There's a daily migration along a small stretch of the Patuxent River each winter — an airborne echo of a much longer, annual journey for thousands of Canada geese.

Each year, 4,000-5,000 Canada geese leave their breeding grounds in northeast Canada to spend the winter months along the Patuxent, specifically at the Merkle Wildlife Sanctuary. From November through March, they drift inland to feed by day and return to the river's edge at night.

"The geese arrive around 10 a.m., and leave around dusk for the water," said Ranger Karen Jarboe of the Maryland Park Service. "The water is their security. Most of their predators are on land."

During the day, geese settle onto the fields and ponds at Merkle in enormous numbers, a nearly ceaseless ripple of dark rounded bodies and long necks in motion, poking the ground for corn, engaging in squabbles, and only occasionally dozing in the sun.

The gathering is said to be the largest concentration of Canada geese on the Western Shore of the Bay.

A two-story glass wall at the Merkle Wildlife Sanctuary's visitor center frames a panoramic view of the activity. Binoculars and a spotting scope are stationed on a counter along its base, where visitors can pull up a seat and enjoy close-up views of the geese. Two outdoor balconies overlook the scene from the upper floor.

December and January are ideal months to visit the Merkle Wildlife Sanctuary, a member of the Chesapeake Bay Gateways Network.

"December is the best time. That's when their journey ends, and the population peaks," Jarboe said.

Canada geese have long wintered in the Chesapeake region, but not on the Western Shore. In fact, some trace the very presence of migratory Canada geese on the Western Shore directly to the 20th century efforts of the Merkle sanctuary founder.

Edgar Merkle, a hunter and conservationist, was born in Maryland in 1900. He was best known as the founder of Merkle Press, in Washington, D.C. When Merkle sold the company in 1962, it was publishing more than 21 million magazines each month, include Time and Sports Illustrated.

Merkle began duck hunting along the Patuxent River in the 1920s. He noted the absence of geese. "I thought the place ought to have some geese," Merkle said in a 1981 interview with The (Baltimore) Sun.

Merkle took action. He bought 400 acres along the Patuxent River in 1932 and immediately introduced six breeding pairs of Canada geese. The first generation migrated in 1934 and returned the next year with their young.

Merkle provided ample habitat for the increasing number of geese and eventually stopping raising cattle because the herd competed with geese for grass.

The effort was so successful that a sanctuary exhibit credits Merkle with "inspiring geese to break their habit of wintering on only the Eastern Shore of Maryland."

In 1970, Merkle transferred his land to the Maryland Department of Natural Resources, and it became the first and only wildlife refuge within the state system.

Today, this kind of private, entrepreneurial project to breed and release captive geese would be impossible. State and federal permits exist for owning captive wildlife in controlled situations, but not for releasing them to the wild.

"It just wouldn't happen," said Mary Goldie, wildlife permits coordinator for the Maryland Department of Natural Resources. "We don't look favorably on releasing captive waterfowl anymore. It's not a good idea."

Goldie said that captive birds weaken the genetic pool of the wild flocks, which are programmed for survival in the wild.

But Edgar Merkle lived at a time when the compounding effects of individual actions on the Bay and its wildlife weren't fully known or appreciated. And while Merkle may have triggered the first sizable migration of Canada geese to Maryland's Western Shore, the geese would have likely arrived for other reasons.

Thanks to the changing landscape, the Bay region has virtually rolled out the welcome mat.

Farm fields are a constant draw, a gathering place where geese search for hay, winter wheat, clover and corn. Technology has made the search easier: Mechanical harvesting equipment leave at least 5 percent of the corn behind in the field.

This reliable food source is one reason that more geese, which would otherwise fly farther south, are now content to spend winters along the Bay.

The birds are also sustained by suburbia-where people provide habitat through their lawns, golf courses and ponds. With so many options available, some Canada geese have elected to stay year-round.

"All those plush lawns and open spaces? That's what geese love," Jarboe said. "They eat the good grass. Not the weeds."

The overall number of Canada geese in Maryland grew significantly during the 20th century. In 1959, the population was estimated at 70,000. In 1986, there were more than half a million.

Because resident Canada geese stay in a limited area, they are often considered a nuisance. Their feces, deposited at least six times a day, can foul nearby waters and leave the area useless for recreation. They can strip grassy areas and feed on farm fields during the crucial spring growing season.

But viewing their migratory cousins at the Merkle Sanctuary is a reminder that geese are actually programmed for the majestic natural rhythm of migration-a rhythm with more balanced demands on the ecosystem. Humans have played an important role in disrupting it.

Jarboe is particularly moved by the family bonds within the flock. Canada geese raise their young in family groups that remain together as they travel south for the winter.

"They mate for life, and they'll mourn the loss of their significant other," he said.

With the addition of neighboring properties, the Merkle Wildlife Sanctuary has grown to 1,670 acres, which are tended largely by a resident crew of the Maryland Conservation Corps. It includes four trails along Lookout Creek and the marshy edges of the Patuxent River, an observation tower with spectacular views, and an active education program.

The Merkle sanctuary is adjacent to Patuxent River Park, also a member of the Chesapeake Bay Gateways Network. Both properties are crossed by the Chesapeake Bay Critical Area Tour, a four-mile route that features educational displays, overlooks and a long wooden bridge across the marsh.

The combined acreage makes a big package for explorations along a relatively unspoiled portion of shoreline. To encounter migrating geese in a flock of thousands — with descendants of those early pairs ranging among the them — visit while the weather is cool. By March, they'll be gone.

"And then it's very quiet here," Jarboe said.