Got some very good advice about my BirdNET-Pi in reply to the issue I raised because the Analyser cannot keep up with Recorder. A cron job to delete recordings more than 10 minutes old every five minutes ensures that the Analyzer does not stalls.
/5 find ~/BirdSongs/StreamData/ -name ".wav" -mmin +10 -delete
Very neat. Also reduced the length of each recording from 30 to 15 seconds, and implemented the experimental ram drive, which sounds way scarier than it ought.
Everything has now been chugging along smoothly for almost three hours. Mind, it hasn't detected any birds yet. Not surprising given the foul weather this morning.