Services · Core

Bat Surveys

All 18 UK bat species and their roosts are legally protected. If you're working on a building, tree or landscape that could support bats, surveys are almost always required — and getting the timing right is critical.

PRA seasonYear-round
Activity seasonMay – September
UK species18
ProtectionEuropean Protected Species

Overview

Bats are among the most strictly protected species in the UK. All 18 resident species and their roosts are protected under the Conservation of Habitats and Species Regulations 2017 and the Wildlife and Countryside Act 1981. It is an offence to deliberately capture, kill or disturb bats, or to damage or destroy a roost — even when bats are not present — without a licence from Natural England.

Bat surveys typically begin with a Preliminary Roost Assessment (PRA): a daylight inspection of buildings or trees to assess their suitability for roosting bats, graded as negligible, low, moderate or high. If the structure scores low or above, further survey is required — typically dusk emergence and dawn re-entry surveys during the active season (May to September), where surveyors watch the structure at dusk and dawn to record bats entering and leaving.

The number and timing of activity surveys is determined by the roost potential: one survey for low-potential features, two for moderate and three for high, spread appropriately across the season. Where a roost is confirmed and will be affected by the development, we prepare and submit European Protected Species Mitigation Licence applications to Natural England, including method statements, compensation design and post-licence monitoring.

When you need this

  • Demolishing, converting, extending or re-roofing a building — particularly older buildings, barns, churches and period properties
  • Felling, pruning or managing mature trees, especially those with cracks, cavities, loose bark or ivy cover
  • Installing external lighting that could illuminate bat commuting routes or foraging habitat
  • Your PEA identifies buildings or trees with bat-roost potential
  • The LPA conditions your permission on bat survey and mitigation

Our approach

  1. 01
    Preliminary Roost Assessment (PRA)

    A daylight inspection of buildings or trees to assess suitability for roosting bats. External and internal features are examined for access points, droppings, staining, scratch marks and other evidence. Each structure is graded negligible, low, moderate or high.

  2. 02
    Dusk emergence / dawn re-entry surveys

    Surveyors are positioned around the structure at dusk and/or dawn to watch for bats emerging or returning. Bat detectors record ultrasonic echolocation calls for species identification. The number of surveys depends on the roost potential grading.

  3. 03
    Species identification and roost characterisation

    Echolocation recordings are analysed to confirm species. Roost type (day, maternity, hibernation, transitional) and roost status are determined from the survey evidence.

  4. 04
    Impact assessment and licensing

    Where a roost is confirmed and will be affected, we assess the impact, design compensatory roosting provision and prepare the EPS Mitigation Licence application to Natural England, including the method statement and monitoring schedule.

Frequently asked questions

01Do I need a bat survey for a loft conversion?+
If your property has any features that could support roosting bats — gaps under tiles, lead flashing, soffit boards, open eaves — then a Preliminary Roost Assessment is recommended before works begin. Older properties, rural buildings and those near woodland or water are particularly likely to support bats.
02What if bats are found in my building?+
The development can still proceed, but it will require a European Protected Species licence from Natural England. This involves a method statement setting out how bats will be protected during works, compensatory roosting provision (bat boxes, integrated bat bricks or a dedicated bat loft) and post-completion monitoring.
03How long does the bat survey process take?+
A Preliminary Roost Assessment can be turned around in one to two weeks. If further surveys are needed, these are spread across the May–September season: one to three dusk/dawn surveys depending on roost potential. Allow for the full season if commissioning a high-potential structure.
04Are bat surveys needed for tree works?+
Mature trees with features such as cracks, rot holes, loose bark, dense ivy or woodpecker holes should be assessed for bat-roost potential before felling or major pruning. This is particularly important for works during the active bat season (May–September).
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