Bat Surveys for Transportation Projects

Transportation projects — highways, bridges, culverts, rail, and transit — frequently intersect with habitat used by federally listed bats. Tree clearing for a road widening, the rehabilitation of a bridge that bats roost in, or work near a culvert can all trigger Endangered Species Act review, and for projects with federal funding or approval, that review runs through Section 7 consultation.

Volant EcoServices provides USFWS-protocol bat surveys for state departments of transportation, Federal Highway Administration contractors, transit and rail agencies, and the prime consultants who support them. Our federally permitted biologists deliver the habitat assessments, bridge and culvert evaluations, and presence/probable absence surveys that keep transportation projects compliant and moving — for the Indiana bat, northern long-eared bat, and tricolored bat across the eastern United States.

Why Transportation Projects Trigger Bat Surveys

Transportation projects commonly involve the kinds of activities that affect bat habitat: clearing forested right-of-way, and disturbing or replacing bridges and culverts that bats use as roosts. The U.S. Fish and Wildlife Service recognizes that at least 24 North American bat species — including the Indiana bat, northern long-eared bat, and tricolored bat — have been documented using bridges and culverts as day and nighttime roosts.

A bat survey requirement is commonly triggered when a transportation project involves:

Clearing or disturbing forested habitat within the right-of-way
Rehabilitation, replacement, or demolition of bridges or culverts that may serve as bat roosts
Work with a federal nexus — Federal Highway Administration, Federal Transit Administration, or Federal Railroad Administration funding or approval — that invokes ESA Section 7 consultation
State-listed species requirements, which can apply regardless of federal involvement

The Transportation Programmatic Biological Opinion

Many transportation projects are addressed under a dedicated framework. The Federal Highway Administration, Federal Railroad Administration, and Federal Transit Administration developed, in collaboration with USFWS, a Programmatic Biological Opinion (PBO) for transportation projects in the range of the Indiana bat, northern long-eared bat, and tricolored bat.

For practitioners working under the PBO in conjunction with the FHWA, FRA, and FTA, the USFWS directs that bridge and culvert assessments follow the Range-wide Survey Guidelines.

Volant designs bridge and culvert assessment programs to meet the Survey Guidelines that the PBO relies on.

How Volant Supports Transportation Projects

Habitat assessments. We evaluate the project area for suitable summer roosting habitat, potential winter hibernacula, and bridge and culvert roosts — the assessment that determines what, if any, survey is required. Under the Guidelines, where no suitable habitat is found, no further presence/probable absence surveys are recommended.
Bridge and culvert bat surveys. Suitability and safety assessments, visual inspection, emergence surveys, and acoustic monitoring of transportation structures, conducted to current USFWS standards. (See our dedicated Bridge & Culvert Bat Surveys page.)
Presence/probable absence surveys. Acoustic and mist-net surveys for forested right-of-way, with all acoustic data manually vetted by federally permitted biologists.
Section 7 documentation and USFWS coordination. Survey study plans submitted to and approved by the appropriate USFWS Field Office, and defensible reporting to support consultation.

Timing: Plan Surveys Around the Survey Season

Transportation projects run on long schedules, but bat surveys do not run year-round — and missing a survey window can delay a project by a full year. A few timing facts that matter for transportation planning, drawn from the current USFWS Guidelines:

Summer active-season surveys in the hibernating range run May 15 through August 15.; while the year-round active portion of the NLEB/TCB range uses March 1–October 15.]
Bridge and culvert survey timing should be coordinated with your local USFWS Field Office, because bat use of structures varies seasonally and geographically.
Negative bridge/culvert survey results are valid for two years when the Guidelines are followed and the report is approved by the local Field Office — a timeframe set to stay consistent with the transportation PBO.
Study plan review can take longer for complex transportation work; USFWS notes that complex projects requiring coordination across multiple Field Offices may take 45–60 days to approve.

Because of these windows and review timelines, the most effective step a transportation agency or contractor can take is to engage a bat biologist early — during planning and design, not after a clearing or construction date is set.

Personnel Qualifications

The Guidelines require that bridge and culvert surveyors, at minimum, complete the USFWS virtual bat and transportation structures training before conducting field assessments, with additional state-specific training required in some states. Surveys that involve capturing and handling listed bats require an ESA Section 10(a)(1)(A) recovery permit.

Both of Volant's principal ecologists hold active USFWS Section 10(a)(1)(A) recovery permits for the Indiana bat, northern long-eared bat, and gray bat.

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