Florida Bonneted Bat and Tricolored Bat Acoustic and Roost Surveys



The Florida bonneted bat (Eumops floridanus) is currently listed as endangered by the U.S. Fish and Wildlife Service (FWS) under the Endangered Species Act (ESA). On September 13, 2022, the FWS proposed to list the tricolored bat (Perimyotis subflavus) as endangered. Tricolored bats are found throughout the eastern United States and Central America and are known to occur in most areas of Florida. The FWS’ listing for the tricolored bat is likely to have a large impact on projects proposing tree clearing in Florida and will likely necessitate species-specific surveys to determine occupancy. Flatwoods provides consulting services assisting clients in both acoustic and roost surveys for projects involving many industries, including residential and commercial development, mining, and utilities.


When a species is listed under the ESA, the FWS works to avoid take (harming, harassing, killing) using various conservation tools authorized under Section 7 and Section 10 of the ESA. These tools include consultation and habitat conservation plans. Flatwoods has extensive experience coordinating with the FWS on all aspects of a project, including performing surveys, initiating consultation, and permitting.


Flatwoods has developed site-specific survey protocol for the Florida bonneted bat and tricolored bat using the survey framework provided in the July 2017 Draft Florida Bonneted Bat Consultation Guidelines as guidance. The purpose of these surveys is to determine if Florida bonneted bats or tricolored bats are likely to be actively roosting or using the site and to locate any active roost(s). Acoustic survey stations are proposed throughout project sites with specific emphasis on potential roost habitat. The surveys entail acoustic and roost surveys in accordance with the developed protocol and FWS concurrence. Flatwoods utilizes acoustic devices (Anabat Express Passive Bat Detectors) at determined locations to maximize the chances of detection of either foraging and/or roosting areas. Omnidirectional microphones are placed above the ground such that they are also above any small trees or shrubs in order to capture species that fly at all but the highest altitudes. These acoustic devices are set up to record from sunset to sunrise for multiple consecutive nights, under suitable weather conditions as defined by the protocol.


Depending upon acoustic results, targeted roost searches are conducted through visual inspection using a tree-top camera system, observations at emergence, or more acoustic surveys. The raw acoustical survey data collected is then interpreted by biologists/ecologists trained and experienced in analyzing and interpreting data. Zero-crossing acoustic data is analyzed using AnalookW software and species are identified using comparisons to call parameter reference libraries for each species. Data is run through a coarse computer filter initially to distinguish bat calls, and any calls flagged by the filter are then analyzed manually to confirm that the call is in fact the target species. Activity levels are then estimated and relationships between bonneted bat or tricolored bat presence or activity and land use cover are analyzed.