2017 Range-wide Indiana Bat Summer Survey Guidelines

2017
RANGE-WIDE INDIANA BAT SUMMER SURVEY GUIDELINES
May 9, 2017
(changes from the 2016 guidelines are in blue)

INTRODUCTION
The Indiana bat (Myotis sodalis) was originally listed as being in danger of extinction under the
Endangered Species Preservation Act of 1966 (32 FR 4001, March 11, 1967), and is currently
listed as endangered under the Endangered Species Act (ESA) of 1973, as amended. This survey
protocol provides the U.S. Fish and Wildlife Service’s (USFWS) recommended guidance on
survey methodology and outlines additional reporting requirements for surveyors.
The following guidance is designed to determine whether Indiana bats are present 1 or likely
absent at a given site during the summer (May 15 to August 15). The phased-approach, which
includes coordination with the USFWS 2, habitat assessments, and acoustic, mist-net, radiotracking, and emergence surveys, supersedes all prior summer survey guidance. Future changes
to this guidance may occur and will be posted on the USFWS Indiana bat summer survey
guidance website
(http://www.fws.gov/midwest/endangered/mammals/inba/inbasummersurveyguidance.html).
Please check this website to ensure use of the most current version of the guidance.
These protocols may be different from those designed for general bat monitoring as part of the
North American Bat Monitoring Program (NABat) 3. NABat surveys may be thought of as
similar to breeding bird surveys and are not project-specific surveys in most cases. Information
from NABat surveys can be considered as part of “best available” information when assessing
whether there is already some existing information on presence of Indiana bats in the vicinity of
a given project. We recommend following these guidelines for presence/probable absence
surveys.
NOTE: These protocols can also be used for northern long-eared bat (NLEB) presence/probable
absence surveys for the 2017 field season. The only difference is our definition of suitable
summer habitat for NLEBs and a weather-related exception in the northern portion of its range.
OBJECTIVES
The objectives of Indiana bat summer survey guidelines are to (1) standardize range-wide survey
procedures; (2) maximize the potential for detection/capture of Indiana bats at a minimum
1

The guidance are not intended to be rigorous enough to provide sufficient data to fully determine population size or
structure.
2
Coordinate with the appropriate state natural resource agencies and any involved federal agency(ies) whenever
“USFWS” coordination is listed. USFWS FO(s) may direct project sponsors to state agencies for existing
occurrence information. Coordinate with your local USFWS FO(s) to understand the process for their area of
jurisdiction.
3
Loeb et al. 2015 available at https://www.fort.usgs.gov/products/23886

1

acceptable level of effort;(3) make accurate presence/absence determinations; and (4) aid in
conservation efforts for the species by identifying areas where the species is present.
BACKGROUND
In 2011, the USFWS developed a multi-agency team to determine whether improvements could
be made to the 2007 Indiana Bat Mist-Net Protocols. The team included members of the four
USFWS regions (Midwest, Northeast, Southeast, and Southwest) where Indiana bats are known
to occur, representatives of state natural resource agencies from three of those four regions
(Midwest, Northeast, and Southeast), and representatives from three federal agencies (U.S.
Geological Survey (USGS), Department of Defense, and U.S. Forest Service). We obtained
informal peer review of the draft guidelines in February 2012, gathered additional information in
2012, and made a revised version available for public comment in 2013 [78 FR 1879, January 9,
2013, and 78 FR 9409, February 8, 2013]. The USFWS implemented revised guidance in 2014.
The USGS conducted initial independent testing of automated acoustic software programs during
the winter of 2014-15 and continues to test new versions of available software. The USFWS
made some additional revisions to the guidelines in 2015 and 2016.
We considered the best available information for all aspects of the guidance. For example,
please see our white paper 4 outlining the methodologies used to determine the minimum level of
survey effort. The USFWS continues to work with local, State, and Federal biologists; scientific
and academic institutions; commercial organizations; and other interested parties to collect
additional data on the distribution, ecology, and biology of the Indiana bat and looks forward to
receiving any additional pertinent information.
GENERAL PROCESS
Indiana bat surveys for some proposed projects will require modification (or clarification) of this
guidance through coordination with the USFWS FO(s) responsible for the state(s) in which the
project occurs 5. If not already required by federal permit, federal action agencies and surveyors
should develop a proposed survey study plan in coordination with the USFWS FO(s) so that all
parties fully understand which methods will be deployed, what assumptions will be made, and
what the various outcomes would be based on the results of each step. Project proponents may
stop survey work at any point once an assumption or documentation of Indiana bat presence
occurs. Pre-survey coordination typically will preclude the need for subsequent reviews of
intermediate steps by USFWS FO(s) during the busy field season. An online directory of
USFWS FO(s) is available at http://www.fws.gov/offices/. Unless otherwise agreed to by the
USFWS, negative presence/probable absence survey results obtained using this guidance are

4

Available at http://www.fws.gov/midwest/endangered/mammals/inba/inbasummersurveyguidance.html
For example, project sponsors for large acreage and/or landscape-scale projects that do not result in permanent
habitat loss and would not pose an ongoing threat of lethal take, especially those proposed by land management
agencies, may work with local USFWS FOs to apply different scales of surveys (broad vs. project-level) or different
types of surveys, such as long-term monitoring results (e.g., forest-wide acoustic transect data) and/or targeted
survey efforts (e.g., sub-sampling of large project areas), to address P/A concerns.
5

2

valid for a minimum of two years 6 from the completion of the survey unless new information
(e.g., other nearby surveys) suggest otherwise. If not already required by federal permit, please
submit all results (negative or positive) from any phase to the USFWS FO(s). We strongly
encourage this coordination as it improves the USFWS’ understanding of (1) the level of survey
effort underway and (2) the distribution of the species. A single report can be submitted at the
end of all phases conducted for a given project.
USFWS FO(s) level coordination is also important during the survey planning process. The
USFWS recognizes that there may be project-specific habitat conditions that do not lend
themselves to surveying with either acoustic detectors or mist-nets even though it met the
definition of suitable Indiana bat summer habitat. The guidelines that are described in this
document are designed to be implemented in habitats conducive to each technique described.
We strongly encourage coordination with the FO(s) prior to implementation of methodologies
that may not be appropriate for site-specific habitat conditions.
Because Indiana bat surveys may result in take, such surveys should only be conducted by a
qualified biologist 7. Generally, a recovery permit for the Indiana bat authorizes the capture of
bats for identification, and handling of bats for measurements, photography, and radio
transmitter attachment. Following this guidance will meet standard USFWS requirements;
however, surveyors also need to ensure they meet all applicable state permitting and reporting
requirements. Failure to follow the survey guidance, as written, and/or failure to follow a study
plan which has received concurrence from the local USFWS FO(s), may result in USFWS FO
recommendations for additional survey effort.
The following provides a step-by-step outline of how Indiana bat summer surveys should be
conducted in 2017. Some of these steps can occur concurrently.
PHASE 1 – INITIAL PROJECT SCREENING
Step 1. Coordinate with the U.S. Fish and Wildlife Service Field Office(s) 8 regarding
existing Indiana bat summer occurrence information.
[Projects located within known Indiana bat summer habitat will not proceed to Phase
2 of this process.]
a) If a project (located within or outside of a known maternity colony home range) is
6

The timeframe may be reduced if significant habitat changes have occurred in the area or increased based on local
information.
7
A qualified biologist is an individual who holds a USFWS Recovery Permit (Federal Fish and Wildlife Permit) for
Indiana bats in the state/region in which they are surveying and/or has been authorized by the appropriate state
agency to net and handle Indiana bats. Several USFWS offices maintain lists of qualified bat surveyors, and if
working in one of those states with authorizations in lieu of a Recovery Permits, the individual will either need to be
on that list or submit qualifications to receive USFWS approval prior to conducting any field work.
8
Coordinate with the appropriate state natural resource agencies and any involved Federal Action agencies
whenever “USFWS” coordination is listed. USFWS FO(s) may direct project sponsors to state agencies for existing
occurrence information. Coordinate with your local USFWS FO(s) to understand the process for their area of
jurisdiction.

3

already covered under an existing Endangered Species Act (ESA) incidental take
authorization (e.g., HCP, BO), then no further summer surveys are needed, follow the
procedures previously authorized by the USFWS FO(s).
b) If there are known Indiana bat summer occurrences (e.g., known roost trees, capture
locations, foraging locations) within the project action area 9; OR
if there are no known Indiana bat summer occurrences within the proposed project
area itself, but the project area is located within a known maternity colony home
range 10; OR
if the project is located outside a known maternity colony home range, but is within
the range of the Indiana bat (note this can change over time), then proceed to Step 2.
Step 2. Conduct Habitat Assessment (Desktop or Field-based; see Appendix A).
a) If suitable summer habitat is present within the action area, then proceed to Step 3.
b) If suitable summer habitat is absent within the action area, then no further summer
surveys are necessary; however, additional coordination with the USFWS FO(s) will
be necessary if Indiana bats may be present during any other season and may be
affected by the proposed project.
Step 3. Assess potential for adverse effects to Indiana bats.
a) If the project is not anticipated to result in adverse effects to Indiana bats (as
proposed), then no further summer surveys are necessary, coordinate with the
USFWS FO(s).
b) If the project may result in adverse effects to Indiana bats but the impacts can be
adequately assessed and conservation measures can be designed to minimize those
effects without additional presence/absence information (this includes all proposed
projects within known maternity colony home ranges, but may include other areas as
well), then no further summer surveys are necessary, coordinate with the USFWS
FO(s) regarding an assessment of the project’s potential effects, development of
conservation measures, and determination of the need for any ESA incidental take
authorization.
c) If the project does not meet the conditions of 3a or 3b, then proceed to Phase 2.

9

The “action area” is defined as all areas to be affected directly or indirectly by the Federal action and not merely
the immediate area involved in the action. [50 CFR Section 402.02]
10
See USFWS Indiana Bat Section 7 and Section 10 Guidance for Wind Energy Projects (Questions 4 & 5)
http://www.fws.gov/midwest/endangered/mammals/inba/WindEnergyGuidance.html

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PHASE 2 - PRESENCE/ABSENCE SURVEYS (NETTING OR ACOUSTIC SURVEYS) 11
During the summer of 2017, presence/probable absence (P/A) of Indiana bats may be determined
by conducting either Step 4 (mist-netting; see Appendix B) or Step 5 (acoustics; see Appendix
C) as outlined below. It is the project proponent’s choice as to which option to use. The summer
survey season is from 15 May through 15 August 12 for either survey option. The minimum
prescribed survey level of effort for any given survey area unit (i.e., ≤123-acre area or 1-km
section of linear project) cannot be completed in a single calendar night regardless of which
survey method (netting or acoustic) is used (i.e., minimum survey effort must be spread over at
least 2 calendar nights). If netting is chosen as the preferred P/A method and an Indiana bat(s) is
captured, then surveyors may immediately begin Phase 4/radio-tracking. Project proponents
must decide whether they will proceed to Phase 4 in coordination with the USFWS FO before
any mist netting occurs. Submit Phase 2 study plans to USFWS FO prior to conducting surveys.
Step 4. Conduct Mist-Netting Surveys following Recovery Unit-based Protocols 13
(see Appendix B)
Northeast and Appalachian Recovery Units (CT, DE, MA, MD, NC, NJ, NY, PA,
eastern TN, WV, VA, VT):
Linear projects: a minimum of 6 net nights per km (0.6 miles) of suitable summer
habitat (see Appendix F).
Non-linear projects: a minimum of 42 net nights per 123 acres (0.5 km2) of
suitable summer habitat.
For example:
• 7 sites, 2 nets/site for 3 calendar nights = 42 net nights
• 7 sites, 3 nets/site for 2 calendar nights = 42 net nights
• 3 sites, 2 nets/site for 7 calendar nights* = 42 net nights
*Maximum of 3 nights of consecutive netting at any given net location. After 3
11

Note: acoustic and/or mist-net surveys should be conducted in the best suitable habitat possible for each survey
type to increase the likelihood of detecting/capturing Indiana bats. In some cases, the most suitable habitat for
effectively conducting surveys may occur outside a project site boundary and may be sampled if landowner
permission is available. For projects with multiple survey areas (e.g., >123 acres or >1 km), survey methods may be
interchanged. For example, acoustics could be used for one 123-acre survey area and netting could be used for
another 123-acre area.
12
With prior USFWS FO approval, a survey may be completed after August 15 if it was initiated in time to be
completed by August 15 and extenuating weather circumstances resulted in delaying completion. Delays as a result
of not meeting the acceptable weather requirements are the ONLY valid justification for surveying after August 15.
13
The Indiana bat populations in the Northeast and Appalachian Recovery Units have been most heavily impacted
by white-nose syndrome to date; therefore, we recommend higher survey effort when compared to the Midwest and
Ozark-Central Recovery Units. We have no recommendations for reducing the minimum level of effort required to
demonstrate probable absence for projects <123 acres in size. Level of effort is based on detection probabilities and
occupancy estimates that were derived from past survey efforts that used the same acreage threshold. Level of effort
is designed to reach 90% confidence in negative survey results (see Niver et al. 2013).

