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Acoustic vs. Mist-Net Bat Surveys: Which Method Does Your Project Need?

Tue, 14 Apr 2026 14:43:53 GMT

If you've been told your project requires a bat survey , the next question is usually: what kind? Not every bat survey is the same, and the method your project needs — acoustic monitoring, mist-netting, or a combination of both — depends on factors that are specific to your site, your project's footprint, and where you fall relative to known bat occurrences.

Choosing the wrong approach, or hiring a firm that can only provide part of the picture, can mean redoing work, missing the survey window, or being sent back to the drawing board by your USFWS Field Office. This article breaks down both methods, explains how they work together under the 2026 USFWS Range-wide Bat Survey Guidelines, and helps you understand what your project actually needs before you make any commitments.

What both methods have in common

Whether a project uses acoustics , mist-netting , or both, the goal is the same: to establish the presence or probable absence (P/A) of one or more target species — the Indiana bat, northern long-eared bat (NLEB), and tricolored bat (TCB) — within the project area during the summer/year-round active season.

Both methods must be conducted by qualified biologists during the approved survey window (May 15 – August 15 for most of the eastern U.S.), must follow a USFWS-approved study plan, and must produce results that are reported to the coordinating Field Office regardless of outcome. The minimum prescribed level of survey effort cannot be completed in a single calendar night, regardless of which method is used. Planning around this multi-night minimum is one of the most common things project managers underestimate when they're scheduling bat survey work.

Acoustic bat surveys: how they work

Acoustic bat surveys use ultrasonic detectors placed at survey sites to record echolocation calls overnight. Trained biologists deploy detectors in locations that maximize detection probability — typically along forest edges, over water features, and near roost habitat — and retrieve them after the prescribed number of nights. The call files are then analyzed using USFWS-approved software programs (currently SonoBat and the latest approved version of Kaleidoscope Pro) to identify species based on call characteristics.

When acoustic surveys are sufficient on their own

If no high-frequency (HF) calls of 35 kHz or greater are detected during acoustic surveys, no mist-netting is required within that survey area, and probable absence for the target species can be established. For many projects with low-to-moderate habitat quality, an acoustic-only survey is a fully valid, more efficient path to P/A clearance.

Acoustic surveys are also the only practical option in some situations. Terrain, site access, dense vegetation, or the absence of suitable net placement locations can make mist-netting physically impractical. In those cases, the biologist should coordinate with the local Field Office before finalizing the study plan, since site-specific conditions that do not lend themselves to standard survey techniques require FO coordination prior to using alternative methods.

What acoustic surveys cannot do

A positive acoustic detection establishes probable presence — and that determination is final. Negative results from follow-up mist-netting at any level of effort do not refute a previously established positive acoustic result. Once the acoustic record shows a target species is active in your project area, presence is established and no amount of additional netting changes that outcome. The project then moves into consultation with the USFWS to determine minimization and mitigation measures.

It's also worth noting that North American Bat Monitoring Program (NABat) acoustic surveys are not adequate to confirm probable absence of target species for project-specific determinations, even though they may provide useful supporting context. If your project area has NABat data on file, that data can inform the study plan, but it does not substitute for a project-level acoustic P/A survey.

Mist-net bat surveys: how they work

Mist-netting involves setting ultra-fine nets across bat flight corridors — typically at gaps in vegetation, along stream corridors, or near known roost features — after dark. Bats flying through the area become briefly captured in the net. The biologist extracts each bat, identifies it by species, records morphological measurements, and may band it or attach a small radio transmitter depending on the study plan objectives. The bat is then released at the capture site.

The permit requirement

This is the most important practical distinction between the two methods. Because mist-netting results in the physical capture of listed bats, it constitutes "take" under the Endangered Species Act. Surveys involving physical capture and handling of federally listed species require an ESA Section 10(a)(1)(A) recovery permit, which authorizes capture for identification and handling for measurements, photography, banding, and radio transmitter attachment. Not every ecological consulting firm holds this permit. Before engaging any firm for mist-net surveys, confirm that the lead biologists have current, active recovery permits covering the specific species present in your project area.

Volant EcoServices' co-founders, Mary Gilmore and Dan Cox, both hold active USFWS Section 10(a)(1)(A) Recovery Permits for Indiana bat, northern long-eared bat, and gray bat. Having two permitted biologists on the same team provides meaningful operational flexibility — particularly for larger projects or tight scheduling windows where split crews may be needed simultaneously across a survey area.

When mist-netting is required

Mist-netting becomes required when acoustic surveys detect probable bat activity. If any HF calls are detected during acoustic Phase 2 surveys, mist-netting at the Phase 2 level of effort is then required within that survey unit. This is why the two methods are so frequently used together: acoustics efficiently screens the site, and netting is triggered only where the acoustic data indicates bat activity.

