Bat Acoustic Data Review

Acoustic surveys for bats are challenging. Today’s bat detectors have become so efficient, it is easy to accumulate tens of thousands of files in a relatively short time. But, there is a steep learning curve just to get up-to-speed on data organization, post-processing, and reporting.

Automated software programs can handle large acoustic data sets. And, this leads us to believe that it will make echolocation call analysis fast while providing highly confident results for species occupancy and bat activity levels.

The problem lies with the plasticity inherent in bat echolocation calls and how bats actually use echolocation. A bat’s need for information, and therefore the type of echolocation call it will use, can change with prey-type, habitat complexity, and behavior. For many species, confident classification can only be achieved on a subset of call types within a bat’s repertoire. The only way to obtain high levels of confidence on species identification is to obtain expert, human review of the recordings in question through services of providing:


 Second Opinions ✺ NABat Reports ✺ Auto-analysis/Expert Manual Vetting ✺ Complete Acoustic Survey Reports

 Our clients include state and federal agencies, tribes, private consultants, and educational institutions.

Explanation of  Services

  1. Second Opinions on already auto-classified full-spectrum files.

    Bat call analysis software simply points the researcher in a direction of likely identification. This ID should also be checked by a bat acoustic expert with hundreds of hours experience recording and interpreting bat calls signals. We provide an important second opinion on individual call identifications as well as entire reports, extremely helpful in confirming or rejecting endangered species presence in your project area.

  2. NABat Reports for manually vetted night-level, site-level species occupancy on summer season stationary point monitoring surveys ~and/or~ 100% manually vetted mobile acoustic transect efforts.

    Send us your original WAV files and meta-data and we will post-process, analyze, and manually vet results, providing you with attributed copies, file-level autoID outputs, example “vouchers” confirming species presence, and calculated up-time from your detector log-files. We get your data ready to upload to NABat and/or the NPS Bat Acoustic Database.

  3. Auto-analysis with Manual Vetting on raw and/or attributed files for species of interest and/or the entire collection at three grades of precision:

    1. Basic Analysis: USF&WS-recommended surveys require results to be reported after they have been analyzed by an automated-classifier, where all recordings are evaluated to obtain Maximum Likelihood Estimates (MLE’s) for presence; acknowledging that both false positives and false negatives will remain. According to the USF&WS, accepting the MLE values at their face value, and the implications for presence will err on the side of presence, and is ok as long as the MLE for presence is reported as an expectation of occupancy. We will evaluate your MLE outputs and determine site-level, or project-level occupancy based on these values alone for the species of interest. We will also provide a file-level summary of species ID based on auto-classifiers for each MLE value suggesting occupancy for the species of interest. No manual vetting of files will be performed, during a “basic” analysis.
    2. High-Level Analysis: Acknowledging that analysis protocols relying upon auto-classifiers alone are deeply flawed when it comes to determining species presence because there is no computer-program sophisticated enough to take into account all the problems inherent in relying upon automated quantitative analysis of "images" (e.g., spectrographs and spectrograms of echolocation calls). This is because there will always be certain qualitative analysis steps required to address the ambiguities in echolocation call recordings created by: (1) the artifacts present in echolocation recordings caused by atypical bat behavior (e.g., the affects active foraging has on the metrics available in sound files vs. those found typical commuting, search phase bat calls), (2) atmospheric affects that change how high-frequency sound behaves in air, thus how faithfully it is recorded for confident analysis (e.g., the affects of micro-climate, temperature, wind, and humidity), (3) the uncontrollable approach angle, speed, and direction with which the bat approaches a stationary microphone --and-- the intensity and/or frequency with which the bat echolocates, any of which can affect signal quality and therefore classification accuracy, and finally (4) the presence of conspecifics and/or allospecifics in the same recording and the affect that multiple bats have on auto-classification accuracy. Therefore, acoustic surveys in which every single recording is manually reviewed not only addresses the identification of false-positives for the species of interest, but also the false-negative classifications that were ignored during a mid-level effort. It also confirms all true-positives and true-negatives thereby producing the most accurate representation of reality. (Not every client will desire to select a High Level Analysis, but the efforts from such a review represent the most robust results possible from acoustic surveys and reduce or eliminate all ambiguities for presence.)

  4. Complete Acoustic Survey Reports: We summarize acoustic data submitted, results of two (2) auto-classification outputs, MLE results and manual-vetting of species of interest.


We Accept

  1. Full-spectrum (FS) Recordings only (*.WAV format; *.WAC format will be accepted, at an additional charge)
  2. For Analysis/Vetting or Complete Reports, data must be submitted on an external storage device, no file-transfers will be accepted (use USB drives for small batches, external hard-drives for large batches)
  3. Data must be organized in separate folders by night and by detector
  4. For 2nd Opinions only, file-transfers will be accepted. If you do not have a file-transfer method, BatSS will set up a secure server to receive files.
  5. We Do Not Accept Zero-cross (Frequency Division) Recordings.


Minimum Requirements for All Data Submitted

  1. State and County Recordings were made. Additional location information is helpful, but not required (e.g., nearest town, landownership, Lat/Long, elevation)
  2. Date(s) of Deployment. Additional site information is helpful (e.g., weather conditions; temperature, dew point, cloud cover, humidity, wind, precipitation)
  3. Make and Model of Detector used (include installed firmware version and all recording settings; inquire for a list of essential settings for your detector if you are unsure of what to include)
  4. Microphone Type and Deployment description (e.g., external cabled microphone, any directional attachments, height above-ground-level (AGL), and orientation and/or azimuth, position in habitat; over water, in clearing, along forest edge, etc.) 
  5. Inquire for NABat Submission Forms to prepare and organize your data according to the USGS NABat Data Analysis guidelines prior to submission.


Pricing and Turn-around Time on Recordings*:

Project Size

2nd Opinions

NABat Reports


Complete Reports

1 – 20 files

$125 flat rate

$145 per each 4-night single-detector recording session 

$175 / $575


21 - 100 files

$175 flat rate

$250 / $650


101  - 499 files

$295 flat rate

$500 / $1,000


500+ files

$125 / hour

$125/hr. either level 


Turn-around Time

5-10 business days

3 business days

2-4 weeks

please inquire

*Fees for the different levels of analysis (basic/full) as listed above in Explanation of Services, paragraph #3.

Small Print
All Pricing and Turn-around Time estimates are based on materials meeting the acceptance and information criteria above. A $50 service charge will be assessed for requests submitted with incomplete information necessitating follow-up requests from Bat Survey Solutions, LLC to complete the submission. 

Submission of raw files, straight off the bat detector, is subject to an Attribution Fee of $250 per detector location, for the first detector location, plus $50 for each additional detector location on the same project, for up to 30-days (1 month) of deployments. Processing additional months for long-term deployments if detectors are not re-located will pro-rated at 10% of the cost for the previous month.

Expedited service may be available at an additional 50% up-charge fee during certain times of the year.


To submit files or discuss your project, contact
John Chenger
Tel/Text: 814.442.4246