British Mammals: Bats
Created | Updated Oct 12, 2015
Artiodactyls | Carnivora | Cetacea | Chiroptera | Insectivora | Lagomorpha | Pinnipeda | Rodentia | Mammal Surveying
The individuals which are so common in South London, even in thickly populated neighbourhoods like Battersea and Chelsea and Vauxhall, must, I think, be principally the pipistrelle... We see it from the spring months until the early winter, both in our open spaces and in the busy street.
- Walter Johnson, 1930, from the London Bat Group website.
There can be few more exhilarating sights in Britain's natural world than bats. To see a pipistrelle buzzing around picking up midges1, a Daubenton swooping over a lake, or an entire colony leaving a cave at twilight, shapes silhouetted against the sky, is unforgettable. Bats are considered to be a good barometer of the health of British wildlife, and DEFRA2 uses numbers of Daubenton's bats to help judge river quality.
There are 16 species of bat resident in Britain, of which two are considered 'endangered', six are 'vulnerable' and a further three are 'rare'. The Wildlife and Countryside Act of 1981 provides statutory protection for bats:
...it is illegal to intentionally kill, injure, take or sell a bat, possess 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 for every bat affected, and up to six months imprisonment are in place for these offences.
Bats are found in all parts of Britain. All British species are insectivores and all hibernate; generally from October until March. Their activity winds down slowly, so that they are still active for very short periods at the start and end of the hibernating period. Bats roost in many places, including caves, old buildings and woodland, though each species tends to prefer one type of habitat.
Bats find their way by a method called 'echolocation', where they send a series of high-pitched clicks and navigate by listening to how long it takes for the sound to come back. They find their prey in the same way, sending out clicks faster and faster as they close in, until they are near enough to pounce.
Species Found In Britain
There are, as stated above, sixteen species of bat resident in Britain; however there may in fact be a seventeenth. The greater mouse-eared bat was believed to be extinct in 1989, when the last known male failed to return to its hibernating roost - the first British mammal to become extinct since the wolf in around 1700. However in 2003, an elderly female was found in Bognor; the following year a young male was discovered hibernating in a tunnel in Chichester. The possibility of the species still being alive and well in small numbers has caused great excitement amongst bat-watchers.
The ubiquitous 'pip' is the most common bat in Britain, and also the smallest genus in terms of size - with wings outstretched, one comfortably fits into a human hand, and its body is slightly shorter than the average human's thumb. Its narrow wings make it extremely manoeuverable, and its erratic zig-zagging flight is easily recognisable in both urban and rural settings. Once spotted, it is possible to watch the same pipistrelle feeding for half an hour or longer; they often circle around the same clearing picking up small flies, and a show of three or four before a light evening sky can be spectacular.
Midge and Nathusius' pipistrelle
Pipistrellus pygmaeus and Pipistrellus nathusii
Midge pipistrelles were only recognised as a separate species in the mid-1990s, when scientists noticed similar bats giving out slightly different echolocation frequencies. They are in fact slightly smaller than their cousins, but only a study of penis colour will tell the two apart3!
A migratory species, Nathusius' pipistrelles were not considered resident in Britain until records began dribbling in around 50 years ago. It is predominantly an eastern European species, capable of travelling 1000km on the continent, although there appears to be at least one permanent roost in the UK; roosts have also been found in Co Antrim and Bristol, though these may have only been seasonal. It is extremely rare in this country.
Common (or brown) and grey long-eared bat
Plecotus auritus and Plecotus austriacus
Again, these are two very similar species, which were only separated in 1960. Both are named for the distinctive ears, which can grow up to 3cm long - almost a third of the total body length. They are quite happy hunting in dense woodland or city parks, adapting well to human influence. While the brown species is common enough to be considered Britain's second most populous bat, the grey variety is restricted mainly to the south-western counties of Dorset, Hampshire and Devon.
Greater horseshoe bat
Named because of its strangely shaped nose, this is Europe's largest horseshoe bat - and Britain's second largest of any bat species - with a 35-40cm wingspan. It can travel up to 15km (10 miles) to find food, which it hunts very low to the ground - often less than metre above it. Sometimes it even hunts from a perch, grabbing insects from the air as they pass. It is the only bat in Britain to give out is echolocation from its nose rather than its mouth, and can live an amazing 30 years.
The greater horseshoe's distribution has been severely reduced in recent years, and it is now only found in south-west Britain. Part of the reason for this is believed to be the sealing off of many old mines across the country. It is considered an endangered species, and numbers are estimated to be only around 4000 in just a dozen colonies - with almost a third of these resident in south Devon.
Lesser horseshoe bat
A little more than half the size of its cousin, the lesser horseshoe is very common in Europe but endangered in Britain. Although it can be found at up 2000m in altitude on the continent, at the northerly end of its distribution in Britain it is only found in low, sheltered valleys.
There are estimated to be 17,000 lesser horseshoe bats in Wales and the south-west of England. Like the greater horseshoe, its range has been affected by the sealing of old mines, but the lesser horseshoe has proved to be more adaptable and thrives in wooded areas. It is one of the few species that is slowly increasing in numbers; a study made from 1993 to 1999 showed that Welsh populations had increased by over 6%, and across the UK there was a 4.8% increase over the study period.
