When Two Bat Tribes Go To War
Greater spear-nosed bats form maternal tribes that go to war with each other. Each tribe comprises up to 25 unrelated females who stick together for years. Not only do these females cooperate to roost and find food, they fly in to rescue each other’s infants from danger. And given the chance, female members of one tribe will try to capture and kill the pups of neighbouring tribes, researchers report in Behavioral Ecology and Sociobiology….
Each female gives birth once a year, and the pups are unable to fly for the first six weeks of their life. During this period pups frequently fall from roost sites in the cave ceiling to the cave floor, where they will die if not retrieved by an adult.
When this happens, pups cry out for help, emitting high pitched ‘isolation calls’. Upon hearing these cries for help, other females in the tribe fly into action, flying down to the stricken pup to guard it, often grooming the infant and trying to get it to attach to their body in a nursing position. If it does it is then flown back to the cave wall to safety.
“One would expect each pup to be visited and then retrieved by only a single female, the mother. Instead, we observed on average 17 visits per pup with over 300 visits to a single pup,” says Bohn. This guarding behaviour is particularly important for greater spear-nosed bats because of the tribes’ war-like tendencies.
Female spear-nosed bats regularly fight those belonging to other tribes, the researchers have found. Females will bare their teeth, bite and chase those who are not part of their own tribe.
They also attack their pups. Sometimes females will bite and attempt to capture stricken pups. “This is when a female grabbed a pup by the teeth and flew off. They happened extremely quickly and we know that in many cases the females left the cave with the pup, because we could hear it screaming outside.” To prevent this happening, females would often guard the pups belonging to their tribe, regardless of whether they had given birth to the infant…. (more @ BBC News)