5

consecutive nights of netting at the same location, you must change net locations
or wait at least 2 calendar nights before resuming netting at the same location.
a) If no capture of Indiana bats, then no further summer surveys are
necessary14.
b) If capture of Indiana bat(s), then stop or proceed to Phase 4
as previously decided in coordination with the FO.
Midwest and Ozark-Central Recovery Units (AL, AR, IA, IL, IN, GA, KY, MI, MO,
MS, OH, OK, central & western TN, and Lee County, VA):
Linear projects: a minimum of 4 net nights per km (0.6 miles) of suitable summer
habitat (see Appendix F).
Non-linear projects: a minimum of 9 net nights per 123 acres (0.5 km2) of
suitable summer habitat.
For Example:
• 3 sites, 1 nets/site for 3 calendar nights = 9 net nights
• 1 sites, 3 nets/site for 3 calendar nights = 9 net nights
The sampling period for each net shall begin at sunset and continue for at least 5 hours
(longer survey periods may also improve success).
*Maximum of 3 nights of consecutive netting at any given net location. After 3
consecutive nights of netting at the same location, you must change net locations
or wait at least 2 calendar nights before resuming netting at the same location.
a) If no capture of Indiana bats, then no further summer surveys are
necessary.
b) If capture of Indiana bat(s), then stop or proceed to Phase 4
as previously decided in coordination with the FO.
OR
Step 5. Conduct Acoustic Surveys 15 (see Appendix C)
Linear projects: a minimum of 2 detector nights per km (0.6 miles) of suitable summer
habitat (see Appendix F).
14

NOTE: For Phase 2 Presence/Absence Surveys, wherever the phrase “no further summer surveys are necessary”
occurs within this document, the USFWS FO(s) is in affect assuming probable absence of Indiana bats.
15
Acoustic surveys are available as a Presence/Absence option throughout the range (i.e., Northeast, Appalachian,
Midwest, and Ozark-Central Recovery Units).

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Non-linear projects: a minimum of 4 detector nights per 123 acres (0.5 km2) of suitable
summer habitat.
2 detector locations per 123 acre "site" shall be sampled until at least 4 detector nights
has been completed over the course of at least 2 calendar nights (may be consecutive).
For example:
•
•

2 detectors for 2 nights each (can sample the same location or move within the site)
1 detector for 4 nights (must sample at least 2 locations)

The acoustic sampling period for each site must begin at sunset 16 and ends at sunrise each
night of sampling.
Optional coarse screening - for high frequency (HF) or myotid calls (depending
on available filters) or Proceed to Step 6
i)

If no positive detection of HF calls (≥35 kHz) or myotid calls, no further
summer surveys necessary.

ii)

If positive detection of HF or myotid calls, then
(a) proceed to Step 6 for further acoustic analysis; OR
(b) assume presence of Indiana bats and coordinate with the USFWS
FO(s); OR
(c) assume presence and proceed to Phase 3.

Step 6. Conduct Automated Acoustic Analyses for each site that had HF or Myotid calls
from Step 5 or ALL sites if Step 5 was not conducted.
(NOTE: cannot skip this step and proceed directly to Step 7)
Use one or more of the currently available ‘approved’ acoustic bat ID programs 17 (use
most current approved software versions available and manufacturer’s recommended
settings for Indiana bat P/A surveys). ‘Candidate’ programs are not yet approved by
USFWS for stand-alone use for Indiana bat P/A surveys, but may be used in conjunction
with one or more of the approved programs. Include your plans for which specific
software program(s) you will use in your survey work plan and submit for USFWS FO(s)
review prior to conducting surveys. Beginning with acoustic data from night one at each
acoustic site, run each night’s data for each site through your chosen ID program(s).
16

Surveys may need to start a little earlier or later than official sunset times (i.e., at “dusk”) in some settings such as
a deep/dark forested valleys or ridge tops to avoid missing early-flying bats or capturing late-flying birds,
respectively. Sunset tables for the location of survey can be found at:
http://aa.usno.navy.mil/data/docs/RS_OneYear.php
17
Approved and candidate programs are listed at
http://www.fws.gov/midwest/Endangered/mammals/inba/surveys/inbaAcousticSoftware.html

7

Review results by site by night from each acoustic ID program used 18.
a) If Indiana bat presence is considered unlikely by all of the approved and candidate
program(s) used in analysis, then no further summer surveys necessary.
b) If Indiana bat presence is considered likely at one or more sites on one or more
nights by any approved or candidate program(s) used in analysis, then
i)
ii)
iii)

proceed to Step 7 for qualitative ID; OR
assume presence of Indiana bats and coordinate with the USFWS FO(s);
OR
assume presence and proceed to Phase 3.

Step 7. Conduct Qualitative Analysis of Calls.
At a minimum, for each detector site/night a program considered Indiana presence likely
(from MLE results) review all files (including no IDs) from that site/night. Qualitative
analysis 19 (i.e., manual vetting) must also include a comparison of the results of each
acoustic ID program by site and night (see Reporting Requirements in Appendix C).
a) If no visual confirmation of probable Indiana bats, then no further summer surveys
necessary20.
b) If visual confirmation of probable Indiana bats, then
i) assume presence of Indiana bats and coordinate with the USFWS FO(s); OR
ii) assume presence and proceed to Phase 3.
PHASE 3. CONDUCT MIST-NETTING SURVEYS TO CAPTURE INDIANA BATS.
If netting was not conducted as the P/A method, then netting may be conducted in Phase 3 to
capture and characterize (e.g., sex, age, reproductive condition) the Indiana bats that are
present in an area and to facilitate Phase 4 efforts. We encourage working with the FOs to
develop Phase 3 netting plans based on best available information (e.g., positive acoustic
locations). There are no minimum requirements for this phase as this is not a P/A phase.
a)

If no Indiana bats are captured, then coordinate with the USFWS FO.

b)

If Indiana bats are captured, then proceed to Phase 4.

18

The approved acoustic identification programs all have implemented a maximum likelihood estimator (MLE) at
this time. If the analysis of collected calls at a given site on a given night results in the probable presence of Indiana
bats with high levels of certainty (P<0.05), then select one of the options available in Step 6b.
19
Qualitative analysis of each acoustic site and night with probable detections of Indiana bats during Step 6 must
include the entire night’s high-frequency call data and not just those files making it through the acoustic analysis
tools as probable Indiana bats.
20
If you identify any suspected mis-identifications from programs, the Service will share those results with the
software manufacturer(s) and the USGS to assist with future improvements and testing of software.

8

PHASE 4. CONDUCT RADIO-TRACKING AND EMERGENCE SURVEYS
(See Appendices D and E).

REFERENCES
Amelon, S.K. 2007. Multi-scale factors influencing detection, site occupancy, and resource use
by foraging bats in the Ozark Highlands of Missouri. PhD Dissertation. University of Missouri
– Columbia.
Duchamp, J.E., M. Yates, R. Muzika, and R.K. Swihart. 2006. Estimating probabilities of
detection for bat echolocation calls: an application of the double-observer method. Wildlife
Society Bulletin 34(2):408-412.
Loeb, S.C., T.J. Rodhouse, L.E. Ellison, C.L. Lausen, J.D. Reichard, K.M. Irvine, T.E. Ingersoll,
J.T.H. Coleman, W.E. Thogmartin, J.R. Sauer, C.M. Francis, M.L. Bayless, T.R. Stanley, and
D.H. Johnson. 2015. A plan for the North American Bat Monitoring Program (NABat). General
Technical Report SRS-208. Asheville, NC: U.S. Department of Agriculture Forest Service,
Southern Research Station. 112 p.
Niver, R.A., R.A. King, M.P. Armstrong, and W.M. Ford. 2014. Methods to Evaluate and
Develop Minimum Recommended Summer Survey Effort for Indiana Bats: White Paper.
Accessed 13 January 2014

Romeling, S., C.R. Allen, and L. Robbins. 2012. Acoustically detecting Indiana bats: how long
does it take? Bat Research News 53(4):51-58.
Yates, M.D. and R.M. Muzika. 2006. Effect of forest structure and fragmentation on site
occupancy of bat species in Missouri Ozark forests. Journal of Wildlife Management
70(5):1238-1248

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APPENDIX A
PHASE 1 SUMMER HABITAT ASSESSMENTS
Summer habitat assessments are Step 2 of Phase 1- Initial Project Screening. The information
below is provided to assist applicants, consultants, and/or project proponents (hereinafter termed
the “applicant”) in establishing whether summer surveys for Indiana bats should be conducted.
As a reminder, the first step for determining presence of Indiana bats at a given site is to
determine whether there is any existing occurrence data available for the vicinity of the project
from the local USFWS FO. This step can be conducted remotely via a desktop analysis (e.g., use
of aerial photography to assess the potential presence of suitable habitat). The applicant is
responsible for developing and providing sufficient information as to whether potentially suitable
summer Indiana bat habitat exists within a proposed project area. If suitable habitat is present,
the applicant should calculate the amount and submit this to the USFWS FO(s) and determine
the need for any presence/absence surveys (Phase 2). Note: if Indiana bats are present or
assumed to be present during any phase, more detailed habitat information may be necessary to
adequately assess the potential for impacts (see attached example Indiana Bat Habitat
Assessment Datasheet). If no suitable habitat is present, no surveys are needed to assess risk
during the summer. Habitat assessments for Indiana bats can be completed any time of year and
applicants are encouraged to submit results and proposed Phase 2 study plans well in advance of
the summer survey season.
PERSONNEL
Habitat assessments should be completed by individuals with a natural resource degree or
equivalent work experience.
DEFINITION FOR POTENTIALLY SUITABLE INDIANA BAT SUMMER HABITAT
Suitable summer habitat for Indiana bats consists of a wide variety of forested/wooded habitats
where they roost, forage, and travel and may also include some adjacent and interspersed nonforested habitats 21 such as emergent wetlands and adjacent edges of agricultural fields, old fields
and pastures. This includes forests and woodlots containing potential roosts (i.e., live trees
and/or snags ≥5 inches dbh 22 (12.7 centimeter) that have exfoliating bark, cracks, crevices,
and/or hollows), as well as linear features such as fencerows, riparian forests, and other wooded
corridors. These wooded areas may be dense or loose aggregates of trees with variable amounts
of canopy closure. Individual trees may be considered suitable habitat when they exhibit the
characteristics of a potential roost tree and are located within 1,000 feet (305 meters) of other
forested/wooded habitat. We recommend that project proponents or their representatives
21

Non-forested habitats typically should be excluded from acreages used to establish a minimum level of survey
effort for Phase 2 surveys.
22
While trees <5 inches (<12.7 cm) dbh that have exfoliating bark, cracks, crevices, and/or hollows may have some
potential to be male Indiana bat summer roosting habitat, the USFWS does not consider early-successional, evenaged stands of trees <5 inches dbh to be suitable roosting habitat for the purposes of this guidance. Suitable roosting
habitat is defined as forest patches with trees of 5-inch (12.7 cm) dbh or larger. However, early successional habitat
with small diameter trees may be used as foraging habitat by Indiana bats. Therefore, a project that would remove
or otherwise adversely affect ≥20 acres of early successional habitat containing trees between 3 and 5 inches (7.612.7 cm) dbh would require coordination/consultation with the USFWS FO to ensure that associated impacts would
not rise to the level of take. The USFWS may request P/A surveys if >20 acres of early successional habitat were
proposed for removal.

