Irish population of Leisler’s Bat largest in Europe
Eleven species of bat have been recorded in Ireland and the largest of these is Leisler’s Bat.
The animal was first described by the eighteenth century German naturalist Heinrich Kuhl and he named the bat in commemoration of the German scientist Johann Leisler.
Globally, the species’ range is from Ireland across mainland Europe and into the Near East. It extends south to North Africa and is found in the Canary Islands and Madeira. Its range doesn’t extend northwards father than the southern extremities of Scotland. Interestingly, there is a large outlying population in Pakistan, Afghanistan and the foothills of the Himalayas.
It is reported to be widespread throughout its range where it occurs from sea level to altitudes of 2,400m. However, some Leisler’s Bat populations have suffered declines, even extinctions. The Irish population is the largest in Europe and the species is common and widespread here.
Leisler’s Bat has golden reddish-brown fur, darker above and paler below. It has a flattish, dark brown face, small eyes and large ears for picking up sounds when it is hunting in the dark. Its main prey are Yellow Dung Flies, moths and other insects.
At this time of year pregnant females have emerged from hibernation and are congregating at traditional maternity roosts. Fifty or more females gather and roost communally waiting to give birth. Males play no part in the birth of their offspring and live a solitary life scattered throughout the countryside.
Females give birth to a single pup in June so the population doubles in the roost. Things can get noisy when all the babies start crying to be suckled as their mothers return to the roost after hunting for food for themselves.
By August the pups are weaned and are foraging outside. Consequently, the nursery roost begins to break up. Males congregate at traditional mating sites and call to the females to join their harems.
In September, the females join the males and mate. The females store the males’ sperm in their bodies, travel to find a suitable hibernation site and start to hibernate as autumn closes in and flying insects become scarce.
Fertilisation is delayed. The arrival of early spring triggers the stored sperm to fertilise an egg so that when the females emerge from hibernation they will be pregnant and pupping time will be synchronised to coincide with the expectation of lots of insect food being available in June.