Are Birds Mammals? Find Out In Our Definitive Guide!

Birds are more related to reptiles than to mammals, so they are not mammals; they belong to the class Aves. Mammalia is the class of mammals. Feathers are unique to birds, whereas fur is unique to mammals.

A bird is more closely linked to an alligator than it is to a bat or any other animal, and all current birds are directly descended from dinosaurs!

The ancestors of birds diverged from the forerunners of mammals over three hundred million years ago, although both birds and mammals share a common progenitor.

The answer to the question “Is a bird a mammal?” is definitely “no!” given the vast amount of time (and evolution) that separates birds and mammals.

We must look at both groups of animals to fully comprehend why a bird is not a mammal.

Is A Bird A Mammal?

The class Aves, a category of creatures in the animal kingdom, includes the bird.

On this page, you’ll learn more about birds: Birds: The Complete Guide

Aves is made up of all of its members (i.e. All birds (both extant and extinct) have numerous characteristics in common. Birds are distinguished by their shared characteristics.

An animal belongs to a different group if it doesn’t have all of these traits.

Similarly, a mammal is one of the Mammalia class of creatures. An animal must have mammalian characteristics in order to be a member of Mammalia–and thus a mammal.

Mammals are members of the class Mammalia. This is a Tiger, a member of the cat family, Felidae.

Birds and mammals have several differences, despite their similarities. Read on to find out what they are…

Brief Guide To Animal Classification: Classes, Orders, Families, Species, Etc.

Eagles, hawks, kites, and other birds of prey belong to the Accipitridae family of birds.


A class of animal is both Aves and Mammalia. Biologists divide animals (and other organisms, such as plants and fungus) into groups, which are known as classes. Classification is the process of organizing species into groups.


Animals are divided into groupings of related species inside a class, and these groupings are even more closely linked to each other. Orders are the names given to these organizations.

Passeriformes are the most abundant order in Aves. This group accounts for more than half of all live birds. Passerines are the members of the Passeriformes order. “Perching birds” or “songbirds,” as passerines are known, are also popular.


People referring to an animal “family” may be familiar with you. A subgroup of animals within an order is called an animal family, such as Canidae.

Tyrannidae, the tyrant flycatcher family, is the world’s largest bird family. Over 400 species of birds may be found there.

Bird And Mammal Classification

By examining the family trees of the animals involved, biologists divide animals into the aforementioned groups.

Physical and behavioral traits are usually shared by species that are closely related. Just a few characteristics are shared by animals that are only remotely related (such as birds and mammals).

Biologists can identify which group an animal belongs by looking for certain traits (or the lack of them).

Animals in the class Aves (birds) have distinct characteristics from those in the class Mammalia (mammal).

Since birds and mammals have evolved for 300 million years, they have changed dramatically in appearance; hence a bird is not a mammal.

Birds Vs Mammals

Despite the fact that birds and mammals are not comparable, there are certain characteristics that the two groups have in common.

This may explain why so many people ask, “Are birds mammals?”

Birds and mammals have a lot in common, but they also have some differences.

Similarities Between Birds and Mammals

Birds and mammals do share certain characteristics, despite the fact that they are very different kinds of creatures:

  • Vertebrates: Vertebrates have backbones, which includes both birds and mammals.
  • Birds and mammals are both endothermic (warm-blooded), which is why they are endothermic. This implies that their body temperatures can be regulated and maintained at a constant level by them. When it comes to example, warm-blooded animals (e.g., humans) can warm themselves up. They don’t have to travel to a warmer place or sunbathe like warm-blooded creatures like lizards do, because they shiver.
  • Both birds and mammals have four-chambered hearts: two chambers in each. The three-chambered hearts of amphibians and most reptiles are less efficient than this system.
  • Birds and mammals breathe air, but the lungs of birds and mammals are different. Birds have both air sacs and lungs, making their respiratory systems incredibly complex.

Differences Between Birds and Mammals

Birds and mammals are classified into separate orders, and the two groups have significant differences in appearance.

Bird Characteristics

The class Aves (i.e., birds) contains a member. Mammalian characteristics that are not shared by birds include the following:

  • Feathers: A variety of feather types cover the bodies of birds. Feathers aid the bird in flight as well as keeping it warm (insulation).
  • Birds don’t have teeth, so they must swallow their meals whole or chop it up into bite-sized pieces with their beaks. According to its diet, a bird’s beak may be highly specialized.

Birds are ancient dinosaurs that soar through the air. The dinosaurs are the forebears of all birds. This explains why birds and crocodilians share a common ancestor, the archosaurs that lived in the Mesozoic Era!

Mammal Characteristics

Mammalia (i.e., animals) This class contains mammals. The following traits are lacking in birds (but present in mammals):

  • Mammalian: the only group of animals with hair (or fur) is mammals, which include chickens, pigs, dogs, and goats. If an animal has actual hair, it’s a mammal.)
  • Young are born to live. All mammals, with the exception of the five monotreme species, give birth rather than lay eggs.
  • Breastfeed their infants to nourish them. All female mammals give milk to their young. Mammary glands, from which mammals get their name, are structures that produce this highly nutritious liquid. Milk comes only from certain kinds of animals.

Bird Adaptations For Flight

All birds’ forebears, including this Flightless Emu, were capable of flying.

Bats are mammals, and insects were flying for hundreds of millions of years before the first birds emerged, therefore being able to fly is not a defining characteristic of birds.

A bat is a flying Mammal, not just birds.

(In case you were wondering, insects are animals, as evidenced by this page: Are Insects Animals? If you want to learn more.)

Birds, including flightless birds such as penguins and ostriches, are descended from birds that could fly, and their bodies show the adaptations required for flight.

Birds’ wings are the most obvious flying adaptation. These are the bird’s forelimbs, as seen from above. Birds may take off, glide, and power themselves through the air by flapping their wings.

To assist in flight, most birds have lightweight skeletons with hollow bones. Birds have to eat a lot of food because their metabolisms (the amount of energy they need) are high. Flying requires a lot of energy, which is why it’s mainly done.

Birds have a variety of air sacs inside their bodies, in addition to lungs. This makes it easier for a bird to move air in and out. Because of the birds’ fast metabolism, this is also a requirement.

Is A Bird A Mammal: Conclusion

Birds are not mammals, as they are classified differently in the animal kingdom and have evolved over 300 years, as we discovered on this page.

The animal kingdom is divided into different divisions, including Aves and Mammalia. We’ve discovered that birds are members of Aves and mammals are members of Mammalia. Different (and similar) features between birds and mammals have also been explored.

You’ll be able to say “No, a bird is NOT a mammal!” the next time someone asks you “Is a bird a mammal?”

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