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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.

Analysis protocols relying upon auto-classifiers alone are deeply flawed when it comes to determining species presence. 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. Artifacts present in echolocation recordings caused by atypical bat behavior (e.g., the affects active foraging and socializing 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 range, approach angle, speed, and direction with which the bat approaches a stationary microphone --and-- the intensity and/or frequency with which the bat echolocates, and other noise in the environment which competes with the bat's ultrasound, any of which can affect signal quality and therefore classification accuracy
  4. The presence of conspecifics and/or allospecifics in the same recording and the affect that multiple bats have on auto-classification accuracy.
  5. Variations in recording hardware, microphones, and recording settings will have significant impact on the number of recordings in a collection that can be classified to species. Liberal settings simply generate a massive data burden of recordings that will never be classified to species, and low end microphones -do not- faithfully record full spectrum sound. 

Considering all of the above, automated classification software is simply a tool to guide the researcher towards the most likely recordings of a particular species. Your data submitted to BCM is reviewed by a bat biologist with years of invaluable experience deploying multiple makes and models of detectors at sites across the country, actively monitoring/recording bats in the wild observing behavior during recordings, and recording voucher calls from individuals where species was confirmed. We review your data with this base of knowledge in mind and offer different levels of analysis services based on clients needs. 


Explanation of  Services

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.

  • False positives with acoustic monitoring are REAL and can significantly needlessly delay your development.
  • If your consultant reports that you have Florida Bonneted bats in your project area, and does -not- have 25+ years of experience interpreting bat calls, it is recommended you get a second opinion on those recordings regardless if you have submitted a report to an agency. 

 If your firm is relatively new to acoustic monitoring for bats, become a partner with BCM to double check your results. 

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.

Auto-analysis with additional Manual Vetting on raw and/or attributed files for species of interest and/or the entire collection at three grades of precision:
    1. MLE Automated Analysis Only: USF&WS-recommended surveys require initial results from 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. Accepting the MLE values at their face value will err on the side of presence, and may be acceptable if there is an expectation of occupancy.

      We will evaluate your MLE outputs and determine site-level, or project-level occupancy based on these values alone. We will run your data using the two leading software in North America, SonoBat and Kaleidoscope Pro, providing file-level results from both software on a single spreadsheet. We will also provide a file-level summary of species ID based on auto-classifiers.  No manual vetting of files will be performed, during a “basic” analysis. Deliverables include summary and file level spreadsheets from both SonoBat and KaPRO, including the master which combines both results at the file level. Researchers then use these spreadsheets to generate virtually any number of related pivot tables to suit. This level of precision is best suited for extremely large datasets and projects where there are no ramifications of reporting false positives for T&E species.

    2. Site Level Analysis With Manual Vetting: Acoustic files are initially classified using the latest version of SonoBat (and KaPRO, if required for USFWS). Representative files of each species in each site folder (which may contains weeks of data) are manually reviewed to confirm presence at that site. A master spreadsheet is generated which can be filtered by site, auto-classified species, and manually reviewed species. Deliverables include the master spreadsheet with any manual review comments. For Indiana bat or Northern longear USFWS requested analysis, the KaPRO output is included, and the master spreadsheet will feature SonoBat, KaPRO, and manual review results side-by-side. All files auto-classified as Indiana bat, Northern longear bat, and Florida bonneted bat are manually reviewed. 

      Deliverables are the master spreadsheet (and optional KaPRO outputs) ready to be summarized for inclusion in your own report. This is the most common analysis and solidly establishes species presence with the least amount of cost regardless of the number of files in the total project. 

    3. High-Level Analysis: When a high level of precision is required, every single recording is manually reviewed to 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. This is the most time consuming analysis and the total number of files will be reflected in the cost. Deliverables include a master spreadsheet showing all files manually reviewed, which is ready for the end user to incorporate into their own analysis/report, etc.

    Complete Acoustic Survey Reports: We summarize acoustic data submitted, results of two (2) auto-classification outputs (SonoBat, KaPRO), MLE results, and manual-vetting of species of interest either by site level, per site per night, or simply project-wide. In addition to the acoustic data, data sheets and photographs can be included. Uptime is calculated from log files. This service is attractive to those renting detectors or are consumed with field work and are looking for a turnkey analysis and report service. Reports can be tailored for compliance for Indiana bat, Northern longear bat, or Florida bonneted bat surveys. 


    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, more than ~10 GB of data  must be submitted on an external storage device (use USB drives for small batches, external hard-drives for large batches)
    3. Data must be organized in separate folders by detector
    4. For 2nd Opinions, file-transfers will be accepted. If you do not have a file-transfer method, will set up a secure server to receive files.
    5. We Do Not Accept Zero-cross (Frequency Division) Recordings.


    Before Starting Your Recording Project

    1. Please follow basic deployment tips to maximize the quality of your recordings. 
    2. Inquire with John for recommended system settings for any Wildlife Acoustics, Pettersson, Binary Acoustics, or SonoBat recording device. Using "default" settings or national monitoring protocols are just GUIDELINES and do not necessarily give you the best recordings with the least data burden.
    3. Need data sheets? Inquire with John for sample electronic datasheet you can complete which will form the basis of the data management and report. Inquire for NABat Submission Forms to prepare and organize your data according to the USGS NABat Data Analysis guidelines prior to submission.


    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.) 



    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