rom the observation window at the National Wildlife Visitor Center, the view across Lake Redington is pure Currier & Ives. A glossy film of ice lies over most of the lake, and the beaver lodge that protrudes from the water is covered by a dusting of snow. Canada geese swim in a crescent of open water. But the landscape's appearance is deceptive. On the Patuxent Research Refuge, where the visitor center is located, the sun is shining, the sky is blue and it's the first don't-need-a-coat day after an interminable winter. The relief is palpable, and it's not limited to the staff. Outside, painted and redbelly turtles crowd together on half-submerged logs stretching their angular brown heads toward the sun.

The turtles aren't the only ones responding to the season's cues. Inside the refuge's research facility, I am ushered into an enclosure with two whooping cranes -- which is two more than most people will ever see. All curvaceous neck and sticklike leg, the white-plumed whoopers -- at five feet, North America's tallest bird -- are among the world's most perilously endangered species. Melodious trills float through the air. (The birds are called whooping cranes because of the noise they make, but the unflattering description is misleading.) Flock manager Jane Nicolich explains that the sound we hear is the "unison call," a duet by male and female. It's the start of breeding season, a critical time at the refuge. The technology for breeding whooping cranes in captivity was developed here; about 25 of the birds are bred at Patuxent every year, and two-thirds are successfully released into the wild.

Patuxent is part of the vast network of wildlife refuges that make up America's National Wildlife Refuge System. But is it a research facility? An animal sanctuary? A recreational area? It's all of these -- and none. This country's refuge system is considered the most comprehensive conservation program in the world, but most people don't understand exactly what a wildlife refuge is. This, the refuge system's 100th year, is a good time to find out.

It celebrates its centennial today, 100 years after President Theodore Roosevelt created the first wildlife refuge at Pelican Island, Fla. Like any good birthday party, this one has presents -- 540 of them. "The refuge system is a gift that America has given to itself," says Eric Jay Dolin, author of "The Smithsonian Book of National Wildlife Refuges." "You walk into a refuge and you're struck by the tranquility of it and you're thinking, 'This is mine.' "

One hundred years ago, Roosevelt's executive order on behalf of the embattled brown pelican population of a five-acre island marked the beginning of what would become an expansive federal land system dedicated to conserving fish and wildlife. Time was of the essence. For the passenger pigeon, it was already too late; for the plains buffalo, it was just in the nick of time. The system that grew in fits and starts from this first designated sanctuary allowed America to preserve some its wild spaces in a way that other nations have not. Today, the massive National Wildlife Refuge System, which is administered by the U.S. Fish & Wildlife Service, covers some 95 million acres (an area larger than Montana). The system is ubiquitous -- its brochures brag that there's a refuge within an hour of every major city in the United States -- and includes everything from arctic tundra in Alaska to the Mojave Desert in Nevada to coral reefs in Key West.

Like Pelican Island, America's earliest wildlife refuges were established for birds. If you look at a map of today's refuge system, you'll see refuges in connect-the-dots formation along North America's four major migratory bird flyways. (As Patuxent biologist Nell Baldacchino puts it, "It's the Motel 6 of the wildlife world.") Other refuges were established specifically to preserve habitat for endangered species. These range from the charismatic Florida panther, of which there are fewer than 100 in the world, to the unprepossessing Moapa dace, a three-inch fish that thrives only in the 90-degree streams flowing from the Warm Springs area north of Las Vegas. Although some 40 million visitors come to the refuge system each year, hosting the public is not their principal function. (The system's official motto is, "Where wildlife comes first," but it could easily be, "We're not parks!") In all, America's refuges provide habitat for 700 species of birds, 200 species of fish and 500 other animal species.

There are more refuges in the seemingly urbanized Washington area than people are aware of -- 2 in Delaware, 6 in Maryland and 14 in Virginia, although not all are open to the public. Nine of these are along the Delmarva shore, marking the path of the Eastern flyway. Accordingly, many of the big attractions at local refuges have feathers. There are exceptions, of course, like Delmarva fox squirrels and Chincoteague's feral ponies. Indeed, Marguerite Henry's 1947 children's book, "Misty of Chincoteague," has helped make the Chincoteague National Wildlife Refuge the fourth-most-visited refuge in the system (the first is the Upper Mississippi River National Wildlife Refuge, which sprawls over four states). Blackwater National Wildlife Refuge on Maryland's Eastern Shore is considered one of the best places in the country to see migratory birds. Local refuges provide habitat for the threatened bald eagle, migration-route pit stops for the tundra swan, breeding ground for the beach-dwelling piping plover and a last chance at survival for the endangered whooping crane.

