Birds are a group of warm-blooded vertebrates, which include all the species found in this group.

These birds are of multiple colors and differ in size. They lay eggs that are coldly resistant to help protect the developing baby from extreme temperatures, especially during the period of rapid growth when the body is still very soft.

Birds have a very high metabolic rate, which means that they need to consume more food than other animals do to sustain life.

Birds have four-chambered hearts, which means that they have the ability to transport oxygen from the atmosphere to the tissues and the reverse, allowing them to live for several hours without oxygen.

Birds have very strong yet lightweight skeletons, which allows them to fly with ease. They have long, thin, and flexible wings. The wings of birds develop from the first joints of the forelimbs, which allows them to fly with ease.