Mist-netting may also be the primary P/A method from the start, depending on site conditions, habitat quality, and USFWS Field Office preferences in your region. For high-quality Indiana bat habitat — mature forest patches with trees of 5-inch DBH or larger — your Field Office may require or recommend leading with netting rather than treating acoustics as the Phase 1 screen.

Federal guidance requires a minimum of two biologists — one permitted and one technician — present for every four net-sets being operated during a survey. Acoustic surveys cannot be completed in a single night and must be split across a minimum of two calendar nights under the range-wide guidance. Designing a study plan that satisfies USFWS requirements simultaneously starts with understanding these minimum staffing and timing constraints upfront.

The hybrid approach: how acoustic and mist-net surveys work together

Most larger projects — or projects in areas with high-quality bat habitat — use a phased approach that combines both methods. This is also the most defensible study design from a regulatory standpoint because it layers multiple lines of evidence into the P/A determination.

Under the 2026 guidelines, the general hybrid sequence works like this:

Acoustic screening. Detectors are deployed at survey sites across the project area for the required number of nights. Files are analyzed using USFWS-approved software.
If no HF calls are detected: Probable absence is established for that survey unit. No netting is required.
If HF calls are detected: Mist-netting is triggered at the Phase 2 level of effort at those locations.
If netting captures target species: Presence is confirmed. Depending on the study plan, radio-tracking may follow to locate roost trees and refine the area of occupancy for USFWS consultation.
If netting produces no captures: Probable absence is established for the netting phase — but only if the original acoustic results did not already establish probable presence . The study plan should be written carefully to make this sequence clear to the USFWS Field Office.

Any project study plan that includes use of both acoustics and mist-netting needs to be written clearly to avoid potential misunderstandings between the project proponent and the USFWS Field Office regarding which method is serving as the P/A method and what the outcomes of each phase mean. This is where having an experienced bat biologist who has written dozens of study plans — and has an existing working relationship with the local FO — makes a material difference.

How to decide what your project needs

A permitted bat biologist should make the final call on survey method after reviewing your project footprint, the habitat assessment, and your local USFWS Field Office's documented preferences. That said, here's a general framework:

Start with acoustics alone if:

The project area has low-to-moderate quality bat habitat (limited mature forest, fragmented cover)
Site access or physical conditions make mist-net placement impractical
The project is in the outer tier of a known occurrence buffer and the Field Office has indicated acoustic-only surveys are acceptable

Plan for mist-netting (or a hybrid) if:

The project area includes high-quality Indiana bat or NLEB roosting habitat (mature forest, riparian corridors)
The project is a large linear project (transmission line, road, pipeline) requiring survey across multiple habitat units
Prior acoustic or occurrence data in the vicinity suggests bat activity is likely
Your USFWS Field Office has historically required netting for projects of this type in this area
You need the most defensible P/A determination possible — for example, on a federally permitted project subject to Section 7 consultation

You will definitely need a permitted mist-net biologist if:

Any acoustic survey conducted on or near the project area has ever detected probable target species presence
The project is already within an inner-tier occurrence buffer and the USFWS FO is requiring capture data to inform minimization measures
Radio-tracking or roost tree identification is part of the scope

What to ask when hiring a bat survey firm

Before signing any contract for bat survey work, get clear answers to these questions:

Does the lead biologist hold an active USFWS Section 10(a)(1)(A) Recovery Permit for the relevant species? Confirm which species are covered — permits are species-specific. A firm permitted only for general wildlife surveys is not cleared to conduct mist-netting for Indiana bat or NLEB.

Has the firm worked with your specific USFWS Ecological Services Field Office before? Study plan review timelines and FO preferences vary significantly by region. A biologist with an established relationship with the FO serving your project area will move faster and hit fewer surprises.

Can the firm handle the full sequence — habitat assessment, study plan, acoustics, mist-netting, and results reporting — under one contract? Splitting these responsibilities across multiple vendors increases coordination risk and can create gaps in the reporting record.

What software is the firm using for acoustic analysis, and is it on the current USFWS-approved list? The approved software list is updated periodically; using an unlisted or outdated version can invalidate acoustic data.

Volant EcoServices provides the full scope of listed bat survey services across the eastern United States — habitat assessments, acoustic P/A surveys, mist-net surveys (both Dan Cox and Mary Gilmore hold active USFWS Recovery Permits for Indiana bat, northern long-eared bat, and gray bat), radio-tracking, and USFWS study plan coordination. Survey season opens May 15. Contact us to discuss your project .

