Vampire bats that form bonds in captivity and continue those ‘friendships’ in the wild also hunt together, meeting up over a meal after independent departures from the roost, according to a new study.
Researchers attached tiny «backpack» computers to 50 vampire bats — some that had previously been in captivity together and others that had lived only in the wild — to track their movement during their nightly foraging outings. By day, the bats shared a hollow tree in Panama, and at night they obtained their meals by drinking blood from wounds they made on cows in nearby pastures.
Tracking data showed that vampire bats set out to forage separately rather than as a group — and those that had established social relationships would reunite during the hunt for what the researchers speculated was some sort of coordination over food.
The findings suggest «making friends» in the roost could create more interdependence among socially bonded vampire bats — meaning they could benefit from each other’s success at obtaining blood meals and join forces when competing with other groups of bats for food resources.
«Everything we’ve been studying with vampire bats has looked at what they’re doing inside of a roost. What nobody has really known up until now is whether these social relationships serve any function outside the roost,» said study co-author Gerald Carter, assistant professor of evolution, ecology and organismal biology at The Ohio State University.
«Understanding their interactions with a completely different group of bats out on the pasture can help us understand what’s going on inside the colony. If every time they leave the roost they’re getting into battles, that can increase the amount of cooperation within the colony.»
Co-author Simon Ripperger, a former postdoctoral researcher in Carter’s lab, later supplemented the tracking data by capturing video and audio of foraging vampire bats. He observed bats clustered together on one cow and others atop separate cows, some drinking from different wounds and some fighting over food access. He also made what are likely the first audio recordings of a specific type of vampire bat vocalization associated with foraging.
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Materials provided by Ohio State University. Original written by Emily Caldwell. Note: Content may be edited for style and length.