An article published in the magazine Plos One reveals that, during their night outings to search for food, female common vampire ( Desmodus rotundus ), meet other companions with whom they have a close social bond. Although social cooperation behaviors of this species were already known, all had been observed in captivity or inside the roosts, but for the first time what takes place outside has also been documented.
“Everything that had been studied about ordinary vampires had focused on what happens inside ‘the house’, but we wanted to know if these social relationships fulfill any function outside the roost “, explains Gerald Carter, researcher at the State University of Ohio.
Vampire bats perch together in trees where they can be seen preening each other and even sharing meals of regurgitated blood with their mates. Previous research has shown that this cooperative behavior is directed at close relatives and social partners. To investigate whether bats’ social ties also influence their foraging behavior, the researchers connected small proximity sensors to 50 common vampire bats, including 27 wild bats and 23 that had been captive for nearly two years , before releasing them. back to his wild refuge in a cattle pasture in Tolé, Panama.
The results revealed that, although tagged bats used to leave their shelters (generally hollow trees) alone, it was very common for females with some type of social bond to gather outside. Additionally, animals that had associated with more companions within also met more friends during their outings.
Union make force
The findings suggest that “making friends” in the roost could create more interdependence among socially linked vampire bats, meaning that they could benefit from each other’s success in obtaining blood food and joining forces when competing with other bat groups for the same. food resources.
The monitoring data was supplemented with video and audio recordings of the bats’ outputs. In some recordings, bats were seen grouped around a cow and drinking from different wounds, while others fought for access to food. Different voices that are probably associated with the search for food were also recorded.
The authors hypothesize that bats may meet with trusted partners during foraging trips to share information about hosts or access to an open wound. They speculate that this collaboration could save the time and effort required to select and attack their prey. According to the researchers, so-called ‘downward sweep calls’, which are similar to the contact calls used to recognize mates at the roost, can also help bats identify friends and foes when hunting.
The researchers add: “How far does ‘friendship’ go? We show that the social ties of vampire bats are not limited to preening and sharing food in the shelter, but that the linked individuals even hunt together, highlighting the complexity of their social relationships”.
