Preliminary Roost Assessment
A Preliminary Roost Assessment (PRA) is the first stage in the bat field survey process. It will comprise a daytime bat walkover survey of the site to identify potential bat roosting, foraging and commuting opportunities within the site boundary and surrounding habitat.
Built Structures
Built structures will be subject to an external inspection for the presence of Potential Roost Features (PRFs) including (but not limited to) lifted roof tiles, hanging tiles, gaps in brickwork, fascia boards and timber cladding. An internal inspection will also be completed, including any roof voids or cellars.
Trees
Trees will be subject to a Ground Level Tree Assessment (GLTA) for the presence of PRFs including (but not limited to) cavities, raised bark and ivy cover.
Foraging and Commuting Habitat
The value of the site for foraging and commuting bats will be assessed based on the habitats present on the site and in the surrounding landscape and taking into account other factors such as light spill and habitat connectivity.
Survey Aids
Ladders, torches and endoscopes will be used to undertake a close inspection of PRFs, where accessible. Evidence of bats including live or dead individuals, droppings, urine staining, scratch marks and feeding remains will be recorded, where present.
Droppings may be collected and sent to a laboratory for DNA analysis to determine species.
Assessment of Suitability
Built structures will be assigned a value based on their suitability for roosting bats, from negligible to high.
Trees will be classified according to whether PRFs were identified (and whether the PRFs could support individual or multiple bats if this can be determined from ground level) or if they could be present but not identifiable from ground level.
If evidence of roosting activity is identified, the built structure or tree will also be classified as a confirmed roost.
Habitats will be assigned a value based on their suitability for foraging and commuting bats from negligible to high.
