Why are birds able to fly?
So there are the obvious ones, hollow bones, wings, aerodynamics etc. but there are also things like they have a more efficient breathing system. Birds have faveolar lungs (basically tubes) the air enters the body, goes into the air sacs, and from there into the lungs. It’s a unidirectional flow (like a big circle) as opposed to the mammalian tidal flow (in and then out again). An added feature of the bird lung is the antiparallel blood supply, so the air goes from the bottom of the bird’s ribcage to the top and out, the blood goes the opposite way, so that the lowest concentration of oxygen in the air is closest to the lowest concentration in the blood, enabling effective transfer of oxygen. (Blood likes oxygen, and tries to get as much as possible. If there is no oxygen in blood it will pull harder on the available oxygen in the air to try and get it. When the blood is well oxygenated the pull is weaker, so having the weak pull where there is most airborne oxygen means that you don’t
