Are Birds Mammals?

Do you know the difference between a bird and a mammal? People often mistake birds for being mammals, but is that really the case?

In order to be classified as a mammal, animals must meet specific biological criteria including hair or fur, be warm-blooded and provide milk for their young. So, are birds actually considered to be mammals?

In this article, we will look at the characteristics of birds and examine whether they fit the criteria needed in order to be counted as mammals.

Are birds mammals?

Birds are definitely not mammals, but rather a separate class of animals known as avians. While both birds and mammals share some common characteristics, such as being warm-blooded and having vertebrae, there are distinct differences between the two.

Mammals are actually characterized very specifically by their hair or fur, milk glands, and by being viviparous (birthing). Additionally, mammals also have warm blood.

In contrast to mammals, all birds lay eggs instead of giving birth to live young. This is one of the key differences between avian birds and mammals.

Other similarities between birds and mammals include that they both breathe air and possess vertebrae. Birds also have feathers that help them fly, whereas most mammals do not have this ability.

All in all, while birds may share some characteristics with mammals, they are still a distinct class of animals that should not be confused with each other.

Photo by Sasha Maslova

What makes a bird, an Avian?

Birds are a unique class of animals that have some features that set them apart from other animals. All birds belong to the class Aves, and they share a few traits that define them as such.

  • feathers – unique to birds and provide them with insulation, and protection from the elements, and even help them fly
  • warm blood, meaning they can maintain a constant body temperature regardless of their environment
  • hollow bones – make them lightweight and able to fly
  • eggs – birds reproduce by mating, laying eggs and incubating them
  • wings – birds have wings and most of them use them for flying

All these features come together to create an animal that is uniquely adapted for life in the air. From soaring eagles to tiny hummingbirds, all birds share these common traits that make them what they are – birds!

Photo by Imogen Warren

So, what exactly are mammals?

Mammals are actually a class of animals that have specific traits that set them apart from other animals.

  • warm blood – they are able to maintain and therefore regulate their body temperatures through burning energy
  • live young – through birth instead of laying eggs as birds or reptiles do
  • fur or hair on their bodies – to help temperature regulation
  • mammary glands – for producing milk
  • four limbs – to enable moving around

Mammals also have slightly larger, in volume, brains than most animals. They also possess an advanced sense of hearing and smell, which helps them navigate their environment better than other species.

However, there are five species of monotremes, which are egg-laying specific mammals. These all live in Australia and/or New Guinea and include species of Echidna and the Duck-billed Playtpus.

Photo by Leif Blessing

What are the most common misconceptions about birds?

A particular misconception about birds is that they can’t fly very far or very fast.

While some species may not be able to fly long distances or reach high speeds, many birds are capable of impressive feats of flight. For example, some migratory birds can travel thousands of miles in a single journey and reach speeds over 20 mph on average.

Birds also have incredibly strong wings that allow them to soar through the air with ease. Most bird species you see on a daily basis in backyards can stay in the air for up to six hours, traveling at 15 miles per hour.

Mating for life

The idea that birds mate for life is a romantic notion that many people hold dear. While it is true that some species pair off to mate for life, it isn’t as common as we would predict.

Albatross is one of the few species of birds that may stay together forever, but even they don’t always remain faithful to their partner. Other birds like flamingos also form long-term relationships with their partners every breeding season.

In most cases, the male bird will court the female by performing elaborate courtship rituals such as singing or displaying his feathers in order to attract her attention. The tropicbird pictured below is flying backwards to impress the female.

Photo by Imogen Warren

If she accepts him, they will form a bond and stay together until either one dies or until the female decides to find another mate. This behavior is seen in many species of birds. However, there are also some species of birds that practice polygyny, where multiple males will share a single female mate.

Touching baby birds will cause the mother to abandon it

The idea that touching or moving a baby bird will result in its mother abandoning it is a myth. Birds actually have a poor sense of smell, so it is unlikely that you would leave enough of a scent directly on the baby bird to cause this to happen, in fact, she may never know. 

In addition, the mother is usually close by, watching their young, so they would be aware of any interference.It is common for young birds to drop to the ground below while practicing flying, so if you find one there, it doesn’t necessarily mean that something has happened to its parents. 

The myth about the mother abandoning her young due to human contact is simply untrue and probably came about by well meaning adults scaring children into not touching the baby birds.

Photo by Imogen Warren

Final Thoughts

No, birds are not mammals. While they share some characteristics with mammals such as having feathers and laying eggs, they lack the defining features of mammals such as fur.


Are penguins really birds and not mammals?

Although penguins are flightless and live in the sea, they still lay eggs and do not produce milk for their young. They have feathers instead of fur and this all makes them birds and not mammals.

What is the weirdest mammal?

That has to be the Duck-billed Platypus. When the Europeans discovered it, they thought it was a hoax, that someone had stuck several different species together to make it.

Are bats birds or mammals?

Bats are the only mammal that flies and they have their own classification because they are so unique. They are mammals because they have fur, give birth to live young and feed them milk.

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