Preliminary roost assessment

In accordance with Bat Surveys for Professional Ecologists: Good Practice Guidelines 3rd  Edition (Collins J, 2016), a preliminary roost assessment should be carried out on the survey building to determine whether any features are present that bats could use for entry/exit points and roosting, and to search for signs of bat presence. Ladders, high-powered torches and binoculars should be used to search for internal and external features including but not limited to;

  • Gaps around windowsills, door frames and lintels
  • Lifted rendering, paintwork, shiplap boarding
  • Soffit boxes, weatherboarding and fascias
  • Lead flashing, hanging tiles and lifted or missing tiles/slate
  • Gaps >15mm in brickwork and stonework
  • Bat specimens (live or dead)
  • Bat droppings and urine staining
  • Feeding remains (e.g. moth wings)
  • Cobweb-free sections of ridge beam

The survey building should then be assigned a measure of potential suitability to determine the extent of future survey work needed. The categories of potential suitability and further survey effort required are as follows;

  • Negligible – Negligible habitat features on site likely to be used by roosting bats – no further survey work,
  • Low – A structure with one or more potential roost sites that could be used by individual bats opportunistically – one survey visit (dusk or dawn),
  • Moderate – A structure with one or more potential roost sites that could be used by bats on a regular basis – two separate survey visits (one dusk and one dawn),
  • High – A structure with one or more potential roost sites that are obviously suitable for use by larger numbers of bats on a regular basis and for longer periods (up to three further surveys),