Class Aves –
– presence of feather, beak and forelimb in form of wing.
– Hind limb adapted to clasping, walking and swimming.
– No glands on skin (only oil gland at tail base).
– Hollow bones (pneumatic).
– Air sacs connected to lungs to supplement respiration.
– Crop and gizzard are additional chambers in digestive system.
– Warm blooded.
– Heart four chambered.
– Sexes separate.
– Fertilisation internal and development direct.
– eg. Columba, Psittacula etc.