Birds are vertebrates with bodies that are adapted for flying.
- Their upper limbs take the form of wings. Some birds, like ostriches and penguins, cannot fly. they use their lower limbs to walk and run.
- Their bodies, except for their legs, are covered with feathers.
- Birds, like mammals, have a constant body temperature. Their feathers help them to maintain their body heat.
- Birds do not have teeth. Instead, they have hard upper and lower jaws that form a beak.
- They have lungs to breathe with.
- birds are oviparous animals: they reproduce by laying eggs. The eggs have hard outer shell.
- the males make nests for the females to lay their eggs in. When the chicks are born, they stay with their parents for a while to be looked after. At least one parent feeds and looks after them.