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1st description :
[출처:http://www.ducks.org/conservation/waterfowl-biology/mallard-lifecycle#1]
Nesting: The Secret to Nesting Success
If you are a predator searching several square miles for a meal, encountering a duck nest would seem like a long shot. But suppose that the nests are concentrated in small patches and in thin strips of grass. Suddenly, your odds are looking up. Although intuitive, the relationship between nest success and grassland expanse was only recently confirmed by USFWS biologists while evaluating the benefits of Conservation Reserve Program (CRP) to ducks.
Brood Rearing: Taking Care of the Ducklings
The more time a hen spends taking care of young ducklings, the less time she has to take care of herself. This precious balance must be met to maximize both the hen's and ducklings' chances of survival. To keep ducklings healthy a hen must brood or keep ducklings warm until they can do it themselves, help ducklings find a good source of food, ensure family bonding as a unit and finally, guide young ducks during migration and help them locate staging and wintering habitat.
The most important time in a duckling's life is the first two weeks of life. This is when the hen must put forth the most energy to keep her ducklings together and safe. A hen's chance of suffering from death increases when she is defending her ducklings.
Post Breeding - Annual Life Cycle
Post breeding is the period in the annual life cycle of a duck bracked by breeding and nesting. Mallards are required to find energy sources to fuel the activities of raising a brood, keeping themselves healthy and regrowing feathers during molt. These energy-expending activities take place during the post breeding period.
Scientist speculate that the reason for there being more drake (male) mallards than female's (hens) in the population is the result of the higher deaths that occur to hens during the post breeding period.
During the post breeding period ducks can experience nutritional stress. Nutritional stress is a situation where nutrients demanded by the body exceeds the amount of nutrients a duck is able to find and eat.
Protein nutrients are extremely important, especially amino acids, the building blocks of life. Perhaps waterfowl select specific foods high in proteins, like bugs, based solely on their nutritional value. The post breeding period coincides with the time of year when insects are most numerous.
Molting: Putting on a New Feather Coat
Ducks depend on their feathers and old, worn feathers must be replaced. Molting is the process of replacing worn feathers. Ducks molt in the late summer and in the early spring.
During the fall ducks molt synchronously, or lose and replace all of their feathers in a short period of time. Synchronous molting renders ducks flightless during a portion of this time thus at a greater risk to predators until the new feathers come in. Losing and replacing all of one's feathers can take up to two weeks. The new feathers are drab in color and considered a duck's basic plumage. In the early spring just as the breeding season gets underway a partial loss of feathers happens when the male ducks put on their alternate plumage.
Feathers are largely made up of proteins and accounts for almost one-third of all protein in the body. The need for large quantities of high protein food may be one reason that male ducks and unsuccessful nesting hens leave the breeding grounds for special molting grounds far away, thereby reducing competition for limited protein resources.
Fall Migration: How Ducks Migrate
Birds migrate long distances from wintering grounds to breeding areas and back again to the wintering grounds with visual and nonvisual cues. Visual orientation mechanisms that ducks use include the sun, polarized light, stars, and even landmarks. Birds use the axes of polarized light to determine the position of the sun and perform sun compass orientation. Navigation at night requires migrants to use stars to orient their direction. Crafty experiments performed in planetariums have shown scientists that some birds actually use a stellar map to find their way around in the night. Landmarks may be important for navigation, not as compasses, but as directional cues. Coastlines, mountain ridges and waterways such as the Mississippi River are major topographic features that may be considered landmarks.
One nonvisual cue that aids in navigation is the Earth's magnetic field. When the Earth's magnetic field is obstructed migrating birds often change or alternate direction and altitude. Homing, another nonvisual cue, is a bird's ability to find its way home when released in an unfamiliar place or direction. The ability to navigate over many miles from breeding to wintering grounds is an amazing adaptation. It is likely that most birds use a combination of visual and nonvisual cues, as well as homing. Navigation and migration behavior is very difficult to study therefore has not been full resolved.
Wintering: Moving South for the Winter
Everyone knows that ducks fly south in the winter, but what do they do and where do they do it? Ducks spend much of their time in the southern portions of the United States and along the coastal fringes where weather conditions are mild. They leave northern nesting areas and head for a warmer climate for several reasons, least of which is because the weather is cold.
