Tuesday, August 30, 2011

Why Do Birds Have Feathers?

Feathers are birds most important feature since, unlike birds, no other animal possesses them. The first living beings to develope feathers did so 150 million years ago. Archaeopterix is the best example.

Its skeleton was more similar to that of reptiles, with teeth and a tail, something that no bird has. But the sternum lacked the keel shape that birds have today, so they could not have the muscles necessary to fly. However, its feathers were identical to those we know today.

Feathers come in many shapes, sizes and colors. But in general, they all share a similar structure. They display a hollow longitudinal axis called rachis onto which the barbs are inserted from the surface of the feather.

Seen through the microscope, these barbs branch into barbules which are interlocked like a zipper. Confronted with such complexity, one question arises: What is the purpose of feathers?

It may seem obvious that the role of the feathers is to enable flight. They are rigid, lightweight, with an unbeatable aerodynamic shape. But are they good for something else?

Yes, most definitely.

When temperatures drop, feathers separate trapping air in-between them. This air is kept warm and acts as an insulating layer that prevents heat loss. This mechanism is so effective that even we humans use it in the manufature of coats and quilts.

Feathers are also waterproof. They provide protection against rain so that the animal doesn't get cold. For waterfowl, impermeability must be total, since they are in constant contact with water. If the body was to get wet, the bird would quickly cool down and might die.

The case of cormorants illustrates this point. Their plumage is not completely water proof, so when they get into the water their feathers get soaked. They absorb so much water that the weight makes their take-off to fly too difficult.

The solution that cormorants find to this conundrum is as uncomfortable as effective: they spread their wings and dry them in the sun. Sometimes shaking also helps.

For owls, the noise caused by flying could easily become a problem. But the surface of their feathers is smooth and hairy. In addition, small teeth in the front border lower the friction between them. This is how they manage to fly silently and are able to hunt without being detected.

All these essential functions make feathers a treasure to take care of. Frequent toileting and bathing are essential.

But no matter how much they care for them, feathers are made up by dead cells and keratin. They will wear off over time: the old must be discarded and replaced with new ones.

Birds of prey cannot afford to have their ability to fly undermined since they depend on it for hunting. This is the reason why they change their feathers in an orderly fashion throughout a two -year period. Thus, there can be three generations of feathers co-existing at any one time in the same animal.

Ducks are an altogether different case. These birds change their flight feathers all at once during the so-called "molting" period. Unable to fly, they look for the protection of large groups in remote locations.

The reason ducks lose all their feathers at once is that they change them twice a year. And so they have winter plumage, in which male and female are almost indistinquishable... and a summer plumage in which the male is totally different.

Be it as it may, all birds shed their feathers and leave them behind wherever they go. It is time we begin to regard feathers not as waste, but as the engineering feat they really are.

Article courtesy of www.wild-bird-watching.com

Grab The Bookmarketer For Your Site

No comments:

Post a Comment