There are 16 bat species native to Britain. All are protected under the Wildlife & Countryside Act 1981(as amended), the Conservation Regulations 1994 and the CROW Act 2000 but some are under a greater threat than others. The worst scenario is the fate of the greater mouse-eared bat, Myotis myotis, which had been declared extinct in this country in 1991(there is now hope that there is still a surviving colony on the south east coast - a very weak female was found in 2001, which unfortunately died soon after discovery.). The last mammal to be recorded as extinct in Britain was the wolf 250 years ago. We do not want to add any more to this list! Of the remaining number only three are listed as not under threat, but they can not be treated with any complacency. Britain is on the northern fringe of distribution for many of these bats making their position all the more vulnerable.

Design:

Bats have the largest surface area to volume ratio of any of the world's mammals, the variety of wing shapes allowing different habitats and prey sources to be exploited. Bats such as the long-eared bats have curved, broad wings making them highly manoeuvrable but slow fliers, able to negotiate cluttered environments such as vegetation. Species such as the noctule have a long, narrow wing enabling them to fly fast, but loosing the ability to move within anything other than an open environment. The long-eared bats feed on insects found within vegetation, such as moths whilst noctules feed on large insects, such as cockchafers (maybugs), that can be found in the open air.

Due to having evolved to fly bats have a narrow weak pelvis as they do not crawl great distances. To this end a bats knees have been rotated - so that they bend 'the wrong way' - thus facilitating landing on vertical surfaces, and roosting head down a position from which they take flight. The reversed knee joint also allows the tail membrane (which extends to the ankles) to aid manouverablity in flight and to be used in conjunction with the wings to envelope prey items, preventing their escape.

In Britain there are two families of bats represented; most are members of the Vespertilionidae or Vesper bat family, while two species are members of the Rhinolophidae or Horseshoe bat family, unsurprisingly being the greater and lesser horseshoe bats.

Feeding:

British bats are all of the sub-order Microchiroptera, and all feed on insects, which they find by using highly sophisticated sonar. Each species emits ultra-sonic frequency calls (within a particular band-width) which 'bounces off' objects, letting them know their location. Most emit the calls through their mouths (so fly with their mouths open), while others emit sounds through special structures such as a noseleaf.

Breeding:

British bats mate in the autumn, the females seeking out males that have established mating roosts. The males display for the females and produce low mating calls to attract their attention, these can be audible to the human ear. Fertilization is delayed until the females come out of hibernation when the weather conditions are suitable and they have established a maternity colony. Gestation can also be put on hold if part way through the pregnancy food becomes scarce. This can reduce the chance of survival of the young bat if it is born too late in the year when food supplies are declining and winter is approaching.

Usually bats have a single young or pup, although twins have been known, once every couple of years. In many species females are reproductively active in their first autumn, the males the following summer. When born a young bat weighs a third of its mothers weight!! Bats are born pink, hairless and blind as are many small mammals; their ears are also closed.

The young feed solely on their mother's milk and most have special hooked incisors or milk teeth enabling them to hang onto their mother's nipple with out the danger of being dropped when the mother takes flight. (Young horseshoe bats do not have these incisors see Horseshoe Bats). The young stay attached to their mother's nipple for the first week of their lives; then as the ears become erect and the eyes open they can be left in crèches in the roost, while the mothers go out to feed. The mothers often return part way through the night to suckle their offspring. Each mother and baby can recognise each others particular call enabling them to reunite in a busy roost. The pup's calls are quite audible and are known as isolation calls (i-calls). Most young are born in June and July, learn to fly around three weeks old and are weaned at six weeks.

Under Threat:

The declining numbers of bats are due to a number of factors, most relating to human interference. Modern agricultural practices do away with hedgerows, wooded areas, rough grassland etc. use for feeding and cover. The use of insecticides and other chemicals which are toxic for bats as well as their prey are also a problem. Many woodland management schemes destroy suitable roost sites and feeding areas; ancient trees provide a home and food source for many creatures but are removed instead of being made safe, and areas of under storey provide a source of food and shelter. Renovation and building work can destroy roosts if the proper channels are not gone through, or unsuitable preservation treatments are carried out that are harmful to bats.

Predation is always going to be a factor, but bats natural predators, such as Tawny owls, take a very small proportion of the bats killed this way each year. (Gulls, corvids, hawks and falcons will occasionally take bats if they are flying in daylight hours. At night negligible numbers are taken by long-eared owls and barn owls). The majority are caught by Felix domesticus, the domestic cat - and they don't even eat them!! Cats like the challenge of catching these fast flying creatures; if you have a cat that is partial to catching bats please keep it in at dawn and dusk, this will also assist the rest of the local small mammal populations as well!

