Bats often roost in absolute darkness and must recognize others through sound and smell. After watching many, many hours of infrared footage of vampire bat food sharing, I’ve noticed that my vampire bats sometimes appear to make brief mistakes by sharing food with the wrong individual.
A typical food sharing sequence starts with the donor approaching and grooming the recipient. The donor licks the recipients mouth (I think this signals an intent to share food). The recipient next begins licking the donors mouth (begging), while the donor remains still. If this mouth-licking persists for awhile and the recipient gains weight, then it’s food sharing. Sometimes a third bat will try to intrude by sticking his face in there and licking the spot where the bloodmeal is being passed. In some cases– what I consider to be a mistake– the donor will start passing food to the intruder for a few seconds, then suddenly have a dramatic reaction where she pushes the intruder away and finds her intended recipient again. In other cases, the recipient will start licking the intruder’s mouth, then suddenly push herself away and try to find the actual donor.
Both of these types of “mistakes” are fairly common. You have to remember that the bats are typically all huddled together in the darkness in a dense tangle of mouths, thumbs, wings, and fur.
Below is the most recent example I came across. It’s not the most clear example, but I’ve annotated it. It started with Dot, a young female, initiating food sharing with Bella. Then Bella slips away (to check for blood at the feeder). Dot begins licking the mouth of Gelfing, a nearby male, but then suddenly stops, pushing him away, and then she starts calling. Later (not in the video) Bella returned and was fed again by Dot for a long time.