The U.S. Fish and Wildlife Service (FWS) continues to focus on protections for bat species that have been ravaged by white-nose syndrome. In 2023, the Northern Long-Eared Bat (NLEB) was uplisted to endangered status. The FWS proposed to list the Tricolored Bat (TCB) as endangered in 2022, with a target date of September 2024 to finalize the listing. However, on April 1, FWS issued a series of guidance documents covering both NLEB and TCB, suggesting that the TCB endangered listing may be accelerated. Like the NLEB, the TCB has extensive habitat throughout the U.S. (37 states for NLEB, and 39 states for TCB). Accordingly, these listings have significant impacts on projects that involve tree clearing.

The four guidance documents are described by FWS as “preview” documents for public review and input by May 1. The FWS notes that they want to provide interested parties with the opportunity to “familiarize themselves with these tools and have the opportunity to ask questions before the final tools and guidance go into effect in summer 2024.” The implication is that the TCB listing will be finalized when the guidance goes into effect.

The four guidance documents include: (1) Rangewide Northern Long-Eared Bat and Tricolored Bat Determination Key; (2) Consultation Guidance for Development Projects; (3) Tricolored Bat Wind Guidance; and (4) Sustainable Forest Management Guidance. All four guidance documents can be found here. This post focuses on the Consultation Guidance and the Wind Guidance.

Consultation Guidance

As noted above, the draft guidance documents apply to both NLEB and TCB, and therefore reflect an update to the April 2023 guidance for NLEB and new recommendations for TCB. The Consultation Guidance provides FWS’ “recommended approach” for new development projects to ensure compliance with the Endangered Species Act (ESA). FWS notes that the guidance will be updated periodically.

The guidance applies both to federal agencies and nonfederal project proponents. Below is a summary of the recommended approach outlined in the guidance for new development projects:

  1. Request an Information for Planning and Consultation (IPAC) Report. If neither species appears on the report, no further action is necessary.
  2. Evaluate project impacts using the Determination Key (an updated beta version of a Determination Key for both NLEB and TCB is available for review between now and May 1 and will be finalized as part of this guidance package). If the outcome is “no effect” or “not likely to adversely affect” (for federal projects), or “is not reasonably certain to cause incidental take” (for nonfederal projects), no further action is needed.
  3. Coordinate with the FWS field office for projects that receive a “may affect” determination from the DKey. If the field office determines that the project is “not likely to adversely affect” or “not reasonably certain to cause take,” no further action is necessary.
  4. For projects determined to be “likely to adversely affect” or where “take is reasonably certain to occur,” incorporate minimum conservation measures into the proposed action. Some examples of the minimum conservation measures in the guidance include: avoiding removal of suitable roost trees within 1.5 miles of capture/acoustic record during roost season; avoiding removing suitable roost trees during the pup season (unless a presence/absence survey has been completed indicating probable absence); and offsetting/mitigating for the impacts of incidental take that were not avoided.

The guidance also explains that areas have been identified where NLEB and TCB are active year-round. For those areas, the guidance suggests additional measures to be implemented between December 15 and February 15, including: avoiding removing known and suitable roost trees within 1/4 miles of a known NLEB and/or TCB roost; avoiding removing suitable roost trees within 1.5 miles of a NLEB and/or TCB capture/acoustic location; and avoiding removing suitable roost trees unless a presence/absence survey has been completed indicating probable absence.

The guidance also includes an appendix that outlines projects that are not eligible for a DKey determination (unless a negative survey has been conducted). Examples of those projects include those that: involve the creation of a new point source discharge from a facility other than a water treatment plant or storm water system; require drilling or blasting; involve herbicide use except in certain conditions; or increase ambient lighting without sufficient measures to avoid or minimize light spill into NLEB or TCB habitat.

For many developments, the key question is whether trees can be trimmed or removed. The guidance provides detailed provisions for both the NLEB and TCB regarding when and how much tree trimming/removal can occur without potentially causing take. With respect to the NLEB, the guidance first outlines the activities that are not eligible to use the DKey. Examples of those include tree trimming/bringing down trees during the summer occupancy season regardless of timing, extent or location; where tree removal would fragment a forested connection between NLEB habitat areas; and tree removal in landscapes with less than 10% forest cover.

Next, the guidance outlines the allowable forest removal in landscapes with greater percentages of forest cover as follows:

Forest cover within the vicinity of the project (%)Allowable forest removal when direct effects (e.g., injury or death) are avoided (acres)
30.0-39.9< 7
40.0-49.9< 14
50-59.9< 23
60-69.9< 34
70-79.9< 48

With respect to the TCB, the DKey is not available for certain actions such as the trimming/bringing down trees suitable for roosting during pup season regardless of timing, extent, or location; during winter torpor in certain areas where TCBs remain active year-round; and when tree removal would occur in landscapes with less than 10% forest cover.

As with the NLEB, the guidance provides for predetermined “not likely to adversely affect” outcomes for tree clearing in areas with greater extents of forest cover for TCB pursuant to the following thresholds:

Forest cover within the vicinity of the project (%)Allowable forest removal when direct effects (e.g., injury or death) are avoided (acres)
10.0-19.9< 1
20.0-29.9< 5
30.0-39.9< 15
40.0-49.9< 30
50-59.9< 45

Wind Guidance

The wind guidance is specific to TCB, and outlines actions that wind projects can take to ensure that incidental take of TCBs is not reasonably certain to occur. The guidance addresses siting, operation, and postconstruction monitoring. Implementation of the guidance is to occur in coordination with the FWS, and will result in a concurrence from the FWS that take is not reasonably certain to occur. The concurrence will be memorialized in a technical assistance letter (TAL).

To meet the siting criteria, wind projects should be sited at least 1,000 feet from the closest suitable roosting habitat and conduct survey work to determine TCB summer occurrence.

With respect to operation, the project has three options: apply a blanket curtailment approach; use an algorithm-based informed curtailment approach; or use a real-time acoustic-activated smart curtailment approach. The guidance includes a series of appendices that outline how these various options would work.

The postconstruction mortality monitoring is dependent on the option chosen. The guidance outlines what would be required under each option. The requirements also vary depending on whether the project is located in one of the year-round active zones.


The guidance documents provide significant detail about FWS expectations of the actions necessary to protect NLEB and TCB. Although the “feedback” period offered by the FWS is informal, it does provide the opportunity to ask questions and provide comment to FWS on their implementation guidelines. Additionally, the guidance clarifies how these requirements will apply in areas in which bats are active year-round, and for the first time, provides a consolidated map identifying these areas.

Figure A. NLEB and TCB hibernating and year-round active ranges.