COLUMBUS, Ohio (WCMH) — Vampire bats share their food by vomiting blood for each other, and now researchers think they might also call their roosting companions to feed on a bleeding animal with them.

“Hunting in vampire bats is something that we just don’t really know anything about,” said Gerry Carter, Assistant Professor at Ohio State University who has been studying co-operation of vampire bats for about 10 years.

“Almost nobody can really watch vampire bats going out and foraging.”

For the study researchers glued proximity sensors onto the fur of the bat before releasing it into the wild, said Carter.

“So these are bats that drink nothing but blood, and they often feed on livestock, and they will fly to a horse or a cow and they make a tiny little bite, sometimes near the foot, or sometimes they’ll just land on the back of a cow and bite somewhere on the back, and then they lick the wound — they take about a tablespoon of blood.”

The researchers found that the bats seemed to be signaling to each other. “Bats that roosted together, and also shared food and groomed, were more likely to encounter each other when they were out foraging.”

Vampire bats vomit blood for other vampire bats to eat as a way to provide their companions and relatives food when the other has an unsuccessful hunting trip.

“It’s something that all female bats do for their offspring while their offspring is developing. They regurgitate the blood that they’ve ingested to feed to their offspring. But this has been co-opted, we think, over evolutionary time that adults will also do this for other adults that have failed to feed, and not just individuals that they’re related to, but also completely unrelated individuals.”

Carter says they think this system is regulated by reciprocity; bats who regurgitate blood for other bats will have the same thing done for them given time.

Facts about vampire bats
  • Bats are the most diverse lineage of mammals. There are around 1,400 – 1,500 species of bats.
  • One out of every 4 mammals is a bat.
  • There are only 3 species of vampire bats.
  • Vampire bats are defined by the fact they only drink blood as a food, about a tablespoon per visit.
  • It’s a parasitic relationship — the bat isn’t helping the blood donor in any way.
  • They are a problem in Latin America because they spread rabies to livestock.
  • Researchers are trying to make vaccines that are socially spread among bats. In the meantime, farmers have to vaccinate their livestock against rabies.

If you’re fascinated by vampire bats, visit Gerry Carter’s website where there’s a fabulous collection of videos and photos. All photos used in this story were taken by Carter.