How do feathers work?
Feathers are the magic material that cover the bodies of all birds and help them to fly. But they're not just for flight. Feathers are fantastic for keeping warm, which is why even flightless birds such as ostriches have them.
Feathers up close
Feathers are made of lightweight material called keratin just like our fingernails. Muscles attached to the base of each one allow the bird to move it around.
Feathers have to handle a lot of wear and tear, so each year birds grow a new set to replace the old ones. This is called moulting. Some birds moult once a year; others do it twice.
Each feather has a central hollow shaft, with a flat area either side called the vane. The bare part at the base of the shaft is called the quill. A vane is made up of many small side branches, all linked together by even smaller branches with hooks, called barbules.
A bird keeps its feathers tidy by ‘zipping up’ the barbules with its bill. Look closely at a feather yourself; see if you can unzip it, then zip it up again.
Colour and care
Some feather colours are made up by pigments produced in birds’ bodies or in their food (greys, browns, reds and yellows).
A flamingo’s pink comes from the tiny plankton that it eats. Others, such as green and blue, are made by the way light shines off the surface feather structure. This is called refraction.
Birds like to keep their feathers clean. They bathe regularly, and use their beak to rearrange them in the right shape and order. This is called preening.
At the same time, they spread a special oil over them from a gland on their back, called the preen gland. This oil is what makes ducks and seabirds waterproof.
The big, stiff feathers on a bird's wings and tail are called flight feathers. These give it the push it needs for flying.
Flightless birds have no proper flight feathers with their feathers being limp and floppy.
Feathers are arranged in lines and patterns, each with a different name. The long flight feathers are called primaries, the shorter flight feathers are called secondaries, and the small feathers that cover their bases are called coverts. Learning the names of these different feather areas helps you to describe the birds you see.
The smaller feathers that cover a bird’s body are called contour feathers. They lie flat against its body to protect it from wind, cold and sun. They also give the body a smooth, streamlined shape for flying.
Birds are warm-blooded, and have to keep a body temperature of about 40°C. Under their contour feathers are tiny soft feathers called down, which lie against the skin and keep the bird warm.
Down is great at keeping in warmth, with people using it to make quilts and duvets.
In cold weather, a bird also fluffs out its contour feathers to trap a layer of warm air.
The look of the feathers can be just as important as what they do.
Some birds such as the nightjar use their feather patterns for camouflage with their feathers looking like dead leaves.
Others, such as the peacock, use them to impress a female with dazzling displays such as the rump of the peacock.