WOLF SWAMP - The wise old bird man has finished his morning's work, but still he will not leave the woods.
By 11 on a bright summer morning, eminent ornithologist Chandler S. Robbins, who turns 84 this month, has put the finishing touches on a survey of bird life in a Garrett County bog that he first studied more than 50 years ago. He has gathered fresh data for a new version of an atlas of Maryland's birds, which he edited. And he has spotted a song sparrow's nest in a rotting stump on land that he bought in the 1950s but rarely has time to visit.
His companions are heading for the car. But Robbins stands motionless on the bank of a slender stream, transfixed by the liquid song of a hermit thrush perched in an oak.
Robbins has heard the melody thousands of times, but it has not lost its power to enchant him. He adjusts the volume on his hearing aids.
Head atilt, he listens for several minutes, then reluctantly turns to go.
"Well, you hate to walk away from a singing hermit thrush," he says, moving into the loose-limbed stride that usually leaves younger hikers stumbling in his wake.
Robbins, who joined the Interior Department's Patuxent Wildlife Research Center in 1945, is a man transparently in love with his work.
He has "almost a childlike love of birds, and it's remarkable that he's never lost that. It's pure," said independent naturalist Daniel Boone, his one-time student and longtime friend.
Robbins has lured several generations of Americans to share his passionate pursuit.
He is the author of a classic field guide that helped make bird-watching one of the nation's most popular pastimes, enjoyed at least occasionally by about one in three adults.
He has also documented the decline of many of his beloved songbirds as the wild woods, meadows and marshes they once inhabited succumb to development.
In 1966, Robbins invented a continentwide survey of the birds that nest in North America. Experts say the Breeding Bird Survey, conducted each year by about 6,000 volunteer bird-watchers, helped create the modern conservation ethic.
"I would put the invention of the Breeding Bird Survey in this class of things that took place in the mid-1960s and early 1970s and triggered the awakening of North Americans to environmental consciousness," said John W. Fitzpatrick, director of the Cornell Laboratory of Ornithology. "It showed some of the patterns that people had begun to sense in the wind but couldn't put any numbers to ... that a significant number of birds were really getting scarce."
That knowledge inspired an international effort to save the birds - especially those that migrate between North and South America - by preserving the land where they spend summers and winters.
Now some of those birds are doing better, but others are not. The Breeding Bird Survey shows that since 1980 about 98 species have increased their numbers - but 114 are declining rapidly.
Robbins' long memory of a world richer in bird life occasionally casts a shadow across his sunny nature.
He has pored through birders' journals back to the 19th century. The old accounts are full of descriptions of "counter-singing" between males of the same species as they staked out territories and tried to attract mates.
Such contests, with competitors chiming in from every direction, are rare now.
"These birds don't have to sing," he said sadly. "There's only one."
Robbins began studying birds as a schoolboy in his Belmont, Mass., back yard. As a young researcher at Patuxent, he explored Maryland from the western mountains to the lower Eastern Shore.
In brief summaries of his travels, published in birders' magazines in the late 1940s and early 1950s, Robbins described a wild Maryland that was already in remnants:
"The last remaining virgin spruce bog ... The only tract of virgin Hemlock remaining ... A magnificent stand of undisturbed deciduous forest."
Most of the wild places he studied still exist - in some cases because of his work. Most recently he was instrumental in helping environmentalists win state protection for Belt Woods in Prince George's County, the "magnificent stand" of 400-year-old oaks, poplars and maples that he described in 1947.
The state steps in
About half the trees were felled to make wood veneer, said environmentalist Ajax Eastman of Baltimore. But in 1997, the state acquired what was left of Belt Woods to forestall construction of a subdivision where the last old trees stand.
Robbins also helped persuade the Maryland Ornithological Society to buy more than a dozen tracts of prime bird habitat. The result, said Boone, is "one of the best systems of private sanctuaries for birds" in the country.
