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This is the VOA Special English SCIENCE REPORT.

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Many people fear the small flying animals called bats. There are stories about bats attacking people and drinking human blood. However, bats are not a threat to people. In fact, they are an important part of our environment.

Bats are mammals, just like humans. There are about one-thousand different kinds of bats in the world. Some weigh less than ten grams. Yet the largest bats are almost two meters long when their wings are extended.

Most people think bats are rare. That is because they hide during the day and are active only at night. However, bats can be found in almost every part of the world.

Not all bats spend their days underground in dark caves. Some rest in trees or other places that keep them safe from attack and changes in weather. Unlike other animals, their bodies are designed to hang upside down. This is the best position for them to take flight suddenly.

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Bats are the only mammals that can really fly. Their wing structure, bones and muscles help them to move quickly. This helps bats in their search for food.

Some bats use a guidance system called echolocation to move around in the dark. The creatures produce a series of noises through their mouth or nose. They can judge their distance from an object by the time it takes for the sound to return.

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Most bats eat insects. Bats provide one of the most effective controls on insect populations. A single, small, brown bat can catch more than one-thousand insects in just one hour. Twenty-million bats live in Bracken Cave in the western American state of Texas. They eat about two-hundred tons of insects every night.

Some bats eat fruit. As they fly, they spread seeds through forests and deserts. Other bats like to eat pollen on plants. They help to make new plants by spreading pollen from flower to flower. A few bats eat meat. They catch small frogs, birds or fish.

No report about bats is complete without a discussion of vampire bats. Three kinds of vampire bats feed on blood. They live in parts of Central and South America. These bats feed mainly on the blood of birds, farm animals and wild animals. They rarely attack people. The bats bite their victims and drink the blood, usually while the animal is sleeping. The harm from such bites comes not from the amount of blood lost, but from any resulting infection.

This VOA Special English SCIENCE REPORT was written by George Grow.