Do I Need a Bat Survey? A Plain-Language Guide to Regulatory Compliance Bat Surveys

Fri, 03 Apr 2026 14:47:02 GMT

You're a project manager, a developer, a transportation agency contractor, or a utility company environmental coordinator. You've just received a comment letter from the U.S. Fish and Wildlife Service — or your environmental consultant has flagged a potential issue — and suddenly someone is telling you that you need a bat survey before your project can move forward.

If your first reaction was "a bat survey? Why on earth do I need a bat survey?" — you're not alone. This is one of the most common questions we hear from new clients at Volant EcoServices. The short answer is that several bat species found across the eastern United States are federally protected under the Endangered Species Act, and projects that might affect their habitat — even indirectly — can trigger specific survey and compliance requirements before construction can begin.

This guide walks you through everything you need to know: who needs a bat survey, what triggers the requirement, when surveys have to happen, where they're conducted, and why the process exists in the first place. By the end, you'll have a clear picture of what's ahead and how to move through it efficiently.

Why Do Bats Have Federal Protection?

Before getting into the logistics, it helps to understand why bats matter from a regulatory standpoint. Three bat species found across the eastern United States are the primary drivers of bat survey requirements for development and infrastructure projects:

Indiana bat ( Myotis sodalis ) — Listed as federally endangered since 1967. Found across much of the eastern United States, the Indiana bat uses forested habitats for roosting and raising young in summer and hibernates in caves and mines during winter. White-nose syndrome — a devastating fungal disease — has caused population declines in recent decades.

Northern long-eared bat ( Myotis septentrionalis ) — Reclassified from threatened to federally endangered in 2023. The northern long-eared bat is particularly sensitive to white-nose syndrome and has experienced dramatic population declines. It uses a wide variety of forested habitats and hibernates in caves and mines.

Tricolored bat ( Perimyotis subflavus ) — Currently proposed as federally endangered. White-nose syndrome has caused estimated population declines of more than 90% in affected colonies, making this one of the most severely impacted bat species in North America.

All three species — Indiana bat, northern long-eared bat, and tricolored bat — depend on forested habitats for roosting, raising young, foraging, and commuting. When a project proposes to clear trees, demolish structures, or disturb caves, mines, bridges, or culverts near suitable habitat, the potential for harm to these species triggers the bat survey process.

Who Needs a Bat Survey?

The short answer: if your project involves a federal nexus and could affect suitable bat habitat, you very likely need to address bats as part of your environmental review process.

A federal nexus means your project involves one or more of the following:

Federal funding — FHWA, FRA, FTA, USDA, or any other federal agency money in the project budget
Federal permits — Section 404 Clean Water Act permits from the Army Corps of Engineers, NEPA review, or any other federal authorization
Federal land — work occurring on or adjacent to federal lands
Federal agency involvement — DOD installations, National Forest lands, Bureau of Land Management areas

If any of these apply, your project is subject to Section 7 of the Endangered Species Act — the provision that requires federal agencies to consult with the U.S. Fish and Wildlife Service to ensure their actions don't jeopardize listed species. Bat surveys are often a key component of that consultation process.

Common project types that trigger bat survey requirements include:

Highway expansion, bridge replacement, and road construction projects
Transmission line and pipeline corridors through forested habitat
Wind energy facility development
Natural gas and oil infrastructure in forested regions
Utility right-of-way clearing and vegetation management
Residential and commercial development involving significant tree clearing
Department of Defense installation management and construction
Timber harvesting and forest management on federal lands
Bridge and culvert rehabilitation or replacement

Even if your project doesn't have a direct federal nexus, state-level review processes in many eastern states may also trigger bat survey requirements. It's always worth confirming with your state's wildlife agency and your local USFWS Ecological Services Field Office early in the planning process.

What Triggers the Requirement — and What Are You Actually Being Asked to Do?

The bat survey requirement is triggered when your project has the potential to affect suitable habitat for Indiana bat, northern long-eared bat, and/or tricolored bat in the eastern United States. "Suitable habitat" generally means:

Forested or wooded areas containing trees at least 3–5 inches in diameter at breast height with features like exfoliating bark, cavities, crevices, or hollows that could serve as roost sites
Caves, mines, rock features, or tunnels that could serve as winter hibernacula
Bridges and culverts that meet minimum size criteria for bat roosting
Riparian corridors, woodland edges, and forest patches used for foraging and commuting

When USFWS determines that your project is within the range of one or more target species and involves suitable habitat, they will typically recommend — or require — that you complete a series of steps before project activities begin.

The general process works like this:

Step 1 — IPaC Review: Your consultant submits your project through the USFWS Information for Planning and Consultation (IPaC) website. IPaC generates an Official Species List identifying which listed species — including Indiana bat, northern long-eared bat, and/or tricolored bat — are potentially present in your project area. This step should happen as early as possible in your project planning.

