The parti-coloured bat (Vespertilio murinus), also known as the rearmouse, is a species in the vesper bat family, Vespertilionidae. It is found across temperate Eurasia, from western and southern Europe through the Caucasus, Iran, Mongolia, northern China, Korea, Afghanistan and northern Pakistan. It measures 4.8–6.4 cm (1.9–2.5 in) in body length, weighs 11–24 grams (0.39–0.85 oz), and has a 26–33 cm (10–13 in) wingspan. Much of the parti-coloured bat's behaviour remains poorly understood because the species is relatively rare. It hunts insects such as mosquitoes, caddis flies and moths using ultrasonic calls, often over water and forests and around street lights. Females form maternity roosts and usually bear twins, while the species migrates long distances and hibernates alone through winter. Its distinctive twittering call is especially noticeable during the autumn mating season. This parti-coloured bat was photographed in Rochovce, Slovakia.

Photograph credit: Charles J. Sharp