Out on the lake, scores of Canada geese are loafing in the warm November sunshine. A raft of ringed-necked ducks is drifting off to our right. A few stray mallards and pied-billed grebes are scattered across the water. Farther out, a half dozen small ducks are bobbing slightly on the breeze-rippled water.

These ducks appear to be small and compact, but distances can make judging size tricky. Two birds cock their tails straight up behind them, just like wrens. A moment later, one disappears below the surface. It has to be a ruddy duck (Oxyura jamaicensis).

The ruddy duck is one of two "stiff-tailed" ducks in North America. The other, the masked duck, is a native of Central and South America. It is rarely seen north of Texas.

Lake Artemesia is an unlikely refuge. It owes its life to the nearby College Park metro station.

To build the station and associated rail beds, crews needed tons of dirt and gravel. They dug a huge "borrow pit" a short distance away.

I'm now standing on the edge of that pit, which has become a well-maintained suburban lake with macadam bike and jogging paths, gazebos and easy access to the adjacent Anacostia River Trail system.

To get here, we drove through a maze of industrial sites and scrap yards, then past the mammoth Washington Post printing and distribution factory. The birds, though, have navigated a more challenging course of more than 1,500 miles.

Ruddy ducks breed in the prairie potholes of the Dakotas and north and west into Canada. There is also a population that lives year-round along the Pacific coast of Mexico and Baja California.

During the winter, ruddy ducks leave their breeding grounds for freshwater ponds on both coasts and the Gulf of Mexico. They also venture onto bays and rivers. The Chesapeake is a favorite destination.

Ruddy ducks are one-third smaller than mallards. Unlike most ducks, the ruddy displays his most colorful plumage in the summer, just like a songbird. In summer, the male ruddy duck is a chestnut hue. He sports a bright blue bill, a black head, a bold white cheek patch and that stiff, black tail. Females, juveniles and winter males are a dusky gray-brown. The male's blue bill fades to dull gray. The white cheeks, which are actually the tops of a broad strap that wraps under the chin, fade a bit. In the female, a faint but discernible dark horizontal line crosses the cheek.

These birds form mating pairs each season. They usually produce a single brood of 5-15 eggs in a floating nest of vegetation in dense northern marshes and ponds. Like the infamous cowbird, ruddy duck females practice parasitic egg-laying. A female will sometimes lay its eggs in the nest of another hen. The surrogate moms don't distinguish among the chicks, and all will receive care.

Incubation lasts a little more than three weeks. The young will fledge 45 days later.

Scientists in Canada annually survey the remote breeding grounds of ruddy ducks and other waterfowl. The data from the Canadian biologists suggest an expanding breeding population. In the United States, the annual Christmas bird count is run by the U.S. Geological Survey. The Midwinter Waterfowl Survey is conducted by the U.S. Fish and Wildlife Service and state resource agencies.

These surveys and others provide snapshots of population health. In 2005, for instance, biologists recorded 36,100 ruddy ducks in the midwinter count along Maryland's Bay and coastal range. The number tumbled to 12,100 in January 2006. In 2007 and 2008, the count climbed back up to just a bit more than 19,000 ruddy ducks.

Extreme summer weather on breeding grounds can result in a catastrophic failure of reproductive success for an entire year. Loss of habitat is even more threatening. A more benign possibility exists, however. Warm weather can result in the birds dispersing more widely than traditional winter weather patterns. If they don't congregate in dense rafts, accurate winter counts can be difficult. More data are needed to better understand the trends.

The birds on Lake Artemesia have survived the vagaries of weather and are diving for the seeds and vegetation that make up the majority of their diet.

Ruddy ducks have relatively large feet, which are placed far back on their bodies. This arrangement, much like that of loons, is ideal for diving and propulsion under water. It makes the birds unwieldy on their feet, though. In their rare moments on land, they often flop forward onto their chests, unable to stand erect.

I know too well that sense of feeling awkward and unbalanced. But standing on the banks of this man-made lake, watching these handsome birds slide beneath the surface of freshwater, I am reminded anew of how graceful life can be. The challenge is to navigate alien landscapes to find a refuge that nourishes me.