Are chickens mammals?

Chicken is one of the most enjoyable animals to keep and raise. They can eat many things that you throw at them, and they are not picky at all. The feeling can be as delightful as keeping a pet like a cat or a dog.

But, when you look at a chicken’s behaviors and appearances, you may be confused with lots of things about it; one of them is what family group of animal the chicken belongs to. So, are chickens mammals? Are they the same class as dogs and cats?

Further reading: Are chickens smarter than dogs?

Are chickens mammals?

Chickens are not mammals. They are in the bird family group, along with other poultry animals like geese, turkeys, and ducks. There are some differences that separate chickens from mammals.

It can be confusing once you take a more in-depth look at the chickens. They share a lot of similarities to mammal branches, or even reptiles. But there are certain behaviors and appearances that show chickens are not mammals.

Chickens are not mammals
Chickens are not mammals

The difference between chickens and mammals

Temperature control

Chickens are warm-blooded animals, just like mammals. This means they maintain their body temperature internally. But the ways both sides control temperature is quite different.

With chickens, they use their combs and wattles, which are located at the top and bottom of the chickens’ head accordingly, and their feathers to keep the temperature stable.

On the other hand, mammals use their sweat glands to keep their body cool and their hair to keep their body warm.

Taking care of offspring

In terms of how the offspring are raised, chickens don’t nurse their baby chicks, unlike mammals. Mammals can produce and provide milk to feed their babies, while chickens don’t.

Chickens do have some impacts on their baby chicks. Baby chicks’ first meal will remain the same for the rest of their lives. And they need their mother to show what is food and water, or they will die due to inadequate nourishment.

Chickens lay eggs

Chickens lay eggs, while mammals don’t, except for platypuses and echidnas. With chickens, the gestation for the potential chicks occurs outside of the hen’s body.

Unlike mammals, chicken’s fertilized eggs aren’t carried inside of the mother’s body during the development of the chicks.

While both types of eggs require an appropriate temperature to develop normally, chicken eggs are kept warm in the nest by the hens, not in womb-like mammals.

Also, chickens never hibernate. And while most mammals aren’t capable of hibernating either, some can like bears, ground squirrels, woodchucks, groundhogs,… usually in the winter to conserve energy.

Chickens are not mammals
Chickens are not mammals

Baby chicks have egg tooth when they are born

When gestation is complete, the mammal offspring will go through the birth canal and exit its mother’s body. With chickens, the chick is technically already outside of its mother’s body.

Now, the baby chick needs to break from the eggshell using its egg tooth, which is a small boney tooth hanging on the chick’s nose end. Once the tooth has done its duty of breaking the shell, it will fall off soon.

Chickens have feathers, not hair and scales

Feather is one of the features that differentiate the fowl species from other species, as well as from 1 breed of chicken to another.

The feathers on chickens are complex, unique, and have lots of shapes and colors. They help define a chicken breed or define a rooster from a hen. On the other hand, almost all mammals don’t have feathers, but instead hair or fur.

Chickens have beaks, mammal have something structurally similar

Another characteristic of chickens and birds, in general, is that they have beaks. While technically mammals don’t have beaks, they have somebody parts that share the same composition as a beak.

A chicken beak consists mostly of keratin. This substance doesn’t stop growing… ever, so it is suitable for the body parts that wear out often.

For a chicken, that body part is its beak. In the case of mammals, those are nails, horns, hooves, and human skin.

Chickens have less dense bones than mammals

Chickens and birds have hollow bones compared to mammals to utilize strength and weight. Birds need hollow bones so that they can fly more efficiently. Most mammals can’t or don’t need to fly in their entire life, so their bones are dense for better ground movements.

Although chickens are bad at flying, they still share some similar body structures to that of birds. They have air sacs that fill up and deflate depending on the airflow coming from the respiratory system.

Even more so, the air sacs can reside inside the bones. They basically fill up the bones with air and put pressure on the bones. This effectively strengthens the bones without adding weight.

Are chickens reptiles?

Chickens are not reptiles. Although reptile share some similarities to chickens, like laying eggs, or presumably having hollow bones, here are some differences to differentiate reptiles and chickens

  • Reptiles are cold-blooded, which means they can’t control their body temperature and it is affected by the environment. Chickens are warm-blooded.
  • As a result, when it is too cold, reptiles will hibernate, while chickens never hibernate.
  • Reptile skeletal structure is different from that of chickens.


So, are chickens mammals? No, chickens are not mammals; they belong to the bird family group, as well as their fellow poultry animals like geese, ducks, and turkeys.

It can be confusing to tell where chickens belong in the animal world, but there are certain differences that define chickens or birds in generals.

Some of the differences include: what chickens use to control temperature, how they take care of their baby chicks, egg tooth in baby chicks, feathers vs. hair or scales, beaks, and hollow bones.

Also, chickens are not reptiles either. They are warm-blooded, they never hibernate due to low temperatures, and their skeletal structure is different.


Image credits – Photo by Kimberly Lake, Kim Gorga on