Bat Surveys
There are 18 species of bat in the UK and all are fully protected by law. Any development of a site housing a bat roost requires a European Protected Species Licence. Bat surveys are therefore often required by the local planning authority.
The first survey is usually a Preliminary Roost Assessment (PRA) which can be carried out at any time of year. A PRA determines the potential a building or structure has for roosting bats. A surveyor examines the building internally and externally, including loft spaces, looking for signs of bats including droppings and feeding remains.
Dusk activity surveys are carried out on buildings and structures that have potential for roosting bats. Between one and three surveys may be required depending on the potential. These surveys can only be carried out between May and September inclusive. Surveyors observe all aspects of the building at dusk using night vision aids and audio equipment to record emerging bats. Recordings are carefully analysed following the survey and the results are presented in a report that can be used as part of the planning process.
Transect surveys or Night-time Bat Walkover surveys are used to assess flightlines and measure bat activity across a site. The method requires surveyors to walk a set path (transect) after sunset using bat detectors to record any bat sounds and the location and time of the activity. These can be carried out between April and October.
Bat hibernation roost surveys are a systematic examination of potential roost features in a building or structure to determine presence/likely absence of hibernating bats, which species are present and characterisation of the roost. Bat hibernation surveys are usually undertaken between November and March with optimum periods being the coldest months, usually January and February. Surveys must be conducted at least four weeks apart.
