Plecotus auritus (Linnaeus 1758)

Bats are the only true flying mammals. They are insectivorous (eat insects), and contrary to popular misconception they are not blind; many can actually see very well (6). 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' (7). They then 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 (7). Brown long-eared bats produce echolocation calls at frequencies between 25 and 50 kHz, which are very quiet, and have earned the species the alternative name of 'the whispering bat' (5). They emerge only after nightfall (2), and their broad wings allow them to fly slowly, but with high manoeuvrability (5). They hunt for flying insects such as moths, beetles and flies whilst on the wing, but also take spiders, earwigs and other invertebrates from leaves or tree bark (known as 'gleaning'), and may even land on the ground to deal with awkward prey (5). Their sense of hearing is so acute that they can home in on prey by listening for the sounds made by the insect as it moves around; they can also hunt by sight (5). Large prey items may be taken to a perch, which can be identified by the heap of insect remains on the floor below (5). Mating takes place in the autumn (2), but fertilisation is delayed until the following spring (6), as females store sperm inside their uterus (womb) during the winter hibernation (6). In April and May maternity roosts typically of 10-50 females form, and unlike many species of bats, males also occur in these roosts (2). A single young (rarely two) is produced around the middle of June (2). When the mother goes out to hunt, the young are left in a 'crèche'; they can fly after 3 weeks, and are independent at 6 weeks of age (5). The brown long-eared bat can live to a maximum of 22 years, but the more likely average life span is 4.5 years (2).

In Britain, bats benefit from a very comprehensive level of legal protection (4). Under the Wildlife and Countryside Act it is illegal to intentionally kill, injure, take or sell a bat, posses a live bat or part of a bat, to intentionally, or in England and Wales, recklessly damage obstruct or destroy access to bat roosts. Under the Conservation Regulations it is an offence to damage or destroy breeding sites or resting places. Fines of up to £5,000 per bat affected and six months imprisonment are in place for these offences (3). Several species of bat also benefit by the public putting bat boxes up.

The brown long-eared bat is the second most common bat in Great Britain (5) after the pipistrelles (7). As the name suggests, it has exceptionally long ears that are almost as long as the body (5). When at rest, the ears are often tucked away under a wing or curled back like ram's horns, with just the long, delicate tragus visible (5). This medium-sized bat has broad wings, the long fluffy fur is grey-brown in colour, becoming yellowish in places, and the belly is a lighter grey (2). Juveniles are pale grey in colour, lacking the brown tinges of the adults (2).

Found in open woodlands, both deciduous and coniferous, as well as parks and gardens (2). Summer roosts and maternity roosts occur in tree holes, bat boxes and attics (2), hibernation occurs in trees, hollow walls, caves, tunnels and mines (5).

Common and widespread (7) throughout Great Britain and Ireland, except for exposed islands (5). Elsewhere it is common and widespread across most of Europe with the exception of Greece, southern Italy and southern Spain (5).

In Great Britain, all bats are fully protected under Schedule 5 of the Wildlife and Countryside Act (1981) as amended, and by the Conservation (Natural Habitats &c.) Regulations (1994). An agreement on the Conservation of Bats in Europe (EUROBATS) under the auspices of the Bonn Convention, also known as the Convention on Migratory species (CMS) is in force, and all European bats are listed under Appendix II of the CMS (4).

Like all bats, this species is vulnerable to a number of threats, including the loss of roost sites; hollow trees are often felled if thought unsafe or 'untidy'. Habitat change and loss, affecting the availability of insect prey and causing the fragmentation of feeding habitat is a serious problem for many bats, furthermore pesticide use has devastating effects, by causing severe declines in insect prey abundance, and contaminating food with potentially fatal toxins (4). Insecticides applied to timbers inside buildings where roosts occur are a particular danger, the initial treatment can wipe out whole colonies (spraying timber where bats are roosting is now illegal), but the effects of these chemicals can be lethal to bats for up to 20 years (4).