Bat Survey Season Opens

Buck Ray, Environmental

May 11, 2023

The field survey season for bats opens May 15, providing a three-month window to determine if federally listed species are present on a project site. Mist-net and acoustic surveys can be completed through August 15.


The U.S. Fish and Wildlife Service (USFWS) has adopted key changes to federal protections for 2023 that could affect development projects within the range of the protected species. The current and proposed changes are summarized below.


Northern long-eared bat listed as endangered


On November 30, 2022, the USFWS reclassified the northern long-eared bat (Myotis septentrionalis) from threatened to endangered under the Endangered Species Act (ESA). The reclassification took effect on January 30, 2023.


The USFWS has issued an Interim Conservation Framework for projects not completed by March 2024 that have a federal nexus and require Section 7 coordination with the USFWS. Projects operating under this framework will continue to follow similar guidelines to the previous 4(d) rule for an additional year.


The bat’s range includes much of the eastern and north-central United States. For projects that extend beyond March 2024 and may affect the species within its range, consultation with USFWS is recommended.


Tricolored bat proposed to be listed as endangered


On September 13, 2022, the USFWS announced a proposed rule to list the tricolored bat (Perimyotis subflavus) as endangered under the ESA. A final rule is expected September 2023, with full implementation of the rule 30 days after issuance.


The range of this species covers most of the eastern two-thirds of the U.S. and is larger than the ranges of other listed bats. According to the species status assessment, tricolored bats may be active outside of the active seasons of other listed bats, encompassing more spring and fall months.


Olsson is prepared to help


Status changes for these bats can affect project work that is ongoing at the time an endangered species listing decision is announced. Determining the presence or absence of an endangered species as early as possible allows the greatest range of planning options for clients.



Olsson’s biologists and natural resources planners hold the federal permits required to conduct surveys for listed bats and are knowledgeable about numerous bat species, permits, regulations, and the consultations needed to comply with the ESA. Our professionals can complete the surveys and the field work to document the species and help developers plan the best course of action for their projects.


Contact Buck Ray at or 405.465.7245 if you have questions about these regulations or potential project impacts.