Dusk and Dawn Surveys
All British bats are insectiverous and are active during the period dusk till dawn, when they are at least risk from predators, from sping until autumn. Because bats are nocturnal, if areas of the building have been identified as possible bat roosts then evening visits to a site will be necessary. Bats can be seen emerging from their roost from dusk onwards. The exact time varies for each species but dusk surveys can provide data upon how many bats are using a property and which elements of the building they are occupying. This data is essential for the planning of works, be it maintenance or new development.
Bats may also use areas around a property for foraging, feeding perches or commuting routes to other areas. Evening surveys should be used to collect data upon bat activity for use in planning development.
Additional information upon how bats use a building can be gathered from dawn surveys. Bats that have been feeding during the night will return to their roost around dawn. Surveys at this time can be used to follow bats back to their roost, helping confirm or identify roosts. Bats returning to their roost around dawn can be seen to swarm around the roost entrance before entering the roost. This can help identify roost entrances and count the numbers of bats present.
Surveys of bat activity and their use of buildings are required in order to complete a Natural England licence to disturb bats. Licences are required for dwelling houses as well as commercial premises.