Of course lack of knowledge is our worst enemy!
 
 

Pipistrelle / Noctule / Daubenton's / Horseshoe Bats / Brandt's / Whiskered / Natterer's
Bechstein's / Serotine / Leisler's / Barbastelle / Long-Eared


PIPISTRELLE

Click here to enlarge

There are two of the Pipistrellus genus, which until recently were described as the 45kHz and 55kHz phonotypes. They have now been declared as separate species. Alternative common names that have been suggested for P. pipistrellus include bandit and masked pipistrelle due to the face being much darker than the body fur and for P. pygmaeus soprano or brown.

Pipistrellesare the smallest of the British bats (when at rest being able to fit into a matchbox) and are the most common species, especially in urban areas.

Despite their size pipistrelles can eat up to 3000 small insects in a nights feed - just the creatures you need around on those summer nights when the mosquitoes come to join you!
 
Wingspan: 190 - 250 mm (7 - 10 ins)
Weight: 3 - 8 g (0.1 - 0.3 oz)
Flight: fast and irregular 
Longevity: 16 years
Summer Roosts: buildings
Winter Roosts: trees & buildings

Basic Differences:
 
  Common pipistrelle

(P. pipistrellus)

Soprano pipistrelle

(P. pygmaeus)

Ultra-sound freq.: 40 - 60kHz, peak 45kHz 40 - 60kHz, peak 55kHz
Size: slightly larger head not quite as large
Features: darker face and ears, contrasts with fur paler more open face, eyes more exposed
Feeding: range of habitats found more around areas of water
Diet: flies, small moths, larger insects midges, mosquitoes, smaller insects
Maternity roost: 20 - 223 bats 30 - 650 bats

The under-recorded new arrival?
Nathusius's pipistrelle (P. nathusii): This larger pipistrelle species used to be recorded as a vagrant but maternity roosts have since been discovered in Britain. Still relatively rare, although large roosts have been discovered in Northern Ireland. It could just be that this species is very under-recorded.

 

NOCTULE

Click here to enlarge

Nyctalus noctula, is now the largest British bat (since the untimely demise of the mouse-eared) and found mainly in England and Wales. Trees are fundamental in the survival of this species as they rely on them all year round.

Noctules tend to emerge before dusk and may be seen feeding amongst the swifts on a summer evening high above the trees. If you take the time to stop and watch them you can tell them apart by their flight patterns.

In the field noctules are often confused with the Leisler's species (also of the Nyclatus genera) which are a little smaller but behaving and call in a similar manner. If you see them in Ireland there will be no confusion .only Leisler's are present!
 
Wingspan: 320 - 400 mm (13 - 16 ins) 
Weight: 18 - 40 g (0.6 - 1.4oz)
Flight: fast, direct, high in the open, steep dives
Longevity: 12 years
Summer Roosts: trees
Winter Roosts: trees, rock fissures
Ultra-sound freq.: 20 - 45kHz, peak at 25kHz
Maternity roosts:  15 - 50 bats
Feeding: deciduous woodland, pasture, water
Diet: moths, beetles, mayflies & winged ants

DAUBENTON'S

Myotis daubentonii, are most commonly associated with areas of water throughout Britain. They are to be seen at dusk feeding over water bodies, very often in groups, picking insects off the suface if the water and udertaking some serious acrobatics in the process!
 
Wingspan: 240 - 275 mm (9 - 11 ins).
Weight: 7 - 12 g (c.1/3 oz).
Flight: low, over water.
Longevity: up to 22 years.
Young: born June to mid July, weaned c. 6 weeks.
Roosts: summer in trees, bridges, caves etc., winter in underground sites.
Ultra-sound freq.: 35 - 85kHz, peaking at 45 - 50kHz. 
Maternity roosts:  20 - 50 bats.
Feeding: over lakes, rivers & ponds. 
Diet: small flies, mayflies & caddisflies.

HORSESHOE BATS

The greater, Rhinolophus ferrumequinum, and the lesser horseshoe, R. hipposideros are both considered endangered. The former can be found in south Wales and south-west England and the latter in Wales, south-west England and western Ireland. Both species can give their presence away by the piles of insect remains that are left underneath favourite feeding perches - most British species feed on the wing.

Baby horsehoes are different to other British baby bats because they absorb their milk teeth before birth! Instead they attach themselves to their mother's breast nipples or the supernummary (pubic attachment) nipples with their canine teeth! These additional nipples are only found in horseshoe species.

Rhinolophus species can be easily distinguished by their noseleaves, which they use to create their echo-location calls.
 
