Great concept! I'm impressed by the level of thought you put into this. It seems you have done your research with these birds and have experimented in other jams with what worked and what didn't. When moving forward with your game, it sounds like you'll have a strong foundation to work from.
Some points I think you may want to consider:
(Only brainstorming here, these aren't suggestions)
- Keep in mind the balance between realism and player enjoyment. I think you're right to move away from the plane controls as those don't seem natural, but controls that are too complex might turn away some players.
- Instead of solely relying on a health bar indicator for how the player is doing, you could also add visual elements for this metric. Maybe something like the birds plumage becoming more vibrant in colors as they eat more insects - signifying a healthier bird. Something like that.
I'm excited to see how this turns out! It's nice to see such a unique perspective on a game concept. Good luck on the project. :)