Evolution of cooperation in vampire bats
Photo credit: Bruce Thomson
A hairy-legged vampire bat
Portrait of a common vampire bat. Photo credit: Brock Fenton
In the field. Photo credit: Michelle Nowak
Filming in a cave in Mexico. Photo credit: Michelle Nowak
A social group of common vampires. Photo credit: Gerald Wilkinson
Photo credit: Gerald Wilkinson
About the project

How does natural selection-- the ruthless struggle for genetic survival-- produce cooperation, altruism, and empathy?

This question poses an important evolutionary puzzle. If some individuals in a population spend energy helping others, then these helpers can be outbred by non-helping "cheats" that reap all the benefits but don't pay the costs. This is called an evolutionary "tragedy of the commons" because the public good of cooperation is exploited by cheats and eventually disappears. Whenever we see helping behavior in nature, helpers must somehow be preventing cheating such that "nice guys finish first." But how?

I’m studying the vampire bat as a new model to understand how the behavior of individual animals can enforce and stabilize cooperation in a complex society.

Why vampire bats?

Like primates, vampire bats are extreme social cooperators. But unlike primates, we can manipulate much of their natural cooperative behaviors in the lab. Vampires bats will naturally share their food with certain partners. Since they drink nothing but blood, which is a nutritionally poor, hard-to-get food, they can starve to death easily. But, they have evolved a vital social safety net. Bats will regurgitate their own food for hungry roostmates, even non-relatives. We think these food donations might represent a social investment which ensures that others will feed them in return. Such complex cooperation might explain why vampire bats (like humans) have a huge brain and neocortex relative to their ancestors.

Many important questions remain:

What social information do vampire bats use to decide whether to donate to others? Do the bats punish freeloaders by reducing donations to partners who don't reciprocate? Do the bats compete to be the best social partners? 

To answer these questions, we are using non-invasive behavioral experiments to test the effects of genetic relatedness, past social experience, and hormones on helping behavior in several colonies of vampire bats.

Why this matters

Vampire bats are distantly related to primates, yet they evolved many of the same prosocial behaviors, such as communal food sharing and social grooming. While studying these bats, we have three goals. First, we want to test current and controversial theories about the evolution of cooperation and its consequences for the animal mind. For example, is social experience or genetic similarity a better predictor of helping in vampire bats? Second, we want to gain insight into the mind of an animal that is so alien to us, and yet might be so similar in so many ways. Do vampire bats distinguish an in-group and out-group (like humans)? Finally, we want to understand more generally how genetic relatedness, brain chemistry, and social experience interact to predict prosocial behavior. For example, oxytocin increases trust and generosity in humans, but also exaggerates our tribalistic and xenophobic tendencies. Will it have the same effect on vampire bats or are humans unique in this respect? We hope you find these topics as profound and fascinating as we do!

What your money can do

We need your support! After years of observations from the field and from captive bats at other institutions, we are finally bringing a colony of vampire bats to our university. We are planning to give them lots of space to fly and socialize, and they will need a gallon of cow blood every week. We are also hoping to support undergraduate students that will help us take care of them. We think it will be a great way to provide research experience for young scientists. Funds will go primarily to caring for the bats, and to analyze sequences of DNA to assess relatedness. We can make this money go a long way!

Potential discoveries

When scientists talk about the social lives of animals, they typically measure genetic structure and the observable patterns of where they live. We want to take things further and closer. In short, we want to use food sharing to understand if and how vampire bats form social bonds. We also want to understand how competition among sharing partners and cooperation between partners might shape the social network.

Our experiments can also help us understand animal cooperation more generally. There has been much work on animal cooperation, but previous studies have either involved relatively simple organisms like microbes, plants, insects, and fish, or cognitively complex animals that have been trained to perform an artificial form of cooperation, like pulling a lever to deliver food. Our study is special because it allows us to conduct controlled experiments on a completely natural form of helping (food sharing) that occurs in the lab but has evolved in the wild.