Step 2 — Habitat Assessment: A qualified biologist visits your site - or conducts a desktop analysis - and evaluates whether suitable bat habitat is present within the project footprint. If no suitable habitat exists, no further surveys may be required. If suitable habitat is present, the assessment documents its type, quantity, and distribution — information that determines what surveys are needed and how much survey effort is required.

Step 3 — Study Plan Development: Your biologist develops a survey study plan describing the proposed survey methods, locations, personnel qualifications, schedule, and expected outcomes. This plan is submitted to the appropriate USFWS Field Office for review and approval before any fieldwork begins. This step takes time — plan for at least 15 business days for standard projects, and 45–60 days for energy projects or complex multi-state projects.

Step 4 — Conduct Surveys: Approved surveys are conducted during the appropriate survey window by qualified, federally permitted biologists. Survey types may include mist-netting , acoustic monitoring , or a combination of both. Hibernaculum surveys and bridge and culvert assessments may also be required depending on your project.

Step 5 — Report Results: Survey results — whether positive or negative — are submitted to the USFWS Field Office. Results inform whether Section 7 consultation is needed, what conservation measures apply, and whether your project can proceed as planned.

When Do Surveys Have to Happen? Survey Windows Explained

This is where a lot of first-time clients get caught off guard: bat surveys can only be conducted during specific windows of the year , and missing those windows means waiting until the following season. For projects with tight schedules, this can be a significant delay if survey planning doesn't start early enough.

Here are the key survey windows established by the USFWS Range-wide Indiana Bat and Northern Long-Eared Bat Survey Guidelines:

Summer Active Season Surveys (mist-netting and acoustic monitoring)

Survey window: May 15 – August 15 in the hibernating range (which covers most of the eastern United States)
Survey window: March 1 – October 15 in the year-round active range for northern long-eared bat and tricolored bat
These surveys are the most common requirement and are what most clients mean when they say "bat survey." They document whether listed bat species are using suitable forested habitat within or near your project area.

Hibernaculum Surveys (caves, mines, underground features)

Winter internal surveys: January 1 – February 28 (traditional window: January 15 – February 15)
Fall emergence surveys: September 15 – October 31
Spring emergence surveys: April 1 – April 21
These surveys are required when your project may affect caves, mines, or other underground features that could serve as winter bat roost sites.

Bridge & Culvert Surveys

Timing varies by project and should be coordinated with your local USFWS Field Office — surveys may be timed to the active season, the winter period, or both depending on the nature of the proposed impact.

The practical implication: If your project involves tree clearing and you're reading this in the spring, you need to act immediately. Study plan approval alone takes at least 15 business days, and surveys must be completed before August 15. If you're reading this in the fall or winter, you have time to plan before the summer survey season — use it. Projects that get their habitat assessments and study plans submitted early are projects that stay on schedule.

Where Are Surveys Conducted?

Bat surveys are conducted within and around your specific project area — not at a distant location or in a representative habitat somewhere else. Survey locations are designed to detect bats that are actually using the habitat your project proposes to impact.

The USFWS Guidelines establish a level of effort (LOE) requirement based on the acreage of suitable habitat your project will affect. The more suitable habitat impacted, the more survey effort required. For standard projects, the LOE is calculated based on 123-acre survey units — for every 123 acres of suitable habitat (or fraction thereof), a minimum number of mist-net nights or acoustic detector nights must be completed.

Survey locations must be within or immediately adjacent to your project footprint, placed in areas that give bats the best opportunity to be detected — forest edges, stream corridors, travel corridors, and water sources. All site locations must be documented with GPS coordinates and submitted as part of the survey study plan for USFWS approval.

Volant EcoServices serves clients across Ohio, Pennsylvania, Kentucky, West Virginia, Indiana, Virginia, and throughout the eastern United States — wherever your project is located, we can mobilize to your site.

What Happens If Bats Are Found?

If listed bat species are detected during surveys, it doesn't automatically mean your project is stopped. What it means is that USFWS must be notified within 48 hours and the consultation process moves to the next level.

For mist-net captures , our biologists immediately initiate radio telemetry to track the captured bat to its roost location. Roost data documents how the bat is using the project area and informs what conservation measures — tree clearing windows, buffer zones, avoidance measures — may be required.

For acoustic detections , the confirmed presence of a listed species triggers coordination with the USFWS Field Office to determine appropriate next steps, which may include additional survey effort, project design modifications, or formal Section 7 consultation .

Formal Section 7 consultation results in a Biological Opinion from USFWS that describes the anticipated effects of your project on listed bat species and establishes Reasonable and Prudent Measures — specific conditions your project must follow to minimize impacts and avoid unauthorized take. These conditions commonly include seasonal tree clearing restrictions, work windows tied to the bat activity calendar, and monitoring requirements during construction.

