Parti-coloured bat

The Parti-coloured Bat or Rearmouse (Vespertilio murinus) is a species of bats in the family of Vesper bats. It is a medium sized bat.


Their twittering call, similar to a bird's call, are to be heard particularly in the autumn during the mating season. The parti-coloured bat has a maximum body size of 6.4 centimeters with a span from 27 to 33 centimeters, and a weight between 12 and 23 gram. Its name is derived from its fur, which has two colours. Its backside is red to dark-brown, with silver-white-frosted hair. The ventral side is white or gray. The ears, wings and the face are black or dark brown. The wings are narrow. The ears are short, broad and roundish.

The highest known age is twelve years.


These bats hunt for their prey, for example mosquitoes, caddis flies, and moths, with ultrasonic sound of around 25-27 kHz. They hunt after twilight at heights of above 10 to 20 meters, for example in open landscape over streams and lakes and above forests or at street lights. In cold weather the bat may remain in its resting place.

There is not much known about the behaviour of parti-coloured bats, as they are quite rare. Female bats live in small groups, of about 50 animals, sometimes up to several hundred adult females. In Western Europe, male groups consist of about 250 animals and are found only during the spring and early summer. These bats migrate, and flights of up to 900 km were found. The furthest migration was determined at 1440 km in the year 1989.

Between October and March, the bats hibernate. They hibernate alone, and can bear temperatures down to -2.6 degrees Celsius.

Reproduction and birth

Females form maternity roosts during May and July and generally give birth to twins. After the pups are weaned females leave the maternity roost. Birth of the young is in western Europe around beginning of June. First juveniles can be found flying as early as 3-4 weeks later.


The parti-coloured bat occurs in Central and Western Europe and in Asia. Its natural habitat is mountains, steppes and forested areas, but in Western Europe, they can mainly be found in cities. The species is protected, as it is threatened by insecticides and changes in their habitat.


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