"When I was a kid, I was completely focused on the birds and paid no attention to the habitat," said Robbins, "but it soon became apparent that if you don't have the habitat, you don't have the birds."
Most people who start out as birders end up as conservationists, he said. "It's a natural evolution. They get excited about birds, and then they realize ... that they have to conserve the land."
Robbins began drawing converts to conservation as the lead author of Birds of North America, published in 1966 as part of the Golden Guides series.
Robbins' book became the most popular field guide of its time, supplanting one published in the 1930s by Roger Tory Peterson, and was a birder's favorite until the 1990s.
"I still consider it a masterpiece," Fitzpatrick said. Its continent-wide range and realistic illustrations made bird identification easier and more fun, said the Cornell ornithologist, who began using it as a teen-ager.
A worried bird-watcher inspired Robbins' next project, the Breeding Bird Survey.
In the early 1960s, a young woman wrote him to say that robins were becoming scarce in her neighborhood. She wanted to know whether the same thing was happening all over the country.
"I had to tell her that we didn't know," Robbins said.
The question nagged at him. To answer it, he designed a drive-through bird survey that exploited another great American passion - the love of cars.
His scheme called for volunteers to get behind the wheel a half-hour before dawn on a calm summer morning and drive a prearranged 25-mile route. Every half-mile, they would stop for three minutes to tally the birds they heard or saw.
Their standardized checklists would go to Patuxent, where experts would use them to form a picture of the comings and goings of more than 400 bird species.
Robbins made trial runs in Maryland, the Midwest and Fairbanks, Alaska. There, he drove a sample loop around the clock, trying to figure out when birds sleep and when they wake in the endless sunshine of Arctic summer.
In 1965, he called a few friends and got 60 volunteers to conduct the first survey in Maryland and Delaware.
The next year he called more friends and got enough skilled birders to cover most major roads east of the Mississippi River. Within three years, the network stretched to the Pacific Ocean.
"People were telling him at the time it was a stupid idea, and Chan did it anyway," Fitzpatrick said. "It is a great lesson in what one quiet, unassuming man can do if he's pretty sure he's right."
The annual survey, which continues to add new routes, significantly widened bird researchers' field of vision. In place of a few snapshots' worth of information, they now have a kaleidoscopic image of the entire continent, changing year by year as the bright flocks flow across the land.
By the late 1970s, one pattern emerging from the survey was the decline of many backyard birds - bluebirds, orioles, sparrows and more.
The data worried scientists and bird-watchers almost as deeply as the discovery 15 years earlier that eagles, hawks and other hunting birds were succumbing to pesticides.
Frank Gill, the Audubon Society's science director, credits Silent Spring author Rachel Carson with sounding "the first big alarm" of modern environmentalism. The survey's findings were "the second big alarm," he said.
"The Breeding Bird Survey has spawned the modern industry of bird conservation," Gill said. "Before, the whole focus was on endangered species. Now everybody's focused on not taking any birds for granted and keeping the common birds common."
In the 1980s, Robbins was part of a research team that proved many birds need large, unbroken tracts of forest, marsh or meadow to rear their young.
The researchers found that in fragments of wild land surrounded by development, the birds had trouble finding food for their nestlings. Forced to cross open ground, they were easy prey for predators.
The scraps of land became traps where unwary birds died or failed to reproduce.
The findings helped change conservation practices, said David W. Mehlman, conservation director for the Nature Conservancy's migratory bird program. Governments and private land preservation groups now try to buy a few big pieces rather than a lot of little ones and to create corridors linking blocks of land.
Robbins still wanders as widely as the birds he loves, banding albatross on Midway Island in the South Pacific, studying songbirds in Guatemala, training young ornithologists in South America. Last year on Midway, he recaptured an albatross he had banded there 45 years ago - a 51-year-old female with a nestful of chicks.
Wherever he goes, a battered pair of binoculars goes with him. Robbins said they're the property of the federal government, which issued them to him more than 40 years ago.