10

APPENDIX A
PHASE 1 SUMMER HABITAT ASSESSMENTS
coordinate with the appropriate USFWS Field Office to more clearly define suitable habitat for
their particular region as some differences in state/regional suitability criteria may be warranted
(e.g., high-elevation areas may be excluded as suitable habitat in some states).
Examples of unsuitable habitat:
• Individual trees that are greater than 1,000 feet from forested/wooded areas;
• Trees found in highly-developed urban areas (e.g., street trees, downtown areas); and
• A pure stand of less than 3-inch dbh 23 trees that are not mixed with larger trees.
DEFINITION FOR POTENTIALLY SUITABLE NORTHERN LONG-EARED BAT
SUMMER HABITAT
Suitable summer habitat for NLEB consists of a wide variety of forested/wooded habitats where
they roost, forage, and travel and may also include some adjacent and interspersed non-forested
habitats such as emergent wetlands and adjacent edges of agricultural fields, old fields and
pastures. This includes forests and woodlots containing potential roosts (i.e., live trees and/or
snags ≥3 inches dbh that have exfoliating bark, cracks, crevices, and/or cavities), as well as
linear features such as fencerows, riparian forests, and other wooded corridors. These wooded
areas may be dense or loose aggregates of trees with variable amounts of canopy closure.
Individual trees may be considered suitable habitat when they exhibit characteristics of suitable
roost trees and are within 1,000 feet of other forested/wooded habitat 24. NLEB has also been
observed roosting in human-made structures, such as buildings, barns, bridges, and bat houses;
therefore, these structures should also be considered potential summer habitat 25. NLEBs
typically occupy their summer habitat from mid-May through mid-August each year 26 and the
species may arrive or leave some time before or after this period.
Examples of unsuitable habitat:
• Individual trees that are greater than 1,000 feet from forested/wooded areas;
• Trees found in highly-developed urban areas (e.g., street trees, downtown areas); and
• A pure stand of less than 3-inch dbh trees that are not mixed with larger trees.

23

Suitable roosting habitat is defined as forest patches with trees of 5-inch (12.7 cm) dbh or larger. However, early
successional habitat with small diameter trees may be used as foraging habitat by Indiana bats. Therefore, a project
that would remove or otherwise adversely affect ≥20 acres of early successional habitat containing trees between 3
and 5 inches (7.6-12.7 cm) dbh would require coordination/consultation with the USFWS FO to ensure that
associated impacts would not rise to the level of take. The USFWS may request P/A surveys if >20 acres of early
successional habitat were proposed for removal.
24
This number is based on observations of bat behavior indicating that such an isolated tree (i.e., ≥1000 feet) would
be extremely unlikely to be used as a roost. This distance has also been evaluated and vetted for use for the Indiana
bat. See the “Indiana bat Section 7 and Section 10 Guidance for wind Energy Projects,” question 33, found at:
http://www.fws.gov/midwest/endangered/mammals/inba/WindEnergyGuidance.html
25
Trees found in highly-developed urban areas (e.g., street trees, downtown areas) are extremely unlikely to be
suitable habitat.
26
Exact dates vary by location.

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APPENDIX A
PHASE 1 SUMMER HABITAT ASSESSMENTS
SUBMISSION OF HABITAT ASSESSMENT AND PHASE 2 STUDY PLAN (IF NEEDED)
If a proposed project may affect (positively or negatively) Indiana bats and the conditions
outlined in Step 3 a or b are not met, a habitat assessment report should be submitted to the
appropriate USFWS FO(s) (and/or to the lead Federal Action Agency, such as the USACE, as
appropriate) along with a draft study plan for the Phase 2 (acoustic or netting) survey (if suitable
habitat is present). Complete reports will include the following:
1. Full names and relevant titles/qualifications of individuals (e.g., John E. Smith,
Biologist II, State University, B.S. Wildlife Science 2007) completing the habitat
assessment and when the assessment was conducted
2. A map and latitude/longitude or UTM clearly identifying the project location (or
approximate center point) and boundaries
3. A detailed project description (if available)
4. Documentation of any known/occupied spring staging, summer, fall swarming,
and/or winter habitat for Indiana bats within or near the project area
5. A description of methods used during the habitat assessment
6. A summary of the assessment findings and a completed Indiana Bat Habitat
Assessment Datasheet (see attached below; use of this particular datasheet is
optional)
7. Other information that may have a bearing on Indiana bat use of the project area
(e.g., presence of fall or winter habitat [caves, crevices, fissures, or sinkholes, or
abandoned mines of any kind], bridges and other non-tree potential summer
roosts.)
8. Any other information requested by the local USFWS FO(s) related to the project
In addition, Phase 2 Study Plans should contain the following:
1. A statement as to which type of P/A surveys will be conducted (i.e., mist netting or
acoustic surveys) and how the proposed survey level of effort (i.e., total # of net
nights or detector nights) was calculated/determined;
2. A map depicting the proposed number of survey sites (mist netting or acoustic) and
their tentative distribution throughout the project area;
3. A tentative list of surveyors names and copies of relevant federal permits (if required
in the project State);
4. A tentative survey schedule (e.g., start date, duration, end date);
5. For mist netting surveys with planned Phase 4 radio-tracking – the approximate
number and distribution of transmitters (e.g., prioritization of sex/age, maximum

12

APPENDIX A
PHASE 1 SUMMER HABITAT ASSESSMENTS
number per site) and a request that bats targeted for tracking may be held for up to 45
minutes 27 to allow for application of transmitters; and
6. For acoustic surveys - information on which specific program(s) will be used and
what level of acoustic analyses will be conducted.

27

Current standard federal Section 10 bat permit conditions require prior written approval from the Field Supervisor
in the USFWS FO(s) if capture times may exceed 30 minutes.

13

APPENDIX A
PHASE 1 SUMMER HABITAT ASSESSMENTS

14

APPENDIX A
PHASE 1 SUMMER HABITAT ASSESSMENTS

15

APPENDIX B
PHASE 2 or 3 MIST-NETTING
Mist-netting can be used as a presence/probable absence method (Phase 2 surveys) or it can be
conducted for the purpose of attempting to capture Indiana bats after detection during acoustic
presence/probable absence surveys (Phase 3 surveys). The same recommendations (e.g., season,
personnel, equipment, net placement, checking nets) apply for either use of mist-netting surveys.
SUMMER MIST-NETTING SEASON: May 15 28 – August 15 29
Capture of reproductive adult females (i.e., pregnant, lactating, or post-lactating) and/or young of
the year during May 15 – August 15 confirms the presence of a maternity colony in the area.
Since adult males and non-reproductive females have commonly been found summering with
maternity colonies, radio-tracking results will be relied upon to help determine the presence or
absence of a maternity colony or large concentrations of bats in the area when only males and/or
non-reproductive females are captured.
PERSONNEL
A qualified biologist(s) 30 must (1) select/approve mist-net set-ups in areas that are most suitable
for capturing Indiana bats, (2) be physically present at each mist-net site throughout the survey
period, and (3) confirm all bat species identifications. This biologist may oversee other
biological technicians and manage mist-net set-ups in close proximity to one another as long as
the net-check timing (i.e., every 10 minutes) can be maintained while walking between nets.
COORDINATION WITH USFWS FO(s)
If not already required by federal permit, we recommend that applicants submit a draft study plan
for all survey phases to the USFWS FO(s) for review and approval. Study plans should include a
map/aerial photo identifying the proposed project area boundaries, suitable bat habitats and
acreages within the project area, and the proposed number and tentative locations of net sites.
EQUIPMENT
Use the finest, lowest visibility mesh mist-nets commercially available, as practicable.
Currently, the finest net on the market is 75 denier, 2 ply, denoted 75/2 (Arndt and Schaetz

28

Due to concerns with transmission of white-nose syndrome, some USFWS FO(s) and state natural resource
agencies have delayed the start of the Indiana bat summer field survey season/mist-netting until June 1.
Surveyors/applicants should always coordinate with local USFWS FO(s) and state natural resource agencies before
beginning surveys.
29
With prior USFWS FO approval, a survey may be completed after August 15 if it was initiated in time to be
completed by August 15 and extenuating weather circumstances resulted in delaying completion. Delays as a result
of not meeting the acceptable weather requirements are the ONLY valid justification for surveying after August 15.
30
A qualified biologist is an individual who holds a USFWS Recovery Permit (Federal Fish and Wildlife Permit) for
Indiana bats in the state/region in which they are surveying and/or has been authorized by the appropriate state
agency to net and handle Indiana bats. Several USFWS offices maintain lists of qualified bat surveyors, and if
working in one of those states with authorizations in lieu of a Recovery Permits, the individual will either need to be
on that list or submit qualifications to receive USFWS approval prior to conducting any field work.

16

APPENDIX B
PHASE 2 or 3 MIST-NETTING
2009); however, the 50 denier nets are still acceptable for use at this time. The finest mesh size
available is approximately 1½ inches (38 millimeters).
No specific hardware is required. There are many suitable systems of ropes and/or poles to hold
nets. The system of Gardner et al. (1989) has been widely used. See NET PLACEMENT for
minimum net heights, habitats, and other netting requirements that affect the choice of hardware.
To minimize potential for disease transmission, any equipment that comes in contact with bats
should be kept clean and disinfected, following approved protocols; this is particularly a concern
relative to white-nose syndrome (WNS). Disinfection of equipment to avoid disease
transmission (e.g., WNS) is required; protocols are posted at
http://www.whitenosesyndrome.org/. Federal and state permits may also have specific
equipment restrictions and disinfection requirements.
MINIMUM PRESENCE/ABSENCE MIST-NETTING LEVEL OF EFFORT (PHASE 2)
The level of netting survey effort required for a non-linear project will be dependent upon the
overall acreage of suitable habitat that may be impacted by the action (directly or indirectly). To
determine the survey effort, quantify the amount of suitable summer habitat within the project
area. NOTE: for projects where other impacts than tree removal are likely (e.g., collision),
ensure that presence/probable absence surveys are designed to cover all suitable habitat within
the entire project area (where exposure to any kind of impacts may be anticipated) and NOT just
the locations where tree removal is planned. Additional guidance for linear project is in
Appendix F.
Conduct Mist-Netting Surveys following Recovery Unit-based protocols 31
Northeast and Appalachian Recovery Units (CT, DE, MA, MD, NC, NJ, NY, PA,
eastern TN, WV, VA, VT):
Linear projects: a minimum of 6 net nights per km (0.6 miles) of suitable summer
habitat (see Appendix F).
Non-linear projects: a minimum of 42 net nights per 123 acres 32 (0.5 km2) of
suitable summer habitat.
For example:
• 7 sites 33, 2 nets 34/site for 3 calendar nights = 42 net nights
31

The Indiana bat populations in the Northeast and Appalachian Recovery Units have been most heavily impacted
by white-nose syndrome; therefore, we recommend higher survey effort when compared to the Midwest and OzarkCentral Recovery Units.
32
We have no recommendations for reducing the minimum level of effort required to demonstrate probable absence
for projects <123 acres in size. Detection probabilities and occupancy estimates were derived from past survey
efforts that used the same acreage threshold (see Niver et al. 2013).
33
A site is defined as a geographic area to be sampled. It can include one or more nets that can be managed by one
Qualified Biologist.

