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a suborder of bats of the order Chiroptera. These bats differ in appearance from members of the order’s other suborder, Megachiroptera (true fruit bats), in that they are smaller, with a body length of up to 14 cm, and the second finger of each of their forelimbs lacks the last phalange and claw. These animals have insectivorous dentition, with sharp, tuberculate cheek teeth. The pinnae are often large, and a coriaceous projection, the tragus, usually is in front of the auditory meatus. Many of these bats have odd-shaped leathery outgrowths at the end of their face. They have small eyes, weak vision, and excellent hearing.
All microchiropteran bats have good echolocation ability. Orientation sounds are generated in the throat and emitted in the form of brief ultrasonic pulses with a frequency of up to 130 kilohertz and a length of 0.2–100 milliseconds. The intensity of these sounds is very high, the sound pressure near the animal’s head may reach 200–300 dynes per sq cm, which, by analogy with frequencies that are audible to man, corresponds to the loudness of a rifle shot. Echolocation, which enables bats to discern obstacles, such as a wire, with diameters of 0.1–0.08 mm, has a range no longer than 10–15 m.
The Microchiroptera are a very ancient group of mammals; fossils belonging to the Eocene epoch have been found. Distributed throughout the world, including the polar regions, the animals are most numerous and varied in the subtropics and tropics. There are approximately 650 species in 138 genera, which are united into 16 families. Forty species are found in the USSR. Exclusively nocturnal or crepuscular animals, microchiropteran bats live in hollows, rock crevices, caves, and secluded corners of farm and residential buildings. Some species have become synanthropic and are rarely found outside human habitats. They usually live in colonies, which can number from several individuals to hundreds of thousands; caves in which as many as 20 million bats live are known.
Microchiropteran bats living in moderate and cold climates are cold-blooded: their temperature during periods of inactivity fluctuates, approximating that of their environment. In the north, hibernation lasts seven or eight months; the bats usually spend the winter in caves, mine galleries, and deep cracks where the temperature does not fall below 0°C. Migrations often precede hibernation, with some species making long seasonal migratory flights.
Microchiropteran bats reproduce once a year; they usually bear one or two unprotected blind young, which begin to feed themselves within 20 to 40 days. In countries with a moderate climate, estrus and mating occurs in the fall; the sperm is stored for the entire winter in the female’s genital tract, with ovulation and fertilization occurring only in the spring. The low fertility rate of bats is compensated by their longevity; in several species some members have a life-span of 20 years.
The overwhelming majority of microchiropteran bats, including all species found in the USSR, feed on insects, which they detect by means of hearing or echolocation and which they catch in flight or, less frequently, gather from leaves and tree trunks. A few tropical species have converted fully or partially to feeding on small birds, small animals, reptiles, fish, the pulp of fruits, the nectar and pollen of flowers, and the blood of homoiothermic animals.
Bats are very beneficial and are protected. They prey on many nocturnal insects, including large-scale agricultural and forest pests and bloodsucking flies. The herbivorous species are pollinators and spread the seeds of a number of tropical plants. In America, microchiropteran bats are a vector of the rabies virus and the agents of some other infectious diseases of man.
REFERENCESKuziakin, A. P. Letuchie myshi. Moscow, 1950.
Airapet’iants, E. Sh., and A. I. Konstantinov. Ekholokatsiia ν prirode. Leningrad, 1970.
Allen. G. M. Bats. Cambridge, Massachusetts, 1939.
Eisentraut, M. Aus dem Leben der Fledermäuse und Flughunde. Jena, 1957.
Biology of Bats, vols. 1–2. Edited by W. A. Wimsatt. New York-London, 1970.