Nathusius' Pipistrelle

There are very few records of this bat in Britain with only 3 maternity colonies; 2 in Northern Ireland and 1 in Lincolnshire. Single grounded bats are turning up grounded at coastal sites and it is thought that these are migrants from mainland Europe. They have also been found on oil rigs in the North Sea. They may remain here all year round with populations increasing from winter and spring migrants from Scandinavia as they are a highly migratory species. The records tend to peak around mid-autumn and early spring.

flight & ultrasound

Emerging in early dusk, Nathusius' Pipistrelle has a rapid flight with deep wing beats when flying in a straight line. It forages 4 - 15 m above ground along rides, paths, woodland edges and over water.

Nathusius' bats echolocation calls range from 38 - 70 kHz and are best heard with a heterodyne bat detector set to about 39 kHz where a series of clicks turns into 'wetter' slaps towards the bottom of the frequency range. To identify the species of Pipistrelle the frequency dial of the bat detector should be turned up and down until the pitch of the 'wet slap' is at its lowest. It is worth paying special attention to any bat with a 'low point' below 41 kHz.

Nathusius' Pipistrelle bat call on a Heterodyne bat detector.

  Nathusius' Pipistrelle bat call on a Time Expansion bat detector.

breeding

The first 2 breeding roosts of Nathusius' Pipistrelle in the UK were found in 1997.

Mating occurs during early autumn at well established mating roosts. Males have mating territories with harems of 3 - 10 females. Females can reach maturity by their first year but most males will not reach sexual maturity until the following year.

Maternity colonies consist almost exclusively of female bats and are occupied from May onwards. Females give birth to two young from late July. The young are fed solely on their mother's milk and females with young to suckle may make several feeding trips during the night, leaving the young inside the roost in a group or crèche. Within three weeks the young make their first flights and by six weeks they can forage for themselves. Most colonies start to disperse soon after the young are weaned.

summer roosts

These are found in hollow trees, bat boxes, cracks in trees and more rarely in buildings. They will sometimes share a nursery roost with other Pipistrelles or Brandt's.

winter roosts

Nathusius' Pipistrelle tends to hibernate in crevices in cliffs, wall cracks, caves and hollow trees.

For more information on this type of Pipistrelle check out the website by Jon Russ: Nathusius' Pipistrelle in Great Britain & Ireland

Description
Head and Body Length	46 - 55 mm
Forearm Length	32 - 37 mm
Wingspan	220 - 250 mm
Weight	6 - 15 g
Colour	Red or chestnut brown in summer, dark brown with grey tips after July moult.
Life Cycle
Mating Period	Autumn.
Maternity Colonies	Established late spring. Young: two born late July, weaned at 6 weeks.
Colony Size	50 - 200
Longevity	Up to 7 years.
UK Status	Rare
Habitat and Food
Summer Roosts	Hollow trees or cracks in trees, bat boxes,  occasionally in buildings.
Winter Roosts	Cliff crevices, wall cracks, caves and hollow trees.
Feeding Habitat	Woodland bat - deciduous and pine forests, sometimes parks.
Food	Medium to large insects.