What would birds look like if they did not have to fight gravity to fly?
The question comes from the premise put forward by some that gravity is not real and that what holds us down is pressure caused by density.
Obviously, this is not the case, but if it were, how would it (yes, conceptually) affect the way birds evolve, develop and/or fly?
[EDIT] To conceptualise a little... Let's say we had evolved on Earth and then been transplanted to an artificial planet. One with no gravity but one where the gas we are surrounded by is dense enough to actually cause some amount of pressure and thus keep us on the ground - a ground which has no gravity because it is perhaps only a metre deep, though wide enough to house every country... and then birds had evolved. (Perhaps they had been put there before we were.)
[COMMENT] This is not about whether the birds of a particular type are viable but is asking what they would look like given time enough in a particular environment.