The key point is that most projects that find listed bats can still move forward — they just move forward with specific conservation measures in place. The goal of the process is not to stop your project but to ensure it proceeds in a way that avoids, minimizes, or mitigates impacts to species that are genuinely imperiled.

What If No Bats Are Found?

If surveys are completed following USFWS Guidelines and no listed bat species are detected, you receive a probable absence determination — a defensible, agency-accepted finding that the listed species are probably not present in your project area under current conditions.

A negative survey result is valid for five years from the year the survey was conducted. This means you have a five-year window to complete your project without re-surveying, provided habitat conditions don't change significantly. If your project timeline extends beyond five years, coordinate with your local USFWS Field Office to determine whether updated surveys are needed.

Why Does This Process Exist? The Bigger Picture

It's worth taking a moment to understand why this regulatory framework exists — not just as compliance obligation, but as a reflection of a genuine conservation crisis.

White-nose syndrome has killed an estimated 6–7 million bats across North America since it was first detected in the United States in 2006. The northern long-eared bat alone has declined by more than 99% at some hibernacula. The tricolored bat has experienced colony declines exceeding 90% across much of its range. These are not abstract numbers — they represent a collapse of bat populations that may take a century to recover.

Bats provide enormous ecological and economic services. They consume billions of insects annually — including agricultural pests — reducing the need for pesticides and providing an estimated $3.7 billion per year in value to North American agriculture. Their loss has cascading effects on the ecosystems they're part of.

The bat survey and ESA compliance process exists because without it, routine development and infrastructure projects — individually small, cumulatively significant — would incrementally eliminate the roosting habitat, hibernation sites, and foraging corridors that these struggling species depend on to survive and recover. The regulatory framework is the mechanism through which society has decided to balance economic development with the obligation to protect species that cannot protect themselves.

At Volant EcoServices, we take that obligation seriously — not as a regulatory checkbox but as the reason we do this work. When we conduct a bat survey, we're not just helping you get a permit. We're contributing to the scientific record of where these species live, what habitats they depend on, and what conditions allow them to persist. That data matters, and it accumulates across thousands of surveys into a picture of population trends that informs conservation for decades.

How to Get Started

If you have a project that may require bat surveys, the most important thing you can do right now is start early . The survey windows are fixed. Study plan approval takes time. Projects that run into bat survey delays are almost always projects where the process wasn't started soon enough.

Here's your immediate action checklist:

Submit your project through IPaC at ipac.ecosphere.fws.gov to generate an Official Species List and determine which target species are in your project area
Contact your local USFWS Ecological Services Field Office to discuss your project and get preliminary direction on whether surveys are recommended
Engage a qualified bat survey firm — surveys for Indiana bat, northern long-eared bat, and tricolored bat must be conducted by biologists holding a valid USFWS Section 10(a)(1)(A) Recovery Permit for the applicable species
Submit your habitat assessment and study plan as early as possible — ideally well before the survey season begins

Volant EcoServices is a woman-owned ecological consulting firm based in Kent, Ohio. Our lead biologists hold a USFWS Recovery Permit for Indiana bat, northern long-eared bat, and gray bat, and our team is qualified to conduct the full range of bat surveys described in this guide — mist-netting , acoustic monitoring , hibernaculum surveys , bridge and culvert assessments , radio telemetry, emergence surveys, and bat acoustic data vetting .

Have questions about whether your project needs a bat survey, or ready to get the process started? Contact Volant EcoServices to speak with a federally permitted bat biologist about your project's survey needs across Ohio, Pennsylvania, Kentucky, West Virginia, Indiana, and the eastern United States. You can also reach us directly at (330) 541-5201 or info@volant.llc .

2026 USFWS Bat Survey Guidelines Released: What Changed and What It Means for Your Project

Fri, 20 Mar 2026 16:46:39 GMT

Today, the U.S. Fish and Wildlife Service (USFWS) released the 2026 version of the Range-wide Indiana Bat and Northern Long-Eared Bat Survey Guidelines — the foundational document governing presence/probable absence (P/A) survey methodology for the Indiana bat ( Myotis sodalis ), northern long-eared bat ( Myotis septentrionalis ), and tricolored bat ( Perimyotis subflavus ) across the eastern United States.

At Volant EcoServices, we base all of our bat survey methodology directly on these Guidelines — from mist-net surveys and acoustic monitoring to potential hibernacula surveys , fall/spring emergence surveys, bridge and culvert assessments, radio tracking, and emergence surveys. When the Guidelines change, the way we design and execute surveys changes with them. If you have an active project — or are planning one — here is what you need to know about the 2026 update.

