What humans can learn about kindness from vampire bats

• What humans can learn about kindness - from vampire bats! They've always had a bit of an image problem. But Dracula's little chums have a secret caring side

It's the series that will open your eyes to the wonders of the animal world. Yesterday, nature writer SIMON BARNES revealed the astonishing lives of birds. Today, he tells why you should learn to love vampire bats - and rats...

The world would be a much happier place if humans were more like vampire bats. It’s their unselfishness I’m talking about: the free giving of something you need but are prepared to surrender to another.

We humans like to think that altruism in any form is uniquely human: a real and above all moral division between us and the rest of the animal kingdom. Vampire bats contradict this view.

All kinds of legends have built up around this pint-sized creature of the night, but one bit at least is true: that they do actually drink blood. There are three species: the white-winged vampire and the hairy-legged vampire prefer the blood of birds, and are adept at clambering through the branches to reach nests and nestlings.

Common vampires prefer to feast on mammals, mostly livestock, but they will on occasions drink human blood. It’s said that the bite is not painful, although — or perhaps because — they use razor-sharp incisors to remove the skin; the resulting wound has been described as looking like a golfer’s divot.

Vampires are around 4in long, with a wingspan of 7in or so. They are adept on the ground, crawling with agile speed to reach a target and search out a convenient blood vessel.

The anti-coagulant in their saliva allows the blood to flow, and they lap it up like a cat with a saucer of milk; on a good night they can take a meal of half their own body weight.

This sounds as if all the odds favour the bats, but this is not so. It’s common for a vampire bat to go through a night without a meal; within three days it will have starved to death. Blood-hunting is a skill that improves over time: year-old bats will fail one night in three; experienced animals fail only one night in ten.

All the same, failure is a fact of life for even the best blood-hunters.

Vampires are social creatures, coming back to the same day-roost at the end of every night. There are some big colonies, up to 2,000, but most are much smaller, and centre on a core population of females who, even if not related, tend to know each other well.

A bat who has failed to find blood in a night’s flying will beg a meal from a neighbour. From a friend, we would say, if we weren’t so terrified of sounding anthropomorphic.

The friend will then regurgitate blood, thus sharing a meal. Under this system, females have been known to live for up to 15 years.

Reciprocal altruism is still altruism; obviously this is a system that works on a mutual back-scratching basis.

Human society depends on the small kindnesses that you perform as a matter of course and that you expect to be performed for you in turn. But it is not just humans who are humane.