Mary Allen
Birds are vertebrates, as are mammals, fish, reptiles, and amphibians. Birds have two legs and two arms, which are wings. Instead of fur, birds have feathers. The feathers are made of keratin. Other animals use this material to make horns, claws, or hair. For humans, it’s their hair and fingernails.
Most birds can fly thanks to their wings and feathers. Some, on the other hand, can run fast, like the African ostrich. It’s also the biggest bird ever. Penguins are birds that cannot fly, but they can swim very well.
A bird also has a beak without teeth. However, some birds have prongs in their beaks, which they use to grab something similar to teeth. New little birds are not born, but hatch from eggs. Female birds often lay such eggs in a nest built for them, or on the ground, for example. Most birds incubate their eggs. This means they sit on the eggs to keep them warm and protect them until the little ones hatch.
Otherwise, birds can be very different. Some live in the dry desert, others in the Arctic or Antarctic. Some eat meat, others grains. The bee elf is the smallest bird, it’s a hummingbird. The largest bird that can fly is the kori bustard from Africa.
The birds descended from the dinosaurs. However, science is still not unanimous about exactly how this works. The closest living relatives of birds are the crocodiles.
Here is an overview of all Klexikon articles about birds.
How is the digestion of the birds?
Birds have a stomach and an intestine. Digestion is therefore very similar to that of mammals. Some bird species eat stones. They remain in the stomach and help to crush the food. This is how the chicken does it, for example.
There is a difference in the urine, which is also called urine. Birds have kidneys like mammals, but they don’t have a bladder. They also don’t have a special body outlet for peeing. The urine from the kidneys flows through the ureters into the intestines. There it mixes with the feces. That is why the droppings of the birds are usually vicious.
The body outlet in birds is called the cloaca. The female also lays her eggs through the same opening. The male’s sperm also flow through the same opening.
How do birds reproduce?
Many birds have specific times when they want to have young. This depends on the season and can happen once or several times. However, other birds are independent of this, for example, our domestic chicken. It can lay eggs all year round.
When a female is ready to mate, she stands still and flicks her tail up. The male then sits on the female’s back and rubs his cloaca on the female’s. Then his sperm flow into the female’s body and fertilize the eggs.
The male’s sperm can live in the female’s body for a long time and repeatedly fertilize eggs there. Bird eggs get a hard shell. Most birds lay several eggs in one nest. Sometimes the mother bird incubates the eggs, sometimes the father bird, or both alternately.
The chick grows an egg tooth on its beak. That’s a sharp elevation. With this, the chick pushes holes in the eggshell in a row. When it then spreads its wings, it pushes the two halves of the shell apart.
There are young birds that leave the nest immediately. They’re called precocial. They look for their own food from the start. This includes, for example, our domestic chicken. Other chicks remain in the nest, these are the nest stools. The parents have to feed them until they fly out, i.e. fledge.
What else do birds have in common?
Birds have the same heart as mammals. It has four chambers. On the one hand, the double blood circulation leads through the lungs to take in fresh oxygen and release carbon dioxide. On the other hand, the cycle leads through the rest of the body. The blood carries oxygen and food throughout the body and takes the waste with it.
The heart of birds beats much faster than that of humans. The heart of the ostrich beats three times as fast, in the house sparrow about fifteen times as fast, and in some hummingbirds even twenty times as fast as in ours.
The body of most birds is always the same temperature, namely 42 degrees Celsius. That’s five degrees more than ours. Very few bird species cool down a bit during the night, the great tit for example by about ten degrees.
The birds do not have a larynx with vocal cords. But they have something similar, namely a tuning head to shape their sounds.
Many birds have a special gland called the preen gland. This allows them to secrete fat. They coat their feathers with it so that they are well protected against water. The preen gland is at the end of the back where the tail begins.