We expect three important outcomes in the next 3 years. We will measure the extent to which vampire bats care about kinship, past social experience, and the possibilities of alternative partners. We will learn if and how vampire bats deter cheating. And we will gain insight into the role of oxytocin in prosocial behavior.


I am deeply interested in the evolution of cooperation and I have been obsessively curious about bats since the age of two. In high school, I did my first experiment by testing what bat house designs my backyard bats preferred. As an undergraduate at Cornell University, I created the first noninvasive method for identifying the prey of vampires using DNA from their feces. I later studied vocal communication and how natural selection shapes animal learning. My previous work has led to seven publications. I’m now a Ph.D. candidate and Ford Predoctoral Fellow at the University of Maryland. I'm truly inspired to be working with Professor Jerry Wilkinson, who first reported vampire bat food sharing in 1984.

You can learn more at our blog: socialbat.org.


Wednesday June 20, 2012
Backer only update
Friday June 15, 2012

Hooray!! We did it!! Thank you all so much!! This project has been my dream for a long time. I will make it worth every penny of your generous support.

Wednesday June 06, 2012

A few updates:

1. I've started building the flight cage to house the vampire bats and I've identified places where we can get cow blood near campus.

2. Our first small publication related to this project is scheduled to be published in about a week. It's a study on the complexity of the contact calls the 3 species of vampire bats produce when they have been separated from their roostmates. I will send the link when it's published online.

3. I've started wrapping up the data analysis and started writing my first major paper on cooperative food sharing based on the data I've collected during my first 3 years in Trinidad, Belize, and at The Organization for Bat Conservation in Michigan. That work was funded completely with several small grants of $2000 or less (a lot can be done with a few thousand dollars).

4. We have only 10 days left and 589 dollars to reach our goal! With this money, we can support the vampire bats we are bringing here from the Chicago Zoo. Please help spread the word!

A huge thank you to all who have supported my project thus far! I'm surprised and inspired by your interest in my project. I hope the rewards I send and findings I report will delight and fascinate you. Thank you again!

Monday April 30, 2012

For those of you are interested in literature relevant to bat ecology, animal communication, animal cognition, and the evolution of cooperation-- I keep a public list of new papers I'm reading here:


Monday April 30, 2012

Just got back late last night from a week-long bat research workshop in Belize. We found a breeding colony of vampires in an old overgrown Mayan ruin and I managed to gather some social data on another group of vampire bats that I brought into captivity for a few days. I have now repeated Jerry's original food sharing experiment (1984 Nature) with 6 different groups of vampire bats (about 45 bats) from Trinidad, Belize, and a captive zoo population at the Organization for Bat Conservation in Michigan. I am hoping to write up the first paper this summer. I'm very psyched!

Once again, I'm overwhelmed by your enthusiastic support for this project. Thank you all so much. This will be the first year I don't attend the scientific meetings on Mammalogy, Behavior, etc-- so I can save money for when we bring vampire bats to campus. But I hope this will enable me to have some very exciting results to present next year.

Sunday April 22, 2012
Backer only update
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This project was successful!
$5 +
Email updates about our research
$25 +
Above + 3 digital photos of one of our vampire bats + PDFs of publications + acknowledgement on the vampire bat research blog (socialbat.org)
$65 +
Above + signed color copy of Prof. Jerry Wikinson’s original study published in Scientific American + personalized thank you letter + bat postcard
$150 +
Above + digital video of food sharing
$600 +
0 BACKERS • Limited Reward (10 of 10 remaining)
Above + you can name one of the vampire bats + framed photograph of your vampire bat
$1,000 +
2 BACKERS • Limited Reward (1 of 3 remaining)
Above + acknowledgement in a scientific publication and a personal invitation to visit the lab at the University of Maryland and to schedule a personal research presentation (near Washington, DC)
and 26 others