Their anatomy isnt too far from humans
However their lungs are larger in order to hold air for longer times when flying, and to help with flight,

*High class Avium are suseptible to lung issues from their wings pushing back on them.

*Middle class have had no negative effects from their wings

*Low class are suseptile to back pain and minor instability during flight.
There is also a physical and psychological occurance during high stress events called a "Feral Fit" to most. [cont.]