Bats

Bats are flying mammals. They are the second largest group of mammals. There are about 1,100 species of bat in the world, but there are more rodents than bats. They are the only mammals which can fly. Their forelimbs have webbed skin covering their fingers, and have become wings. Bats flaps their wings and fly like a birds. There are other mammals which look like they can fly, such as flying squirrels and gliding possums. These do not actually fly but they glide through the air like a kite.

Bat Facts

The wings of a bat are made of two thin layers of skin stretched over the bat’s arm and fingers. The finger bones of bats are much more flexible compared with those of other mammals. The wings of bats are much thinner than a bird’s wing. This has helped the bats to be able to twist and turn in the air much more quickly and accurately than a bird. Their thin wings are delicate and they get torn easily. Fortunately, the thin layer of skin which forms the wings can be regrown. Therefore small tears can mend quickly.

Bats have a thumb and 4 fingers like us. The bat’s fingers are very long compared to its body. Their wings can reach partway down their legs. When they fly, they do not just flap up and down like birds. They spread their wings and pull themselves through the air as if they were doing the butterfly swimming stroke. The wings are also used to hold insects and fruits while eating. On the wings, you can find small bumps which are very sensitive to touch – just like what we have on our finger tips. Each bump has a tiny hair in the centre. These sensitive bumps help the bats to feel how the air is flowing over their wings. Then they can change the shape of their wings to fly more efficiently.

A Bat In Flight - Photo Credit Dietmar Nill, PLoS Computational Biology
A Bat In Flight - Picture Credit Dietmar Nill, PLoS Computational Biology

What do bats eat?

Bats can be found in most parts of the world except for the very coldest places. You can find them in the forests, deserts, jungles and cities.  About 70% of these bats eat mainly insects. This group of bats hunt their prey by emitting sounds waves and listening to the echo to locate the prey. Each bat is typically able to eat one third of its body weight of insects each night. A group of bats can eat tons of insects each year! So, if there were no more bats, we would have the problems of too many insects.

Fruit Bats

Many bats eat fruit. These fruit eating bats will feed on sweet fruit juice. They will pull the fruits off the tree with their teeth, then fly back to their resting place with the fruit in their mouth. Then they will crush open the fruit and eat it. The seeds and pulp are spat onto the ground. These seeds will take root and begin to grow into new fruit trees. Some bats feed on nectar. These long muzzles and can stick out their tongues very far. While sipping the nectar from flowers, pollen will get stuck on their fur. When the bats take flight the pollen is dusted off. That is how bats help to pollinate plants. Although some of the fruit-eating bats are pests to farmers who owns fruit plantations, like it or not bats play an important role in spreading the fruit seeds, pollinating flowers and keeping insects under control. Many tropical plants depend entirely on bats for spreading their seeds.

Vampire Bats

Only 3 species of bats feed on blood. Example, the Common Vampire Bat, the White-Winged Vampire Bat and the Hairy-Legged Vampire Bat. The Common Vampire Bat will suck the blood of mammals like cows and horses, and the Hairy-Legged Vampire Bat and White-Winged Vampire Bat suck the blood of birds. They will not turn into Count Dracula, so, we are safe! These blood sucking bats are the only parasites that are mammals. Some species even eats vertebrates. For example, the Leaf-Nosed bats in Central America, South America and the two types of Bulldog Bat that feed on fish. These types of bats are found on almost all continents. They use echolation to detect tiny ripples on the surface of the water to locate the fish. When they “see” the tiny ripples, the bats will swoop down near the water and use the claws on their hind feet to grab the fish out of the water. The bats will then take the fish to their resting place to eat. Two species of bats eat bats. For example, the American False Vampire bat  and the Ghost Bat of Australia.  One species of bat called the Greater Noctule bat catches and eats small birds in the air. Some predators of bats are Bat Hawks and Bat Falcons.

Smallest and Biggest Bats

The smallest bat is the Kitti’s Hog-Nosed Bat. It is about 29 to 34mm (1.2 to 1.5 inches) long, 15cm (6 inches) across the wings and weighs about 2-2.6gram (0.08 oz). The biggest species of bat is the Giant Golden-crowned Flying-fox which is 34 cm (13.5 inches) long. It has a wingspan of 1.5 m (5 feet) which is almost as long as an average man is tall.

Bat Species

There are two main groups of bats. The large fruit eating bats are known as megabats and the smaller bats are known as microbats and they eat insects, blood, fish, lizards, birds, pollen and nectar. Not all megabats are larger than microbats. The major difference between the two groups bats are.

  • Microbats are able to emit sound waves and listen to the echoes to locate objects. The sounds will hit something and they will bounce back. The bat hears the echo and can tell where the object is. Most megabats are unable to do this, but megabats have a very good eyesight to hunt their prey.
  • Microbats do not have a claw on its second toe of the forelimb. Megabats do.
  • The ears of microbats do not close  to form a ring.
  • The fur of a microbats is different from that of a megabat.
  • Microbats live everywhere in the world except for the Antarctic and most of the Arctic. Megabats are mostly found in the tropics.
  • The majority of the world’s bats are microbats. There are about 200 species of megabats.

Microbats usually have small eyes, and can’t see well – but none of them are blind. The microbats will use their eyesight when they are unable to locate objects the echoes due to long distances. Bats have good senses of smell and hearing. They hunt at night to avoid competition with birds and they travel as far as 800 kilometres (500 miles) just to look for food. Bats have the best hearing of all land mammals. They often have big ears compared to the size of their bodies.

Brown Bats Hiding - Public Domain Photograph by Jim Conrad
Brown Bats Hiding

More Information About Bats

Bats are active at night. Most bats will travel hundreds of miles to hibernate. They will only hunt when the weather is warm enough for the insects to be active. Some bats even hibernate in caves for 6 months. Bats rarely fly in the rain because the rain makes it hard for them to listen to echoes, so they would be unable to find food in the rain. Some bats live alone and others live in big groups in caves. Scientists have found that bats make many different kinds of sound to communicate with each other.

Most bats have a breeding season, which is in the spring for species living in a temperate climate. Bats have 1 to 3 babies in a season depending on the species and on whether there is food and places to rest. Mothers tend to have only 1 baby at a time because she has to fly and to hunt at the same time while pregnant.  She nurses her baby with milk until they are nearly adult. This is because a young bat cannot hunt on its own until its wings are fully developed. Its wings are too small to fly. Young microbats become independent at the age of 6 to 8 weeks but the megabats do not become independent until they are 4 months old. A single bat can live for over 20 years.

Bat Guano

Bats’ poop (bat feces) is very rich in nutrients. In some places it is collected from caves, packed and sold to farmers to be used as fertilizer. Believe it or not, The dung was even used to make gunpowder in the U.S. Civil War! The bats will eat as much food as their bodies can take in just before they hibernate. They will be very fat by then. When hibernating, their bodies will get all the energy they need from this fat. However, they don’t need much energy then, because the bat is very inactive at that time. The supply of fat will last until the spring season.

Bat Conservation

Organizations for Bat Conservation have done a lot to teach people how important bats are in controlling insect pests and pollination. In the United Kingdom all bats are protected. Bats can also be a tourist attraction. For example, about 100,000 tourists per year will visit the Congress Avenue Bridge in Austin, Texas at twilight to watch the bats leave their resting place.

 

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