All about birds why are birds able to leave virtually everywhere on earth biology junction

Birds live virtually everywhere on Earth because they have evolved endothermy, the ability to use their metabolism to maintain a constant body temperature.
Birds belong to the class aves; they have an extremely efficient, one way breathing system with additional air sacs. Flying birds have strong, hollow bones and powerful flight muscles. Most birds can fly, they have a strong heart and an efficient way of breathing; which are necessary for birds to fly.