Many people have heard of vampire bats, if only for the tales of bloodsucking animals so aptly named. What is less well-known is the prevalence of social structure and helpful behavior practiced by these bats, though whether this activity is a product of altruism or reciprocity is still an area of study.
Vampire bats consume only blood, either from mammals or birds, depending on the species, and they attempt to consume up to half their body weight each night – which makes sense, as blood is a nutrient-poor material for subsistence. Hunting can be difficult though, and there are often cases in the wild where an individual fails to eat that night. Vampire bats die of starvation if they fail to eat for a few days, which appears to have led to the observed social behavior. The vampire bats who have fed that night can and will share regurgitated blood with starving bats, even if the bats share no relationship. This has led to questions of reciprocity; if the behavior isn’t being enforced by a genetic mechanism of kin selection, then do the donor bats ever receive some kind of reward for their behavior? Reciprocity has been observed, but as an area under current study, it is still early to determine the drivers of this behavior.
Another social behavior attributed to these bats are grooming patterns observed amongst the bats, once again not necessarily along kin lines. This, coupled with an observed female hierarchy, calls to mind images of more social creatures – primates, for example. While studying social species more closely related to humans may be the obvious choice for shedding insight into the biological underpinnings of our society, this field course has distinctly opened my eyes to the unique possibilities available in less obvious choices for study, like the blood-sucking vampire bat.