What the USFWS Changed in 2026

The USFWS identified three primary changes in the 2026 Guidelines. Understanding each one helps project proponents and their consultants plan accordingly.

1. Streamlined Document Structure

The most immediately noticeable change is structural. The 2026 Guidelines document has been reduced by nearly half compared to previous versions. The USFWS explicitly states that this reduction was made to improve flow, clarity, and navigation — not to reduce the rigor of the survey requirements themselves.

What this means for your project: The core survey requirements — level of effort, survey windows, personnel qualifications, submission requirements — remain in place. The streamlined document should make it easier for project proponents and surveyors to locate relevant guidance quickly, but the underlying compliance expectations are unchanged. If you were planning surveys based on the 2024 Guidelines, coordinate with your local USFWS Ecological Services Field Office to confirm that your study plan aligns with the new 2026 version before submitting.

2. DNA Collection — New Instructions for Species Identification

One of the most substantive technical changes in the 2026 Guidelines is the formal inclusion of new instructions for DNA sample collection as a tool for species identification — specifically to reduce the need for wing biopsy punches, which are the most invasive of the DNA collection methods.

The 2026 Guidelines prioritize DNA collection methods in the following order, from most to least preferred:

Fecal collection — lowest risk of injury or additional stress; preferred when bats opportunistically defecate during processing or when feces can be collected below a known roost
Wing swabbing — second preferred method; provides adequate DNA while considered safe for the animal
Buccal swabs — less preferable due to potential for stress or injury during insertion
Wing biopsy punches — acceptable but least preferred; leaves a hole requiring healing and carries risk of tearing or infection

This hierarchy reflects a broader USFWS emphasis on minimizing stress and harm to listed bats during handling — particularly important for already-imperiled species like the Indiana bat and northern long-eared bat. The Guidelines note that fecal collection, wing swabbing, and buccal swabs can achieve approximately 95% efficacy for species identification, while wing biopsy punches reach approximately 98% — a relatively small difference that the USFWS has determined does not justify the additional invasiveness of biopsy collection as a first choice.

What this means for your project: If your survey captures a bat from the genus Myotis that cannot be readily identified to species in the field — a situation that arises most often with Indiana bat and little brown bat ( Myotis lucifugus ), which can be difficult to distinguish — DNA collection may be authorized or requested by the USFWS Field Office. Your survey team should be prepared to collect fecal or wing swab samples as the preferred methods. It is important to note that wing swabbing, buccal swabbing, and wing biopsy collection can only be conducted by individuals whose Section 10(a)(1)(A) Recovery Permit explicitly authorizes those activities. Collection of guano opportunistically, however, does not require a permit unless the bat is being held beyond the permitted 30-minute processing window.

At Volant EcoServices, our lead biologists Mary Gilmore and Dan Cox hold USFWS Recovery Permits for Indiana bat, northern long-eared bat, and gray bat, and our team is trained in appropriate handling and DNA collection procedures consistent with the updated Guidelines.

3. Western Species Identification — New Language for Western Myotis Species

The 2026 Guidelines include new language related to the identification of western Myotis bat species in portions of the NLEB and tricolored bat ranges that overlap with acoustically similar western species. This primarily affects surveys conducted in the western portions of these species' ranges — states such as Kansas, Nebraska, North Dakota, South Dakota, Montana, and Wyoming — where species like the long-eared myotis ( Myotis evotis ), western small-footed bat ( Myotis ciliolabrum ), and canyon bat ( Parastrellus hesperus ) can cause acoustic misidentification issues.

The 2026 FAQ confirms that for surveys in these western overlap zones, no acoustic software programs are currently approved as stand-alone tools. Surveyors must use two candidate programs and apply manual vetting protocols to confirm or reject species identifications.

What this means for your project: For the vast majority of Volant's clients in Ohio, Pennsylvania, Kentucky, West Virginia, Indiana, Virginia, and the broader eastern United States, this change has limited direct impact — the problematic western species overlap areas are outside your project geography. However, if you are working on a project in the range fringe states, this language is important. Coordinate with your local USFWS Field Office to confirm which software programs are approved and what manual vetting standards apply to your specific project location.

What Did Not Change in 2026

Given the scope of the document restructuring, it is worth being explicit about what the 2026 Guidelines did not change — because some of the most consequential requirements from recent years remain fully in effect.

Tricolored bat remains in scope. The 2026 Guidelines continue to include tricolored bat as a target species alongside Indiana bat and northern long-eared bat. The TCB-specific level of effort — using the NLEB LOE as the standard — remains in place. As the 2026 FAQ confirms, preliminary USFWS and USGS review indicates this LOE is sufficient to demonstrate P/A of tricolored bat throughout its range. The tricolored bat is currently proposed as federally endangered, and its inclusion in P/A survey planning remains essential for projects in suitable habitat.

