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Birds are members are the Aves family and are not mammals. Mammals are classified as species that have hair, give birth to live young, and that feed milk to their young. In contrast, birds have feathers rather than hair and they lay eggs rather than give birth to live young. There are a group of birds that are sometimes referred to as honorary mammals, but these are still not truly mammals.
For any animal to be considered a mammal it must have certain species characteristics. The animal must have hair and any animal that has hair is classed as a mammal. Virtually all mammals, apart from a small handful, give birth to live young, and the mothers feed their live young on milk. The milk is produced by mammary glands, which is where the name mammal actually comes from. There are believed to be nearly 6,500 species of mammal in the world today.
Birds are classified as part of the Aves class. This means that, among other characteristics, they have feathers. They do not have teeth but do have beaks and they lay eggs.
It is worth noting that a class of mammals called monotremes actually lay eggs, although the eggs have a softer shell than those belonging to birds.
There is a small group of birds, called ratites, that are sometimes referred to as being honorary mammals. The kiwi is one example of these five species.
These unusual bird species do lay eggs and do not produce milk, but they have bones that are more like mammalian bones than bird bones, they have a similar body temperature, and they have whiskers on their face as well as a plumage that is similar in texture and appearance to hair. All five species originate in New Zealand, where there were no land-dwelling mammals until they were introduced by Europeans in the 1800s.
Related Read: How Many Species of Birds Are There in the World?
The duck-billed platypus is one of the most unique and unusual animals in the world. It is classified as a mammal although it could arguably have its own family of animals.
It has stingers that can deliver a toxin to its prey, which is very rare in the mammalian kingdom. The platypus also lays eggs, which would normally exclude it from the mammalian definition. These eggs hatch between seven and ten days. The platypus does not have nipples but does produce milk and excretes it via sweat glands so that their young can consume it.
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Birds are part of the Aves family and are not considered mammals because they do not have hair, they do not give birth to live young, and they cannot produce milk.
There is a small number of birds that are sometimes referred to as honorary mammals but are still not scientifically considered mammalian, while there are some species of wild animal that are so unusual that they defy typical definition. The duck-billed platypus, for example, shares some traits with birds and reptiles, and some with aquatic animals, but because it has hair and produces milk to feed its young, the egg-laying Australian animal is classified as a mammal.
Looking for more interesting facts about birds? Check out our list of birds with the largest wingspans in the world
Featured Image Credit: Pixabay
Robert’s obsession with all things optical started early in life, when his optician father would bring home prototypes for Robert to play with. Nowadays, Robert is dedicated to helping others find the right optics for their needs. His hobbies include astronomy, astrophysics, and model building. Originally from Newark, NJ, he resides in Santa Fe, New Mexico, where the nighttime skies are filled with glittering stars.
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