Lookin' Good in a Survival Suit!
By Dr. Bob Bailey
The only thing that comes between a duck and the real world are feathers. But protecting a duck’s tender body from sun, rain, sleet and ice is only one function of the feathers, or the plumage covering a bird. Plumages have to solve a bunch of problems for ducks, and unlike humans, they can’t just go to the closet and select the right clothes for the occasion. For example, too much and too little heat is a continual challenge for waterfowl because they have to retain a high, constant body temperature. A duck may need to insulate against heat loss on a cold winter night, yet the next day, dissipating the heat- wave generated on a migratory marathon could be a real problem. In addition, the plumage is constantly exposed to sunlight, water, vegetation, mud, snow and ice, all of which produce wear and tear, and cause the feathers to fade. Yet the plumage has to stay in great shape over winter to attract the attention of the most discerning spring female. And she is certain to expect nothing less than every perfect feather in its place.
So how does the average drake cope with the elements and stay pretty? Well, nature has designed a survival suit for drakes that kind of doubles as a tuxedo. So what is this survival suit made of and how does it work?
There are two basic kinds of feathers covering the body of the duck and nature has kind of woven them into an all- purpose suit. Pennaceous feathers are the ones with a feather vein running roughly up the middle, to add strength and form to the feather. Pennaceous feathers, or “pennae” form the “contour” feathers that protect the outside of the bird’s body. These are intricately overlapped along “feather tracts” that follow the shape- contours of the body. Underneath the pennae, are separate tracts of “down” feathers. These are wispy, fluffs of feathers that sprout like shrubs and provide most of the bird’s insulation. Although pennae or contour feathers cover the entire body, they originate only from a number of tracts, which are not evenly spread over the body. On the other hand, down grows in areas within and outside the pennaceous feather tracts.
These two types of body feathers gives nature a number of options when it comes to the design of the duck’s survival suit. The size and shape of the outer feathers depends on what part of the body they cover and what they are needed for in that area. For example, contour feathers on the head of the drake blue- winged teal in Fred’s photos are very small. Head feathers are needed for protection and insulation, but they are also colorful and laid out in complex patterns designed to attract the attention of hens. Small feathers on the head are replaced often, because they are susceptible to damage and wear. These feathers cannot be maintained by preening (which this drake is doing in all of the photos), and their colors and condition are important to courtship and attracting a mate.
On the other hand, feathers in other pennaceous tracts are larger and designed to cover areas within and outside of contour feather tracts. For example, when a duck’s wings are spread in flight, large areas of “aptera” where contour feathers are absent are exposed along the upper sides and back, to rapidly dissipate heat generated by strenuous physical activity.
Although some contour feathers are replaced frequently, larger body feathers are changed only twice per year, and the flight feathers on the wing, usually only once. This makes upkeep of the survival suit a real priority for ducks, especially for drakes hoping to impress a hen with their stunning appearance.
Drakes like this blue- winged teal spend a lot of time “preening” their feathers to straighten out any “wrinkles” and to be sure every plume is in its place. They “comb” their feathers by drawing them through the finely spaced lamellae in their bill, to remove any stains and restore feather shape and position. They will dig down into the feathers to fluff- up the down and get rid of external parasites, like the common feather louse. While preening, the drake will often wash and rub the back of his head against an oil- gland at the base of his tail, to get a small drop of oil, which he spreads over the contour feathers to waterproof and protect them, and to make them shine lustrously for the hens. Practical and good lookin’ – now that’s the kind of survival suit anyone would be proud of!