WHAT ARE BATS?
Bats are members of a class of animals called mammals. They have hair and mother bats feed their pups with milk produced in their mammary glands. Bats differ from all other mammals in one most interesting way; they have wings and can fly. The scientific name, Chiroptera, means hand-wing.
HOW DO BATS FLY?
Bats fly by flapping their wings. The wings are moved by strong muscles in the back, chest, and shoulders. During the wing stroke, the part of the wing between the body and the fifth finger pushes downward against the air, providing lift. Lift is the force that keeps the bat aloft. The part of the wing between the second and the fifth fingers pushes backward against the air, providing thrust. Thrust is what keeps the bat moving forward.
HOW MANY SPECIES OF BATS ARE THERE?
There are roughly 850 species of bats. The order Chiroptera has two suborders, megabats and microbats. The majority of megabats belong to a group known as flying foxes. Their faces resemble the faces of foxes or dogs, with large eyes, simple ears, and simple noses. Microbats have small eyes, large ears, and complexly shaped noses.
WHERE DO BATS LIVE?
Most bats live in tropical and temperate land areas. Their flying ability has even resulted in their populating isolated Pacific islands. The greatest variety of bat species is found in tropical regions where food is most plentiful, where the climate makes it easy for bats to maintain their body temperature at a necessary level.
WHEN ARE BATS ACTIVE?
Most bats are active at night, except when the moon is bright. In the dark there is less danger from predators, and a greater opportunity to access food.
HOW, WHEN, AND WHERE DO BATS REST?
During the times of year when bats are active, they spend the day in their roost. Roosts are resting places that help protect bats from predators and weather. Roosts also provide places for mating, raising pups, and hibernating. Roosts may consist of single bats, or groups up to a million or more. Some roost in plain sight, however most bats have roosts that are well hidden, such as caves. At their roost, bats hang head-down. Their weight pulls on special tendons in their legs, which in turn pull on their toes, causing the toes to lock around or against the roost. This saves energy because muscles are not being used. Some bats in temperate regions save energy during the day by entering a state of torpor. This is a temporary deep sleep during which the bat's body temperature cools down to the temperature of its surroundings. The bat warms up again when it wakes in the evening.
ARE BATS REALLY BLIND?
All bats can see, and megabats rely to a certain extent on their vision to locate food. Megabats have a special reflective layer that acts to trap light. This allows vision in even dim light and causes their eyes to shine when illuminated.
HOW DO BATS SMELL AND HEAR?
Most bats have a keen sense of smell. This sense helps fruit- and nectar-eaters find food. It also helps bat mothers pick out their own pups from among a crowd of infants from within a nursery colony. All bats have a good sense of hearing and use their ears to help themselves function in the dark. Only microbats use hearing as a tool to capture their hearing.
HOW DO BATS FIND THEIR WAY AROUND IN THE DARK?
Microbats navigate and capture their prey in the dark by using echolocation. An echolocation bats emits and directs short pulses of ultrasound through its mouth and complex nose. The sound bounces off the prey and returns as echoes to the bats ears. The bat interprets the echoes to avoid obstacles and locate prey. When many bats are hunting insects in the same area, each bat emits sound of a slightly different frequency so its calls will not be confused by other bats. Some insects can detect the bats ultrasonic calls and take action to avoid capture.
WHAT DO BATS EAT?
Flying uses up a large amount of energy, so bats have a huge appetite for their size. Bats typically eat only the energy rich part of their foods and digest it very rapidly. Most microbats eat only insects. Some eat other small animals such as rodents, frogs, fish, and other bats. Vampire bats feed on the blood of animals. A few microbats each fruit, nectar, and pollen. Most megabats eat fruit or nectar produced by flowers. Fruit eaters are attracted by the color and smell of ripe fruit. They consume the juices of the fruit and smaller seeds and discard the fiber. Nectar-eating bats have long tongues that reach deep into the flowers. These bats get pollen on their faces and carry from flower to flower, pollinating plants.
WHAT DO BATS DO DURING THE COLD SEASON?
Bats in the temperate zone face several months when food is scarce or unattainable. Some bats migrate to warmer areas where food is more abundant. Some bats hibernate. During hibernation, the bat's body functions slow down, and its body temperature drops to that of its hibernation site. They require very little energy to stay alive during this state. The bat survives on its store of fat until spring comes and food is once again available.
HOW ARE BATS HELPFUL TO THE ENVIRONMENT?
The foods that bats eat make bats crucial to the preservation of most of the Earth's ecosystems. Insect-eating bats typically consume about half their own weight in insects during a night's hunting. Without this occurring, the insect population could explode, threatening crops and the balance of nature. Bats that eat fruit disperse small seeds in their droppings, sometimes scattering them in locations far from the parent plant. Because many fruit-eating bats live in tropical areas, they play a vital role in maintaining such habitats as rain forests. Bats that eat nectar and/or pollen, carry pollen from flower to flower, helping to pollinate plants. Pollination makes it possible for the plant to produce fertile seeds that grow into new plants.
HOW ARE BATS IN DANGER OF BECOMING EXTINCT?
Throughout the world, bats have become increasingly threatened largely through the actions of humans. Many of the larger megabats have been hunted for food or because they have been mistakenly seen as a threat to fruit crops. Many bats have died after eating insects that have ingested pesticides. Even more serious, has been the impact of habitat destruction. Bats are also threatened by cave explorers who sometime kill a whole colony of hibernating bats simply by disturbing them. Hibernating bats will starve to death if awakened and forced to use up their store of energy before winter is over.
WHAT CAN PEOPLE DO TO HELP BATS SURVIVE?
People need to appreciate the importance of bats, and to learn what various bat species need to survive. By joining organizations devoted to protecting bats, people can help influence public opinion so that policies that protect bats can be adopted. On a personal level, people can avoid disturbing roosting bats in the wild, can use humane methods of dealing with bats roosting in human dwellings, and can even build special houses for bats to roost in.
RESEARCH AND WRITING ACTIVITIES
- lift, thrust, echolocation, pups, roosts, megabats, microbats, torpor,
- fruit-eaters, nectar-eaters, migrating, hibernate, ecosystems, caves, nursery