  Greater horseshoe (R. ferrumequinum) Lesser horseshoe (R. hipposideros)
Wingspan: 350 - 400 mm (14 -16 ins). 200 - 250 mm (8 - 10 ins).
Weight: 17 -34 g (c.1 oz). 5 - 9 g (c. 1/3 oz).
Flight: fly from perches, low-flyers. Low-flyers, glean off objects.
Longevity: up to 30 years. up to 21 years.
Young: born mid-July, weaned c. 7 weeks. born mid-June to mid-July, weaned c. 6 weeks.
Roosts: summer in buildings, winter in caves, cellars etc. summer in buildings, winter in caves, cellars etc.
Ultra-sound freq.: 82 kHz, with little variation. 110 kHz, with little variation.
Maternity roosts:  50 - 200 bats. 30 - 70 bats.
Feeding: deciduous woods, permanent pasture, water, along hedgerows. deciduous woods, permanent pasture, wetland, parkland.
Diet: chafer & dung beetles, crane-flies, caddisflies. Midges, small moths, lacewings wasps, spiders.

BRANDT'S

Myotis brandtii is very similar in appearance to the whiskered bats. The two species are very difficult to tell apart in the hand. For instance you need to examine the third premolar!!
 
Wingspan:  200 - 250 mm (8 - 10 ins)
Weight:  4 -8 g (0.1 - 0.3 oz)
Flight:  
Longevity:  
Young:  
Summer Roosts:  buildings
Winter roosts underground sites
Ultra-sound freq.:  
Maternity roosts:   
Feeding:  occasionally woodland, open parks & gardens
Diet:  small moths & insects

WHISKERED

Myotis mystacinus is easily confused with Brandt's especially when handling live specimens. The two species have only recently been separated so the differences between the two are still to be defined. Both are relatively widespread throughout England and Wales, Brandt's being thought to slightly fewer in numbers. When handled the whiskered will often gape (i.e. hold its mouth open) and vocalise audibly.
 
Wingspan: 200 - 250 mm (8 - 10 ins) 
Weight: 4 - 8 g (0.1 - 0.3 oz) 
Flight:  
Longevity: 24 years
Summer Roosts: buildings
Winter Roosts: underground sites
Ultra-sound freq.:  
Maternity roosts:  30 - 70 bats
Feeding: occasionally woodland, open parks & gardens
Diet: small moths & insects

NATTERER'S

Myotis nattereri has a direct flight and a call very similar to the Daubenton bat. They have longer ears than the other British Myotis species of bat.

Click here to enlargeMyotis nattereri
 
Wingspan: 245 - 300 mm (10 -12 ins)
Weight: 7 - 12 g (0.2 - 0.4 oz)
Flight: most often low slow flyers, glean flightless insects. 
Longevity: 20 years.
Summer Roosts: underground sites 
Winter Roosts: tree-holes, stone buildings
Ultra-sound freq.: 35 - 80 kHz, peak 50 kHz
Maternity roosts:  20 - 100+ bats
Feeding: woodland, parkland, hedgerows, water boundary vegetation
Diet: flies, moths, spiders

BECHSTEIN'S

Myotis bechsteinii is very rare in Britain - only eight maternity roosts are known. They are also rare across their known range in Europe. This species has special protection in Annex II of the EU Habitats & Species Directive.

A study of a colony in a Dorset woodland by the Vincent Wildlife Trust showed that they have relatively small foraging ranges, preferably within woodland with a high dense canopy and understorey, with water present. The area of high forest or woodland matrix, preferably oak, required to support this species is sizeable. The size and quality of the woodland affects the size of the maternity colonies. Holes created by green woodpeckers appear to provide preferable roost sites.

We now have our first county record for this species! A mature male discovered in the roof apex of a house on the outskirts of a town with no mature woodland in sight!! Not where it should be at all!!

Bechstein's have relatively long ears (but not a long as the long-eareds!) because they are listening for quiet sounds so this enhances their hearing ability. For this reason also they have a very quiet echo-location call, which is very often not picked up by electronic bat detectors. Just like long-eared bats, the Bechstein's gleans insects from the vegetation.
 
Wingspan: 260 - 320 mm (10 - 13 ins) 
Weight: 7 - 13 g (0.2 - 0.5 oz)
Flight: gleans, amongst vegetation, highly manoeuvrable
Longevity:  
Summer Roosts: trees 
Winter Roosts: caves & tunnels 
Ultra-sound freq.:  
Maternity roosts:  20 - 80 bats 
Feeding: woodland, parkland & enclosed vegetation 
Diet: moths, flies & beetles 

SEROTINE

Eptesicus serotinus is a large bat, similar in size and habitat in the field to the noctule, but unlike the noctule it is often found roosting in buildings. Their distribution is restricted to southern Britain, but may be under recorded due to the similarity of their call to that of the noctule and the leislers.