Renowned for its feeding habits, the 'water bat' is an incredible species. It can pick up pond-skaters from the surface of a pond or lake without getting its wings wet, and can even use its tail to do this. It is incredibly manoeuverable, and prefers to feed over lakes, ponds and slow moving water. Water bodies with a woodland edge form a perfect habitat for Daubenton's bats; these sites attract plenty of small flying insects and provide nearby roosting sites. It is found in all regions of the UK.
Daubenton's bats are one of only two species in Britain believed to carry European Bat Lyssavirus, a form of rabies. In 2002, a Scottish naturalist and licensed bat handler became only the second person in the world to die of the type two version of the virus, probably after being bitten or scratched by a bat4. Research is ongoing, but all results to date show that the risk of infection from a bat is minuscule - especially to the general public.
Only recognised as a separate species to Brandt's bat in 1971, the whiskered bat is very small, with a wingspan of only 25cm - about the same as a blue tit. Its name comes from the hairy muzzles around its mouth. Often described as 'shaggy', it has short dark fur, usually with golden flecks on the tips on its back. It is often mistaken for the pipistrelle because of its small size, but has a distinctive direct flight, and occasionally glides for brief moments.
Numbers and distribution of whiskered bats are unclear, as it is often confused with Brandt's bat. Its conservation status is 'uncommon', and it occurs across England, Wales and southern Scotland.
It is easy to confuse Brandt's bat with the whiskered bat. In fact, without looking at the genitalia or teeth, it is almost impossible to be certain which is which as the species are so similar in appearance. Brandt's bat tends to come out earlier in the evening, has slightly smaller ears and is a little larger. Without seeing the two together, however, these small differences are not much help.
It is considered to be 'uncommon' in Britain and occurs in all parts of the country.
The pink jaws of Natterer's bat make it distinctive. It also has the ability to catch insects in its tail fringe, and has a distinctive spinal protrusion which makes its tail appear to be heart-shaped. It has adapted well to the loss of deciduous woodland, its former habitat, and as long as there is open water or marsh to feed near it is happy to live almost anywhere.
Britain's largest bat has an average weight of 32g and a wing span of 36cm - about the length of an adult human's forearm. Noctules have very long, narrow wings, and utilise these very well by flying high and then gliding, picking up insects on the way down. They are one of the few British bats that commonly emerge before sunset, and are fairly common in southern England and Wales.
This bat is also known colloquially as the lesser noctule; it is similar in form, is also a fast flyer which tends to hunt high in the air and - not surprisingly - is a little smaller than the noctule. In Ireland, where noctules are not present, Leisler's bats have taken over that ecological niche entirely.
Bechstein's bat is very rare in western Europe, and the UK population consists of only around 1500 individuals congregated around Dorset. It is particularly noticeable for its long ears, which can be up to 2.5cm long - the longest of any British species (apart from the long-eared varieties). Only nine breeding roosts are known in the UK, as it prefers a very specialised type of damp deciduous woodland. Secretive and elusive, little is known about this species.
Restricted to the south-east of England, the Serotine is a medium-sized bat that occasionally makes its home in people's attics. Although powerfully built, it is a relatively slow flyer, having rather well-rounded wings. Apart from the Daubenton, it is the only British bat to be known to carry rabies, and often loses its shy and retiring character when infected.
The bat equivalent of the British Bulldog, barbastelles are unmistakeable - squat-faced, thick-eared and flat-snouted. Forget vampires; this truly is a bat to scare children with.
They are considered fairly rare in the UK, with just a few populations in southern Wales and England. Sometimes emerging before sunset, they generally feed over water or by plucking insects off vegetation.
As noted above, it is illegal to handle bats without a special license, which can only be obtained after undertaking a training course with The Mammal Society. However, there are other, legal ways in which you can get close to the world's only flying mammal.
A great way to find bats is with a bat detector. These are available at various prices, starting at around £50 in the UK, and work rather like a radio - converting the high-frequency echolocation sounds into a noise the human ear can hear. Some cheaper varieties can only pick up one or two species (usually long-eared and pipistrelles), but there are some excellent low-priced models that can pick up a range of frequencies from 20-140kHz, suitable for most species. For guidance, horseshoe bats transmit around 30kHz, pipistrelles and Daubentons around 45-55kHz, and noctules at 130kHz. They make for an excellent activity on an evening walk.
Bats also need somewhere to roost, and rather than open up your attic to them it is possible to buy 'bat boxes', made along the lines of nestboxes for birds. These can be hidden in trees or on sheltered walls to provide a good habitat for bats.
Many nature groups, including local Wildlife Trusts, organise bat walks through the summer months. These are often excellent, with experienced walk leaders explaining what is before you. If you have never experienced bats close up, this kind of walk may be just what you need to be introduced! Londoners should particularly look out for walks led by London Bat Group, a charity with an excellent reputation.