Birds Birds are vertebrates (animals with backbones) with wings and feathers. Most birds can fly, using powerful muscles to flap their wings.

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1 Birds Birds are vertebrates (animals with backbones) with wings and feathers. Most birds can fly, using powerful muscles to flap their wings. But a few bird speces do not have strong enough wings to fly, and so these birds are flightless. Birds bidoes are covered with a light, tough lyer of feathers and they have very light skeletons. Instead of teeth, they have hornlike beaks, or bills. Birds hatch from eggs, and many species build nests where their egs and young can develop in safety.

2 Feathers Shaft Vane Barbs Shaft Afterfeather Barbs Afterfeather Quill

3 Nests Many bird species lay their eggs in shelters called nests. They provide a safe, warm place for the parent bids to care for their eggs and chicks, hidden from predators and protected from bad weather. Different birds make their nests using different materials. Some gather sticks, grass, and leaves, while others use tree branches, mud, stones, or even their own saliva. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. The smallest bird nests are those of some hummingbirds, tiny cups which can be a mere 2 cm (0.79 in) across and 2 3 cm ( in) high. At the other extreme, some nest mounds built by the dusky scrubfowl measure more than 11 m (36 ft) in diameter and stand nearly 5 m (16 ft) tall. Not all bird species build nests. Some species lay their eggs directly on the ground or rocky ledges, while brood parasites lay theirs in the nests of other birds, letting unwitting foster parents do all the work of rearing the young. Although nests are primarily used for breeding, they may also be reused in the non-breeding season for roosting and some species build special dormitory nests or roost nests (or winter-nest) that are used only for roosting.[3] Most birds build a new nest each year, though some refurbish their old nests. [4] The large eyries (or aeries) of some eagles are platform nests that have been used and refurbished for several years.

4 Eggs Fun Fact: In weight, one ostrich egg is equal to 4,700 eggs of the bee hummingbird. Birds begin life inside hard-shelled eggs, laid by the female. The young bird grows from a single cell into a chick, protected by the eggshell. When it is ready to survive in the outside world, it cracks open the shell and hatches out. The egs must be kept warm while the young bird develops inside, so the parent birds often sit on them to protect them from the cold Birds of different species produce eggs of all colors and sizes. Most birds lay more than one egg at one time, and together these are known as a clutch. Birds begin life inside hard-shelled eggs, laid by the female. The young bird grows from a single cell into a chick, protected by the eggshell. When it is ready to survive in the outside world, it cracks open the shell and hatches out. The egs must be kept warm while the young bird develops inside, so the parent birds often sit on them to protect them from the cold Birds of different species produce eggs of all colors and sizes. Most birds lay more than one egg at one time, and together these are known as a clutch. Birds begin life inside hard-shelled eggs, laid by the female. The young bird grows from a single cell into a chick, protected by the eggshell. When it is ready to survive in the outside world, it cracks open the shell and hatches out. The egs must be kept warm while the young bird develops inside, so the parent birds often sit on them to protect them from the cold Birds of different species produce eggs of all colors and sizes. Most birds lay more than one egg at one time, and together these are known as a clutch. The egs must be kept warm while the young bird develops inside, so the parent birds often sit on them to protect them from the cold Birds of different species produce eggs of all colors and sizes. Most birds lay more than one egg at one time, and together these are known as a clutch.

5 Flying Birds fly by flapping their wings. Flight involves moving upward, against the force of gravity, and forward too. The power for this comes when the massive chest muscles pull the wings down. These muscles are 10 times bigger than the muscles that pull the wings back up. The size and shape of the wings affect the way a bird flies. A swift s pointed wings help it to dart about at great speed, while the very long wings of an albatross enable it to glide with little effort. Smaller birds usually have more rapid wing beats than bigger birds, but this uses up more energy. Tiny hummingbirds, fueled by energy-rich nectar, buzz around with such skill that they can hover in midair and even fly backward. Swift Bird Birds fly by flapping their wings. Flight involves moving upward, against the force of gravity, and forward too. The power for this comes when the massive chest muscles pull the wings down. These muscles are 10 times bigger than the muscles that pull the wings back up. The size and shape of the wings affect the way a bird flies. A swift s pointed wings help it to dart about at great speed, while the very long wings of an albatross enable it to glide with little effort. Smaller birds usually have more rapid wing beats than bigger birds, but this uses up more energy. Tiny hummingbirds, fueled by energy-rich nectar, buzz around with such skill that they can hover in midair and even fly backward. Birds fly by flapping their wings. Flight involves moving upward, against the force of gravity, and forward too. The power for this comes when the massive chest muscles pull the wings down. These muscles are 10 times bigger than the muscles that pull the wings back up. The size and shape of the wings affect the way a bird flies. A swift s pointed wings help it to dart about at great speed, while the very long wings of an albatross enable it to glide with little effort. Smaller birds usually have more rapid wing beats than bigger birds, but this uses up more energy. Tiny hummingbirds, fueled by energy-rich nectar, buzz around with such skill that they can hover in midair and even fly backward. Birds fly by flapping their wings. Flight involves moving upward, against the force of gravity, and forward too. The power for this comes when the massive chest muscles pull the wings down. These muscles are 10 times bigger than the muscles that pull the wings back up. The size and shape of the wings affect the way a bird flies. A swift s pointed wings help it to dart about at great speed, while the very long wings of an albatross enable it to glide with little effort. Smaller birds usually have more rapid wing beats than bigger birds, but this uses up more energy. Tiny hummingbirds, fueled by energy-rich nectar, buzz around with such skill that they can hover in midair and even fly backward. Birds fly by flapping their wings. Flight involves moving upward, against the force of gravity, and forward too. The power for this comes when the massive chest muscles pull the wings down. These muscles are 10 times bigger than the muscles that pull the wings back up. The size and shape of the wings affect the way a bird flies. Fun Fact: Hummingbirds can stay in one place in the airby beating their wings times per second.

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