Are Birds Mammals? (All You Need To Know)

All living plants and animals on earth are divided into different categories according to their morphology and structure as well as their evolutionary history. This fascinating branch of science is called taxonomy, and it helps scientists name different species and understand how they are related.

The last common ancestor of birds and mammals is thought to have lived more than 300 million years ago, and today the differences between the two animal classes are evident. So can birds be mammals? What’s the difference between the two?

Birds are not mammals, although they are all chordates in the animal kingdom. In fact, birds belong to their own class called Aves, while mammals belong to a class called Mammalia. Birds evolved more than 150 million years ago from a group of dinosaurs known as theropods. That’s a bit later than mammals, which first appeared 200 million years or more before today’s.

The different evolutionary histories of birds and mammals can be shown very clearly on a cladogram, a family tree of a life form. Birds and mammals are separate clades, but if you go back far enough, they share many common ancestors.

Time and countless generations have markedly distinguished modern birds and mammals from those long-extinct common ancestors, and this taxonomic distinction means that no bird is a mammal and vice versa.

Modern birds and mammals may have many differences, but we also have a lot in common. Read on for an in-depth look at what makes mammals like us different from our feathered friends.

Birds are not mammals but are classified as birds

How are birds different from mammals?

Birds differ from mammals in many ways. Some of these differences are obvious, while others require a closer look at their behavior. Some of the differences cannot be seen without looking closely at how their bones and organs differ.

Read on to learn more about how birds differ from mammals.

physical difference

wing

One of the most obvious differences between birds and mammals is that our feathered friends have wings. All birds have wings, including flightless species such as ostriches and penguins. Birdwings are modified forearms with hand bones fused together. Bats are the only mammals with wings, although some mammals, such as flying squirrels, can use the membranes between their limbs to glide.

European bee-eater spreading its wings

bill/beak

Another obvious difference between birds and mammals is the beak. Birds have toothless, horny beaks instead of toothed jaws like mammals. The beak is an interesting structure that can range in shape and size, from the tiny conical beak of the common redbird to the huge, colorful beak of the toucan.

Birds lack teeth and heavy bony jaws because the weight would make flight more difficult. However, the beak is more than just a feeding tool. Their beaks are used for a variety of tasks, such as cleaning themselves, spearing fish, digging holes, and even making sounds.

Mammals don’t have beaks, with one exception. The platypus from Australia is an interesting animal. These unusual mammals have a soft beak like a duck’s, but no teeth.

Normal Redpoll with roost off

feather

Birds are the only living animals with feathers. Feathers are unique structures that birds use for insulation and flight. Birds have many different types of feathers on different parts of their bodies. However, they can be divided into two main groups, leaf feathers and down feathers.

Mammals differ from birds in that they have fur or hair instead of feathers. Fur is a great insulating and protective covering and is present on all mammals for at least part of their lives.

close blue throat

Of course, wings, beaks, and feathers aren’t the only anatomical differences between birds and mammals. The following body structures are found in birds but not mammals:

• hollow bone
• scaly legs
• syringe
• air bag
• gizzard
• wishbone
• Cloaca

sports

Another clear difference between birds and mammals is how the two groups move. Most birds can fly, and all species are bipedal, meaning they walk upright on two legs. Many birds can swim with their legs, and some can even swim at high speeds using their wings as propulsion.

Mammals have the same variety of locomotion patterns as birds, although the vast majority of them are not flyable but are quadrupeds, meaning they walk on four legs.

Hyacinth Macaw in flight

reproductive difference

The fundamental difference between birds and mammals is that they lay eggs instead of giving birth to live young. Both birds and mammals use internal fertilization, but birds lay eggs long before their chicks are ready to take their first breath.

This strategy allows female birds to shed their babies earlier, and often enlists their mates to assist in incubating the eggs. Different birds parent in different ways, but many males make great fathers, and some even do all the incubation and care themselves!

Mammals give birth to live babies. However, infant development varies widely, with some mammalian babies being blind and helpless, while others can walk and run even on their first day! Most male mammals are fatherless and do not feed or care for their babies in any way.

Moor hen sitting on the nest

What makes a mammal?

Mammals are hairy, warm-blooded vertebrates. The most unique and typical feature of mammals is their ability to produce milk from mammary glands. No other animal feeds its young in this way.

Mammalian brains also differ from those of birds and other animals in that they have a neocortex, the part of the brain used for many higher functions. Ossicles are another set of unique features found in mammalian skulls. These three small bones in the middle ear are used for hearing.

Similarities Between Birds and Mammals

There are probably far more similarities than differences between mammals and birds! Both groups are very diverse and successful, living across the globe.

Birds and mammals are two of the most intelligent classes in the animal kingdom, both of which have the ability to regulate body temperature through metabolism. We have similar organ systems to birds, although there are important differences in the reproductive and gastrointestinal tracts.

Both birds and mammals display high levels of parental care, which is rare in the animal kingdom, although there are examples of great animal parents from many different categories.

Great horned owl perched on a tree

Is there any bird that is a mammal?

Birds and mammals are technically very different animal types. Their last common ancestor is thought to have existed more than 300 million years ago.

No bird can technically be called a mammal, though one quirky bird has earned the title of “honorary mammal.”

New Zealand’s kiwi is an unusual flightless bird that forages slowly on the forest floor after dark. Their elongated feathers even look like fur, with long, bristly whiskers growing from them.

New Zealand kiwi

Do birds produce milk?

Birds are one of the few animals that feed their young. They share this advanced parental care with mammals, but the two groups differ in what and how they feed their babies.

Birds do not have mammary glands, so they cannot be said to produce milk. Birds usually feed their babies the proper food they’ve gathered, but some go a step further. Pigeons and doves, for example, produce something called crop milk. This isn’t real milk, but the high-protein liquid that both parents produce and feed the chicks for the first two weeks or so.

Birds feed their young with their beaks, while mammalian young drink from their mother’s mammary glands. However, some mammals do feed their young after weaning in a similar manner to birds.

Wolves feed their begging young with regurgitated meat, as birds feed chickens. Both male and female birds can feed their young, but only female mammals produce milk.

Greater flamingo feeding its young with milk

Birds and Mammals FAQ

Are chickens mammals?

chicken is from Phasianidae family. These familiar game birds are no more closely related to mammals than to any other bird species.

Are penguins mammals or birds?

Penguins are birds. They may look very different from the common songbirds we see every day in our yard or neighborhood, but they share a common ancestor with all other birds.

Do mammals lay eggs?

Birds lay eggs, which is one of the main differences between them and mammals that lay live young. However, some remarkable Australian mammals can lay eggs. The platypus and the four extant echidnas are very unusual in that they lay eggs.