The dented eyepieces haven't been round since who knows when. The original leather cover has been rubbed away. Its cowhide replacement, stitched for him years ago by a Puerto Rican ornithologist, is on the down side of well-worn.
He could swap them for a snazzy new pair. But he won't.
"A lot of good birds in here," he said with an affectionate pat.
Longtime friends say that of all his adventures, Robbins is most elated by a study he is just wrapping up: a series of return visits to Maryland spots that he first studied in 1949 and 1950.
"He's said many times it's a dream come true," said Boone.
"We're looking for changes, and figuring out why the changes have happened, and thinking ahead to the future," Robbins says, scanning the fringes of Wolf Swamp.
Old times and new
He surveyed this wild corner of Western Maryland in 1949, following a narrow track past an old farmhouse and wading through the swamp's deepest meanders.
He found a sun-drenched bog tucked between two mountain ridges. Marsh grasses and spruce trees grew in a basin of shallow water, enclosed on two sides by forested slopes.
It was a haven for warblers, thrushes and woodpeckers, two kinds of hawks and a rare owl. In the 1949 survey, he found 25 different species in all. With about 372 nesting pairs of birds per 100 acres, the air was as thick with melodies as the midway at a county fair.
Today the farm track is a road leading to a private school. A bridge traverses the bog. Water levels have risen, killing most of the spruce trees.
And though most of the same bird species are still there, "there are by far fewer birds than there were 50 years ago," said Barbara Dowell, a Patuxent research center colleague who has worked with Robbins for roughly two decades.
"In many cases you find just one of a species, and that's not good," Dowell said. "If you see one alone, it's not likely you'll see any the following year."
The two scientists haven't finished tallying the results of the study, which they conducted between 1999 and last year. For one thing, Robbins refuses to concede that a missing bird is gone for good until he's absolutely certain.
He and Dowell have returned to Wolf Swamp a half-dozen times recently - for yet another project. They're collecting the first of five years' worth of data for a planned update of the Maryland bird atlas.
Although few species have disappeared completely, especially in lightly populated Garrett County, Robbins expects the new edition will show changes all across the state.
"It's interesting that we have the birds that we do," Robbins said. "I shudder to think what the next 50 years will bring."
In Central Maryland, field-nesting birds are in grave trouble as farm fields shrink.
The vesper sparrow, so named because it sings in the evening, "is almost completely gone in Baltimore and Howard counties," Robbins said.
The once-common Eastern towhee, which nests in abandoned fields, is also in decline. "We don't have abandoned fields any more. They're put to other uses - parking lots or shopping centers or whatever."
Devastation by deer
And everywhere deer are wreaking havoc, their numbers so great and their hunger so relentless that they are changing the character of the forests.
Not long ago on hillsides like the one above Wolf Swamp, a layer of shrubs and saplings grew wherever sunlight reached the forest floor.
Today that middle layer is mostly gone. The trees are stripped of their leaves as high as a tall man can reach. Only a scattering of mosses and ferns are left at ground level.
It is the same all over the state, said Robbins.
Many songbirds that nest at or near ground level - warblers, wood thrushes, vireos and others - return each year to the woods where their parents raised them. Each year, the deer consume more of the nest sites and insect-laden plants they need.
In many cases the nests fail because of the lack of food for the young.
"A lot of them may nest for their lifetime and not raise any young," Robbins said.
As he walks along the banks of the Casselman River after lunch, Robbins stops to listen to a redstart's song. The bird was once common at the Patuxent refuge, but deer have eliminated most of its nest sites and it is a rarity there now."
"It's sad," says Robbins in an uncharacteristically somber moment.
"It's really sad for me to have this knowledge over a long period of time, to know we've made the changes that have caused the birds to leave."
One hand ruffles his snowy flattop, as though brushing away dark thoughts.
"I refuse to be depressed about what's happened because we can't do anything about that," he says. "I prefer to think about the future and what we can do to protect the things we love."