17

APPENDIX B
PHASE 2 or 3 MIST-NETTING
•
•

7 sites, 3 nets/site for 2 calendar nights = 42 net nights
3 sites, 2 nets/site for 7 calendar nights* = 42 net nights

Maximum of 3 nights of consecutive netting at any given net location. After 3
consecutive nights of netting at the same location, you must change net locations
or wait at least 2 calendar nights before resuming netting at the same location.
a) If no capture of Indiana bats, then no further summer surveys are
necessary35.
b) If capture of Indiana bat(s), then stop or proceed to Phase 4
as previously decided in coordination with the FO(s).

Midwest and Ozark-Central Recovery Units (AL, AR, GA, IA, IL, IN, KY, MI, MO,
MS, OH, OK, and central & western TN):
Linear projects: a minimum of 4 net nights per km (0.6 miles) of suitable summer
habitat (see Appendix F).
Non-linear projects: a minimum of 9 net nights per 123 acres (0.5 km2) of
suitable summer habitat.
•
•

3 sites, 1 nets/site for 3 calendar nights = 9 net nights
1 sites, 3 nets/site for 3 calendar nights = 9 net nights

Maximum of 3 nights of consecutive netting at any given net location. After 3
consecutive nights of netting at the same location, you must change net locations
or wait at least 2 calendar nights before resuming netting at the same location.
a) If no capture of Indiana bats, then no further summer surveys are
necessary.
b) If capture of Indiana bat(s), then stop or proceed to Phase 4
as previously decided in coordination with the FO(s).

MIST-NETTING SURVEYS TO CAPTURE INDIANA BATS AFTER ACOUSTICS WERE
USED AS P/A METHOD (PHASE 3)
If netting was not conducted as the P/A method, then netting may be conducted to capture
and characterize (e.g., sex, age, reproductive condition) the Indiana bats (documented
34

A net is defined as any combination of individual panels and poles (e.g., single, double, triple high) to fill the area
(e.g., corridor) being sampled.
35
NOTE: For Phase 2 Presence/Absence Surveys, wherever the phrase “no further summer surveys are necessary”
occurs within this document, the USFWS FO(s) is in affect assuming probable absence of Indiana bats during the
summer.

18

APPENDIX B
PHASE 2 or 3 MIST-NETTING
through the Phase 2 acoustic P/A survey) present in an area and to facilitate radio-tracking
(Phase 4) efforts. We encourage working with the FO(s) to develop Phase 3 netting plans
based on best available information (e.g., positive acoustic locations). There are no
minimum requirements for this phase as this is not a P/A phase.
a) If no Indiana bats are captured, then coordinate with the USFWS FO.
b) If Indiana bats are captured, then proceed to Phase 4 as previously decided in
coordination with the FO(s).
NET PLACEMENT
Potential travel corridors (e.g., streams, logging trails) typically are the most effective places to
net (although other places may also be productive; see Carroll et al. 2002). Place nets
approximately perpendicular across the corridor. Nets should fill the corridor from side to side,
extending beyond the corridor boundaries when possible, and from stream (or ground) level up
to the overhanging canopy. Nets of varying widths and heights may be used as the situation
dictates. A typical set is at least 5 m to 9 m high consisting of two or more nets stacked on top
one another and from 6 m to 18 m wide. If netting over water, ensure there is enough space
between the net and the water so that captured bats will not get wet.
Occasionally it may be necessary or desirable to net where a suitable corridor is lacking. The
typical equipment described in the section above may be inadequate for these situations,
requiring innovation on the part of the surveyor (see Humphrey et al. 1968). See Kiser and
MacGregor (2005) for additional discussion about net placement.
Although no minimum spacing between mist-nets is being specified, surveyors should attempt to
evenly distribute net set-ups throughout suitable habitat and must provide written justification in
their report if net set-ups were not distributed throughout suitable habitat (i.e., why were they
clumped?). Net set-ups can be repeatedly sampled throughout the project, but generally no more
than 2-3 nights at a single location is recommended. In addition, changing locations within a
project area may improve capture success (see Robbins et al. 2008; Winhold and Kurta 2008).
Photo-document placement of nets.
SURVEY PERIOD
The survey period for each net shall begin at sunset 36 and continue for at least 5 hours (longer
survey periods may also improve success).

CHECKING NETS

36

Surveys may need to start a little earlier or later than official sunset times (i.e., at “dusk”) in some settings such as
a deep/dark forested valleys or ridge tops to avoid missing early-flying bats or capturing late-flying birds,
respectively. Sunset tables for the location of survey can be found at:
http://aa.usno.navy.mil/data/docs/RS_OneYear.php.

19

APPENDIX B
PHASE 2 or 3 MIST-NETTING
Each net set-up should be checked approximately every 10 minutes (Gannon et al. 2007). If
surveyors monitor nets continuously, take care to minimize noise, lights and movement near the
nets. Monitoring the net set-up continuously with a bat detector (ideally using ear phones to
avoid alerting bats) can be beneficial: (a) bats can be detected immediately when they are
captured, (b) prompt removal from the net decreases stress on the bat and potential for the bat to
escape (MacCarthy et al. 2006), and (c) monitoring with a bat detector also allows the biologist
to assess the effectiveness of each net placement (i.e., if bats are active near the net set-up but
avoiding capture), which may allow for adjustments that will increase netting success on
subsequent nights. There should be no other disturbance near the nets, other than to check nets
and remove bats. Biologists should be prepared to cut the net if a bat is severely entangled and
cannot be safely extracted within 3 or 4 minutes (CCAC 2003; Kunz et al. 2009).
Capture and handling are stressful for bats. Emphasis should be on minimizing handling and
holding bats to as short a time as possible to achieve field study objectives. Indiana bats should
not be held for more than 30 minutes after capture, unless the individual is targeted for radiotracking. Bats targeted for radio-tracking should be released as quickly as possible, but no
longer than 30 minutes 37 after capture, or as allowed in federal and state permits. See Kunz and
Kurta (1988) for general recommendations for holding bats.
WEATHER, LIGHTING, AND OTHER ENVIRONMENTAL CONDITIONS
Severe weather adversely affects capture of bats. Some Indiana bats may remain active despite
inclement weather and may still be captured while others in the same area become inactive.
Therefore, negative surveys combined with any of the following weather conditions throughout
all or most of a sampling period are likely to require an additional night of mist-netting 38: (a)
temperatures that fall below 50°F (10°C) 39; (b) precipitation, including rain and/or heavy fog,
that exceeds 30 minutes or continues intermittently during the survey period; and (c) sustained
wind speeds greater than 9 miles/hour (4 meters/seconds; 3 on Beaufort scale) for 30 or more
minutes.
NOTE: Provided that nets are not dripping wet, surveyors can resume netting to meet the
minimum 5-hour requirement after short periods of adverse weather. If nets are under good
cover, light rain may not alter bat behavior. However, if no bats are being captured during
marginal weather, coordinate with the USFWS FO(s).

37

Current standard federal Section 10 bat permit conditions require prior written approval from the Field Supervisor
in the USFWS FO(s) if capture times may exceed 30 minutes.
38
With prior USFWS FO approval, a survey may be completed after August 15 if it was initiated in time to be
completed by August 15 and extenuating weather circumstances resulted in delaying completion. Delays as a result
of not meeting the acceptable weather requirements are the ONLY valid justification for surveying after August 15.
39
If using this guidance for NLEB: Overnight survey temperatures may be lower in northern portions of the NLEB
range, please coordinate with the local USFWS FO in the northern portion of the range for any variation in
temperature requirements.

20

APPENDIX B
PHASE 2 or 3 MIST-NETTING
It is typically best to place net set-ups under the canopy where they are out of moonlight,
particularly when the moon is half-full or greater. Net set-ups illuminated by artificial light
sources should also be avoided.
The shining of lights, and noise should be kept to a minimum with no smoking around the survey
sites. In addition, the use of radios, campfires, running vehicles, punk sticks, citronella candles
and other disturbances will not be permitted within 300 feet of mist nets (or acoustic detectors)
during surveys.
DOCUMENTATION OF INDIANA BAT CAPTURES
If an Indiana bat(s) is captured during mist-netting, protocols for radio-tracking and emergence
survey requirements, as provided in Appendix D and E, respectively, should be followed. In
addition, the appropriate USFWS FO(s) must be notified of the capture within 48 hours (or in
accordance with permit conditions), and the sex and reproductive condition of the bat and GPS
coordinates of the capture site should be provided. Ensure GPS coordinates are recorded for
each individual net set on datasheets.
Several species of bats from the genus Myotis share common features which can make
identification difficult; Indiana bats and little brown bats (Myotis lucifugus) can be particularly
difficult to distinguish. Photo-documentation of all bats captured and identified as Indiana bats
and the first 10 little brown bats per project are requested to verify the identifications made in the
field.
Photo-documentation should include diagnostic characteristics:
• a ¾-view of face showing ear, tragus, and muzzle
• view of calcar showing presence/absence of keel
• a transverse view of toes showing extent of toe hairs
If a bat from the genus Myotis is captured during mist netting that cannot be readily identified to
the species level, then species verification may be attempted through fecal DNA analysis.
Collect one or more fecal pellets (i.e., guano) from the bat in question by placing it temporarily
in a holding bag (15 minutes is usually sufficient, no more than 30 minutes is recommended).
The pellet (or pellets) collected should be placed in a small vial (e.g., 1.5 ml) with silica gel
desiccant; pellets from each individual bat should be stored in separate vials and out of direct
light. Fees charged by independent laboratories for sequencing fecal DNA samples is generally
inexpensive (approx. $50 per guano sample), however, it has been challenging to identify labs
willing to consistently conduct these analyses. Any additional information and a list of available
laboratories will be made available on the Indiana bat webpage on the USFWS’s Region 3
website (http://www.fws.gov/midwest/Endangered/mammals/inba/index.html).

21

APPENDIX B
PHASE 2 or 3 MIST-NETTING
SUBMISSION OF MIST-NETTING RESULTS
Provide results of netting surveys to the appropriate USFWS FO(s) in accordance with
previously agreed upon 40 timeframes and formats 41. If Indiana bats are captured, this report
should also include the results of subsequent radio-tracking and emergence counts. Reports
should include the following:
1. Copy of prior phase reports (if not previously provided).
2. Explanation of any modifications from original survey plan (e.g., altered net
locations). 42
3. Description of net locations (including site diagrams), net set-ups (include net
heights), survey dates, duration of surveys, weather conditions, and a summary of
findings.
4. Map identifying netting locations and information regarding net set-ups, including
lat/long or UTM, individual net placement, net spacing (i.e., include mist-netting
equipment in photographs of net locations), and adequate justification if net setups are not evenly distributed across suitable habitat within the project area.
5. Full names of mist-netting personnel attending each mist-net site during an
operation, including the federally-permitted/qualified biologist present at each
mist-net site. Indicate on the field data sheet the full name of person who
identified bats each night at each site.
6. Legible copies of all original mist-netting datasheets (see example datasheet
below) and a summary table with information on all bats captured during the
survey including, but not limited to: capture site, date of capture, time of capture,
sex, reproductive condition, age, weight, right forearm measurement, band number
and type (if applicable), and Reichard’s wing damage index score (Reichard and
Kunz. 2009).
7. Photographs of all net set-ups, as well as all Indiana bats and the first 10 little
brown bats captured from each project, so that the placement of netting equipment
and identification of species can be verified. Photographs of bats should include
all diagnostic characteristics that resulted in the identification of the bat to the
species level.
8. Any other information requested by the local USFWS FO(s) related to the project.

