The fourth edition of the Bat Conservation Trust Good Practice guidelines has recently been published and there is now a greater emphasis on the use of Night Vision Aids (NVAs), such as infra-red and thermal imaging cameras during activity surveys.  Activity surveys to determine presence / likely absence of bat roosts will now comprise dusk emergence surveys only, with dawn re-entry surveys no longer routinely recommended due to the risk of bats returning early and being missed.  In addition, the minimum time between surveys has increased from two weeks to three weeks to allow a wider sample of the activity over the recommended survey period.