It looks like they are using audio. Even with poor audio on my phone I find that it works very well. Once in a blue moon I'll get an ID I am doubtful of from BirdNet but it's rare in my experience.
though i would be hopeful for bird audio, as differentiating their calls is something the birds themselves excel at, so it could very well be a great usecase for ai
while it's not perfect it's not really producing hallucinations of pterodactyls or anything like that