No, Birds do not fall under the category of mammals, they are avians. Birds do possess certain characteristics that are similar to mammals, such as being warm-blooded, possessing a vertebrae, or breathing through their nose, but still, they are not mammals due to a key difference – the ability to give birth to live young.
To understand this better, you need to go through the different characteristics that distinguish a mammal and a bird.
Why Birds are Not Mammals?
All the living creatures on the earth are scientifically classified under different classifications and birds fall under the Animal kingdom. When this category is subdivided, birds are classified as Aves, and Mammals are classified as Mammalia.
Based on prehistoric studies, it was found that birds and mammals have common ancestors, thus they might share certain common characteristics, but birds and mammals got split in the evolutionary tree a million years ago.
Thus, birds also breathe air, warm-blooded and some birds even feed milk to young ones (with exception). However, the rest of the characteristics that a creature needs to meet to fall under the category of mammals were not present in birds.
What are Mammals?
Mammals belong to the animal kingdom and have unique traits, such as –
- They have their entire body covered with fur or hair.
- Their heart has four chambers, a trio of bones present in the middle ear, a singular bone with a lower jaw, and the presence of a diaphragm.
- Mammals can regulate their body temperature and are warm-blooded. Thus, without getting affected by the season, their body temperature remains the same due to regulation.
- The female mammal gives birth to live young and also feeds them through their mammary glands.
These are a few of the most basic characteristics, and as the complexity of animals increases, so does the list of classifying characteristics.
What are Aves?
Birds are categorized as Aves and they have unique characteristics, such as –
- They lay eggs to reproduce offspring and do not give birth to live young.
- They have breaks which are alternative to jaws and these are shaped differently based on what they feed on.
- Instead of hair, they have features that help in insulation and flight. The design of the wings makes the bird take flight. However, there are also exceptions as some birds cannot fly and are flightless birds, such as Kiwis, Ostrich, and Penguins. Some birds also have scaled legs.
- Birds also have wings which are constructed of hollow bones and provide structural support.
- They also share a close relationship with reptiles and have a shared ancestry with dinosaurs. They are also classified in the category of Diapsida which includes the modern reptiles including crocodiles.
How Birds and Mammals are Similar?
Birds and mammals both are warm-blooded animals, i.e. endothermic animals. Both these categories of animals can regulate their body temperature. Thus, they can adapt to colder temperatures and do not need to change their location. Both have vertebrates or backbones. Both birds and mammals can breathe air, but there is a difference in lung formation.
Moreover, birds have a complex respiratory unit. They both have food-grinding capabilities. Birds and mammals both have four-chambered hearts and both are present across the globe be it in marine, terrestrial, or even harsh climates.
How Do Birds and Mammals Differ?
Let’s look at the difference between birds and mammals:
Outer Appearance
Birds have feathers, whereas mammals have fur or hair on their body. Birds have wings and even flightless ones, whereas mammals do not (with the exception of bats). Moreover, birds have beaks or bills whereas mammals have jaws. Birds have scaled legs, hollow bones, air sacs, and wishbones, however, mammals do not have any of these.
Physiological Difference
Birds have smaller hearts when compared to mammalian hearts which are bigger. Birds walk upright on legs and also swim using the legs but mammals cannot fly and some mammals walk on four legs. Mammals have a strong sense of vision, smell, and hearing. Birds only have strong eyesight and the smell and hearing senses are not quite developed. When compared with birds, mammals use less vocalization and mostly depend on non-vocal ways to communicate, such as body language and scent marking.
Food Habits
Mammals can be carnivores, herbivores, and also omnivores, thus having a broad diet range, due to variation in the presence of teeth. However, birds do not have teeth and they use beaks instead and can be classified as carnivores, herbivores, omnivores, insectivores, and more, based on the specific diet they consume.
Reproductive System
Birds lay eggs and mammals reproduce live young but both have to go through internal fertilization processes. Birds do not carry their offspring but mammals do carry the young ones after giving birth. Moreover, birds do not have any special glands to feed the baby, whereas mammals have mammary glands that produce milk to feed the young ones.
Other Features
Birds always form large flocks and stay together, mammals can either choose to live in social groups or in solitary. Birds live a long time, and some like parrots can even outlive mammals.
Which Bird is Similar to Mammals?
Kiwi, which is native to New Zealand, is a flightless bird and has small, pointy features. These form a coat and have bristles around the nose. Its feathers appear like hair and it is compared to hedgehogs and badgers. Being a flightless bird, it is also called an “Honorary mammal”.
