Myotis dasycneme (Boie, 1825)
Vespertilionidae

Near Threatened

Description

A medium-large bat, it is the largest trawling bat, being larger than both the Daubenton's (Myotis daubentonii) and the long-fingered bat (Myotis capaccinii) with a forearm length between 43 to 49 mm and a weight between 13 and 18 g. It has dense pale grey-brown dorsal fur sharply demarcated with the white light-grey ventral fur. The face is reddish or light-brown while other skin parts are coloured grey-brown. Juvenile bats are characterized by a dark spot on the lower lips that becomes lighter with age. The tragus is short for a Myotis bat and bent forward, similar to Daubenton's bat. Just like other trawiling bats, the feet are very large and with long bristles. This bat is characterized by its muzzle which has a swollen appearence compared with similar species.

Distribution

The pond bat has a patchy distribution in northern Europe, from northern France through Belgium and the Netherlands, Denmark, southern Sweden and the Baltic states to Russia. The southern limit runs from northern France, northern Germany and in the east to northern Croatia and Romania. It's distribution runs up to the River Yesiney in central Siberia going through Russia and Kazakhstan.

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Roosts and phenology

Roost mostly found in human buildings like roof spaces of churches, church towers, wall cavities, behind cladding or under roof covering. Also, during summer, tree holes have been known to be used as nursery roosts in Hungary. Single animals have also been known to be found bat boxes. Nursery colonies usually consist almost exclusively of adult females with their young and usually comprise between 20 to 750 animals (an average of 132 females in the Netherlands). Males form separate colonies of up to 70 individuals, but usually around seven. Nursery roosts are switched frequently and can be shared with Natterer's bats (Myotis nattereri) and common pipistrelles (Pipistrellus pipistrellus). In areas with dense populations of pond bats in the Netherlands, nursery colonies can be found at almost every 10 km. The young are born from mid-June and building-dwelling colonies leave their roosts as early as from mid-July. Females probably reach sexual maturity in their second year.

From middle August to early September, pond bats congregate at swarming sites, also used by several other species. Males occupy mating roosts in buildings, tree holes and bat boxes. Mating takes place from the second half of August in the male roosts or in the winter roosts and probably also at swarming sites. This species is considered a medium-range migrant. Usually, lowland populations hibernate in adjacent low mountain ranges in northern Germany, the Netherlands and Russia, with recorded movements of up to 300 km from the summer roosts. The longest recorded distance is 350 km in Belgium. If suitable wintering roosts are found within summer habitats, populations are relatively sedentary. In winter it usually roosts in caves, mines and bunkers, with roosts of up to 700 wintering animals found in Russia, and up to 6,000 animals in Denmark.

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Habitat and diet

This species occurs in areas rich in slow-flowing broad rivers, canals, lakes and ponds mostly in lowlands in the summer period. In winter, the pond bat can be found in low mountain ranges.

The food consists almost exclusively of aquatic insects such as gnats, mosquitoes and caddis flies, captured directly from the water surface as well as moths and beetles in terrestrial habitats. Just as other trawling bats, it hunts over calm waters, clear of vegetation such as duck weed, usually flying somewhat higher than Daubenton's bats (Myotis daubentonii) at around 50 cm. To a lesser extent it may also use large reed beds, meadows and forest edges and observations of individuals hunting over the sea surface are known, especially during mass appearences of small crustaceans. Like other trawling bats, the pond bat takes prey with its long hind feet or tail membrane from the water surface.