How Bats Use Buildings
Buildings can be used by bats during any part of the year but are most likely to be present during the summer months. Whilst all species of British bat will at times make use of built structures, there are a number of species that are particularly linked to buildings.
Pipistrelle species
Both Common and Soprano pipistrelle are crevice dwellers that use many features on and in a building but relatively rarely enter the roof void. Features used in summer include soffits, fascias, barge-boards, weather boarding, between roof felt/membrane and tiles/slates, around window frames, in cavity walls, under hanging tiles and lead flashing. In winter pipistrelle species may use cavity walls or crevices deep in solid walls.
Long-eared species
During summer long-eared bats will use crevices in the roof structure and under the ridge during the day although they occasionally roost in the open within the roof void and frequently fly within the roof void. They can also be found in roofs during the winter. Long-eared bats tend to prefer older buildings.
Greater and lesser horseshoes
Both species of horseshoe bat use buildings during the summer months. Usually they are found using roof spaces where they need flight access (due to their poor ability to crawl) but can also use boiler rooms often situated in cellars or in seperate buildings. In the winter horseshoe bats can make use of unheated cellars for periods of torpor.
Brandt’s and whiskered
These species of bats are crevice dwellers and in the summer months may use crevices formed by the structure within a roof space but may enter roof spaces to fly around. They also make use of external features such as hanging tiles soffits, cavity walls and ridge tiles.
Serotine
Serotine make use of crevices within buildings for summer use. They are not usually found in the roof void. Serotine are likely to use buildings during the winter too, with the cavity wall likely to be an important feature.
Leisler’s
Leisler's can be found using crevices within buildings during the summer. They are not usually evident within the roof void. In winter Leisler's make use of cavity walls.
Natterer’s
In summer Natterer's bat are frequently found in crevices in timbers of the substantial type often found in old barns but in other buildings too.
Which bat species are most likely to be found in various parts of a building?
As an alternative approach to how bats use buildings, the key features of a building and specific built structures will now be listed with the most likely species of bat and season of the year that they are used. It must be emphasized that this is an indicative guide to most common associations only.
Cavity walls
Serotine, Leisler's and pipistrelle species all year round. Natterer’s, brown long-eared, Brandt’s and whiskered in summer.
Roof spaces
Long-eared, greater and lesser horseshoes and Natterer’s in summer.
External features
Pipistrelle species, Leisler’s, Brandt’s and whiskered during summer.
Cellars (Heated or unheated)
Heated cellars – greater and lesser horseshoes in summer.
Unheated cellars – greater and lesser horseshoes in winter.
Roof structure
Long-eared bat species, Brandt’s, whiskered, pipistrelle species, Natterer’s, serotine and Leisler’s in summer. Long-eared in winter.
Solid wall with cracks and crevices
Pipistrelle species especially in winter.
Other built structures with special features
Barns
Natterer’s and long-eared.
Churches
Pipistelle species, long-eared species, serotine
Bridges
Daubenton’s in summer.