Bat Surveys - Stages

Why is a Bat Survey Required?

Survey work is often required to advise on how a development, or essential works, may impact on a European Protected Species (EPS), and would also be required by Scottish Natural Heritage for an application for an EPS licence, should one be required. 

Bat survey work is needed if the owner/developer, the local planning authority, architect or agent consider that there is a reasonable likelihood of bats being present and affected by the project proposal. 

Stage 1 - Preliminary Roost Assessment

The initial survey is used to assess the general suitability of the habitat for use by bats, and can be undertaken at any time of year.

In some instances, the Preliminary Assessment can give an indication that a structure is not suitable for use by bats, which would allow a project to continue without the need for any additional survey work or a Scottish Natural Heritage EPS Licence. 

Where suitability for roosting has been identified, Stage 2, summer bat activity (presence/absence) survey work will be required.

Stage 2 - Bat Presence/Absence Surveys

Stage 2 (dusk emergence & dawn re-entry surveys) will be necessary where;

  • Evidence of bats was found during the daylight site survey, or
  • It was not possible to conclude that there was negligible potential for bats to utilise the structure/s affected by the development proposal

Field signs of bats are not always visible, dependent on the structure of the building; therefore, where suitability for roosting identified, Stage 2 surveys will be needed to confidently confirm the presence or absence of bats.

Survey Effort, Timing & Frequency

The number of summer bat presence/absence surveys required will vary depending upon the potential for the site to support bat roosts: where further survey is required, between one and three summer activity surveys are usually adequate to gather sufficient data to have confidence in a negative result or, where bat roosts are found, to inform an impact assessment - i.e. sites of low value in the most impoverished areas in terms of bat species will require lower levels of survey effort compared to the richest.

The optimal period for the identification of summer roosting sites is between mid-May and mid-August; where more than one Stage 2 survey is required, the surveys should be spaced through the active season, at least two weeks apart, and there should be at least one dawn and one dusk survey visit .

Bat Roosts - Mitigation & Licensing

All bat species found in Scotland are classed as European Protected Species (EPS). They receive full protection under the Conservation (Natural Habitats, &c.) Regulations 1994 (as amended). 

When bat roosts are found at a development site, or at a site where essential works are required, it will be necessary to protect the bat population from damaging activities and to reduce or remove any impacts on bats as a result of the development or works: 

  • Timing constraints may be required for some of the works;
  • It may be necessary to incorporate compensatory roosting opportunities into the project design.

Once Stage 2 survey work is completed, a Species Protection Plan (or Bat Mitigation Plan) is produced - anyone who wishes to carry out works that will cause disturbance to bats and/or where a bat roost will be damaged or destroyed, or access obstructed, at any time of year, will require a Scottish Natural Heritage (SNH) Works Affecting Bats licence: the Species Protection Plan will be an important consideration when considering the impact of planning applications on bats and will support an application for a European Protected Species licence.

Protection for Bat Roosts During Works

Watching Briefs - an EPS licence may specify that the works to structures where bats are known to roost must be overseen by a licensed bat worker, following an approved methodology. It may also be necessary for a licensed bat worker to visit a site, post-works, to 'sign-off' any roosting provision for bats incorporated into a project. 

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