Only thirteen genes separate vampire bats from other small flying mammals that more commonly feed on fruit or insects. The loss or inactivation of this genetic toolkit enables these bats to thrive on a blood based diet. Their bodies are built to process iron and protein efficiently while storing little fat or carbohydrate. This remarkable discovery came from an international collaboration and was reported in the journal Science Advances.
While blood is a poor caloric source for most mammals, these bats have adapted in a way few organisms have. It is difficult to sustain life on a diet that is almost all liquid. Yet these bats manage it, an adaptation described by researchers as unusual even within their own group.
Among the approximately one thousand four hundred bat species, only three rely on the blood of other animals for nourishment. The majority of bats eat insects, fruit, nectar, pollen, or occasionally meat from small amphibians and fish. The three blood specialists are the common vampire bat Desmodus rotundus, the hairy footed vampire Diphylla ecaudata, and the white winged vampire Diaemus youngi. These animals inhabit regions of Central and South America. Their body length is around eight centimeters, with a wingspan near eighteen centimeters.
100 samples show a year’s worth of blood from twenty five cattle
Bats emerge at night to feed by biting and then licking the blood from livestock and other animals. By day they roost in darkness, hanging upside down in colonies that can range from about one hundred to well over a thousand individuals. A typical colony might drink the blood of twenty five cows in a year. Their preferred prey tends to include cattle, wild ungulates, and chickens, with dogs and humans being far less common targets.
Vampire bats approach their prey from the ground, roost nearby, and move toward the target on all fours. They possess a small set of teeth designed for a liquid diet, and their few teeth are sharp. Each bat has a thermal sensing area on its nose that leads it to a warm spot just under the skin where blood flows. After biting, the bat licks up the blood and its saliva contains components that prevent the blood from clotting.
With such a low calorie intake, vampire bats cannot survive long without a meal. But they live in tight communities where sharing is common. When a member is in trouble, healthier individuals may regurgitate food to help a hungry neighbor. The moment is critical, and to perform this altruistic act, the bats rely on memory to recall whether the distressed bat has helped others before. One researcher notes that the social behavior resembles a form of collective memory and reciprocity that goes beyond kinship ties. If an individual has helped others in the past, it is rewarded by future assistance.
Earlier work from researchers at the University of Illinois and Ohio University showed that this unusual social pattern extends to gut microbiota. The study concluded that bats within the same colony share more similar gut biomes than bats from different colonies. Bats that live in close proximity tend to harbor similar gut microbial communities, suggesting a coordinated, social microbiome. This discovery highlights how social structure and lifestyle influence internal ecosystems among these animals.
For further reading, see works cited in the scientific record: Science Advances and Nature Ecology & Evolution, which discuss the genetic and microbial dimensions of vampire bat biology and behavior.