I have always been interested in learning more about flock simulation so this caught my eye. The low-poly visuals and the simple, soothing sound is really nice and fits the gameplay pretty well. The birds feel pretty natural in how they form a flock - it doesn't feel gamey or artificial but at the same time it feels responsive enough which seems like a hard balance to get. I feel like that's a hard thing to notice but it's probably one of the most impressive things to me :).
The only thing that holds this game back is for me personally the game lacks purpose / a goal. This game takes the endless mode approach, so the satisfaction has to come from the inherent satisfaction that comes from maintaining and growing the flock. I would compare it to agar.io but less stressful. I could see a lot of people enjoying this as a tranquil endless game to blow off steam. But for me, some kinds of in level goals, enemies, or a level-based game that used the same mechanic would be a lot more satisfying. So there is nothing wrong with what you have here, I just think I am not in your target audience :).
Overall though, this is a fantastic submission for a 48 hour game jam and I think you should continue working on it. You could keep the design as is and just add more to it and keep catering to the tranquil-loving audience, or you could make it more level-based or slightly more stressful gameplay, and I could see it being successful either way.
I would love to have your rating / comments on my game as well, so I can know what to improve.