Passive acoustic monitoring on your own computer.
GrizEars is the acoustics workspace in GrizCam Desktop. It is free on Windows and macOS, it opens standard audio files (WAV and FLAC) from most recorders, and it runs on your own computer. Sign in once; after that it works offline for up to 180 days.
A season of recordings, then findings.
Point GrizEars at a folder of recordings, multi-channel included. When the file names carry the site, date and time, GrizEars reads them, so every recording and every annotation lands at its clock time.
Run the bundled detectors over the folder: Perch 2.0 for birds and PNW-Cnet v5 for owls and raptors. Review each detection on the spectrogram, draw your own boxes around calls, and label them. Clustering groups similar sounds so you can find patterns before you label everything.
For the soundscape as a whole, the biodiversity report charts acoustic indices (ACI, entropy, events, background noise) over time. Export annotations and clips for statistics or training data. All of this is in the free version.
Your own detector, without code.
When the sound you study has no detector, train one from your own annotations. Pick one of six bioacoustic foundation models, set aside part of your files to test against, and GrizEars reports how well the detector does on recordings it never saw. Training your own detectors is part of GrizCam Desktop Pro.
The worked example: the Cry Wolf classifier, a wolf-howl detector trained this way on The Cry Wolf Project's Greater Yellowstone recordings.
Where and when each call happened.
The recorder map shows every site colored by its detections. The biologger map follows a collared animal's GPS track, with its audio and motion data on the same timeline, so a call ties to the place the animal was.
See it on one wolf: wolf 1513F's journey across Yellowstone's Northern Range, reconstructed from her biologger collar.
Uncommon owls of Greater Yellowstone.
The Greater Yellowstone owl bioacoustics pages come from a recorder archive worked in GrizEars: what each uncommon owl sounds like, with measured frequency and cadence.
What it does not do yet.
GrizEars is the broadest free desktop for this work, not the deepest. Other tools cover more species out of the box and identify bats automatically; GrizEars does neither.
You need a GrizCam account, even for the free version. Direction of arrival, which estimates where a sound came from, works only on recordings from GrizCam's multi-microphone array. And GrizCam Desktop is in beta, so expect change.