The reasons that this question might have sprung up are very obvious. There’s a great deal of similarity between birds and what is commonly understood to be a mammal.
So, are birds mammals? No, You Birds are not mammals as they belong to a different class called Aves, which is related to reptiles rather than mammals. Mammals have a different class called Mammalia. Coming to the fact, mammals are the only animals having hair whereas birds are the only living animals having feathers.
Both categories of animals have analogous organs and characteristics but there are very distinct differences too which we will discuss in this article at length.
First, let’s have a look over the similarities that bode all the confusion about birds being mammals.
Similarities Between Birds and Mammals?
- They are both endothermic (hot-blooded) organisms that both have an inner mechanism regulating their body temperature that makes them fit for thriving in an even adversarial cold climate and unlike amphibians and reptiles, they do not need external stimuli to heat up their bodies.
- Both have a sophisticated and complex respiratory system with lungs playing a central part however in birds, air sacs play a vital role in addition.
- Both have a four-chambered heart which means their hearts consist of a right and left atrium and right and left ventricle and birds’ cardiovascular system functions more or less on the same lines as that of mammals.
- Both are vertebrae i.e., both have a skeletal system while in the case of birds, the bones are hollow which justifies their ability to venture into flights.
Isn’t that an overwhelming volume of similarities? That perhaps explains why is the question so prevalent. Now, let’s delve into whether birds are mammals or not?
Characteristics Of Birds?
A straight answer to whether birds are mammals would be no. Birds belong to a whole different class of animals called Aves. Sounds jargonish? Ok, let me clarify it for you.
Biologists have categorized the whole amount of fauna available on the planet into a system that is called animal classification.
This system has categorizations, sub-categorizations, and several horizontal and vertical branches. These categories widely are kingdom, phylum, class, order, family, genus, and species.
These divisions are based on certain shared characteristics that effectively mean that all the animals sharing the same phylum have a binding trait that has caused them to be clubbed under one head.
The characteristics start becoming more specific as we move down lower in the classification chart.
Characteristics Of Mammals?
We must understand what being a mammal entail? Since that’s only how we will be able to tell them apart from the birds? The defining characteristic of all mammals is the possession of mammary glands. Yes, these are the very glands that are responsible for secreting milk in humans.
If at all you are wondering why I said humans when commonly you believe it to be true for just females, the truth is that all mammals possess these regardless of sex.
In humans too, both males and females have mammary glands but they are not active in males because their brain doesn’t secret a particular hormone that signals mammary glands to start operating.
Besides the possession of mammary glands, another major mammalian characteristic is giving birth to their young ones. There exist a few exceptions such as the duckbill platypus which lay eggs but their eggs are distinct in the sense that they do not have a hard coating as that of avian eggs, which is the category that birds belong to.
All mammals have hair. Hair has an insulating purpose which is they regulate the body temperature. That is the reason you see animals in freezing cold climates develop a thicket of hair such as in the case of a polar bear or a Siberian husky.
What class then do birds belong to?
Birds belong to the class Aves, not the class Mammalia to which all the mammals belong. But the interesting thing to note is that they have the same phylum which explains the myriad similarities they exhibit.
Looking at the classification chart tells that these respective classes split at some juncture of biological evolution, and went on to acquire different physical and anatomical traits that put them in the different categories that we learn today.
Characteristics of Aves?
The defining feature of avian physiology is that avians lay eggs. Female birds lay eggs which are then fertilized by their male partners and then incubated which hatch to let the little ones out. These eggs are encased in a protective hard coating of calcium carbonate.
Another prominent feature that is crucial to mention in explaining the distinction between birds and mammals is that birds do not have teeth. They swallow their food directly and in particular cases, their beaks are even customized as per their dietary requirements so that they can break their food into little pieces.
For example, the robust pointed beak of a woodpecker facilitates it to probe for insects in the hard bark of trees.
Birds instantly shove their food down in the crop located at the end of the esophagus in the gastrointestinal tract to either store it for nursing or microbial action.
Birds are surrounded by a cloak of feathers that do not only serve the function of insulation as hair does in mammals, these feathers help avians fly.
Though there are exceptions in the form of examples of flightless birds such as penguins and ostrich that is more a result of climatic adaptation and not a group anomaly.
Interesting thing is that both feathers and hair are made up of a similar protein called keratin.
Differences Between Birds and Mammals (Do Both Lay Eggs?)
Similar as it is with similarities, the differences between avians, birds specifically, and mammals abound. These differences cover various aspects such as reproductive, gastrointestinal, anatomical, and behavioral.
The reproductive systems of birds are comparatively less developed than that of mammals. Birds have a single ovary whereas mammals generally possess two.
Moreover, mammals bode their progenies through live births while birds lay eggs with a hard-shell coating.
In the case of monotremes which are an exception in mammals and lay eggs, their egg coating is soft and not hard and as protective as of avian.
Birds do not chew their food; they directly swallow, unlike mammals who have a full-fledged teeth system that forms a primary part of their digestive system. This is because birds need to nurse their babies who hatch out of eggs while mammals use their mammary glands to feed their babies.
Mammals’ bodies produce milk which is organic nutrition while in the case of birds, parents prey and gather food and disgorge it in their babies’ mouths until they develop adequately to hunt for themselves.
In mammals, insulation is done by the hair while birds grow a blanket of light feathers around their bodies which not only regulates temperature but contributes to their ability to fly.
Birds are anatomically designed in all ways whether it’s their hollow skeletal system to their powerful respiratory system courtesy of an enormous number of air sacs to fly whereas mammals are devoid of this capacity.
Why birds aren’t mammals?
One thing birds have is the wing. Some birds don’t have wings. Some of these wings are vestigial with EMU. The only animal with wings is Bat.
Bat wings are hand-made wings that make the wings more powerful than a bat. Birds can be found as the only live Therapod dinosaur species, and they are considered reptiles.
The dinosaur and other animal species were first found 145 million years ago.
Using asteroid X-ray technology 60 million years ago the avians were able to develop diverse species.
Conclusion – Are Birds Mammals?
No, birds are not mammals. They form a category of their own which is called Aves. Comparatively, they are closer to amphibians or reptiles since they are all descendants of a common ancestor archosaurs but with mammals, they cannot be claimed to even be distantly related.
Frequently Asked Questions
Is a bird a mammal?
Birds are not mammals, they are just birds. Mammals have hair and fur which is not similar to feathers. Sometimes you might see hair on the heads and face of birds but that don’t make a bird a mammal.
Is a bird a reptile or a mammal?
Birds are neither reptiles nor a mammal, they belong to a separate class called Aves. However, it is easy to find out some mammalian characteristics in birds but that does not make a bird or a reptile.
What are birds considered?
The birds in the kingdom of Animalia belong to Phylum Chordata, the classes Ves. Although these classifications might appear to be artificial, these general groupings emphasize that birds are connected by many of their traits.
Is a bird a mammal Why?
A bird is not in the mammal’s category and rather belongs to the ave animal group. Birds and mammals have many similar traits which don’t make anyone confused but there are several differences.