What do all birds have in common?

Birds are vertebrates, like mammals, reptiles and amphibians, they have a backbone. All birds have feathers and every feathered animal alive today is a bird. Birds are warm blooded and carefully regulate their body temperature within a narrow range, mainly by controlling their metabolism. All birds lay eggs. read more

According to PawNation, all birds have feathers, lightweight skeletons, beaks, a four-chambered heart and also lay eggs. Birds are warm-blooded vertebrate that have two legs used for walking, hopping, running or perching. read more

All birds have wings, although not all birds fly. Nor are wings confined to Aves; bats are flying mammals and most insects have wings. Birds' bodies are beautifully designed for flight, with strong chest muscles and just enough curve to their wings to provide lift. read more