One of the smaller British bats, weighing less than 9 g and with a wingspan of 250 mm, the lesser horseshoe is confined to Wales and the west of England. Lesser horseshoes hunt in sheltered valleys and
woodland, often near water. During
daylight hours they roost, usually in old buildings, hanging upside down, with their wings wrapped around their teaspoon-sized bodies. Seen close-up, this tiny bat has greybrown fur and large triangular ears which, unusually for a bat, are very
The complex U-shaped noseleaf, which gives the horseshoe bats their common and scientific names, is a key part of their echolocation system - emitting and controlling a cone of ultrasound. It also allows horseshoe bats to echolocate
even when they are carrying prey in their mouths. As with most bats, they are most likely to be identified using a bat detector to pick up the sounds that
they use for navigation and hunting. The lesser horseshoe produces a constant high
frequency warble at 110 kHz. The bats use the Doppler shift, detecting a change in
frequency of the sound reflected by moving prey. Heard on a heterodyne bat detector the lesser horseshoe sounds rather like a Dr Who sound effect!
Although bats are generally considered secretive, they still leave signs of the presence: larger roosts will have heaps of droppings, and they may return to regular roosts to dismember larger insects, sometimes leaving tell-tale remains on the ground beneath. The droppings are distinctive: short links of 2 or 3 sections.
© David Chapman
Lesser horseshoe bats, their roosts and hibernation sites, are the subject of extensive legal protection, specifically the Wildlife & Countryside Act 1981 and the European Habitats Directive. Although populations in Europe have declined dramatically in
some areas, in Britain and particularly Wales, numbers appear to have increased, possibly as a result of the changes in landscape management and preservation of hedgerows, and less intensive farming practices. The lesser horseshoe bat is a UK BAP species.
Monitoring of summer maternity and hibernation roosts by licensed bat workers. Mist net trapping by licensed bat workers. Emergence surveys. Bat detector monitoring. Cat kills and incidental reports.
During the summer lesser horseshoe bats spend their days roosting in old, undisturbed
buildings, particularly old churches and farm outbuildings. They fly directly to their roosting site where they hang upside down, so they need suitably large entrances and roof spaces. Mating occurs in the autumn and the female stores the sperm until the spring. Pregnancy takes about 78 days and the young are born in July/August. While males are often solitary, females congregate into maternity colonies and they may huddle together in cold weather. At first the mother may carry the single pup with her whilst foraging, but older juveniles stay in the roost. From October the bats move to winter roosts (usually within 5 km of the summer roost),
where they hibernate in groups of up to several hundred. Hibernation sites need to have constant low temperatures but high humidity. In Cornwall many horseshoe bats use old mine
workings, but natural caves and old cellars are also used. Lesser horseshoe bats eat a range of
insects, predominantly flies, which they hunt flying low beneath the tree canopy, sometimes
gleaning insects from leaves or branches.
Although lesser horseshoe bats can live for up to 21 years they are particularly vulnerable to human impacts. The requirement for winter and summer roost sites often results in conflicts with property owners seeking to develop old barns or close dangerous mine adits. Modern agricultural practices reduce the number of insects available for the bats to feed on and timber treatments used carelessly in property
maintenance are directly toxic to bats.
Colonies of lesser horseshoe bats occur across eastern and central Cornwall to the Lizard. They are absent from the extreme west of the county and the Isles of Scilly. Over the last 10 years monitoring indicates the population is increasing. Found from France across Europe to Russia, the lesser horseshoe bat has declined across its range and disappeared from northern central Europe.
Half-a-dozen lesser horseshoe bats regularly keep one Cornish artist company in his attic studio. There are even indications that they recognise him as they seem to use a different call when he enters the room, compared to other visitors.
Did you know?:
Lesser horseshoe bats venture further underground than any other British bat,
sometimes being found 20 m below ground level.