Vampires aren’t usually associated with acts of kindness, but when it comes to vampire bats, these bloodsuckers are actually quite caring. A new paper in the journal Royal Society Open Science tells the heartwarming tale of a baby bat who was adopted by its mother’s pal after she passed away suddenly. While this isn’t the first time such behavior has been reported in bats, it is the most well-documented, as the animals in question are part of a captive group at the Smithsonian Tropical Research Institute (STRI) in Panama. As a result, there is over 100 days’ worth of surveillance footage depicting the journey of one baby vampire bat and his care providers.
The two adult female bats in the story first met as part of a research project into the social bonds of vampire bats and how they form. Those working on the study collected wild animals from three sites stretching across Panama, a sample selected as the groups were geographically isolated, and therefore would be strangers. After putting the trio of population samples in a cage together, the researchers began observing their behavior via infrared surveillance cameras.
New friendships blossomed between the unfamiliar bats, evidenced by grooming and food sharing – which sees these animals lovingly sick up some blood and share it with a pal. This altruistic behavior strengthens the survival of the group, as members who miss out on food are supported by their roost buddies. These behaviors were the focus of the study, which hoped to track how relationships formed, so the researchers were unwittingly gathering firm evidence of the bond forming between two newly acquainted bats, Lilith and BD. Though they didn’t realize it at the time, this footage would prove very revealing when, following the unexpected death of Lilith who was the parent to a 19-day-old pup, BD did something quite remarkable.
"Shortly before Lilith died, I noticed that the pup would occasionally climb onto BD, and I suppose this may have initiated a cascade of neuroendocrine mechanisms that caused BD to start lactating," said Imran Razik, then short-term fellow at STRI and doctoral student at the Ohio State University, in a statement. BD had no familial motivation to start producing milk but began lactating on the same day Lilith died and began nursing, grooming, and even sharing food with her adopted pup.
To better understand the sequence of events that lead to BD’s adoption, Razik and colleagues decided to review their footage – and sure enough, there they saw BD and Lilith forming a firm friendship. When Lilith was alive, they had been primary grooming partners, and BD had shared food with Lilith more than any other bat in the roost. However, Lilith did not appear to share food with BD. They also found that BD appeared to have a case of baby fever, showing far more interest in the pup than any other female.
First, we see Lilith receiving blood from her chum BD, who in the second clip is giving some to the now-orphaned pup. Gerry Carter lab surveillance camera video
Moreover, the data confirmed Razik's initial impression – BD helped the pup at rates much higher than any other female. "We're wondering if somehow the experience of being in captivity motivates individuals to invest in other bats at higher rates or adopt orphaned pups in critical need," said Razik, who thinks adoptions such as this could give new insights into what aspects of the brain or our environment influence parental-care decisions.
"As a new parent myself, I have come to realize the utter power of baby cuteness! I feel that my brain has been completely rewired. Most of us can understand the strong desire to adopt … It is inherently fascinating to consider the neuroendocrine mechanisms that underlie [these traits], the stimuli that trigger them, how they differ across species or individuals and how these traits might even be pre-adaptations for other forms of cooperation." said paper co-author and STRI research associate Gerry Carter