The vampire bat that donates blood to starving friends
Vampire bats throw up blood into a starving friend's mouth to keep it alive — and remember who helped them.
The short version
Vampire bats survive on blood alone and starve after two missed nights, so well-fed bats regurgitate blood to share with hungry roost-mates. They remember who has helped them and preferentially feed those bats back, a true reciprocity network.
Why it's so weird
- ✓The Vampire Bat throws up a meal of blood into a starving friend's mouth to keep it alive.
- ✓The Vampire Bat survives on blood and nothing else, one of the only mammals on Earth to do so.
- ✓The Vampire Bat needs a fresh blood meal every night and can starve to death after missing just two nights in a row.
- ✓The Vampire Bat remembers exactly who has helped it before and feeds those friends back first.
- ✓The Vampire Bat runs a tiny blood-sharing friendship economy that scientists call reciprocity.
The full story
A vampire bat will throw up a meal of blood into a starving friend's mouth, just to keep it alive. Meet one of the only mammals on Earth that survives on blood and nothing else. Every single night it needs a fresh meal, and if it fails to feed two nights in a row, it can actually starve to death. So these bats made a kind of deal with each other. A bat that fed well will bring up some of its blood and share it with a hungry roost-mate who came home empty. But it is not random kindness. They remember exactly who has helped them in the past, and they are far more likely to feed the friends who once fed them. Scientists call it reciprocity, basically a tiny blood-sharing friendship economy hanging upside down in a cave. Generous, gross, and weirdly loyal. Follow for more weird animal facts.
Watch the 45-second version
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