40

As discussed in the Introduction, we encourage coordination with USFWS FO(s) prior to implementation of any
surveys to ensure that all parties agree upon the need for surveys, the methods proposed, and the decisions from
various survey results.
41
In 2016, the USFWS implemented a new standardized approach for reporting of bat survey data. In addition to a
traditional written report, federal permit holders are now required to submit their survey data using the standardized
permit reporting spreadsheets available on the R3 Indiana Bat Summer Survey Guidance webpage
(http://www.fws.gov/midwest/Endangered/mammals/inba/inbasummersurveyguidance.html).
42
If the USFWS previously agreed upon the study plan we need to understand whether the revised work still
accomplished the agreed upon methods

22

APPENDIX B
PHASE 2 or 3 MIST-NETTING
REFERENCES
Arndt, R.J. and B.A. Schaetz. 2009. A tale of two deniers: nylon versus polyester mist nets. Bat
Research News 50(3):57.
Carroll, S.K., T.C. Carter, and G.A. Feldhamer. 2002. Placement of nets for bats: effects on
perceived fauna. Southeastern Naturalist 1:193-198.
Canadian Council on Animal Care (CCAC). 2003. CCAC species-specific recommendations on
bats. 9pp. Available at:
http://www.ccac.ca/en/CCAC_Programs/Guidelines_Policies/GDLINES/BatsFinal20Ma
y03.htm (Accessed October 30, 2008).
Gannon, W.L., R.S. Sikes, and the Animal Care and Use Committee of the American Society of
Mammologists. 2007. Guidelines of the American Society of Mammologists for the use
of wild mammals in research. Journal of Mammalogy 88:809-823.
Gardner, J. E., J.D. Garner, and J.E. Hofmann. 1989. A portable mist-netting system for
capturing bats with emphasis on Myotis sodalis (Indiana bat). Bat Research News 30:1-8.
Humphrey, P.S., D. Bridge, and T.E. Lovejoy. 1968. A technique for mist-netting in the forest
canopy. Bird-Banding 39(1): 43-50.
Kiser, J.D. and J.R. MacGregor. 2005. Indiana bat (Myotis sodalis) mist net surveys for coal
mining activities. Pp. 169-172 in K.C. Vories and A. Harrington (eds.), The Proceedings
of the Indiana bat and coal mining: a technical interactive forum Office of Surface
Mining, U.S. Department of the Interior, Alton, IL. Available at:
http://www.mcrcc.osmre.gov/MCR/Resources/bats/pdf/Indiana_Bat_and_Coal_Mining.p
df. (Accessed October 06, 2011).
Kunz, T.H. and A. Kurta. 1988. Capture methods and holding devices. Pp. 1-29 in T.H. Kunz
(ed.), Ecological and behavioral methods for the study of bats. Smithsonian Institution
Press, Washington, D.C.
Kunz, T.H., R. Hodgkison, and C.D. Weise. 2009. Methods of capturing and handling bats. Pp.
3-35 in T.H. Kunz and S. Parsons (eds.), Ecological and behavioral methods for the study
of bats, second edition. The Johns Hopkins University Press, Baltimore, Maryland.
MacCarthy, K.A., T.C. Carter, B.J. Steffen, and G.A. Feldhamer. 2006. Efficacy of the mist-net
protocol for Indiana bats: A video analysis. Northeastern Naturalist 13:25-28.
Reichard, J.D., and T.H. Kunz. 2009. White-nose syndrome inflicts lasting injuries to the wings
of little brown myotis (Myotis lucifugus). Acta Chiropterologica 11: 457-464.

23

APPENDIX B
PHASE 2 or 3 MIST-NETTING
Robbins, L.W., K.L. Murray, and P.M. McKenzie. 2008. Evaluating the effectiveness of the
standard mist-netting protocol for the endangered Indiana bat (Myotis sodalis).
Northeastern Naturalist 15:275-282.
Winhold, L. and A. Kurta. 2008. Netting surveys for bats in the Northeast: differences associated
with habitat, duration of netting, and use of consecutive nights. Northeastern Naturalist
15:263-274.

24

APPENDIX B
PHASE 2 or 3 MIST-NETTING

25

APPENDIX B
PHASE 2 or 3 MIST-NETTING

26

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
SUMMER ACOUSTIC SURVEY SEASON: May 15 – August 15 43
PERSONNEL44
Overall: Acoustic surveyors should have either completed one or more of the available bat
acoustic courses/workshops (e.g., BCI, BCM, AnaBat) or be able to show similar on-the-job or
academic experience.
Detector Deployment: Acoustic surveyors should have a working knowledge of the acoustic
equipment and Indiana bat ecology. Surveyors should be able to identify appropriate detector
placement sites and establish those sites in the areas that are most suitable for recording highquality Indiana bat calls. Thus, it is highly recommended that all potential acoustic surveyors
attend appropriate training and have experience in the proper placement of their field equipment.
Acoustic Analysis: Acoustic surveyors should have a working knowledge of the approved
acoustic analysis programs. Thus, it is highly recommended that all potential acoustic surveyors
attend appropriate training and have experience in the analysis of acoustic recordings.
Qualitative Analysis: Individuals qualified to conduct qualitative analysis of acoustic bat calls
typically have experience: (1) gathering known calls. This provides a valuable resource in
understanding how bat calls change and the variation present in them; (2) identifying bat calls
recorded in numerous habitat types; (3) familiarity with the species likely to be encountered
within the project area; and (4) individuals must have multiple years of experience and must
have stayed current with qualitative ID skills. A resume (or similar documentation) must be
submitted along with final acoustic survey reports for anyone making final qualitative
identifications.
COORDINATION WITH USFWS FO(s)
If not already required by federal permit, we recommend that applicants submit a draft study plan
for all survey phases to the USFWS FO(s) for review and approval. Study plans should include a
map/aerial photo identifying the proposed project area boundaries, suitable bat habitats and
acreages within the project area, the proposed number and tentative locations of acoustic
monitoring sites, and the identification of the approved acoustic software program(s) (and
version #) used for analysis of calls for the specific project. If a single software program is used
for analysis, surveyors will not be allowed to switch programs from what was originally
identified in their final study plan.
DETECTOR AND MICROPHONE REQUIRED CHARACTERISTICS
Full-spectrum and/or zero-crossing detectors are suitable for use in this survey protocol.
43

With prior USFWS FO approval, a survey may be completed after August 15 if it was initiated in time to be
completed by August 15 and extenuating weather circumstances resulted in delaying completion. Delays as a result
of not meeting the acceptable weather requirements are the ONLY valid justification for surveying after August 15.
44
Coordinate with your local FO regarding any state-specific requirements.

27

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
Directional, hemispherical, and omnidirectional microphones are acceptable for acoustic surveys.
The use of external microphones on an extension cable is the preferred deployment as it further
limits degradation of call quality. Recording without directional horns on hemispherical and
omnidirectional microphones is preferred as the addition of these systems may result in some
signal degradation and directional microphones are commercially available.
Use recommended manufacturer detector settings for conducting Indiana bat P/A surveys unless
otherwise noted on the Service’s Indiana Bat Summer Survey Guidance webpage.
ACOUSTIC SAMPLING PROTOCOL
Detector/Microphone Placement
Detector/Microphone placement is critical to the successful isolation of high-quality bat call
sequences for later analysis. The following locations are likely to be suitable sites for
detectors/microphones, including, but not limited to: (a) forest-canopy openings; (b) near water
sources; (c) wooded fence lines that are adjacent to large openings or connect two larger blocks
of suitable habitat; (d) blocks of recently logged forest where some potential roost trees remain;
(e) road and/or stream corridors with open tree canopies or canopy height of more than 33 feet
(10 meters); and (f) woodland edges (Britzke et al. 2010). Of equal importance to acoustic site
selection is the surveyor’s working knowledge of the sampling volume and area of highest
sensitivity within the zone of detection around a given microphone, which helps to ensure that
detector placement as well as microphone selection and orientation are best suited for a particular
site to ensure the detection zone is free of clutter. Detection distance, placement (e.g., location,
orientation, height of microphone), and specific features (e.g., vegetation, water, and other
obstructions) at the sample site should dictate whether a directional, hemispherical, or
omnidirectional microphone is used. If detectors/microphones are placed in unsuitable locations,
effective data analysis may be impossible, and the results of the sampling effort will likely be
invalid.
Many features (e.g., vegetation, water, wind turbines, high-tensile power-lines, micro-wave
towers) can obstruct and reflect call sequences recorded in the field and thereby reduce the
surveyor’s ability to record high-quality bat call sequences. The following recommendations are
provided to aid surveyors in their selection of acoustic sites (also see Chenger and Tyburec
2014). If surveyors choose acoustic sites outside of these recommendations, then adequate
justification for doing so should be provided with the acoustic survey report provided to the
USFWS FO(s); otherwise, results from these sites will not be accepted. Surveyors should deploy
microphones: (a) at least 10 feet (3 meters) in any direction from vegetation or other
obstructions (Hayes 2000; Weller and Zabel 2002; Chenger and Tyburec 2014); (b) in areas
without, or with minimal 45, vegetation within 100 feet (30 meters) of highly directional
microphones or 33 feet (10 meters) from other microphones; (c) parallel to woodland edges; and
45

If necessary, surveyors can remove small amounts of vegetation (e.g., small limbs, saplings) from the estimated
detection zone at a site, much like what is done while setting up mist-nets. Deployment of detectors/microphones in
closed-canopy locations that typically are good for mist-netting are acceptable as long as the area sampled below the
canopy does not restrict the ability of the equipment’s detection zone to record high-quality calls (i.e., the vegetation
is outside of the detection zone).

28

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
(d) at least 49 feet (15 meters) from known or suitable roosts 46 (e.g., trees/snags, buildings,
bridges, bat houses, cave or mine portal entrances).
Elevating a detector greater than 3 meters above ground level (AGL) vegetation may
dramatically improve recording quality. Microphones can be attached horizontally to a pole to
listen out into flight space, rather than just listening up from the ground. This will serve to
increase the volume of airspace sampled and avoid the distortion effect of recording near the
ground. However, the relationship between the zone of detection and the vegetation, not the
placement of the detector is the most important consideration during site selection.
Surveyors should distribute acoustic sites throughout the project area or adjacent habitats. In
most cases, acoustic sites should be at least 656 feet (200 meters) apart. If closer spacing is
determined to be necessary or beneficial (e.g., multiple suitable habitats and acoustic sites
immediately adjacent to each other), sufficient justification must be provided in the acoustic
survey report submitted to USFWS FO(s).
Verification of Deployment Location
It is recommended to temporarily attach GPS units to each detector (according to manufacturer’s
instructions) to directly record accurate location coordinates for each acoustic site that is paired
with the acoustic data files. Regardless of technique used, accurate GPS coordinates must be
generated and reported for each acoustic detector location.
Verification of Proper Functioning
It is highly recommended that surveyors ensure acoustic detectors are functioning properly
through a periodic verification of performance to factory specifications (a service currently
offered or in development by several manufacturers). It may be possible that independent
service bureaus would be willing to perform this service, providing that a standard
test/adjustment procedure can be developed.
It is also recommended to ensure equipment is working during set-up in the field. This can be
done simply by producing ultrasound (e.g., finger rubs, calibrator, or follow the equipment
manufacturer’s testing recommendations) in front of the microphone at survey start and survey
finish. These tests document that the equipment was working when deployed and when picked
up (and by assumption throughout the entire period). Detector field settings (e.g., sensitivity,
frequency, etc.) should follow the recommendations provided by the manufacturer. Surveyors
should also save files produced by detectors (e.g., log files, status files, sensor files) as an
excellent way to provide documentation when equipment was functioning within the survey
period. Many types of detectors allow for setting timers that initiate and end recording sessions.
This saves battery life as well as reducing the number of extraneous noise files recorded.
However, if the units are visited when the timer is on (i.e., unit is in standby mode), the surveyor
cannot verify that the unit is functioning properly. This is particularly important in areas where
no bat activity is recorded for the entire night or during the last portion of the night. In these
cases, if the surveyor cannot demonstrate that the detector was indeed functioning properly
46

If the surveyor discovers a potential roost and wishes to document bat use, please refer to Appendix E for
guidance on conducting emergence surveys and contact the USFWS FO(s).

