Roost Emergence and Re-entry Surveys
The aim of these surveys is to observe bats emerging or re-entering features identified during the preliminary roost assessment. Summer is the best time of year to carry out these surveys, with the optimal survey period being May to August. For structures that are of Low Suitability for roosting bats a minimum of one survey is typically required; however more surveys may be required depending on how suitable the structure is for roosting bats. It is important to bear in mind that all surveys must be undertaken at least two weeks apart and in good weather conditions, so it is recommended to get these surveys organised as soon as possible.
Activity surveys are usually carried out between April and October. These surveys determine flight paths, species present and features within the habitats on site used by bats. The level of survey effort required will be determined by a preliminary ecological appraisal. A minimum of three activity transects should be carried out for sites of Low Suitability for foraging and commuting bat, comprising of a mix of dusk and dawn surveys. Sites of higher suitability for bats would require up to two survey visits per month between April and October.
If a potential roost feature has been identified during the Preliminary Ground Level Tree Roost Assessment, but the tree is not safe to climb; a nocturnal survey may be required to establish the presence or absence of roosting bats. Nocturnal surveys need to be carried out at dusk and/or dawn during the bat most active season from May to September.