Did you know that birds do not breathe in and out like we do?
Birds have a different breathing system with rigid lungs that act like filters. Air flows through the lungs to air sacs that are sandwiched between muscles and limbs, acting as bellows to move the air.
Birds basically breathe in and out at the same time! Oxygen is rapidly absorbed and Co2 is quickly released as air flows against a huge number of tiny blood vessels in the lungs.
It is because of this design that birds can fly vigorously for great distances without getting tired. Some birds will fly up to 7,000 miles non-stop during migration seasons!
God has designed an amazing way for birds to breathe so they can be wondrously efficient flying machines.
(Source: Inspired Evidence Von Vett & Malone)