29

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
throughout the survey period, then the site will need to be re-sampled, unless adequate
justification can be provided to the USFWS FO(s).
Selection of acoustic sites is similarly important. Suitable set-up of the equipment should result
in high-quality call sequences that are adequate for species identification. Nights of sampling at
individual sites that produce no bat calls may need to be re-sampled unless adequate justification
(e.g., areas with significant bat population declines due to WNS) can be provided to the USFWS
FO(s). Modifications of the equipment (e.g., changing the orientation and/or microphone type)
at the same location on subsequent nights may improve quantity and quality of call sequences
recorded, which can be determined through daily data downloads. If modifications of the
equipment do not improve call identification, then the detectors will need to be moved to a new
location.
Orientation
Detectors deployed with directional microphones should be aimed to sample the majority of the
identified flight path/zone. Omnidirectional microphones deployed on a pole in the center of the
flight path/zone should be oriented horizontally. In some circumstances, it might be desirable to
aim a directional microphone straight up in smaller forest openings. As always, the goal is to
sample as large a volume of likely bat flight space as possible as long as it is free of clutter.
Hemispherical microphones should be aimed vertically, creating a dome-like detection field.
Hemispherical microphones are best suited for open areas where deploying at heights greater
than 3 meters AGL is problematic because of the lack of structure to hide the microphone and
prevent it from becoming a novel item of interest to bats. Vertical orientation, however,
precludes the use of weatherproofing for protection of the microphone, since no currentlyapproved weatherproofing system will adequately protect the microphone of a detector aimed
vertically. Once acoustic sites are identified, photographs documenting the orientation, detection
zone (i.e., “what the detector is sampling”), and relative position of the microphone should be
taken for later submittal to the USFWS FO(s) as part of the acoustic survey report (See
Submission of Acoustic Survey Results for additional description).
Weather Conditions
If any of the following weather conditions exist at a survey site during acoustic sampling, note
the time and duration of such conditions, and repeat the acoustic sampling effort for that night 47:
(a) temperatures fall below 50°F (10°C) during the first 5 hours of survey period; (b)
precipitation, including rain and/or fog, that exceeds 30 minutes or continues intermittently
during the first 5 hours of the survey period; and (c) sustained wind speeds greater than 9
miles/hour (4 meters/second; 3 on Beaufort scale) for 30 minutes or more during the first 5 hours
of the survey period. At a minimum, nightly weather conditions for survey sites should be
checked using the nearest NOAA National Weather Service station and summarized in the
survey reports.

47

With prior USFWS FO approval, a survey may be completed after August 15 if it was initiated in time to be
completed by August 15 and extenuating weather circumstances resulted in delaying completion. Delays as a result
of not meeting the acceptable weather requirements are the ONLY valid justification for surveying after August 15.

30

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
Weatherproofing
Most bat detectors are not weatherproof when delivered from the factory. Recording without
after-market weatherproofing is preferred as the addition of these systems may result in some
signal degradation. The decision to weatherproof detectors or not should be determined
nightly based on the likelihood of precipitation in the survey area. If necessary, detectors
should be placed in after-market weatherproof containers and an external microphone, attached
by an extension cable should be deployed greater than 3 meters AGL.
For directional microphones, the use of a polyvinyl chloride (PVC) tube 48, generally in the form
of a 45-degree elbow the same diameter as the microphone (Britzke et al. 2010) is acceptable, if
the situation requires the use of after-market weatherproofing. The microphone should be placed
facing the open end of the elbow and as close to the opening as is consistent with the aim of
weatherproofing. The microphone should be pointing at an angle below horizontal so water will
not collect in it. Corben & Livengood (2014) showed that the direction of greatest sensitivity of
tubes like this varies greatly depending on details of the specific tube shape and the exact
position of the microphone. Often the greatest sensitivity will be pointed up at a substantial
angle (up to 45 degrees) above horizontal when the microphone itself is pointing 45 degrees
below horizontal. Users should be aware of the characteristics of the setup they use so they can
know what region is actually being sampled. Again, the preferred option for weatherproofing
detectors is to detach the microphone from the detector so that the detector can be placed in a
weatherproof container but the microphone (tethered by a cable) remains unobstructed.
Other after-market weatherproofing systems may become available and approved by the USFWS
provided they show that call quality and the number of calls recorded are comparable to those
without weatherproofing.
MINIMUM LEVEL OF EFFORT
The level of acoustic survey effort required for a project will be dependent upon the overall
acreage of suitable habitat that may be impacted by the action (directly or indirectly). To
determine the acoustic survey effort, quantify the amount of suitable summer habitat within the
project area. NOTE: for projects where impacts other than tree removal are likely (e.g.,
collision), ensure that presence/probable absence surveys are designed to cover all suitable
habitat within the entire project area and NOT just the locations where tree removal is planned.

Linear projects: a minimum of 2 detector nights per km (0.6 miles) of suitable summer
habitat (See Appendix F).
At least 1 detector location for at least 2 calendar nights.
Non-linear projects: a minimum of 4 detector nights per 123 acres (0.5 km2) of suitable
summer habitat.
48

The PVC option has only been tested with AnaBat detectors and directional microphones. It may not perform as
well with other detector microphone combinations.

31

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
2 detector locations per 123 acre "site" shall be sampled until at least 4 detector nights
has been completed over the course of at least 2 calendar nights (may be consecutive).
For example:
•
•

2 detectors for 2 nights each (can sample the same location or move within the site)
1 detector for 4 nights (must sample at least 2 locations)

The acoustic sampling period for each site must begin at sunset 49 and ends at sunrise each night
of sampling.

ANALYSIS OF RECORDED ECHOLOCATION CALLS
Step 5. Optional coarse screening - for high frequency (HF) or myotid calls (depending on
available filters) or Proceed to Step 6.
a) If no positive detection of HF calls (≥35 kHz) or myotid calls, no further
summer surveys necessary.
b) If positive detection of HF or myotid calls, then
i)
proceed to Step 6 for further acoustic analysis; OR
ii)
assume presence of Indiana bats and coordinate with the USFWS FO(s);
OR
iii)
assume presence and proceed to Phase 3.
Step 6. Conduct Automated Acoustic Analyses for each site that had HF or Myotid calls
from Step 5 or ALL sites if Step 5 was not conducted.
Use one or more of the currently available ‘approved’ acoustic bat ID programs 50 (use
most current approved software versions available and manufacturer’s recommended
settings for Indiana bat P/A surveys). ‘Candidate’ programs are not yet approved by
USFWS for stand-alone use for Indiana bat P/A surveys, but may be used in conjunction
with one or more of the approved programs. Include your plans for which specific
software program(s) you will use in your survey work plan and submit for USFWS FO(s)
review prior to conducting surveys. Beginning with acoustic data from night one at each
acoustic site, run each night’s data for each site through your chosen ID program(s).
49

Surveys may need to start a little earlier or later than official sunset times (i.e., at “dusk”) in some settings such as
a deep/dark forested valleys or ridge tops to avoid missing early-flying bats or capturing late-flying birds,
respectively. Sunset tables for the location of survey can be found at:
http://aa.usno.navy.mil/data/docs/RS_OneYear.php
50
Approved and candidate programs are listed at
http://www.fws.gov/midwest/Endangered/mammals/inba/surveys/inbaAcousticSoftware.html

32

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
Review results by site by night from each acoustic ID program used 51.
a) If Indiana bat presence is considered unlikely by the approved and candidate
program(s) used in analysis, then no further summer surveys necessary.
b) If Indiana bat presence is considered likely at one or more sites on one or more
nights by any approved or candidate program(s) used in analysis, then
i)
proceed to Step 7 for qualitative ID; OR
ii)
assume presence of Indiana bats and coordinate with the USFWS FO(s);
OR
iii)
assume presence and proceed to Phase 3.
Step 7. Conduct Qualitative Analysis of Calls.
At a minimum, for each detector site/night a program considered Indiana presence likely,
review all files (including no IDs) from that site/night. Qualitative analysis 52 (i.e.,
manual vetting) must also include and present within a written report a comparison of
the results of each acoustic ID program by site and night (see Reporting Requirements
below).
a) If no visual confirmation of probable Indiana bats, then no further summer surveys
necessary53.
b) If visual confirmation of probable Indiana bats, then
i) assume presence of Indiana bats and coordinate with the USFWS FO(s); OR
ii) assume presence and proceed to Phase 3.

SUBMISSION OF ACOUSTIC SURVEY RESULTS
NOTE: All raw data, including log files, MUST be maintained for a period of 7 years and be
made available to the USFWS FO(s), if requested. Failure to do so may result in invalidation of
survey results.

51

The approved acoustic identification programs all have implemented a maximum likelihood estimator (MLE) at
this time. If the analysis of collected calls at a given site on a given night results in the probable presence of Indiana
bats with high levels of certainty (P<0.05), then select one of the options available in Step 6b.
52
Qualitative analysis of each acoustic site and night with probable detections of Indiana bats during Step 6 should
include the entire night’s high frequency call data, including “no ID” files, and not just those files making it through
the acoustic analysis tools as probable Indiana bats in Step 6.
53
If you identify any suspected mis-identifications from programs, the Service will share those results with the
software manufacturer(s) and the USGS to assist with future improvements and testing of software.

33

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
Provide results of acoustic surveys to the appropriate USFWS FO(s) within 10 days of
completing the survey unless otherwise agreed upon with the local USFWS FO(s) 54. Each
acoustic survey report should include the following 55 (also, see checklist at end of this
appendix):
1. Copy of habitat assessment (if not previously provided)
2. Explanation of any modifications from original survey plan (e.g., altered site
locations) 56
3. Full names of all personnel conducting acoustic surveys, including those that
selected acoustic sites and deployed detectors
4. Full name and resume of individual(s) conducting qualitative acoustic analyses (if
applicable)
5. Description of acoustic monitoring sites, survey dates, duration of survey, weather
conditions, and a summary of findings
6. Table with information on acoustic monitoring and resulting data, including but
not limited to: detector GPS coordinates for each detector, survey dates, survey
hours
7. Map identifying acoustic detector locations and a corresponding table including
the GPS coordinates. Include arrow(s) showing direction(s) of microphone(s).
8. Photographs documenting the location of each detector, the orientation of the
detector, and the detection zone (i.e., what the detector sampled). Please include
detector and something for scale (e.g., vehicle, person) in photographs.
9. Description of acoustic detector brand(s) and model(s) used, microphone type, use
of weatherproofing, acoustic monitoring equipment settings (e.g., sensitivity,
audio and data division ratios), deployment data (i.e., deployment site, habitat,
date, time started, time stopped, orientation), and call analysis methods used
10. A description of how proper functioning of bat detectors was verified
11. Discussion of what software program(s) was/were used (including settings).
12. Acoustic analysis software program output/summary results by site by night (i.e.,
number of calls detected, species composition, MLE results, settings files)

54

As discussed in the Introduction, we encourage coordination with USFWS FO(s) prior to implementation of any
surveys to ensure that all parties agree upon the need for surveys, the methods proposed, and the decisions from
various survey results.
55
In 2016, the USFWS implemented a new standardized approach for reporting of bat survey data. In addition to a
traditional written report, federal permit holders are now required to submit their survey data using the standardized
permit reporting spreadsheets available on the Indiana Bat Summer Survey Guidance webpage
(http://www.fws.gov/midwest/Endangered/mammals/inba/inbasummersurveyguidance.html).
56
If the USFWS previously agreed upon the study plan we need to understand whether the revised work still
accomplished the agreed upon methods.

34

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS
13. Discussion for any site/nights with zero bat calls (were additional nights added?
was detector functioning? was placement appropriate?).
14. If manual vetting was used, discussion of how this was done (e.g., what keys were
used?).
15. If manual vetting was used, detailed analysis and results of any qualitative
acoustic analysis conducted on those projects where a program(s) considered
Indiana bat presence likely, including justification for rejecting any program MLE
results (if applicable). We recommend providing a table with each species ID
from the program(s), suggested species ID from manual vetting, and rationale for
any changes.
16. Any other information requested by the local USFWS FO(s) related to the project.

