All bats are vocal, but some are more vocal than others.
This chattiness reveals their individuality, with more talkative bats acting more boldly, researchers report January 29 in Proceedings of the Royal Society B. Bats might broadcast their personalities to others from a distance, which could play into social dynamics within a colony, the finding suggests.
“This study is a major step forward in our understanding of behavioral types in bats and how those relate to patterns of social vocalization,” says Erin Gillam, a behavioral ecologist at North Dakota State University in Fargo.
Despite vocalizations being widespread in the animal kingdom, the idea that they could reflect an individual behavioral type is relatively unexplored. Bats offer a good case study because the flying mammals are both highly social and vocal, using echolocation to navigate and hunt for prey and social calls or complex songs to communicate.
Behavioral ecologist Theresa Schabacker of the Free University of Berlin wanted to see if bats’ social calls also reflected their personality traits, such as how exploratory they were. During fieldwork in the Santa Rosa National Park in Costa Rica, she and her colleagues captured 60 wild male Pallas’s long-tongued bats (Glossophaga soricina handleyi). In a series of trials, the researchers brought individual bats to an experimental site at night. There, the team recorded the bats’ behavioral and vocal responses to the new environment, a newly introduced rubber ball and an offer of food from a feeder lit by a torch — to simulate foraging with an element of risk.
Observations and statistical analysis showed that bats consistently differed in the number of alert calls they produced. Bats found to be bolder at feeding, more curious with the ball and exploratory in their new environment were also more likely to sound alerts. And the more agitated the bats were — acting restless and flying for longer — the more sounds they made. Why intrepid bats are more vocal isn’t clear, though the researchers suggest the behavior could reflect a proactive style of confronting challenges.
How exactly the various behavioral types play into social hierarchies is also unknown. Yet some species of bats are known to eavesdrop on the echolocation and social calls of others near them in flight, Gillam says, so this intel could be of benefit. “What if bolder individuals are better at finding insect patches?” she asks. “Perhaps bats encountering a bold individual during flight might benefit from following it.”