A preliminary bat roost assessment may identify the requirement for bat activity surveys and allocate a suitability category of bat roost potential.
Presence/absence bat activity surveys include dusk and/or dawn vantage point visits to watch, listen for and record bats exiting or entering a structure or tree.
These surveys are required if:
–The preliminary roost assessment has not ruled out the reasonable likelihood of a bat roost being present
–A comprehensive inspection survey is not possible due to restricted access
–There is a risk that the evidence of bat use may have been removed
This type of survey aims to identify the presence of roosting bats and the requirement for mitigation. The surveys may also highlight a feature which is of value to commuting and foraging bats.
The timings of bat activity surveys are highly seasonal and prescribed in the current best practice Bat Conservation Trust guidelines. On low and moderate suitable structures, identified during the preliminary bat roost assessment one of these surveys must be undertaken between May and August inclusive to cover the bat maternity season, while two of the three surveys on high suitability structures need to be completed during the same period.
In addition to vantage point visits, bat activity surveys may also comprise of bat activity transect surveys. This involves ecologists walking predetermined transect routes to observe, listen for and record bats in flight. The purpose of this survey is to establish habitats or features of importance to roosting, commuting and foraging bats. Remote monitoring of bat activity can also be used to compliment transect surveys.
Bat activity transect surveys should be undertaken once a month between May and October.