REFERENCES
Britzke, E.R, B.A. Slack, M.P. Armstrong, and S.C. Loeb. 2010. Effects of orientation and
weatherproofing on the detection of bat echolocation calls. Journal of Fish and Wildlife
Management 1(2):136-141.
Chenger, J.D. and J.D. Tyburec. 2014. Comparing bat detector deployments at different heights,
in different orientations, and using different microphone types. Poster presentation at the
Southeast Bat Diversity Network Meeting, Nacogdoches, TX. February 2014.
Corben, C., and K. Livengood. 2014. Weather protection for Anabat detectors. Poster
presentation at the Southeastern Bat Diversity Network Meeting, Nacogdoches, TX.
February 2014.
Hayes, J. P. 2000. Assumption and practical considerations in the design and interpretation of
echolocation-monitoring studies. Acta Chiropterologica 2:225-236.
MacKenzie, D.I., and J.A Royle. 2005. Designing occupancy studies: general advice and
allocating survey effort. Journal of Applied Ecology 42:1105-1114.

Weller, T. J., and C. J. Zabel. 2002. Variation in bat detections due to detector orientation in a
forest. Wildlife Society Bulletin 30:922-930

35

APPENDIX C
PHASE 2 ACOUSTIC SURVEYS

General Checklist for Acoustic Surveys of Indiana Bats
The following items should be documented and clearly presented
within acoustic bat survey reports submitted to the Service
.
ACOUSTIC SURVEY INFO
 Project Name
 Site ID No./Name
 State and County
 Site Lat./Long. Coordinates
(e.g., decimal degrees, NAD83)
 Approx. accuracy of Lat./Long. Coordinates
 Survey Date(s)
 Person who Selected Acoustic Site(s)
 Person who Deployed Detector(s)
 Detector Brand & Model
 Microphone Brand & Model
 Microphone Type:
Directional/Hemispherical/Omnidirectional
 Type of Weatherproofing (if any)
 Microphone Height above Ground-level
Vegetation(m)
 Distance from Nearest Vegetation or other
Obstruction (m)(apart from veg. on ground)
 Horizontal Orientation of Microphone
(1-360°)
 Vertical Orientation of Microphone
(assuming 0° is parallel with horizon)
 Photographs of Detector Set-up at each Site
 Detector Settings (all settings used for each
brand/model of detector. For example,
sensitivity, gain, data division, 16k high
filter, sample rate, min./max. duration, min.
trigger freq., trigger level, etc.)
 Survey Start Time (military)
 Survey End Time (military)
 Methods used to Field-test proper
Functioning of Detector
 Were calls collected in Full Spectrum or
Zero Crossing?
 Habitat Type and/or Feature Surveyed
 Weather Conditions during Survey Period

ACOUSTIC ANALYSIS INFO
 Program used to convert Full Spectrum to
Zero Cross (if applicable)?
 Filter(s) used (if any) and parameters used
(e.g., CFRead, noise, bug, etc.)
 Name of Service-approved Bat ID Software
Program(s) and Version(s) used and
Candidate program(s)(if used)
 Program Settings (if applicable):
o Min. # of pulses for species ID
o Min. # of pulses per group ID
o Min. discrim. prob. for species ID
o Other relevant settings affecting ID
o Suite of species/groups included in
program analysis
 Table summarizing Number of Calls ID’d
for each Species/Site/Night/Program
(including MLE p-values)
 If Qualitative Analysis was conducted,
include Number of Calls Confirmed through
Qualitative ID for each Species/Site/Night
 Full Name of Person(s) who conducted
Qualitative Analysis
 Additional Survey Reporting Requirements
 Acoustic Report Appendices:
o data sheets and maps,
o photographs of detector set-ups,
o computer screen captures of
representative bat species identified
during acoustic analyses, and
o resume(s) highlighting relevant
qualifications of person(s) who
conducted qualitative analysis
(e.g., experience visually identifying
Myotis, certificates of training,
publications etc.)

36

APPENDIX D
PHASE 4 RADIO-TRACKING
PERSONNEL
Transmitter Attachment: A qualified biologist 57 who is experienced in handling Indiana bats
and attaching radio transmitters must perform transmitter attachments, as further explained in the
protocol below.
Tracking: Biological technicians and/or a qualified biologist who is experienced in tracking
transmittered bats must be present and actively involved in all tracking activities for Indiana bats
as further explained in the protocol below.
METHODS
If one or more Indiana bats are captured, the following radio-tracking protocols will be
applicable:
1. Biologists should coordinate in advance with USFWS FO(s) regarding recommendations
for the number and distribution of transmitters (e.g., prioritization of sex/age, maximum
number per site) and whether foraging data would be beneficial to collect. Also,
professional judgment should be used to determine whether attachment of transmitters
could compromise the health of a bat. Since the maximum holding times for Indiana bats
targeted for radio-tracking is 30 minutes 58, or as allowed in federal and state permits,
surveyors should be prepared to place transmitters on bats immediately following their
capture to minimize holding times.
2. The radio transmitter, adhesive, and any other markings (e.g., wing bands) should weigh
less than 5% of pre-attachment body weight (Aldridge and Brigham 1988, American
Society of Mammalogists 1998), the total weight of the package (transmitter and
adhesive) may not exceed 6% of the bat’s body weight, and must comply with any
USFWS and state permits. In all cases, the lightest transmitters capable of the required
task should be used, particularly with pregnant females and volant juveniles. With
pregnant bats, biologists should always use the lightest transmitter possible but no more
than 5% of their expected non-pregnant weight.
3. Proposed radio telemetry equipment (e.g., receivers, antennas, and transmitters) and
frequencies should be coordinated with the appropriate state natural resource agency and
USFWS FO(s).
4. The qualified biologist or biological technician(s) should track all radio-tagged bats
captured to diurnal roosts in accordance with permit requirements. We generally
57

A qualified biologist is an individual who holds a USFWS Recovery Permit (Federal Fish and Wildlife Permit) for
federally-listed bats in the state/region in which they are surveying and/or has been authorized by the appropriate
state agency to mist-net for Indiana bats. Several USFWS offices maintain lists of qualified bat surveyors, and if
working in one of those states with authorizations in lieu of a Recovery Permits, the individual will either need to be
on that list or submit qualifications to receive USFWS approval prior to conducting any field work.
58
Current standard federal Section 10 bat permit conditions require prior written approval from the Field Supervisor
in the USFWS FO(s) if capture times may exceed 30 minutes

37

APPENDIX D
PHASE 4 RADIO-TRACKING
recommend tracking until the transmitter fails, fall off, or cannot be located for at least 7
days and should conduct a minimum of 2 evening emergence counts at each identified
roost (See Appendix E for Emergence Survey Protocols). However, biologists are
encouraged to continue radio-tracking efforts for the life of the transmitter. Biologists
should contact the USFWS FO(s) immediately if they plan to cease tracking efforts
before the 7-day tracking period ends. If landowner access is denied, approximate roost
locations (i.e., coordinates) should be determined using triangulation.
5. Daily radio telemetry searches for roosts must be conducted during daylight hours and
should be conducted until the bat(s) is located or for a minimum of 4 hours of ground or 1
hour of aerial-searching effort per tagged bat per day for 7 days. However, multiple bats
captured at the same net location or nearby may be tracked simultaneously. Once a
signal is detected, tracking should continue until the roost is located. At a minimum,
biologists should document all ground and aerial-searching effort for all bats not
recovered during radio-tracking for submittal with the survey report. For each roost
identified during tracking, the biologist should complete a “USFWS Indiana Bat Roost
Datasheet”.
6. To minimize potential for disease transmission, any equipment that comes in contact with
bats should be kept clean and disinfected, following approved protocols; this is
particularly a concern relative to WNS. Protocols are posted at
http://www.whitenosesyndrome.org/. Federal and state permits may also have specific
equipment restrictions and disinfection requirements.
SUBMISSION OF RADIO-TRACKING RESULTS
Phase 4 radio-tracking results should be included with the Phase 2 or 3 mist-netting report and
submitted to the appropriate USFWS FO(s). Each report should include the following
information related to radio-tracking efforts 59:
1. Copy of prior phase reports (if not previously provided)
2. Explanation of any modifications from original survey plan (e.g., number of transmitters
used, frequency of transmitters changed) 60
3. Map and narrative detailing all ground and aerial searching effort for all bats not
recovered during radio-tracking and relative to the negotiated or agreed effort as
determined by the appropriate USFWS FO(s)
4. Map summarizing Indiana bat data collected from summer surveys for the proposed
project (e.g., project area boundary and results from the site habitat assessment, acoustic
survey, mist-net survey, radio-tracking, and emergence surveys)
59

In 2016, the USFWS implemented a new standardized approach for reporting of bat survey data. In addition to a
traditional written report, federal permit holders are now required to submit their survey data using standardized
permit reporting spreadsheets available on the Indiana Bat Summer Survey Guidance webpage
(http://www.fws.gov/midwest/Endangered/mammals/inba/inbasummersurveyguidance.html).
60
If the USFWS previously agreed upon the study plan we need to understand whether the revised work still
accomplished the agreed upon methods.

38

APPENDIX D
PHASE 4 RADIO-TRACKING
5. Full names and permit numbers of personnel who attached transmitters to Indiana bats
and full names of all personnel conducting radio-tracking efforts
6. Photographs of all roosts identified during radio-tracking
7. Legible copies of all original USFWS Indiana Bat Roost Datasheets
8. Any other information requested by the local USFWS FO(s) where work was conducted

REFERENCES
Aldridge, H., and R.M. Brigham. 1988. Load carrying and maneuverability in an insectivorous
bat: a test of the 5% “rule.” Journal of Mammalogy 69:379-382.
American Society of Mammalogists. 1998. Guidelines for the capture, handling and care of
mammals. Journal of Mammalogy 79:1416-1431.

39

APPENDIX D
PHASE 4 RADIO-TRACKING

USFWS INDIANA BAT ROOST DATASHEET
Biologists (Full Name):_________________________ Date:_____________________
UTM: Zone________ Easting _______________ Northing________________ OR
LAT_______________ LONG_______________
Property Owner:_____________________________ Phone#____________________
State________________________ County___________________ Site #___________
Roost #__________________ Roost Name:___________________________________
Roost Tree Data
Species: ________________________________________ Live __ Snag __ Other __
(if other, explain) ________________________________________________________
DBH (in or cm)___________________ Total Height (ft or m)___________________
Height of roost area (if known)______________Dist. from capture site___________
Roost position aspect (deg)_________
Exfoliating bark on bole (%)_____________ Describe: sloughing __ platy__ tight__
Cavities present? ____ If so, describe:_______________________________________

Roost Decay State: 1 2 3 4 5 6 7 8 9 Other

40

APPENDIX D
PHASE 4 RADIO-TRACKING
Roost tree or snag canopy position: Dominant __ Co-Dominant __ Suppressed __

Surrounding Habitat Condition
Canopy closure at roost (%) _______________
Approximate woodlot size (ac or ha)______________ Distance to non-forest (ft or m)____________
Describe forest/woodlot current condition (mature, partially cut-over, burned, insect damage, etc.)
_________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
Additional Comments__________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________
_____________________________________________________________________________________

41

APPENDIX E
PHASE 4 EMERGENCE SURVEYS
PERSONNEL
Qualified biologists 61, biological technicians, and any other individuals deemed qualified by a
local USFWS FO may conduct emergence surveys for Indiana bats by following the protocols
below.
EMERGENCE SURVEYS FOR KNOWN INDIANA BAT ROOSTS
The following protocols should begin as soon as feasible after identification of a diurnal roost
(ideally that night):
1. Bat emergence surveys should begin one half hour before sunset 62 and continue until at
least one hour after sunset or until it is otherwise too dark to see emerging bats. The
surveyor(s) should be positioned so that emerging bats will be silhouetted against the sky
as they exit the roost. Tallies of emerging bats should be recorded every few minutes or
as natural breaks in bat activity allow. There should be at least one surveyor per roost.
Surveyors must be close enough to the roost to observe all exiting bats but not close
enough to influence emergence. That is, do not stand directly beneath the roost, do not
make noise or carry on a conversation, and minimize use of lights (use a small flashlight
or similar to record data, if necessary). Do not shine a light on the roost as this may
prevent or delay bats from emerging. Use of an infra-red, night vision, or thermalimaging video camera or spotting scope is encouraged but not required. Likewise, use of
an ultrasonic bat detector may aid in identifying the exact timing of bats emerging and
may be used to help differentiate between low- and high-frequency bats species, and
therefore, is strongly recommended. If multiple roosts are known within a colony, then
simultaneous emergence surveys are encouraged to estimate population size. [Note: If a
roost cannot be adequately silhouetted, then the local USFWS FO(s) should be contacted
to discuss alternative survey methods].
2. Bat activity is affected by weather; therefore emergence surveys should not be conducted
when the following conditions exist: (a) temperatures that fall below 50°F (10°C); (b)
precipitation, including rain and/or fog, that exceeds 30 minutes or continues
intermittently during the survey period; and (c) sustained wind speeds greater than 9
miles/hour (4 meters/second; 3 on Beaufort scale).
3. Surveyors should use the attached (or similar) “Bat Emergence Survey Datasheet”.

