
The greater mouse-tailed bat in the wild. (Photo: YouTube)
Yovel and his team figured out something interesting: When bats hear other bats hunting, they will flock to that area. Yovel compares this to someone eating chips in a crowded and noisy space – it's a distinctive sound that has a particular meaning. While the sonar range of each bat is limited – around 10 meters – if they eavesdrop on others around them, they form a more efficient array of sonar.
This means that the bats end up finding more prey – they prefer a particular type of flying ant that's hard to find, but easy to catch. Ultimately it means the bats are coordinating as a group – even though they are not hunting together purposefully, the result is that they are. This means that the whole group benefits more than if individuals were hunting alone.
Why does this matter? "This idea of animals moving together to improve their foraging efficiency – it’s hard to get this kind of evidence," Yovel said.
There is one drawback to the group method: All the added stimuli can make it difficult for bats to focus. "This came as a surprise to us," Yovel said. "When the density of bats is too high, they seem to experience interference, but it's not a sensory or sonar interference. The bats actually suffer from an attention interference." This is an important difference – he makes the comparison between a ball being thrown at you while you are trying to swat a fly. You can only pay attention to the ball, but that doesn't mean you don't perceive the fly. So there is a trade-off here when bats forage in a group: when it's too dense, all the noise can be distracting, and some of the advantage of the group is lost.
If all of this sounds complicated, that's because in a way, it is. "It's a unique example of how you can do a controlled behavior study on a wild animal freely behaving in our natural environment. Most of the time animals experiments are done in labs," said Yovel.
This is the first time that full nights of audio were recorded on-board wild bats. But it's not likely to be the last, as Yovel and his Bat Lab have plenty more questions that only the bats can answer.
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Related Topics: Animals