Bat surveys & development sites – the lowdown

The UK has 18 species of bat with 17 known to breed here. All of these bats are protected by UK and International legislation.

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How much a development on a particular site will affect bats will depend very much on the site itself – including the habitat and structures present. Many sites across the UK contain open areas with habitats and features which bats use for foraging and commuting i.e. travelling to and from roost and foraging areas. If there are structures of any age, there is the potential that bats might be present.

Advice given to planners by the government is that survey reports and mitigation plans are required for all development projects that could affect bats.

The Surveys

 Extended Phase 1 Survey

Initially, as with all developments, a preliminary ecological survey is recommended, usually in the form of an Extended Phase 1 Survey to highlight any protected species or habitats which could be affected during and/or after the development. The survey will also report on what protected species are on site and/or likely to use the site.

Timeframe - Depending on the size of the site it should take no more than a day to survey and approximately three days to produce a report and a map of the habitats.

If the survey find that bats are likely to be affected by the development, then dedicated bat surveys should be carried out. The type of survey depends on what habitats and structures are currently on the site. The survey should also be matched with predicted, specific impacts of the development activities.

Whatever the development it is recommended to engage with an ecologist as early as possible - this will help in planning ecology into the design, timetable and budget of the development early on. 

Thomas with an Anabat and attached BatNav.

Thomas with an Anabat and attached BatNav.

Initial Bat Survey or Scoping Survey

A professional bat survey is generally aimed at an assessment of the impacts that could arise from activities linked to the development. Surveys can focus on structures such as buildings, bridges and trees where bats could roost. This can be done almost at any time of year and involves a thorough inspection of the structure for the presence of bats. It should be noted that these types of survey have the potential to disturb bats, which is against legislation. Therefore, anyone who carries out this type of survey must have a licence issued by either Natural England, Scottish Natural Heritage or Natural Resource Wales.

Emergence and Re-entry survey

These involve watching the structure from strategic points at dusk and dawn using bat detectors and other recording equipment to identify if bats are using the structure, how many are there, where are they emerging/entering from and what species are they. These surveys are advised to be conducted between March and mid-August when bat activity is at its greatest.


Depending on the nature and size of the development, mitigation measures can include:

Mitigation and compensation methods can include:

  •      changing the location of the work

  •      changing work methods or timing to avoid bats

  •      creating, restoring or improving roosts (and replacing any that will be damaged or removed)

  •      creating, restoring or improving habitats including foraging areas

  •      managing and maintaining habitats in the long term

  •      monitoring the roost status after the development

  •      limiting the use of wind turbines to particular times of day or year, or weather conditions (eg stopping blades in low winds)

Mitigation License

If the impacts to bats cannot be avoided (even with mitigation work), a European Protected Species mitigation licence will be required after the development has been granted planning permission. These licences permit works affecting bats that would otherwise be illegal without the licence in place.  

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Should you have any questions relating to bats then get in touch with Nevis and ensure your project is on the right track from the beginning.

Environmental Management is more than just ecology, speak to the experts – speak to Nevis.