Methods & Technology

Active Monitoring

  • Acoustic surveys at randomly distributed locales
  • North American Bat Monitoring protocol survey component:
    • Mobile acoustic surveys along road transects
  • Bat house installation w/regular monitoring to determine use and species richness
  • Monitoring of randomly distributed transects within vineyards to assess use, richness, and temporal changes in species diversity

Passive Monitoring

  • North American Bat Monitoring protocol passive (stationary) point survey component:
    • Two or four passive data collectors will be deployed for multiple nights at various features (e.g., grassland, oak woodland, pond, riparian corridor) across the landscape within predetermined sampling grids. A grid cell sample unit of 10 km by 10 km (100 km²) has been determined as an effective sampling framework in context with NABat’s focal analytical goal for regional and range-wide assessments. The grid was developed by the U.S.D.A. Forest Service for use in the inter-agency “Bat Grid” monitoring program in the Pacific Northwest and has now been expanded across Canada, the United States, and Mexico, including California’s Central Coast.


North American Bat (NABat) Monitoring protocols:

For Passive Acoustic Surveys

  • ANABAT Swift passive bat detectors
  • Wildlife Acoustics Song Meter SM3BAT Full-spectrum bat detector/recorder 

For Mobile Acoustic Surveys

  • ANABAT Swift  bat detector w/car mount 

General Bat Monitoring & Distribution Studies:

For Active Monitoring

  • Pettersson M500-384 USB Ultrasound Microphone paired w/Android device

For in-field teaching, public demonstrations, and active monitoring by citizen scientists and elementary school students

  • Wildlife Acoustics Echo Meter Touch paired with iPhone/iPad

For heterodyne (focused/limited frequency) monitoring & surveys

  • Pettersson D240X Ultrasound Detector connected to a Zoom H2 recorder 

Loaner units for citizen scientists

  • Wildlife Acoustics Song Meter SM2BAT
  • Wildlife Acoustics Song Meter SM2BAT+
  • Wildlife Acoustics Song Meter SMZC 


  • Kaleidoscope Pro (Wildlife Acoustics) – for zero-crossed file inspection and full spectrum analysis
  • SonoBat (SonoBat, Inc./Joe Szewczak, Humboldt State University) – for full spectrum analysis
  • AnaLookW software for zero-crossed file inspection

Manual vetting

The importance of manual vetting of bat call files cannot be undervalued. For every location, to ascertain presence of a species, we manually vet a sufficient number of files in order to establish at least one peer review-able voucher. We tailor our vetting process to fit the need of our studies, which on occasion may result in the inspection of each bat call file that we have recorded. We consider both false positive and false negatives when interpreting the results from our auto-classifier programs.