Why do bats hunt in flocks?

Using GPS tracking and voice recordings of over 1,100 interactions between bats, researchers from Tel Aviv University found the survival advantage of being in a pack * The study was published in the journal Current Biology

When a bat hunts at night, it relies on its sonar sounds to find food. But when he finds food - bats nearby listen to him and write about the bargain. This is the conclusion of a new study conducted by Dr. Yossi Yuval and student Noam Zweikel, together with their colleagues from the Laboratory for Sensory Perception and Cognition in the Department of Zoology at Tel Aviv University. The results of the study were published this weekend in the journal Current Biology.

"We call this behavior the 'Bamba effect'," explains Dr. Yuval. "When you are sitting in a dark movie theater and someone in the theater starts eating bamba, everyone in the theater knows that someone is eating bamba and more or less where that bamba is. Bats work in a similar way."

When one bat finds a swarm of insects, the other bats within earshot hear about the discovery. This is extremely useful information, given that a bat can only use its active sonar to detect an insect from a very close distance of less than ten meters - but it can hear when another bat has detected an insect from a hundred meters away.

The collective hunting method of the large-eared insect bats, examined in the new study, is particularly useful in view of the fact that these bats feed mainly on flying ant colonies. These queens tend to group together in search of males, but they can fly great distances and this means the bats have to cover huge distances in search of food. By listening to the other members, the bat increases its chances of winning the entire pot.

Dr. Yuval and his colleagues believe that the bats represent a unique opportunity to examine social hunting, since they use active sonar to find their way in the dark. That's why the researchers attached tiny GPS devices (one of the smallest in the world) and recording devices for monitoring ultrasonic sound waves to the bats - and let the bats do their thing.

"The ultrasonic recordings open a window into the sensory perception of the bat, even when it is flying at an altitude of 500 meters somewhere above the Sea of ​​Galilee," says Dr. Yuval. "I can look at the sonar recordings and tap from that when a bat attacks prey and when it communicates with another bat. This is an almost impossible task with other animals."

However, recovering the recorded information was not a simple task. The recording devices fell off the bats after a week, so the researchers had to search for them on foot. At the end of the search operation, they found about 40% of all the devices. The same devices that were placed recorded over 1,100 interactions between the bats that participated in the study and their friends. The analysis of the data indicates that bats band together to increase the chances of finding prey.

"Essentially," concludes Dr. Yuval, "the bats improve their chances by acting as an 'array of sensors.' Of course, this strategy has limits: bats seem to prefer to hunt in flocks with high density, but not too high. In a flock that is too dense, the bat constantly has to follow other bats and cannot concentrate on attacking the food. Imagine you are trying to catch a fly flying near you and suddenly someone throws a basketball at you - the fly will slip away."