If potential roosting habitat is first evaluated during “pre-construction surveys” shortly before the start of construction, it may be too late to appropriately mitigate impacts and projects may experience significant delays. “Pre-construction surveys for roosting bats” should not be the first requirement of a mitigation measure.

Habitat assessments should be performed during the project planning stage to determine if roosting habitat occurs in a project area. Habitat assessments should be conducted by a biologist with significant knowledge of bat roosting ecology in California.

Impact assessments and mitigation are site- and project-specific. They may require studies to determine habitat use patterns (e.g., seasons of use, type of roost, species, numbers). Conducting habitat assessments during the planning stage allows time to determine potential project impacts, and to develop more efficient and effective mitigation approaches (e.g., construction timing) if roosting habitat is found.

Pre-construction surveys should be used to confirm prior conclusions, not as the first effort to assess habitat and determine project impacts. Pre-construction surveys should be considered a final effort before construction impacts occur (e.g., confirm that a roost is vacant).

Conducting a timely bat habitat assessment and requiring appropriate mitigation measures informed by the best available bat ecology knowledge allows for better biological outcomes and reduces the likelihood of unexpected project delays.