The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, May 14, 2006

The Importance of Feathers
by Ro Wauer

A recent article in Birder's World, one of the better birding magazines that I subscribe to, has an excellent article titled "What Feathers Do." Since I am constantly on the lookout for good ideas for my nature notes, this one struck me as not only a good one but very pertinent, as well. Our springtime bird migration has just about ended, and those of us who appreciate birds are still excited about what we saw.

Author Peter Stettenheim listed 23 feather functions. Although many, such as flying, shielding body parts, repelling water, and used as nesting material, are obvious, most are not so distinct. The 23 functions, listed in his order, include: conserving body heat, regulating body temperature, shielding body parts, repelling water, flying, swimming and diving, floating, snow-shoeing, tobogganing, bracing, feeling, hearing, making sounds, muffling sounds, foraging, ensuring food supply, keeping clean, aiding digestion, constructing nests, transporting water, sending olfactory signals, eluding predators, and sending visual signals.

A bird's feathers not only shields the soft body parts, but they also conserve body heat and regulate body temperature, especially important for birds in very cold and very hot climates. Feathers serve as marvelous insulation; when the feathers are erected, they allow warm air near the body to escape. And during rainy periods they are held in position to allow water to run off. This works best for those species that preen their feathers, arranging their feathers in an interlocking position as well as providing a valuable cleaning function. And water birds in particular coat their feathers when preening with oil from their uropygial gland. A few water birds such as the anhinga, however, do not have sufficient oil and must stretch out their wings to dry their feathers after fishing. Many water birds that chase prey underwater possess unique feathers that are stiff but smooth to reduce drag when moving through the water. And some are able to retain air in the downy layer for buoyancy and insulation.

Many birds of the snowy north have feathered toes that help them get around in deep snow, acting like snowshoes. And some of these same northern birds possess overlapping belly feathers that are firm and slick for sliding across snow on their bellies instead of walking.

Most owls possess feathers about their ears, a facial disc that helps their hearing. Their posterior ear coverts are movable flaps of skin that are positioned to catch sounds and determine their direction. And an owl's flight feathers and body contour feathers have a soft texture that muffle the sound of passing air and of rubbing against each other in flight. And on nocturnal owls, their outer flight feathers are fringed to lessen the sound of air turbulence.

Two of our local birds are good examples of using feathers while foraging. Reddish egrets hold their wings over their feeding sites, thus shading the water to better see prey, and mockingbirds often flick their wings out to startle prey into making a move. And what about the many bird species that use feathers to aid digestion? Grebes are good examples, as these fish-eating species swallow their own feathers, which decompose into a soft material to line their gizzards to protect it against sharp fish bones. Undigested remains are regurgitated periodically as pellets, filled with remains and feathers.

Grebes, ospreys, peregrines, and several shorebirds actually transport water to cool their nests during hot weather. These birds soak their belly feathers that are modified to increase their capacity for holding water and to withstand repeated wetting and drying.

And we all are fully aware that feathers provide significant visual signals that might be helpful during courtship or frightening off predators. Think of the red coverts of red-winged blackbirds, the white patches of mockingbirds, the head plumes of various quail, and various gorgets of hummingbirds. Without feathers birds would not be birds, and the world would be a sad place without them.


At 8:05 AM, Anonymous Anonymous said...

Here is a video explaining how feather arrangement on the wing makes the flight possible.


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