In response to a talk I gave at the bat meetings, some people saw a problem in the experimental design of my partner choice tests, because I had a condition where a bat can't reciprocate, but not a condition where a bat won't reciprocate. I do know that hungry bats will beg other hungry bats, … Continue reading You can’t help me or you won’t? What kinds of “cheats” should a food-sharing bat care about?

In my opinion, reciprocity in vampire bats has not been demonstrated unambiguously. This is because all the evidence to date has really been correlational. My singular obsession recently had been trying to setup and perform the "perfect" reciprocity test in vampire bats. Vampire bats are a good candidate for this kind of experiment because they … Continue reading Manipulating vampire bats’ social relationships: not so easy

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 … Continue reading Vampire bats regurgitating food to the wrong individual

It's crucial for my future experiments to have very precise estimates of relatedness of "my" vampire bats. While working on other things (like scoring videos), I've been slowly adding microsatellite markers to increase the precision of my measures of relatedness. (By the way, one of the best explanations of what relatedness is, can be found here). I … Continue reading Relatedness and kin discrimination in vampire bats (and a few updates)

"Direct reciprocity" occurs when individuals are more likely to help individuals that helped them previously, while "generalized reciprocity" (also called "upstream reciprocity") occurs when individuals are more likely to help after they have been helped by any individual. So direct reciprocity is like "I'll scratch your back if you scratch mine" and generalized reciprocity is … Continue reading Generalized reciprocity in vampire bats?

Cooperative behaviors, such as food sharing, can be studied under a spectrum of conditions from completely natural to very artificial. For example, a careful observer in the field can measure the extent to which male chimpanzees will share meat in the wild after a hunt, or an experimenter in the lab can test the extent … Continue reading Vampire bats will feed trapped individuals through a cage wall

New paper available here Key points We re-examined the well-known but controversial case of reciprocal food sharing in vampire bats. What factors predict the decisions of vampire bats to donate food to hungry roost-mates? In collaboration with the Organization for Bat Conservation, we collected a larger sample of food sharing data than ever before under … Continue reading Food sharing in vampire bats: reciprocal help predicts donations more than relatedness or harassment