Are Birds Mammals?

By Geoffrey Migiro on October 9 2018 in World Facts

Birds are not mammals, but belong to a category of their own.
Birds are not mammals, but belong to a category of their own.

Birds are members of a group of animals known as Aves. Birds are warm-blooded vertebrates which have toothless-beaked jaws, feathers, lightweight skeleton, high metabolic rate, and lay hard-shelled eggs. The Aves are divided into two clades, the Neognathae which features all the birds and the Palaeognathae which includes the weak flying tinamous and the flightless ratites. Aves are the most successful tetrapods in the world with over 10,000 living species. Although they have some similarities, birds are not mammals.

Similarities Between Birds and Mammals 


Both mammals and birds are endothermic (warm-blooded) and maintain a constant body temperature. These animals can regulate their temperatures, therefore they don’t rely on external heat sources to stay warm. Birds and mammals can live anywhere on earth because they are warm-blooded.


Mammals and birds are grouped as vertebrates since they have a skeletal system and backbones. However, birds have hollowed bones with crisscrossed matrixes for extra strength. The structural matrix gives the bones enough strength to endure the pressure of landing and taking off.

Care of Young Ones 

The birds and mammals care for their young ones for a certain period after they have been born or hatched. The amount of time it takes for their young ones to learn how to fend for themselves varies from one species to the other.


The blood of both the mammals and birds has white and red blood cells. The red blood cells of these animals have hemoglobin (a protein molecule which is responsible for oxygen transportation). The erythrocytes of birds have a nucleus which is absent in mammals.

Differences Between Birds and Mammals 


All birds lay hard-shelled eggs that are fertilized internally. Birds create an elaborate nest where they lay their eggs. The birds then sit on the eggs until they hatch to keep them warm as the chick develops. Other than the five monotreme species (the four echidna species and platypus) which lay soft-shelled eggs, most mammals are viviparous and give birth to live young ones.

Feeding of Young 

Birds have toothless, beaked jaws and they have to cut their food into small pieces before they eat. Mammals chew their food before swallowing using their teeth. Birds have gastroliths, also known as gizzard stone or stomach stone, which grinds the swallowed food before it’s digested.

The birds take care of their young ones and feed them beak-to-beak. The mammals feed their young ones with milk from their mammary glands. Mammals get their name from these glands, and no other type of animals produce milk. Although the egg-laying mammals do not have nipples, but they have mammary glands. The young monotremes lick the milk from the mammary patches on their mother’s belly.

Other Differences

The skin of all mammals is covered by fur while the bird’s body is covered with feathers. Other than helping them fly, these feathers keep them warm. In birds, gaseous exchange occurs in the air capillaries while in mammals it takes place in the alveoli of the lungs. Aves produce sounds using their syrinx muscles while mammals use the pharynx.

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