Are the aerodynamics of a bird flying at high altitude significantly different than a bird flying at low altitude? I would imagine a bird adapted for low, short flights (such as between bushes and trees) would have a difficult time flying at a higher elevation. What sort of air patterns are the wings of a high-flying bird adapted to mitigate or take advantage of? For instance, I imagine cross-breezes are strong and more frequent, meaning a bird with wings suited for low altitudes would have to flap much more to avoid being pushed around.
For this question I'm only really concerned with the aerodynamics. Obviously a high-flying bird will also be adapted for less oxygen in the air and flying for longer without needing to eat, but that's slightly out of the scope of this question.
Apologies if this is a repeated question, I couldn't find anything relevant here/elsewhere.