Put it down over winter but just picking it back up.
Bat detection/identification with ultrasonic recordings. It's been fun building the data pipeline to manage the ~30GB+ of WAV files generated every night, run through some identification processes (currently using https://github.com/rdz-oss/BattyBirdNET-Analyzer) and build a UI (mostly vibe coded lol) to help with replay, cataloging, etc.
I'm using an AudioMoth currently (https://www.openacousticdevices.info/audiomoth), am thinking about extending it to do some of the preprocessing in the field to scale things up a bit.
really cool, data pipeline alone sounds like fun challenge