This species has a physical feature may be visible if they fly close to you - the membrane of their tail does not reach to the tip, giving them a partial free-tail.
 
Wingspan: 320 - 380 mm (13 - 15 ins)
Weight: 15 - 35 g (0.5 - 1.2 oz)
Flight: high flyers, close to vegetation, suburbia
Longevity: 19 years
Summer Roosts: buildings
Winter Roosts: buildings
Ultra-sound freq.: 15 - 65 kHz, peak 25 - 30 kHz
Maternity roosts:  15 - 30 bats
Feeding: pasture, parkland, tall hedgerows, suburban areas
Diet: dung beetles, chafers, moths, flies

LEISLER'S

Nyctalus leisleri is a little smaller than the noctule but very similar in appearance. Leisler's are found through out Britain and are relatively common in Ireland. The old name for this species was the "hairy-armed" bat due to the fact that the under fur extends onto the wing membrane and the forearm.
 
Wingspan: 260 - 320 mm (10.5 - 13 ins)
Weight: 12 - 20 g (0.4 - 0.7 oz)
Flight: high and fast in the open, dives
Longevity: similar to noctule?
Summer Roosts: trees & buildings
Winter Roosts: trees, buildings & caves
Ultra-sound freq.: 15 - 45 kHz, peak 25 kHz
Maternity roosts: 20 - 50 bats
Feeding: woodland, parkland, suburban areas
Diet: flies, moths, caddis-flies, beetles

BARBASTELLE

Barbastella barbastellus is a rare species but is found throughout Britain, existing naturally at very low densities. The barbastelle has distinctive features with a pug-like face and very broad ears.

Most barbastelle roost records are in buildings but this is due to the fact that they are more likely to be discovered. A survey carried out by Frank Greenaway in West Sussex found the majority were found in trees. Within an area of ancient woodland the roosts were predominately found to be dead stumps of oak and beech, in areas with a high dense canopy and dense understorey. Woodland of this calibre is very scarce and many of the veteran trees having been removed.

The largest maternity colony found in a building is found in Norfolk within an historic barn (this is the only known permanent breeding site within a building). Barbastelles are expected to forage in wooded river valleys and low over water, but the Norfolk bat group recorded bats form this particular roost feeding below the beach cliffs and along the beach itself!!
 
Wingspan: 250 - 300mm (10 -12 ins)
Weight: 6 - 13 g (0.2 - 0.5 oz)
Flight:  
Longevity:  
Summer Roosts: trees & buildings 
Winter Roosts: underground sites 
Ultra-sound freq.:  
Maternity roosts:  not known in Britain
Feeding: wooded river valleys, meadows & over water 
Diet:  

LONG-EARED

The brown long-eared, Plecotus auritus and the grey, P.austriacus are often referred to as 'whispering bats' because their echo-location calls are very quiet, barely audible with a bat detector. The brown long-eared is widespread throughout Britain and Ireland, while the grey is rare and only found along the south coast.

The hearing of a long-eared is very sensitive aided by large ears (as the name suggests); being able to pick up sounds of insect movements - just the rustle of wings as they warm up. The ultrasonic frequencies are emitted through the nose so another noticeable characteristic of a long-eared in flight is that it will have its mouth closed! The fact that their hearing enables them to detect insects that are not in flight means that long-eareds can still feed in weather conditions when there is little insect activity. Feeding off surfaces in this manner is referred to as gleaning.  As with other species that catch relatively large prey they use feeding perches.

When in torpor or hibernation long-eareds fold up their ears and tuck them under their wings, so that just the tragus (inner ears) are visible, giving the impression of a bat with particularly small ears! Sometimes when at rest the ears are only partially folded into a rams' horn shape.

The two species are difficult to tell apart even in the hand. A simple anatomical difference is the length of the thumb - the brown having a longer thumb than the grey. The grey long-eared is also much more aggressive when being handled!
 
  Brown long-eared (P.auritus) Grey long-eared (P.austriacus)
Wingspan: 230 - 285 mm (9 - 11 ins)  245 - 300 mm (10 - 12 ins)
Weight: 6 - 12 g (0.2 - 0.4 oz)  7 -14 g (0.2 - 0.5 oz)
Flight: dives & glides, gleans  dives & glides, gleans
Longevity: 30 years  assumed similar to brown
Summer roosts: older buildings & trees  older buildings 
Winter roosts: buildings, caves & trees  caves & tunnels - few records
Ultra-sound freq.: 25 - 50 kHz, peak 35 - 40 kHz  
Maternity roosts:  10 - 30 bats  unknown in Britain
Feeding: woodland, parkland, orchards  assumed similar to brown
Diet: moths, flies, beetles, spiders, earwigs  assumed similar to brown


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