Professional Bat Survey Services for ESA & Regulatory Compliance

Mist-netting is the primary method for confirming presence or probable absence of Indiana bat (Myotis sodalis), northern long-eared bat (Myotis septentrionalis), tricolored bat (Perimyotis subflavus), and other sensitive bat species. Our federally permitted biologists strategically deploy fine-mesh nets along forest edges, stream corridors, travel corridors, and water sources following the most current USFWS Range-wide Indiana Bat and Northern Long-Eared Bat Survey Guidelines. Captured bats are carefully identified to species, sexed, aged, measured, and safely released, with all data documented in accordance with USFWS recovery permit conditions and agency reporting requirements. Capture of Indiana bat, northern long-eared bat, or tricolored bat triggers immediate notification to the appropriate USFWS Field Office and initiates radio telemetry protocols.

Acoustic surveys deploy ultrasonic detectors to record bat echolocation calls, providing a non-invasive method for monitoring bat activity across project areas over multiple nights. These surveys are particularly valuable for documenting activity of Indiana bat, northern long-eared bat, and tricolored bat in habitats where mist-netting is impractical, and are required as the primary survey method for tricolored bat in areas outside the Indiana bat and northern long-eared bat range. All acoustic surveys follow the most current USFWS bat survey guidelines, including approved detector equipment, placement protocols, and weather condition requirements. Acoustic data collected by Volant is analyzed using USFWS-approved software and manually vetted by our federally permitted biologists to ensure defensible, agency-ready results.

Section 7 of the Endangered Species Act requires federal agencies to consult with the U.S. Fish and Wildlife Service to ensure federally funded or permitted projects do not jeopardize listed species or adversely modify critical habitat. Volant supports clients through both formal and informal Section 7 consultation for projects affecting Indiana bat, northern long-eared bat, tricolored bat, and other federally listed wildlife across Ohio, Pennsylvania, Kentucky, West Virginia, Indiana, and the eastern United States. Our team prepares Biological Assessments, coordinates directly with USFWS Field Offices, and provides the survey documentation needed to move the consultation process forward efficiently and keep projects on schedule.

Radio telemetry is conducted following the capture of Indiana bat, northern long-eared bat, or tricolored bat during mist-net surveys to identify day roost locations, maternity colonies, and habitat use patterns within the project area. Small radio transmitters are attached to captured bats and tracked across the landscape by our biologists using ground-based and, when necessary, aerial telemetry methods. Roost tree locations, foraging areas, and movement corridors documented through radio tracking provide critical data for ESA Section 7 consultation, Biological Assessment preparation, and the development of avoidance and minimization measures for project siting and tree clearing decisions. Radio telemetry for Indiana bat and northern long-eared bat is conducted in accordance with USFWS recovery permit conditions and current survey guidelines.

Bat habitat assessments evaluate the suitability of landscapes for supporting Indiana bat, northern long-eared bat, tricolored bat, and other sensitive species — and are a required component of the USFWS bat survey process before presence/probable absence surveys can be designed and approved. Our assessments document summer/year-round active season habitat features including trees with exfoliating bark, cavities, and crevices suitable for roosting, as well as foraging corridors, water sources, and forest stand characteristics relevant to each target species. We also assess potential winter hibernacula and bridge and culvert structures as required by the USFWS Guidelines. Habitat assessment results are submitted to the appropriate USFWS Field Office for review and approval, and form the foundation for all subsequent survey planning and level of effort calculations.

Emergence surveys are conducted at dusk to document bats exiting potential roost trees, structures, bridges, or culverts — providing direct evidence of roost occupancy and, when Indiana bat, northern long-eared bat, or tricolored bat are present, triggering additional radio telemetry and agency notification protocols. These surveys are an important component of ESA compliance for projects involving tree clearing, structure demolition, or bridge and culvert work near suitable bat habitat. Our biologists conduct emergence surveys following USFWS protocols, documenting species composition, emergence timing, roost size, and bat activity patterns to inform project siting decisions, work window determinations, and conservation planning. Emergence surveys may also be required at potential hibernaculum entrances during fall or spring staging windows as part of hibernaculum presence/probable absence assessments.

Potential roost tree surveys identify and document trees with features suitable for roosting Indiana bat, northern long-eared bat, and tricolored bat within a proposed project area. Survey criteria include trees with exfoliating bark, cavities, cracks, crevices, and structural deterioration that provide the microhabitat conditions these species require for day roosting, maternity colonies, and staging. Indiana bat roost trees typically consist of live trees and snags at least 5 inches dbh with loose bark, while northern long-eared bat and tricolored bat may use a somewhat broader range of tree features and species. Roost tree survey results directly inform tree clearing plans, pre-clearing emergence survey requirements, work window determinations, and ESA compliance documentation — and are a critical tool for avoiding unauthorized take of listed bat species during construction and land management activities.

Accurate species identification is the foundation of defensible bat survey results. Following automated analysis using USFWS-approved software, our federally permitted biologists conduct manual qualitative review — visual vetting — of echolocation call files to confirm or correct species identifications, with particular attention to files where Indiana bat, northern long-eared bat, or tricolored bat presence is indicated or suspected. This manual vetting process is especially important for distinguishing Indiana bat from acoustically similar little brown bat (Myotis lucifugus), and for identifying tricolored bat in areas where other high-frequency species are abundant. Several members of our team have completed advanced acoustic identification training workshops and maintain current knowledge of approved software programs, regional call libraries, and USFWS vetting standards. All acoustic analysis is documented and reported in formats that meet USFWS Field Office submission requirements. For clients with existing acoustic datasets needing independent review, Volant also provides standalone acoustic data vetting services.

Bat species inventories document the full community of bat species present within a given area using mist-netting, acoustic monitoring, and other detection methods — providing baseline ecological data that supports conservation planning, long-term population monitoring, and regulatory compliance. Inventories may include documentation of Indiana bat, northern long-eared bat, tricolored bat, and a range of other eastern US bat species including gray bat (Myotis grisescens), little brown bat, big brown bat (Eptesicus fuscus), eastern red bat (Lasiurus borealis), and others. Species inventory data is valuable for natural resource managers, conservation organizations, land trusts, and military installations seeking to understand bat community composition and population trends on their properties over time. Volant designs inventory programs to meet USFWS reporting standards and integrates inventory results with habitat assessments and long-term monitoring frameworks as needed.