bat surveys of buildings and structures
B.A.T. Ecological specialises in undertaking comprehensive bat surveys of buildings, including those of cultural and historical importance such as churches and those with heritage listed status, as well as other complex structures and underground sites. B.A.T. Ecological reports are clear, concise and will stand-up to scrutiny, and include evidence-based conclusions and recommendations tailored to your project.
Please get in touch if B.A.T. Ecological can help you and your project with any bat surveys, reporting, licensing, or mitigation / compensation design and implementation - firstname.lastname@example.org | +44 (0) 7870 157022.
Bat surveys of buildings, built structures and underground sites are required wherever (re)development or renovations could affect bats or their roosts. Most often, bat surveys and a report are required to support a planning application, however good practice (to minimise the risk of committing a legal offence) is to undertake bat surveys prior to any renovations of buildings or structures that support features where bats are reasonably likely to roost, irrespective of whether formal consent is required. Bats are opportunists and could roost almost anywhere, however the places where they are most often found within buildings are: apertures beneath roof tiles, ridge tiles and lead flashing; cavities within masonry including missing mortar; soffit boxes and roof voids (including along roof timbers); behind cladding, barge boards and fascias, and around window frames, shutters and lintels. They can then also be found roosting or hibernating in cellars, culverts, tunnels, bridges, old walls, ice houses and grottos, as well as caves and mines.
Bat surveys of buildings, built structures and underground sites usually start with a preliminary daytime roost assessment, which should always be conducted by an appropriately licensed bat ecologist if the professional surveyor is intending on inspecting any features that could support bats with a torch or endoscope. A preliminary daytime bat survey visit by a licensed bat ecologist has several aims but the main objectives are: a) to assess the overall suitability of the building or structure for bats (usually in line with the current survey guidance); b) to identify any features that roosting bats could exploit; and c) to conduct a search for any evidence of bats in accessible areas.
It is important to note that the absence of bat evidence does not necessarily equate to evidence of bat absence because in many situations it is not possible to inspect all locations where bats could roost within a building or structure - bats can squeeze into apertures of less than 15 mm, and they can also occupy buildings and structures for different purposes at different times of year, including only transiently.
In achieving the objectives above an experienced surveyor (provided with access to most areas) will be able to determine one of the following from a preliminary roost assessment: whether bats are present (if evidence is apparent); whether bats are reasonably likely to be present (if no evidence of them was identified but there are places where they could roost); or, whether the likelihood of bats being present is negligible (because there was no evidence of them and there are very few or no places where they could roost). If an experienced, licensed bat surveyor assesses the likelihood of bats being present in a building or structure as negligible, then further surveys are not usually required, however, if bats are present, or are reasonably likely to be present, then further surveys are usually necessary.
Typically, additional surveys of a building or a structure comprise a suite of nocturnal (dusk emergence and / or pre-dawn re-entry) bat surveys that can be undertaken from May to September. However, they can potentially comprise further daytime visits if the presence of hibernating bats is reasonably likely (especially if surveys have not been conducted in the winter previously), or potentially Autumn swarming surveys using advanced methods for underground sites with the potential to support this mating phenomenon.
Nocturnal roost characterisation surveys are usually required even if there is a known bat roost because Local Planning Authorities and the Statutory Nature Conservation Organisation (e.g. Natural England) need information on the type of roost present (e.g. maternity, mating, hibernation, transient), as well as how the bats use it, when considering whether to issue planning consent or a development licence respectively. At least two separate nocturnal surveys are usually required when a bat roost has been confirmed, often three. When a bat roost hasn’t been identified from a preliminary roost assessment, but the building or structure has been assessed as being reasonably likely to support bats, then the level of nocturnal survey effort required will reflect the overall potential suitability of the building or structure for these animals as assessed by the surveyor.
Typically, in line with current guidelines, a building with low potential suitability for bats / bat roosts will require one nocturnal survey; a building with moderate potential suitability will require at least two separate survey visits; and a building with high potential suitability will require three separate survey visits. The current survey guidance that relates to this is provided here. Note that the preferred window for nocturnal surveys is May to August. On a nocturnal survey a sufficient number of surveyors are stationed at suitable vantage points around a building or structure, to watch all features that could be used by roosting bats.
Please contact me if you need help with any of the above regarding buildings or structures, or any related bat licensing or mitigation / compensation design and implementation: email@example.com | +44 (0) 7870 157022.