Different Between Mammals and Birds

Different Between Mammals vs Birds

Mammals and birds are the most evolved groups of animals with a great variety among them. Both these groups have special ecological niches. Never is it hard to identify a mammal from a bird, but at the same time it is important to discuss the drastic changes between them. The diversity, physiology, body shapes, and many other distinctions are interesting to know about both mammals and birds.


Mammals are warm-blooded vertebrates belong to Class: Mammalia, and there are more than 4250 extant species. It is a tiny number compared to the total number of species in the world, which is around 30 million as of many of the estimations. However, this small number has conquered the whole world with dominancy, with great adaptations according to the ever-changing Earth. One characteristic about them is the presence of hair all over the skin of the body. The most discussed and most interesting feature is the milk-producing mammary glands of the females to nourish the newborns. However, males also possess mammary glands, which are not functional and do not produce milk. During gestation period, the placental mammals possess a placenta, which nourishes the foetal stages. Mammals have a closed circularity system with a sophisticated four-chambered heart. Except in bats, the internal skeleton system is heavy and strong to provide muscle attaching surfaces and a firm stature for the whole body. The presence of sweat glands over the body is another unique mammalian feature that separates them from all other animal groups. Pharynx is the organ that produces vocal sounds in the mammals.


Birds are also warm-blooded vertebrate animals belong to the Class: Aves. There are about 10,000 extant bird species, and they have preferred the three-dimensional aerial environment with great adaptations. They have feathers covering the whole body with adapted forelimbs into wings. The interest about birds elevates because of some specializations seen in them viz. Feather-covered body, beak with no teeth, high metabolic rate, and hard-shelled eggs. In addition, their lightweight, but strong bony skeleton made up of air-filled bones makes it easy for the birds to be airborne. The air-filled cavities of the skeleton connect with the lungs of the respiratory system, which makes it different from other animals. Birds are more often social animals and live in groups known as flocks. They are uricotelic, i.e. their kidneys excrete uric acid as the nitrogenous waste product. In addition, they do not possess a urinary bladder. Birds have a cloaca, which has multi purposes including excretion of waste products, and mating, and laying eggs. Birds have specific calls for each species and they differ with the mood of the individual as well. They produce these vocal calls by using their syrinx muscles.

What is the difference between Mammals and Birds?

• Species diversity is higher among birds compared to mammals.

• The mammal body has hair-covered bodies, while birds have feather-covered bodies.

• Mammalian skeleton is heavy, whereas the birds have a lightweight skeleton with air-filled bones.

• Mammals have mammary glands to produce milk to nourish newborns, but birds do not.

• Mammals have strong teeth for mechanical digestion of food, while birds have a beak without teeth. However, they have either gastroliths or show geophagy for mechanical digestion of food.

• In mammals, the respiratory gas exchanging occurs in alveoli of lungs, whereas in birds it takes place in air capillaries.

• Mammals have a single respiratory cycle, but birds have a double respiratory cycle.

• Birds have air sacs, but mammals do not.

• The red blood cells of mammals do not contain a nucleus, while those of birds contain a nucleus.

• Mammals produce vocal sounds using the pharynx, while birds use syrinx muscles for sound production.