It's because of early conservation efforts like the one at Pelican Island that these shorebirds aren't just a memory. Historians have nicknamed the 1800s "the Age of Extinction." From mid-century onward, people began to notice that things -- be they buffalo or birds or forests -- were disappearing. Several early milestones of the conservation movement are clustered in the years before and after the turn of the 20th century: The Sierra Club was founded in 1892, and the disparate Audubon societies, which had existed in various incarnations since 1886, united under one banner in 1905. The preface to the online Library of Congress collection, "The Evolution of the Conservation Movement, 1850-1920," charts the change in the national zeitgeist with a list of cultural markers that includes everything from the popularity of landscape painting to a vogue for travel writing to the rise of amateur ornithology as a pastime.

In the late 1800s, sportsmen like Roosevelt played an important role in the burgeoning conservation movement. The fact that the man who became known as the "Conservation President" was a big-game hunter may sound counterintuitive to modern ears, but study and collection went hand-in-hand for early naturalists -- John James Audubon's famous avian portraits are of taxidermied specimens. (Roosevelt himself was a skilled taxidermist as a youngster.) In an era predating wildlife protection agencies, hunters were in the best position to notice and protest dwindling wildlife populations. The involvement of sporting groups with conservation efforts persisted, one of the most successful examples being the Federal Duck Stamp program, which has raised more than $600 million to protect waterfowl habitats since 1934.

Of course, not everybody with an interest in birds was a naturalist or a sportsman -- many were market hunters. Women's hats decorated with ornate arrangements of feathers, and sometimes whole birds, were very much in vogue. The National Museum of American History's online exhibit, "The Feather Trade and the Rise of the Conservation Movement," cites an 1886 observation by ornithologist Frank Chapman, who identified feathers and "parts" from 40 different native birds atop ladies' hats in New York City. In the same exhibit, a 1901 advertisement for a millinery supplier lists "finest quality starling bird used very effectively with any trimming" among its many feathered offerings.

It was in the service of preposterous headgear that many of America's native shorebird populations were decimated. (In addition to feathers, eggs were often sought after as curios.) "Outrage over mass slaughter for ladies' fashion" led to the founding of many of the original Audubon Societies, says Mike Daulton, the National Audubon Society's assistant director of government relations. Among the outraged was Paul Kroegel, a German immigrant whose house on the Indian River Lagoon in Florida overlooked Pelican Island. By the time Kroegel arrived in the area, the island's herons and spoonbills were already gone, but its brown pelicans were still in residence and under siege by hunters. Kroegel took it personally. In the spirit of the wildlife refuge system to come, he made it his business to stand guard over the tiny mangrove island with his 10-gauge shotgun.

Because of its abundance of bird life, Kroegel's part of Florida was popular with naturalists as well as market hunters. One, Chapman, the observer of ladies' hats, was a curator at the American Museum of Natural History in New York and a member of the American Ornithologists' Union. Kroegel was one of four men who were hired as wardens after the ornithologists' union and the Florida Audubon Society got legislation passed protecting non-game birds. (Two of the four were killed protecting birds from plume-hunters, a reflection of what big business the feather trade actually was.) Chapman had like-minded allies in the Roosevelt administration, and it was through them that the president heard about the island's plight. When, in 1903, Roosevelt decreed Pelican Island a refuge, Kroegel officially got the post he'd taken on long before.

"It's very symbolic that [Roosevelt's] first executive act of conservation legislation had to do with birds," says historian and presidential biographer Edmund Morris. "Birds were his primary passion."

