Evaluating Bat Use of Culverts in Virginia and Opportunities to Streamline Consultation for VDOT Projects

About the report

Transportation projects in Virginia frequently require coordination with the U.S. Fish and Wildlife Service (USFWS) to address the potential effects on federally listed bat species. Although existing tools provided by USFWS and the Federal Highway Administration offer effective pathways for many projects, individual coordination is still needed to address some projects, and workload demands are associated with the guidance. Structure assessments for bats represent one area of substantial workload. Although project-specific investigations have been conducted on bat use of structures in Virginia, no systematic, statewide studies have quantified culvert use. This study evaluated opportunities to improve the efficiency and consistency of bat-related coordination through two complementary components: (1) development of a structured framework to guide a follow-up culvert field study intended to better inform culvert survey requirements and decision-making and (2) evaluation of broader streamlining opportunities through interviews with Virginia Department of Transportation (VDOT) staff, Virginia-based USFWS staff, and state departments of transportation and USFWS field office representatives from six other states.

Literature and structure assessment data indicate that bat use of certain culverts is rare and primarily associated with larger concrete structures, with limited evidence of use in smaller or metal culverts that comprise most of VDOT’s inventory. Of more than 8,300 bridges and culvert complexes reviewed from Virginia’s structure assessment datasets, 2.9% had evidence of bat use. Of those structures, 94.7% were bridges. Landscape analyses showed no clear differences in land cover composition within 500-m and 1-km buffers around bridges and culverts used by bats, and significant (although weak) associations were observed with distance to forest and streams. Findings were used to create a sampling framework for a subsequent field study focused on metal culverts and smaller concrete culverts.

Interviews with 18 practitioners identified some common challenges across VDOT and USFWS staff, including high workloads associated with recurring activities such as tree cutting, structure assessments, and the need for clearer and more consistent project information. State departments of transportation and USFWS field office staff from other states reported similar challenges and described the use of targeted data collection to improve coordination, standardized conservation measures, and state-specific programmatic approaches.

Findings indicate that near-term improvements can be achieved by improving the consistency and clarity of project submittals, identifying project types for streamlining by tracking those that require additional coordination, and initiating the development of a streamlined approach for tree cutting. This report outlines a structured approach for tree-cutting activities that defines recurring scenarios, establishes thresholds for streamlined pathways, and applies standardized conservation measures, while maintaining appropriate review for higher risk conditions. These efforts provide a framework for improving coordination efficiency while supporting data-informed, long-term streamlining strategies.

_{Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.}

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