Lesser horseshoe bat
Rhinolophus hipposideros
The lesser horseshoe bat is one of our smallest British species. At rest it hangs with the wings wrapped around the body and is about plum-sized. Like the greater horseshoe bat, it has a complex noseleaf which is related to its particular type of echolocation system.
Lesser horseshoe bat facts
| Description | |||
| Head and body length |
35 - 45mm | ||
| Forearm length | 35 - 42mm | ||
| Wingspan |
200 - 250mm | ||
| Weight |
5 - 9g | ||
| Colour |
Adults pinky buff- brown, juveniles greyish (until first summer after birth) | ||
|
Life cycle | |||
| Mating period | September to November | ||
| Maternity colonies | Established late spring. Young: one, born mid-June to mid-July weaned at six weeks | ||
| Colony size | 30 to 70 bats (occasionally 400) | ||
|
Longevity |
Up to 2l years | ||
| Habitat and food | |||
|
Summer roosts |
Originally cave dwellers, now roofs of larger houses and stable blocks | ||
|
Winter roosts |
Caves, mines, tunnels, cellars | ||
| Feeding habitat | Open deciduous woodland, scrub, parkland, wetland and permanent pasture | ||
| Typical food | |||
| Flies (mainly midges) | small moths | Caddis flies | spiders |
In the summer lesser horseshoe bats emerge about half an hour after sunset as it is getting quite dark. The emergence follows a period when the bats fly around within the roost with some appearance outside the roost entrance; presumably they are testing the conditions outside before emergence. Although there are peaks of activity at dusk (and also at dawn) bats are active all night throughout the breeding season. Lesser horseshoe bats are sensitive to disturbance and twist their bodies as they scan their surroundings before flying off.
Lesser horseshoe bats feed amongst vegetation in sheltered lowland valleys. They fly close to the ground, rarely more than five metres high, with frequent circling over favoured areas and often "gleaning" their prey off stones and branches. Large prey is often taken back to a temporary night roost or sometimes dealt with whilst hanging in trees. Feeding remains are found in such places, particularly in porches and the entrance to tunnels.
Breeding
Mating takes place during autumn, sometimes later. Maternity roosts are almost always formed in buildings and may be occupied from April, though most breeding females do not arrive until May.
Maternity colonies of the lesser horseshoe bat are of mixed-sex, with up to a fifth of the colony being male. Approximately half to
Lactation probably lasts four to five weeks, by which time the young can fly from the roost. They are completely independent at six weeks and nurseries disperse between August and October (occasionally November). Most young are sexually mature in their second autumn.
Summer roosts
Lesser horseshoe bats were originally cave dwellers, but summer colonies are now usually found in the roofs of larger rural houses and stable blocks offering a range of roof spaces and a nearby cellar, cave or tunnel where the bats can go torpid in inclement weather. They prefer access through an opening that allows uninterrupted flight to the roof apex, but they are capable of using more inconspicuous gaps. The colony may shift between attics, cellars and chimneys throughout the summer depending on the weather. The whole colony may form a dense cluster, especially in cooler weather during lactation, but if the roost gets very hot they hang spaced slightly apart.
Winter roosts
The lesser horseshoe bat uses caves, mines, tunnels and cellars as hibernation sites. They hibernate from September or October until April and frequently into May. Lesser horseshoe bats are often active in the hibernacula in autumn and spring especially towards dusk in warm weather, when feeding is more likely to be successful. They appear to select places with similar temperatures to greater horseshoe bats, preferring temperatures of up to 11°C and with a high humidity.
Males tend to arrive earlier than females and are often more numerous. Many sites only have one or a few bats hibernating in them and it is rare to find large numbers in a site. Even when aggregated, lesser horseshoe bats do not cluster but hang a little apart from their neighbours, usually exposed, but sometimes in open crevices. They may be found from almost ground level to over 20 metres and venture much further into underground sites than other bats.
Ultrasound
Lesser horseshoe bats have an almost constant frequency call, about 110kHz. On a bat detector a series of continuous warbles can be heard.
Status and distribution
This species has shown a marked decline in numbers and distribution particularly in western and northern Europe although there is evidence of a recent increase in some areas. The lesser horseshoe bat is rare in the British Isles and is confined to Wales, western England and western Ireland.
Conservation
The decline of the lesser horseshoe bat is attributable to several factors including disturbance to roosts and intensive agricultural practices. Lesser horseshoe bats are particularly sensitive to disturbance especially of their nursery and winter roosts. These sites need to be specifically protected and entrance holes left unobstructed. The conservation of their feeding habitats and food sources is of paramount importance. The use of pesticides has probably led to a decrease in their available food source.
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