Photo credit: www.popsci.com
To evade poisoning from their prey, certain species must depend on visual indicators. However, the frog-eating fringe-lipped bat (Trachops cirrhosus) utilizes sound as its main tool, tuning into calls made by frogs and toads during mating season. This unique behavior allows the bat not just to locate its food, but also to distinguish between frogs that are safe to eat and those that are toxic. This research provides the first evidence that such eavesdropping predators can adapt their hunting strategies as they gain experience. The findings are discussed in a study published on April 29 in Proceedings of the Royal Society B.
Fringe-lipped bats are carnivorous and inhabit areas ranging from Panama to Brazil. According to Bat Conservation International, their name derives from the distinctive wart-like bumps on their lips and muzzle, which may serve to secrete protective factors against toxins found in the frogs they consume.
These bats are highly adept listeners, with studies indicating their sensitivity to the mating calls of over 12 different amphibian species. When a fringe-lipped bat hears such a call, it promptly moves toward the source within seconds. However, not every call guarantees a satisfactory meal; some calls may belong to larger amphibians or species that could be harmful to the bats.
To navigate these risks, fringe-lipped bats have developed a method reminiscent of caller ID used in mobile phones. When they recognize calls from unpalatable species, they can choose to ignore them, conserving energy for safer options. Unlike modern communication technology, frogs and toads do not come with built-in “spam” alerts, making it unclear how bats discern between different frog calls until now.
[ Related: How bats avoid crashing into one another. ]
“It’s fascinating that these bats rely on calls from an entirely different animal group for hunting,” stated Logan James, a co-author of the study and postdoctoral researcher at the Smithsonian Tropical Research Institute (STRI). He further commented that while previous studies confirmed the bats’ learning abilities, this research specifically tested how they fine-tune their responses based on auditory cues from their natural prey.
In the recent study, researchers assessed how both adult and juvenile wild-caught fringe-lipped bats reacted to recordings of mating calls from 15 local frog and toad species, encompassing both edible and toxic varieties as well as those too large for the bats to consume.
The team confirmed prior findings indicating that adult bats responded more vigorously to sounds from palatable species. Conversely, the juveniles, on average, did not differentiate between the calls based on palatability, indicating a learning curve in their development.
Closer analysis revealed that while juveniles could discern larger prey from their calls, they struggled with recognizing toxic species. This suggests that young bats may initially respond based on size, gradually learning to identify dangerous species as they mature.
“We have been studying this intriguing species for years and have a solid understanding of its behaviors,” remarked Rachel Page, another co-author and STRI staff scientist. She noted that this was the first time researchers tested juvenile bats, and the findings mirrored the learning processes observed in human children, who require time and experience to develop discernment skills.
The research team posits that this ability to listen and learn could be widespread among the animal kingdom. Fringe-lipped bats are not the only predators capable of eavesdropping and utilizing auditory cues to discriminate between edible and dangerous prey. The study underscores the importance of early experiential learning in shaping predatory responses in the wild.
“This study illuminates how development and learning influence eavesdropping behavior, which may extend beyond bats to other predators navigating sophisticated sensory environments,” concluded Ximena Bernal, a research associate at STRI and co-author of the study. She expressed hope that this work would motivate further research on how early experiences affect foraging decisions among predators.
Source
www.popsci.com