/Maybe a standalone IoT monitoring device could be placed in forests to count each and every bird./
This is actually the 'real' research motivation behind the bird classification work: Slap a microphone to the side of a tree, pick it up in a month, and get some accurate picture of what species have been in the area.
Birds are relatively easy to observe, thanks to their vocalizations, which makes them an indicator species. We have a good idea what many species eat, so they end up telling you quite a lot about the surrounding ecosystem.
However, it turns out that the 'soundscape problem' where the microphone is just attached to a tree is a bit more difficult than identifying foreground birds only, using a device that can be pointed in the relevant direction by the user.
We've been encouraging further work on the soundscape problem by hosting the BirdCLEF and Kaggle competitions, and have been seeing steady progress. Improvements in the 'hard' soundscape problem have been driving improvements in the 'consumer' identification algorithms.
https://www.kaggle.com/c/birdclef-2021/overview
[source: I've been working with the BirdNet folks on and off for the last few years, and co-host the Kaggle competitions.]