Bag of Chips Effect Helps Bats Find Food

Similar to how a bag of chips being opened somewhere in the vicinity makes one feel hungry, bats too are attracted when one of their kinds approaches some food.

The greater mouse-tailed bat (Rhinopoma microphyllum) uses a type of sonar mechanism to navigate and find prey. When it approaches an insect, the bat sends out signals around the insect to help it zero in on its prey. When these signals go out, scientists have found, other bats in the area are alerted that there is food nearby.

The study, published in the journal Current Biology, calls this the Bag of Chips effect. The scientists, led by Tel Aviv biologist Yossi Yovel, developed tiny chips with a microphone and GPS that can record high frequency bat calls. These chips were fitted on to the greater mouse-tailed bats, a highly social species of bats that migrate to spend the summer in Israel.

The chips were attached with surgical glue which wore off after a week, causing the chips to fall off the bats. The scientists then had a hard time clambering into caves and among foliage to recover the chips. The team could retrieve only 40 per cent of the recorders but had recordings of 1,100 bat interactions.

The scientists found that when a bat created the typical signals while homing in on food, other bats within a range of about 330 feet, or 100 metres, moved toward the place where the call originated to supposedly look for food themselves.

The scientists believed that the calls were not meant to communicate information to other bats, and that the other bats which came close were eavesdropping on the bat that had found the food.

Bats can hear prey when it is 33 feet, or 10 metres, away, but they can hear other bats when they are 100 metres away. Since all bats use some kind of echolocation, this study might prove to be an insight into bat behaviour in general, which, as the scientists point out, is not very different from human behaviour.

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