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The Bats of London
This is an introduction to the species of bat that can be seen in Greater London, where they can be seen, and some ideas on how to tell them apart. This is often difficult however, and some species can only be reliably identified by experts in the hand. Bat detectors are a valuable tool, and can often reveal the presence of bats when they are difficult to see when flying close to trees in the dark. Why not join the London Bat Group and go out in the company of more experienced bat watchers and learn the "tricks of the trade".
The pipistrelle, Pipistrellus sp.
These tiny animals weigh about 4 to 6 grams, have a wingspan of 19 to 25cm and eat midges, mosquitoes and other small insects that they catch and eat on the wing. A single pipistrelle can eat up to 3000 midges, caddis flies, mosquitoes and other similar small insects in a night. The pipistrelle is the most common species of bat in Britain, and mostly roosts in houses under eaves and soffit boards which means that their roosts are found more often than other species.
The noctule, Nyctalus noctula
The noctule bat is one of the largest bats found in Britain, and is often the first to emerge from its roost, sometimes before sunset. Weighing some 18 to 40 grams and with a wingspan of 32 to 40cm it has a sleek golden coloured fur and broad brown ears.
The Daubenton's bat Myotis daubentonii
The Daubenton's bat is a medium sized bat weighing 7 to 12 grams and with a wing span of 24 to 27cm. It was often called the water bat in the past because of its distinctive habit of flying in a level flight about 10cm above the surface of water bodies such as lakes. The Daubenton's feeds on small flies such as caddis flies and midges and roosts in trees or tunnels and bridges which are generally near water. Daubenton's can be seen mainly in west London sites like Wimbledon Common; the Grand Union Canal in Hillingdon and Bushey Park, but can also be found on sites like Hampstead Heath and Beech Hill Lake in Barnet.
Natterer's bat (Myotis nattereri)
The Natterer's bat is similar to the Daubenton's, and individuals have been found in Highgate Woods and the grounds of Chiswick House and in 1996 a tree roost was found in Hillingdon. Work is being planned by London Underground Ltd to enhance a major autumn site for this species that has recently been found near Highgate Wood.
The brown long-eared bat Plecotus auritus
As suggested by the name, the brown long-eared bat has remarkably large ears which are nearly as long as its body. It is a medium sized bat weighing 6 to 12 grams and has a wingspan of 23 to 28cm. Although nationally, the brown long-eared is regarded as the second most common species, it is less common in London as it appears to be less well able to survive in urban surroundings. This animal is the bat that is most frequently found roosting inside roof spaces where it likes the ridge beams of older properties.
The serotine bat Eptesicus serotinus
Another large bat, weighing 15 to 35 grams and with a wing span of 32 to 38cm the serotine feeds on flies and moths but is particularly fond of cockchafer beetles which it can catch by landing on the ground. The serotine is mainly found in the outer boroughs of London such as Bromley, Havering and Sutton where it feeds over mature parkland or pastures.
A number of other species of bat are occasionally found, especially in the outer London boroughs. The Leisler's bat (Nyctalus leisleri) is a smaller cousin of the noctule and weighs 12 to 20 grams and has a wingspan of 26 to 32 cm. There is one known summer roost of Brandt's bats (Myotis brandtii) in Hillingdon otherwise this bat is extremely rare in London, and for the similar whiskered bat (Myotis mystacinus) there are only occasional individual records.