Syrlya happens to be a bird that's still roughly in the same size range as Strange. That would make full body collision bad enough, let alone a full body collision in the air.

Which is probably how this occurs, while Syrlya is trying to get used to flying and Strange is frantically searching and there's a wrong turn taken and suddenly Syrlya's whole orientation is thrown off and he's flapping his wings wildly to try and get ahold of himself while plummeting.

At least they're not that high off the ground.