During much of the winter ducks loaf about eating and storing up nutrients in preparation for the long trip back to the breeding grounds.
Waterfowl can withstand very cold temperatures, but when their food source is eliminated they must leave northern areas in search of mild temperatures. When shallow ponds or lakes freeze over with ice ducks can no longer reach aquatic plants and insects for meals. Ducks that feed on seeds or waste grain must also leave the area when snow falls cover their foods.
Ducks winter in mild areas where food is plentiful and the water rarely freezes like the Mississippi Alluvial Valley in the southern area of the United States. Another great wintering place for ducks is coastal northern California and along the central valley of California.
Spring Migration: How Ducks Migrate
Birds migrate long distances from wintering grounds to breeding areas and back again to the wintering grounds with visual and nonvisual cues. Visual orientation mechanisms that ducks use include the sun, polarized light, stars, and even landmarks. Birds use the axes of polarized light to determine the position of the sun and perform sun compass orientation. Navigation at night requires migrants to use stars to orient their direction. Crafty experiments performed in planetariums have shown scientists that some birds actually use a stellar map to find their way around in the night. Landmarks may be important for navigation, not as compasses, but as directional cues. Coastlines, mountain ridges and waterways such as the Mississippi River are major topographic features that may be considered landmarks.
One nonvisual cue that aids in navigation is the Earth's magnetic field. When the Earth's magnetic field is obstructed migrating birds often change or alternate direction and altitude. Homing, another nonvisual cue, is a bird's ability to find its way home when released in an unfamiliar place or direction. The ability to navigate over many miles from breeding to wintering grounds is an amazing adaptation. It is likely that most birds use a combination of visual and nonvisual cues, as well as homing. Navigation and migration behavior is very difficult to study therefore has not been full resolved.
Pre-nesting: Who Leads and Who Follows?
The female duck always makes the choice for the breeding area because she is homing to the site of her birth or a site where she successfully hatched a nest.
2nd description :
[http://www.startribune.com/lifestyle/homegarden/11346726.html]
Q.I live in a townhouse complex with a man-made pond thatattracts many ducks. Some of them have mallard bodies, but do not have green heads. I used to think they were all female until I looked closer. What could be causing the males' lack of color?
A. Mallards molt, a process in which their feathers are shed and replaced, twice a year. Juvenile males reach sexual maturity and begin molting into the bright plumage of the adult male as early as September. In June or July, adult male mallards lose their colorful breeding plumage and return to the brown coloring of the female. This is called the "eclipse plumage." Male mallards replace their head feathers first, which provides them with better camouflage. For about a month, when the birds' wing feathers are being replaced, they are unable to fly. By August or September, the males once again molt into their bright breeding plumage.
Q. Is there a way I can get rid of pigeons that sit above my kitchen window? Someone told me owls would keep the dirty birds from perching on the wires above my kitchen window. The droppings are gross and unsanitary, especially near an open window where food is prepared.
A. Pigeons usually congregate where there is an abundant food supply, such as in city parks where people eat lunch or near bird feeders. Generally, pigeons don't eat from feeders but they do feed on the seeds that other birds drop.
If you have feeders, you might want to remove them until the pigeons move on to a more tempting site. You could try putting a lawn sprinkler under the wires on which the birds perch, then turning it on when they arrive. Or you could invest in a fake owl, which may help as a short-term deterrent.
3rd description :
[http://www.birds.cornell.edu/homestudy/quiz/quiz-question-2]
In mid-summer after breeding, the male Mallard has a complete molt, producing a dull-colored basic plumage, aptly termed the eclipse plumage. Male Mallards in eclipse plumage look remarkably like females, but their bills are light olive green, while females' are orange marked with black. Because flight feathers are also molted at this time, the birds become temporarily flightless and tend to be very secretive. The male Mallard's basic plumage is kept only a few weeks; it is soon lost in a molt of the body feathers which produces the brightly colored head and other distinctive features of the breeding plumage. The timing of this molt is related to courtship in Mallards, which begins in the fall.
