Are Birds Mammals? Explaining Their Animal Classification

Quick Answer:

• No, birds are not mammals . They are considered avians.
• Birds aren’t considered mammals even though many of them are warm-blooded and breathe oxygen.
• Mammals give birth to live young. Birds, on the other hand, lay eggs.

Birds are not mammals , but avians. Unlike mammals, they do not have fur or hair — instead, they have feathers, though sometimes they possess bristles on their heads or faces that resemble hair. They are not mammals even though they are warm-blooded, breathe air, and possess vertebrae, which are other mammalian characteristics.

They’re not mammals even though some species gather in flocks for foraging, hunting, childrearing, and protection the way mammals do in herds.

Birds exclusively lay eggs . Some, like chickens , can even lay eggs without a male, but those eggs are infertile. No bird gives live birth. Many are intensely protective of their young, but (and this is the big thing) no bird nurses its young with milk the way mammals do.

But Don’t Pigeons Feed Their Babies With Milk?

Pigeons and doves don’t feed their babies with milk, even though it may look like they do. Pigeon “milk” is a substance that’s made from fat and protein-rich cells that line the parents’ crop, which is a pouch found in the throat that stores food before it’s sent to the rest of the gastrointestinal tract to be digested.

Like the milk produced by mammals, it not only has proteins and fats but antioxidants, antibodies, and helpful bacteria. It is even controlled by prolactin, the hormone that controls mammalian lactation.

But crop milk is semi-solid, not liquid, and it isn’t delivered through teats, secreted from patches like it is for the echidna , or in grooves like it is for the platypus . It is regurgitated from the parent to the squab. The squab is fed crop milk exclusively for the first week after it hatches. Flamingos and emperor penguins also feed their chicks with something like crop milk. By the way, both the mother and the father produce crop milk, another thing that makes them different from mammals. Only female mammals produce milk for their young.

How Do Birds Take Care of Their Young?

Chicks are born naked, blind, and helpless and need at least one parent to protect them, feed them and keep them warm 24 hours a day for a surprisingly long time. The great frigatebird , for example, takes care of its chicks for nearly two years.

Squabs are first fed crop milk while other chicks are fed soft-bodied insects or bits of other prey such as small mammals, reptiles, and birds that are smaller than their parents or part of the parents’ regurgitated dinner. Even after some chicks fledge, or start to grow feathers, they will demand that the parent feed them for several weeks. Some chicks are so labor-intensive to raise that not only do both parents do it, but they enlist the help of their previous brood of chicks.

On the other hand, the chicks of scrubfowls and brush turkeys are independent almost from birth, and they don’t need any parental care at all. Others such as the cuckoo simply lay their eggs in another bird’s nest and hope it doesn’t notice. Interestingly, the foster parents often do not notice, and there are many pictures of some tiny bird delivering food to a chick that’s already twice its size and has managed to kill off all the biological offspring.

Birds do not carry their children around like mammals do, they keep them in nests until they are able to fly. Some nests are hidden in trees, houses, or underground. Baby birds start out naked without feathers and need warmth of mother birds to keep warm. Eventually, they sprout baby feathers and later grow adult feathers.

More Reasons Why Birds Aren’t Mammals

Another thing birds have, that most mammals don’t, are wings. Not every bird can fly. In some cases (as with the emu ) their wings are vestigial. The only mammals that have proper wings are bats . Bats can actually outmaneuver birds because their wings are actually their hands.

Birds are the only living therapod dinosaurs, and many scientists actually consider them a type of reptile . They are younger than reptiles or mammals, having appeared about 140 million years ago. The asteroid that killed off the other dinosaurs 60 million years ago allowed birds to diversify into a dazzling array of forms, from the tiniest hummingbird to the 9-foot tall ostrich .

Another thing that separates avians from mammals is their skeletons. Birds have hollow places in their bones that allow them to fly, which is why even the tallest ostrich only weighs about 286 pounds even though it gave up flying a while ago.

Up Next:

• 13 Fun Facts About Animals
• 9 Animals That Fly (That Aren’t Birds!)
• Discover 7 Animals That Glide

The post Are Birds Mammals? Explaining Their Animal Classification appeared first on A-Z Animals .