Survey windows are unchanged. The summer survey season for the hibernating range remains May 15 – August 15. The year-round active survey season for NLEB and TCB remains March 1 – October 15. These windows govern when surveys must be completed to produce defensible presence/probable absence determinations.

Level of effort requirements are unchanged. The minimum survey LOE for mist-netting and acoustic surveys — the number of net-nights and detector-nights required per 123 acres of suitable habitat — remains the same as established in recent versions of the Guidelines. The combined acoustic and mist-netting approach remains available and is required for TCB surveys in areas outside the NLEB and IBAT range.

Study plan approval requirements remain in place. Surveyors are still required to receive prior, site-specific approval from the USFWS Field Office before conducting P/A surveys. Study plans should be submitted as early as possible — the Guidelines note that FOs can typically review and approve within 15 working days, but complex projects or energy projects can require 45–60 days. Plan accordingly.

Negative survey validity periods are unchanged. Negative P/A survey results remain valid for a minimum of five years from the year surveys are completed, assuming no significant habitat changes or new nearby detections. Negative bridge and culvert survey results remain valid for two years.

AudioMoth remains unacceptable. The 2026 Guidelines continue to explicitly exclude the AudioMoth detector (Open Acoustic Devices) from use in P/A surveys pending further refinement and testing. If your survey program uses AudioMoth as a primary detection tool, those results will not be accepted by the USFWS.

Acoustic Software — Check the Approved List Before Submitting Your Study Plan

The USFWS included a prominent reminder in the 2026 Guidelines update: review the approved acoustic software list before submitting your study plan for 2026 surveys. The approved software list is maintained separately from the Guidelines document and is updated as new programs and new versions are tested. The 2026 FAQ confirms that Kaleidoscope Pro versions using the approved 5.4.0 Bats of North America classifier and SonoBat 30 versions using approved Regional Pack classifiers remain acceptable for use.

At Volant EcoServices, our acoustic data vetting team stays current with approved software versions and classifier updates. All acoustic data we collect or vet is analyzed using the most current USFWS-approved programs and is manually reviewed by our federally permitted biologists to ensure defensible, agency-ready results.

What This Means If You Have a Project in 2026

If your project is in the planning stages and you have not yet conducted bat surveys, the 2026 Guidelines are the version that applies to your work this season. Here is what we recommend:

Start early. Study plan review and approval by the USFWS Field Office takes time. For standard projects, plan for at least 15 working days. For energy projects, complex linear projects, or multi-FO coordination, allow 45–60 days or more. Submitting early in the calendar year gives your project the best chance of completing surveys within the appropriate survey windows.

Use IPaC first. Submit your project through the USFWS Information for Planning and Consultation website (IPaC) to generate an official species list and determine which of the three target species — Indiana bat, northern long-eared bat, and/or tricolored bat — are within your project area. This step should happen before any survey planning begins.

Confirm your survey method is appropriate. The 2026 Guidelines allow mist-netting, acoustic surveys, or a combined approach for most projects. The combined approach continues to offer flexibility for projects with challenging survey conditions or limited high-quality mist-net locations. For TCB-only range projects, the acoustic or combined approach is required.

Coordinate on DNA collection if relevant. If your project involves capture of Myotis bats with ambiguous species identification, discuss DNA collection authorization and preferred methods with your USFWS Field Office ahead of time. Ensure your permitted biologist's recovery permit explicitly authorizes the collection methods that may be needed.

Have Questions About the 2026 Guidelines and Your Project?

Volant EcoServices follows the most current USFWS bat survey guidelines for all presence/probable absence surveys, acoustic monitoring, hibernaculum assessments, bridge and culvert surveys, radio tracking, and emergence surveys. Our team monitors guideline updates as they occur and ensures that every study plan we develop reflects current USFWS requirements.

If you have questions about how the 2026 Guidelines affect your specific project — whether you are a developer, transportation agency, utility company, or land manager — contact Volant EcoServices to speak with a federally permitted bat biologist. We serve clients across Ohio, Pennsylvania, Kentucky, West Virginia, Indiana, Virginia, and the broader eastern United States.

This post was written on the date of the 2026 Guidelines release, March 20, 2026. As with all regulatory guidance, project proponents should consult directly with their local USFWS Ecological Services Field Office for project-specific questions and study plan approval. The full 2026 Guidelines and associated FAQ are available at fws.gov .

Volant Volunteers at MAPS Stations to Support Avian Conservation

Thu, 25 Sep 2025 10:28:01 GMT

At Volant, our commitment to ecological stewardship goes beyond consulting—it’s a personal and professional passion. Recently, our co-founders took that commitment into the field by volunteering at Monitoring Avian Productivity and Survivorship (MAPS) stations, contributing to one of North America’s most important long-term bird monitoring programs.

