what makes a bird a bird. It's perfect for flying, is great for keeping warm,
and comes in so many colors and patterns. Maybe the most amazing thing about
feathers is that they're made out of the same stuff as your toenails.
The down filling in down comforters or down jackets
is feathers. Both a polar bear's fur and a penguin's down feathers are great
insulators, allowing these animals to survive in very cold conditions.
Down feathers don't have the barbules
that allow a feather to "zip up" so instead of holding a
firm shape, down feathers are fluffy. This makes them great insulators,
because they trap air in their tiny spaces.
Most chicks are born covered in down, but even adults keep some down
feathers on their body, underneath other feathers.
These contour-shaped feathers are designed for flight.
Each barb of the main shaft has barbules that allow it to zip up with the
barb next to it. So, the feather makes a stiff, light airfoil. Birds preen
to "close the zippers" so that they can fly efficiently.
The close-up above shows how the
barbules on flight feathers interlock to make a single strong surface
that is still incredibly light.
Compare the two feather at left. The white one belongs to a flightless
bird (a rhea). It doesn't have any barbules, so it looks more like
a down feather than a flight feather.
A feather is a great billboard for attracting mates.
Color and pattern are also useful for camoflage which helps some birds avoid
predators and helps others sneak up on their prey. A peacock's tails and deer's
antlers do the same job to attract a mate.
Not all colored feathers are actually
colored. The pheasant feather at left is a beautiful pattern made
of different colored pigment.
But the parrot feather above isn't actually blue! It gets its color
from the way light hits it and refracts off it the same way
colors appear on soap bubbles.