Nathusius's pipistrelle  (Pipistrellus nathusii)

Bats are the only true flying mammals. In Britain they are insectivorous (eat insects), and contrary to popular misconception they are not blind; many can actually see very well (8). All British bats use echolocation to orient themselves at night; they emit bursts of sound that are of such high frequencies they are beyond the human range of hearing and are therefore called 'ultrasound' (6). Bats listen to and interpret the echoes bounced back from objects, including prey, around them, allowing them to build up a 'sound-picture' of their surroundings (6). Nathusius's pipistrelles produce echolocation calls at frequencies between 38 and 70 kHz (5). They emerge during early dusk (2) and hunt with fast manoeuvrable flight, for flying insects (2).

Mating takes place between late July and early September (2), during this time a single male defends a mating territory of 3 to 10 females against other males (2). Fertilisation is delayed until the following spring (8), as females store sperm inside their uterus (womb) during hibernation (4). In April and May maternity roosts of 50-200 females form (2). Two young are normally produced in late July, which are able to fly at 4 weeks of age (2). In autumn, many individuals undertake a migration to the southwest in order to escape the worst of the winter weather (8); occasionally individuals have covered distances of more than 1,000 kilometres in parts of Europe (6). This bat is known to live to a maximum of 7 years (2).