Why do I need a bat survey?


Bats are a legally protected species in the UK, under the Wildlife and Countryside Act 1981 (As Amended) and The Conservation of Habitats and Species (Amendment) (EU Exit) Regulations 2019.

As a protected species, bats are a material consideration when a planning authority is determining a development proposal in accordance with the National Planning Policy Framework (NPPF) and the BS42020: 2013 Biodiversity Code of Practice for Planning and Development.

A bat survey is therefore often required to satisfy the planning authority that there won’t be impacts on bats. If there are to be impacts, a bat report should be submitted to set out that any impacts will be appropriately avoided, mitigated, or compensated for, such that a breach in legislation won’t occur because of the development.

Who carries out a bat survey, and who is responsible?


The legislation afforded to bats makes it an offence to recklessly disturb roosting bats. Therefore, a bat survey should be undertaken by an expert ecologist holding a bat survey licence, issued by Natural England.

It is typically the responsibility of the planning applicant or their agents to organise and pay for a bat survey, by commissioning a Natural England bat licenced ecologist to carry out the work.

What is the process for bat surveys?


Bat surveys for planning applications follow the national guidelines set out in the Bat Surveys for Professional Ecologists: Good Practice Guidelines.

Preliminary Bat Roost Assessment

The first step in the process is to carry out a ‘Preliminary Bat Roost Assessment’, also termed a ‘Daytime Bat Survey’ or ‘Scoping Bat Survey’. A Preliminary Bat Roost Assessment can be undertaken at any time of the year and is essentially a rapid disk assessment of the likelihood of roosting bats to be present at a given building, tree, or other structure. It involves an external survey, and an internal survey including searching any loft voids or cellars present for evidence of bats such as bat droppings or actual bats. The assessment is made within the context of the surrounding area’s suitability for bats.

The outcome of the Preliminary Bat Roost Assessment is to classify the bat roost suitability of a building with reference to the survey guidelines as either negligible, low, moderate, high or a confirmed bat roost, which with reference to the survey guidelines will inform if nocturnal bat surveys are required to establish the presence/ likely absence of roosting bats or characterise any bat roosts present.

Nocturnal Bat Emergence/ Re-entry Surveys

Also known as ‘dusk/ dawn’ surveys, or ‘bat activity’ surveys.

Put simply, during nocturnal surveys bat surveyors are positioned outside a building at dusk or dawn watching for any bats flying in or out. With reference to national guidelines, to give confidence that bats are absent, between one nocturnal survey for low suitability buildings to three nocturnal surveys for high suitability/ confirmed roosts may need to be undertaken. The surveys can only be carried out when bats are active, and therefore the seasonal survey window for nocturnal bat emergence/ re-entry surveys is May – August/ September each year. If a building, structure, or tree is assessed as negligible bat roost suitability during a Preliminary Bat Roost Assessment, no nocturnal bat surveys will be required.

What if there are roosting bats at my property, will it stop my planning application?


Very rarely will roosting bats stop a planning application, provided the required bat survey and mitigation reports are submitted prior to determination.

To prevent impacts to bats occurring, it may be the case that simple avoidance measures can be written into a bat report to be submitted to the planning authority.

If roosting bats are present in the building and impacts to bats because of the development proposals cannot be avoided, then the bat report for your planning application may include a recommendation for a Natural England mitigation licence to be obtained, in order to undertake the works lawfully. Following the granting of planning permission, a Natural England bat mitigation licence can then be applied for. Bat mitigation licences usually include the following components and conditions:

  • A works schedule including seasonal timing of the works to avoid times when bats are at their most vulnerable.
  • A method statement for the works detailing how impacts to bats will be avoided, mitigated, or compensated for.
  • High-risk tasks supervised by a Natural England licensed bat ecologist on site.
  • Compensatory bat roosts appropriate to those lost, such as installing bat boxes.

For low conservation status bat roosts, works can typically proceed under a Natural England bat ‘low impact’ licence, also termed a Bat Mitigation Class Licence (BMCL). A registered consultant working under this licence can carry out licensable work for development projects more time and cost efficiently, with reduced documentation, timing and mitigation requirements.


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