Wild bats recognize ringtones tied to food rewards up to 4 years later
Scientists studying memory and learning in frog-eating bats have made a surprising discovery, demonstrating that they can recognize ringtones tied to food rewards up to four years later. This behavior is believed to be useful in helping the bats hunt for frogs in the wild, and offers new insights into the way animals balance the benefits of long-term memory with its high metabolic cost.
The research was carried out by biologists working at the Smithsonian Tropical Research Institute, who began by studying the ways wild bats could be trained to respond to food cues. These initial experiments involved 49 bats that were played mobile phone ringtones through different speakers. When the bats responded to two tones in particular, they were rewarded with bait fish, while the other three tones offered them no reward.
The bats quickly learned to ignore the unrewarding tones and swoop straight in when they heard the tones corresponding with their fishy reward. The bats were then microchipped and released into the wild in Panama, with the researchers then recapturing eight of them between one and four years later. In follow-up experiments, the bats recognized and responded to those same two tones. Untrained bats twitched their ears in response, but didn't close in on the speakers and rewards.
“Frog-eating bats are an excellent emerging model organism for studying cognitive and sensory ecology,” explained study author M. May Dixon. "Learning plays a big part in their lives."
The scientists believe that this ability to learn and retain information helps the bats distinguish between the different calls of frogs in the wild, and remember which ones are good to eat and which may be poisonous or too big to carry. The scientists also point to previous research outlining the high metabolic cost of long-term memory from an evolutionary perspective, and how it can impact on short-term memory, reduce cognitive flexibility and prolong decision making.
The findings demonstrate a previously unknown cognitive ability in bats, and suggests this type of long-term memory that helps them recall rarely-sighted prey may be an evolutionary advantage.
“I’m interested in memory capacity in animals and what causes long-term or short-term memories, what ecological conditions select for different memory lengths, what is important to remember and to forget,” said Dixon.
The research was published in the journal Current Biology.