bat

Distribution

Bats are particularly abundant in the tropics. In West Africa, for example, more than 30 genera embracing nearly 100 species have been cataloged; in the United States 19 genera, totaling about 45 species, are known. Of the 18 bat families, 3—the vesper bats (family Vespertilionidae), free-tailed bats (family Molossidae), and horseshoe bats (family Rhinolophidae)—are well represented in the temperate zones. A few American leaf-nosed bats (family Phyllostomidae) range into mild temperate regions. Several vesper bats range well into Canada.

The Vespertilionidae are found worldwide except in the polar regions and on isolated islands. The brown bats of genus Myotis have a range almost equal to that of the entire order. The free-tailed bats and sheath-tailed bats (family Emballonuridae) also encircle the Earth but are restricted to the tropics and subtropics. The horseshoe bats extend throughout the Old World, the roundleaf bats (family Hipposideridae) and Old World fruit bats (family Pteropodidae) throughout the Old World tropics, and the leaf-nosed bats throughout the New World tropics and slightly beyond. The other families have more restricted ranges.

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Importance to humans

Most bats are insectivorous, and they are important to humans primarily for their predation on insects, for pollination, and for seed dispersal. Little is known of the spectrum of insect species consumed, but the sheer quantity is formidable. The Mexican free-tailed bats of Texas have been estimated to consume about 9,100 metric tons (10,000 tons) of insects per year. Bats would thus seem to be important in the balance of insect populations and possibly in the control of insect pests.

Some bats feed on pollen and nectar and are the principal or exclusive pollinators of a number of tropical and subtropical plants. Others feed on fruit and aid in dispersing seeds, although bananas and figs must in some cases be protected from fruit-eating bats by early harvest or by nets.

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Vampire bats (family Phyllostomidae, subfamily Desmodontinae) are considered serious pests of livestock in some parts of tropical America because the small wounds they cause provide egg-laying sites for parasites and because the vampires may transmit rabies and trypanosomiasis to cattle. Other bats also carry rabies or related viruses.

The guano (droppings) of insectivorous bats is still used for agricultural fertilizer in many countries and in the past was used as a source of nitrogen and phosphorus for munitions. Large guano deposits, in addition, cover and thus preserve many archaeologically interesting artifacts and fossils in caves.

In tropical regions large colonies of bats often inhabit houses and public buildings, where they attract attention because of their noisiness, guano, and collective odour. In western culture bats have been the subject of unfavourable myths; in parts of the Orient, however, these animals serve as symbols of good luck, long life, and happiness. In some parts of Southeast Asia and on some Pacific islands, flying foxes (Pteropus) are hunted for food. Small bats are also widely but irregularly eaten.

Certain physiological aspects of some bats, particularly those involving adaptations for long hibernation, daily lethargy, complex temperature regulation, acoustical orientation, and long-distance migrations, are of interest to biologists.

In species and numbers, bats constitute an important and generally nonintrusive form of wildlife. Several zoos have established interesting exhibits of bats; indeed, some flying foxes and fruit bats have been exhibited in European zoos since the mid-19th century, and they have been kept widely for research purposes. Bats are interesting pets but require specialized care.