61

A qualified biologist is an individual who holds a USFWS Recovery Permit (Federal Fish and Wildlife Permit) for
federally-listed bats in the state/region in which they are surveying and/or has been authorized by the appropriate
state agency to mist-net for Indiana bats. Several USFWS offices maintain lists of qualified bat surveyors, and if
working in one of those states with authorizations in lieu of a Recovery Permits, the individual will either need to be
on that list or submit qualifications to receive USFWS approval prior to conducting any field work.
62
Surveys may need to start a little earlier or later than one half hour before official sunset times (i.e., before “dusk”)
in some settings such as deep/dark forested valleys or ridge tops, respectively. Sunset tables for the location of
survey can be found at: http://aa.usno.navy.mil/data/docs/RS_OneYear.php

42

APPENDIX E
PHASE 4 EMERGENCE SURVEYS
4. Surveyors should also complete an “Indiana Bat Roost Datasheet” for each roost known
to be used by one or more Indiana bats (see Appendix D for an example).
5. Completed datasheets should be included in reports prepared for the USFWS.
EMERGENCE SURVEYS FOR POTENTIAL INDIANA BAT ROOSTS
In some limited cases (e.g., individual hazard tree removal during the active season), surveyors
may have the option of conducting emergence surveys for individual potential Indiana bat roosts
to determine use prior to removal. The following protocol applies to these surveys:
1. Consult with the local USFWS FO(s) to determine whether a tree(s) that needs to be
felled/ cleared may be potential roosting habitat for Indiana bats and whether conducting
an emergence survey is an appropriate means of avoiding take of Indiana bats 63. In
general, the USFWS only approves of conducting emergence surveys as a means of
avoiding direct take of bats for projects that only affect a very small number of potential
roosts (e.g., less than or equal to 10) 64 in relatively small project areas. An online
directory of USFWS offices is available at: http://www.fws.gov/offices/.
2. If the USFWS FO(s) approves/concurs with Step 1, then follow the emergence guidelines
for Emergence Surveys for Known Indiana Bat Roosts (above) to determine if any bats
are roosting in the tree(s).
3. At the conclusion of the emergence survey:
a. If no bats were observed emerging from the potential roost(s), then it maybe
felled immediately. If safety concerns dictate that a tree cannot be felled
immediately (i.e., in the dark), then the tree(s) should be felled as soon as possible
after sunrise on the following day. If a tree is not felled during the daytime
immediately following an emergence survey, then the survey has to be repeated,
because bats may switch roosts on a nightly basis. Immediately after the tree is
felled, a visual inspection of the downed tree must be completed to ensure that no
bats were present, injured, or killed. The USFWS FO(s) should be contacted
immediately, if bats are discovered during this inspection.
b.

If 1 or more bats (regardless of species, because species identification cannot
reliably be made during visual emergence counts alone) are observed emerging
from the roost, then it should not be felled, and the USFWS FO(s) should be
contacted the next working day for further guidance.

63

If a potential bat roost tree poses an imminent threat to human safety or property, then emergency consultation
procedures should be followed as appropriate. (50 CFR §402.05). If a hazard tree does not pose an imminent threat,
then the USFWS requests that it be felled during the bat’s inactive season (i.e., generally from October – March, but
contact the FO for specific dates for your area.) When possible, felling of potential roost/hazard trees should be
avoided during the primary maternity period (June – July) to avoid potential adverse effects to non-volant pups.
64
Areas containing >10 hazard trees will be assessed by the USFWS on a case-by-case basis with the project
proponent.

43

APPENDIX E
PHASE 4 EMERGENCE SURVEYS

SUBMISSION OF EMERGENCE SURVEY RESULTS
Emergence survey results should be included with the mist-netting survey report, unless the
survey was completed as an evaluation of potential roosts, and should be submitted to the
appropriate USFWS FO(s) for review. Each survey report should include the following
information related to emergence survey efforts 65:
1. Copy of prior phase reports (if not previously provided)
2. Explanation of any modifications from the Phase 4 emergence count study plan
(e.g., number of potential roosts surveyed), if applicable
3. Summary of roost emergence data
4. Map identifying location of roost(s) identified during radio-tracking and/or
emergence surveys for Indiana bat(s) including GPS coordinates
5. Full names of personnel present during emergence survey efforts and who
conducted emergence surveys of roosts
6. Photographs of each identified roost
7. Copies of all “Emergence Survey” and “Indiana Bat Roost” datasheets
8. Any other information requested by the local USFWS FO(s) where work was
conducted
9. Copy of the pre-approved site-specific written authorization from USFWS and/or
state natural resource agency (if required)

65

In 2016, the USFWS implemented a new standardized approach for reporting of bat survey data. In addition to a
traditional written report, federal permit holders are now required to submit their survey data using standardized
permit reporting spreadsheets available on the Indiana Bat Summer Survey Guidance webpage
(http://www.fws.gov/midwest/Endangered/mammals/inba/inbasummersurveyguidance.html).

44

APPENDIX E
PHASE 4 EMERGENCE SURVEYS

USFWS BAT EMERGENCE SURVEY DATASHEET
Date: _________________ Surveyor(s) Full Name:_________________________________________
State: _____ County: ___________________ Project Name: _________________________________
Site Name/#: _____________________ Roost Name/# ______________________ Bat #:___________
Lat/Long or UTM of Roost: ____________________________________________________________
Description of Roost/Habitat Feature Surveyed: ___________________________________________
_____________________________________________________________________________________
Bat Species Known to be using this Roost/Feature (if not known, leave blank):
_____________________________________________________________________________________
Other Suspected Bat Species (explain): ___________________________________________________
Weather Conditions during Survey (temperature, precipitation, wind speed):
____________________________________________________________________________________
Survey Start Time: ____________ Time of Sunset: ____________ Survey End Time: ____________

NOTE: Emergence surveys should begin ½ hour before sunset and continue until at least one hour after sunset or
until it is otherwise too dark to see emerging bats. The surveyor(s) should position him or herself so that emerging
bats will be silhouetted against the sky as they exit the roost. Tallies of emerging bats should be recorded every few
minutes or as natural breaks in bat activity allow. Please ensure that surveyor(s) are close enough to the roost to
observe all exiting/returning bats, but not close enough to influence emergence (i.e., do not stand directly beneath
the roost and do not make unnecessary noise and/or conversation, and minimize use of lights other than a small
flashlight to record data, if necessary). Do not shine a light on the roost tree crevice/cave/mine entrance itself as this
may prevent or delay bats from emerging. If available, use of an infra-red, night vision, or thermal-imaging video
camera or spotting scope and an ultrasonic bat detector are strongly recommended but not required.
Time

Number of Bats
Leaving Roost*

Comments / Notes

45

APPENDIX E
PHASE 4 EMERGENCE SURVEYS
Site Name/#: ______________________ Roost Name/#: ___________________________

Time

Number of Bats
Leaving Roost*

Comments / Notes

Total Number of
Bats Observed
Emerging from the
Roost/Feature
During the Survey:

* If any bats return to the roost during the survey, then they should be subtracted from the tally.

Describe Emergence: Did bats emerge simultaneously, fly off in the same direction, loiter, circle,
disperse, etc. If a radio-tagged bat was roosting in the tree, at what time did it emerge?
_____________________________________________________________________________________
_____________________________________________________________________________________

______________________________________________________________________________
46

APPENDIX F
LINEAR PROJECT GUIDANCE
For linear projects (e.g., pipelines and roadways), surveyors have the option to use either
mist nets or acoustic detectors in any given 1-km segment of suitable habitat. A survey site
may also cover other associated linear project facilities (e.g., access roads) that are located
within a pre-determined distance of each segment. When possible, surveyors should seek
out the best available survey sites located within the footprint of the project alignment, and
directly adjacent to, or near, the alignment if no suitable sites are available within the
footprint. Because the best survey sites for capturing/detecting bats may fall outside of a
project footprint, the surveyor and project proponent should coordinate with the appropriate
USFWS FO to establish a project-specific maximum distance from the centerline or project
boundary prior to initiating surveys.
Tentative survey site locations along linear projects should be included in a proposed study
plan to be reviewed and approved by the USFWS FO. One site should be surveyed within
each approximate 1-km segment that contains suitable forested habitat along the proposed
workspace. It is not appropriate to cumulatively add up each habitat block crossed until
1km of habitat has been traversed. Segments along a linear project that do not contain
suitable habitat should be skipped until the next patch of suitable habitat is encountered
(Figure 1). Establishing exactly how many survey sites are needed for presence/absence
surveys along a linear project often involves some give and take particularly in fragmented
habitat areas (Figure 1, rows B and C). The final number of survey sites could be greater
than the minimum number of sites prescribed in the protocol in order to adequately cover
the areas of suitable habitat to be impacted. When available, habitat quality and quantity
(e.g., size and location of suitable maternity roost trees) from on-the-ground habitat
assessments can be used to fine tune and guide the placement of survey sites. In some
marginal habitat areas, the quality and quantity of the existing habitat may be low enough to
justify skipping some survey segments (e.g., Figure 1, Site 11). Likewise, some isolated
woodlots, fencelines or individual trees may be considered too isolated and/or small to
independently support bats and may be skipped if the USFWS FO concurs. Habitat
suitability in fragmented areas should be assessed on a site-specific basis and consider
habitat configuration and connectivity to other suitable habitat patches. In general, we
recommend surveying a few more sites for a project than the absolute minimum required.
In instances where a mist netting survey has been proposed, but no suitable mist net sites
can be found or accessed within a particular segment, biologists should contact the USFWS
FO for further guidance or ideally agree in advance as to how such situations will be
handled when encountered in the field (e.g., an acoustic survey may be substituted).
Similarly, if an area of forest habitat that seemed suitable from aerial photography appears
to be unsuitable or of particularly low quality upon field inspection, then you should
coordinate with the USFWS FO to determine if an area may be exempted from surveys. To
avoid problems, any significant departures from previously agreed to survey plans should be
justified and coordinated with the USFWS FO prior to leaving the field.

47

APPENDIX F
LINEAR PROJECT GUIDANCE

FIGURE 1. Conceptual linear project (black double lines) through relatively contiguous (A.)
and fragmented (B. and C.) forested habitats (green patches) delineated into approximate 1km survey sections. Numbered red stars represent suitable survey sites (1-11) on or near the
project boundaries. Blue lines represent natural streams (A. and B.) and a ditch (C.).
Yellow-green patches near Site 11 represent low-quality habitat.

48