It was a passion of long standing. The asthmatic boy who fed squirrels with an eye dropper and opened a natural history museum in his bedroom became a published ornithologist as a teenager and a young man who filled his collegiate lodgings with animals living and dead. The Smithsonian Institution still has many of the specimens Roosevelt brought back from trips to Africa and Egypt; a rhino from his collection will be on view in the National Museum of Natural History's renovated Mammal Hall when it reopens in November. Though Roosevelt traded his plan to become a professional naturalist for the pursuit of public life while he was in college, Morris points out that he was no dilettante; as president, he was regarded as the country's leading expert on North American game mammals.

Roosevelt combined "the naturalist's compulsion to conserve and the democrat's desire to share," wrote William Henry Harbaugh in his biography, "Power & Responsibility: The Life and Times of Theodore Roosevelt." It's an observation borne out by statistics. As president, Roosevelt established 5 national parks, 150 national forests, 51 wildlife refuges and 18 national monuments, including the Petrified Forest and the Grand Canyon. And the refuge system is still growing: Its newest facility, the Cahaba National Wildlife Refuge, was established last year in Alabama, the most extinction-prone state in the continental United States.

The refuge system's first 100 years were characterized by cycles of conflict and renewal. Partly because it was created on an ad hoc basis, its mandate has not always been easy to define. The system didn't have a formal mission statement until 94 years after it came into being: The National Wildlife Refuge System Improvement Act, which passed in 1997 to a collective sigh of relief from system advocates and administrators, required all refuges to create 15-year conservation plans and spelled out six acceptable public uses -- hunting, fishing, wildlife observation, wildlife photography, environmental interpretation and environmental education. But the debate about what constitutes compatible use is ongoing, most famously in the case of the proposal to drill for oil on the Arctic National Wildlife Refuge. The richness and diversity of the wildlife on the 19.2 million acre refuge, one of the largest intact ecosystems in the world, has earned it the nickname "America's Serengeti."

Though recent years have seen record increases in its budget, the chronically under-funded refuge system is struggling with a $2 billion operations and maintenance backlog. "The budget at least needs to be doubled," says Noah Matson, director of the public lands program at Defenders of Wildlife. "Cities are funding stadiums that cost more than that." Advocates point out that the refuge system gets one-fifth the funding per acre as the National Park Service. Some refuges don't have signage, much less extravagances like public bathrooms. At the same time, marauding invasive species like the nutria and the kudzu vine are destroying indigenous ecosystems. And wilderness spaces themselves are rapidly diminishing. "Habitat loss and fragmentation is the biggest challenge we face worldwide," says U.S. Fish & Wildlife Service director Steve Williams.

As it moves into its second century, the refuge system has no shortage of supporters. The CARE (Cooperative Alliance for Refuge Enhancement) coalition, which lobbies for refuge system funding, includes everyone from the Wilderness Society to the National Rifle Association. The public service announcements planned for the refuge system's centennial reflect this diversity: Presenters include rocker Don Henley and NASCAR driver Ward Burton. "I see a lot of hope," says Evan Hirsche, president of the National Wildlife Refuge Association, a refuge advocacy group that serves as the voice of the system's 36,000 volunteers. "As the population doubles and competition for land and water intensifies, the refuges will be the cornerstone of conservation in this country."

And the system is no more decrepit than the next centenarian. "The great thing about the refuge system is that it works," says the Audubon Society's Daulton. "It has a 100-year track record of successful bird conservation."

The system's formal centennial celebration will take place where it all started: at Pelican Island. However, many local refuges are hosting festivities of their own. Williams hopes visitors who come to these centennial events will learn more about how wildlife refuges work. "If people understand the important role they play, it will be easier for us to garner the support we think is essential for preserving these special places," he says.

"We're ready to show them a good time."

Nicole Arthur is a staff writer for Weekend.

A great blue heron is one of many natural wonders to behold at the Blackwater National Wildlife Refuge in Cambridge, Md. The refuge's annual Eagle Festival is Saturday.Women's hats decorated with ornate arrangements of feathers, such as the one at left, were very much in vogue in post-Victorian society. As a response to this and other threats to animals, President Theodore Roosevelt, right, created the first national wildlife refuge 100 years ago.A Delmarva fox squirrel, left, has a snack. At right, a dragonfly at the Patuxent Research Refuge, located between Washington and Baltimore.A saltwater marsh at Chincoteague National Wildlife Refuge on Virginia's Atlantic coast.