Dan Cox participated at the MAPS station located at Shaker Village of Pleasant Hill in Kentucky , while Mary Gilmore volunteered at the station in Cuyahoga Valley National Park in Ohio. These experiences allowed us to engage directly with the science that informs conservation strategies and deepened our connection to the ecosystems we work to protect.

What Are MAPS Stations?

MAPS stations are part of a continent-wide network established by the Institute for Bird Populations (IBP). These stations operate during the breeding season and use standardized mist-netting and banding protocols to collect data on bird demographics—such as age, sex, and reproductive status. The goal is to monitor trends in avian productivity and survivorship, which are critical indicators of ecosystem health.

Why MAPS Matters

Birds are excellent bioindicators. Changes in their populations often reflect broader environmental shifts, including habitat loss, climate change, and pollution. MAPS data helps scientists and land managers understand these changes and develop informed conservation strategies. The program has been instrumental in identifying population declines and guiding habitat restoration efforts across North America.

Why Volant Participates

As ecologists, we rely on robust data to inform our work. Volunteering at MAPS stations allows us to contribute to the very datasets that shape conservation policy and practice. It also keeps us grounded in the fieldwork that underpins our consulting services. Participating in MAPS aligns with our mission to support science-based environmental solutions and gives us a chance to collaborate with other professionals and volunteers who share our passion for wildlife conservation.

Moreover, these experiences enrich our understanding of the landscapes we serve. Whether it’s the rolling hills of Kentucky or the forested valleys of Northeast Ohio, each MAPS station offers a unique glimpse into the local avian community and the broader ecological dynamics at play.

Looking Ahead

We’re proud to support MAPS and encourage others in the environmental sector to get involved. Whether through volunteering, funding, or simply spreading awareness, every contribution helps strengthen the scientific foundation of conservation.

Stay tuned for more field stories and insights from our team as we continue to engage with the ecosystems we serve—both professionally and personally.

Interested in long-term ecological monitoring or avian survey services for your property or project? Contact Volant EcoServices to discuss how our team can support your conservation goals across the eastern United States.

Could Bats Help Control the Spotted Lanternfly Invasion?

Thu, 03 Jul 2025 17:18:22 GMT

Bats vs Spotted Lanterfly

The spotted lanternfly ( Lycorma delicatula ) has become one of the most notorious invasive species threatening forests, agriculture, and ecosystems across the eastern United States. As this insect rapidly expands its range, land managers and researchers are urgently seeking natural solutions to control its spread.

A new study published in Forests (MDPI, 2023) offers a hopeful — and surprising — potential ally in the fight: bats.

The Spotted Lanternfly Problem

Originally from Asia, the spotted lanternfly was first detected in Pennsylvania in 2014 and has since spread across the Northeast and Mid-Atlantic. Its preferred host, the invasive tree of heaven ( Ailanthus altissima ), is common along roadsides, forest edges, and disturbed habitats — making containment especially difficult.

These insects cause extensive damage by feeding on sap from trees and plants, weakening them and leaving behind a sticky residue that promotes mold growth. The economic impacts are significant, affecting vineyards, orchards, timber, and even tourism.

Bats as Natural Pest Control

Recent research reviewed global studies on forest-dwelling bats and highlighted emerging evidence that some native bat species may be consuming spotted lanternflies.

This is promising news for several reasons:

Bats are voracious insect predators, capable of eating thousands of insects in a single night.
Utilizing native species for pest control reduces reliance on pesticides and promotes ecosystem balance.
Bats often forage along forest edges, roadsides, and near water — the same areas where spotted lanternflies tend to congregate.

While more targeted research is needed to fully understand the extent of bat predation on lanternflies, early findings suggest that enhancing bat habitat could be part of an integrated pest management strategy.

Supporting Bats, Supporting Forest Health

At Volant EcoServices, we specialize in bat research and habitat assessments. Protecting and enhancing bat populations isn’t just good for biodiversity — it may also provide tangible benefits in controlling invasive pests like the spotted lanternfly.

We assist clients with:

Acoustic monitoring to document bat activity
Roost surveys and habitat evaluations
Conservation planning that promotes healthy bat populations

As this research evolves, we’re optimistic about the role native wildlife can play in restoring balance to our forests.

Interested in learning more?

Read the full article here .

Interested in bat habitat assessments, acoustic monitoring, or conservation planning that supports healthy bat populations on your property or project site? Contact Volant EcoServices to speak with our team about bat survey and conservation services across Ohio, Pennsylvania, Kentucky, and the eastern United States.