Editor’s note: This article first appeared in the July 12, 2022 flipbook.

A group of researchers led by a UT grad student discovered that wild frog-eating bats can remember sounds their prey make for up to 4 years by training them with an abnormal cue — cell phone ringtones. 

While a human user might tap a notification after hearing a distinct incoming mail ringtone, these bats were trained to fly to prey when the cue was played. The study, which slowly mixed and gradually replaced a male túngara frog’s mating call with a ringtone, tested if the bats could be trained to differentiate the cue and remember it after four years in the wild. 

“The answer was an astounding yes,” Rachel Page, a scientist at the Smithsonian Tropical Research Institute, said in an email. “This is truly extraordinary — it would be like remembering cues associated with a meal you had four years later. We now know that these bats have the potential for very long memories for prey cues, and don’t have to relearn them each time.”

May Dixon, who led the study when she was a graduate student at UT studying cognition and foraging in neotropical bats, said this multiyear project examined wild-caught frog-eating bats, as opposed to those in captivity, to accurately present the species’ memory capabilities. 

Researchers trained the bats by exposing them to the mating call of their prey and rewarding them with food when they flew towards the sound, which gradually evolved into a distinct ringtone. The study showed that from one to four years later, all eight re-captured bats from the initial training portion would respond to the original ringtone during a follow-up test, and could discern it from three other ringtones.

“The reason we use these sounds is (because) they are something the animals would never hear in the wild,” said Dixon, now a postdoctoral scholar at Ohio State University. “We could be sure that the only experience the animals had with it was the experience that we train them with. But it’s actually not that dissimilar to the sounds of the frogs.”

Although humans may value a long memory capacity, forgetfulness can be a beneficial adaptation to animals as it eliminates the confusion of old memories competing with newer information, Dixon said. 

“In a world full of change, the conditions during an animal’s life might be very different from the conditions during his parent’s life,” Dixon said. “How long they might be able to learn and remember some condition during their life could determine how well they’re able to respond to the environment.”

A long memory may help the bats know which frogs to approach and which not to, and may enable them to eat rare or seasonal frogs without having to relearn their calls after long periods, Dixon said. 

“This, at least, gives us a threshold that (a frog-eating bat’s) memory might be longer than we might think,” Dixon said. “Hopefully in the future, we’re going to be able to do more comparative studies where we can see how this bat memory compares to other bats and other animals as well.”