Have you ever heard the old saying, “Birds of a feather flock together"? But what if birds had fur? Would they flock togeth…ur? No, that doesn't sound right! I guess it's a good thing birds have feathers.

Birds seem to think so. Feathers are unique to birds. In fact, you might say they're one of the bird's defining characteristics. If it's got feathers, it's a bird. If it's a bird, it's got feathers.

Are feathers merely the equivalent of bird clothes? Or do they serve other purposes? As a matter of fact, scientists and bird lovers can tell you that feathers serve several important purposes for birds.

Feathers are a bit like clothes for birds. Birds certainly aren't concerned with the latest fashions, but they do like to stay warm. As warm-blooded creatures, they must keep their internal body temperature carefully regulated.

Feathers help birds to do this by providing insulation. Some birds have special feathers that keep them both warm and dry. Consider the penguin's special feathers that keep these flightless birds warm and dry in the coldest of conditions.

Of course, feathers also allow birds to do one of their favorite things: fly. Without their aerodynamically-designed feathers, birds would be waddling around on the ground like the rest of us! (Of course, don't mention this to penguins, since they're still a bit touchy about the whole flight thing…)

Although birds don't worry about fashion, the colors of their feathers can have an impact on how easy it is for them to find mates. Many bird species feature marked differences between the coloring of males versus females. More brightly-colored birds may find mates more easily.

While the coloring of some birds may attract other birds, sometimes feathers help make birds invisible…at least to predators. In this way, feathers can serve as camouflage. For example, the winter feathers of the Willow Ptarmigan are pure white. This helps the bird to blend in with its snowy surroundings and avoid predators.

Scientists think bird feathers may have evolved from scales like you'd find on a reptile. This view is supported by the fact that some birds still have scales on their lower legs and feet. As feathers began to develop, they took on a few different forms.

For example, the largest feathers on a bird are called contour feathers. These include the flight feathers and the tail feathers. They give birds their shape and color.

Underneath the contour feathers are soft, fluffy down feathers. Down feathers provide most of the insulation birds need to stay warm. They're so good at this that humans have used them for many years in down jackets and feather pillows.

A few other types of feathers found on many birds include semiplumes, filoplumes, and powder feathers. Semiplumes are like a cross between down and contour feathers. They provide insulation while helping to maintain a bird's shape.

Filoplumes are the simplest feathers. Hair-like and usually stiff, filoplumes sit under the contour feathers. They feature sensory receptors that help birds understand what's going on with their contour feathers.

Powder feathers can be found on certain birds, such as pigeons and herons. They grow continuously and disintegrate at their tips into a fine powder. The function of this powder is not completely understood, but some scientists believe it may help with waterproofing.

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