Ecology advice

Bats surveys

Information for planning applicants, agents and developers

If you are submitting a planning application that may affect bats (for example, if the roof will be significantly affected by the works) you may have questions about bats and planning such as:

  • why do I need a bat survey?
  • what does a bat survey involve?
  • will I still be able to go ahead with my development if I have bats?

For information on who can carry out bat surveys, you can search for ecological consultants online, or you could visit the Institute of Ecologists and Environmental Managers. On this website, you can search the institute’s commercial directory of consultants to find local ecologists who can carry out the work for you. We recommend that you obtain a number of quotes as prices can vary considerably. If you have any further questions, please contact us.

Information for ecological consultants

For a bat survey report to be accepted, the consultant must be able to demonstrate that sufficient survey effort has been carried out (in accordance with page 39 of the Bat Conservation Trust (BCT) Good Practice Guidelines). As a general rule, this would include a daytime internal and external survey of the site and at least two activity surveys, conducted with sufficient manpower and equipment. For example, surveys of multi-pitch buildings using a single surveyor are generally considered to be inadequate. Any deviation from BCT good practice should be justified within the report.

We expect bat survey reports to include sufficient detail to enable the ecology unit to feel confident in the findings of the survey and use them to inform subsequent recommendations. For this to be possible, we need to see certain essential information such as date of survey, who carried it out and details of their relevant experience (with licence number where appropriate), weather conditions, suitably sourced desk study of existing information, detailed methodology, detailed plan of the site, detailed results and subsequent recommendations with an explanation and justification for any conclusions. This is a uniform standard that we expect from all consultants and failure to adhere to this standard could result in the report being rejected by the district ecologist. Should a survey submitted with a planning application indicate that further survey work is required this will automatically invalidate your planning application at submission.

Bat surveys are assessed against the BCT bat survey, good practice guidelines – in particular, see pages 27-28.

As a consequence of the recent judicial review (the Cheshire case), if a natural England protected species derogation is required, discussion of the three derogation criteria will be needed in the report in order to justify the potential use of a planning condition. In addition, the report should include sufficient information to illustrate that appropriate mitigation measures will be possible within the scheme.

Useful survey information

The presence of a protected species, such as bats, may have a significant impact on the progress of a planning application. It is however possible for both applicant and wildlife to coexist in a mutually agreeable manner. The need for a bat survey can be highlighted to the applicant through pre-application advice or after a planning application has been submitted and ecological recommendations are provided to the planning officer. A first Initial bat survey is carried out to assess the bat potential of a site, building or trees, and can be carried out at any time of the year. If follow up bat surveys are required after the initial bat survey these should be carried out at the appropriate times of the year which are from May to the end of August.

Factors that trigger the request for a bat survey include:-

  • The local habitat has high potential to support bats, such as nearby woodland, watercourses, or mature hedgerows
  • The location is close to a known bat roost (or in some cases is already known to be a bat roost). Generally, a recent bat record within 1km is considered to be significant.
  • The building or structure is of a type likely to support bats. For example, houses with a pitched, tiled roof or a stone built farm building.
  • The proposed works are of a nature likely to affect or obstruct a bat roost if a roost is present.
  • The proposed works would alter conditions such as lighting, in such a way, that if a bat roost was present the location would no longer be suitable for bats.

A bat survey is to be conducted by an experienced and licensed bat ecologist. Bat surveys require an appropriate level of expertise to be conducted properly. Surveys not conducted to this standard will not be accepted, and the consultant will be asked to review or repeat their work.

Bat surveys have two main objectives. Firstly, to establish if a building or structure is suitable for use by bats and then secondly to establish if any bats are present. As such there are two parts of a full bat survey. An initial or ‘phase 1’ bat survey looks at the building both externally and internally. It will assess the structure for potential access points, evidence of existing bat use (droppings, staining, individuals etc) and assess the building in the context of its surrounding habitat. Initial surveys can be conducted throughout the year.

The next stage is to conduct an activity survey. This is a survey that is carried out either at sunset or sunrise (or ideally both) and looks for bats leaving or entering the structure. Bat Conservation Trust guidelines state that 2-3 surveys should be conducted. Consultants will use highly sensitive microphones (bat detectors) to listen for audible evidence of bats around the building. The optimal time period for carrying out activity (dusk and dawn) surveys is between May and August as this represents the peak activity period for bats. Bat are mostly in hibernation between November and March and hibernation sites will usually be in different locations from roosts used during the summer.

Bat surveys cannot conclusively prove or disprove the presence of bats, however there are acceptable standards that need to be met to ensure that sufficient survey effort has been completed.

For further information please contact