There were many days when Chandler Robbins rose before the sun to partake of the dawn chorus — the gentle coo of the mourning dove, the dulcet strain of the American robin, the fluting of the wood thrush, all heralding the arrival of morning.

Among fellow birdwatchers, Mr. Robbins, who died March 20 at 98, was revered as a father of modern ornithology. He was the principal author of “Birds of North America: A Guide to Field Identification,” a bible for millions of enthusiasts who spend their happiest hours scanning the skies for winged creatures.

Mr. Robbins documented avian life around the world, including on the Pacific island of Midway, where in 1956 he tagged a young Laysan albatross who came to be known as Wisdom. She is the oldest known wild bird, a matriarch who laid an egg as recently as December.

But for more than six decades, he worked primarily in the environs of Washington, as an ornithologist at the Patuxent Research Refuge in Laurel, Md. In the 1950s, he documented the damage wrought by the pesticide DDT, including its thinning effect on osprey and eagle eggshells. Rachel Carson, a colleague at the time, relied on his research for her 1962 environmental manifesto “Silent Spring.”

An early champion of citizen science, Mr. Robbins founded the North American Breeding Bird Survey, an initiative that has grown since its founding in 1965 to involve thousands of volunteer birders in an annual effort of exacting rigor to measure the continental bird population. It is one of the two most significant avian monitoring programs of its kind. Mr. Robbins participated in the other, the National Audubon Society’s Christmas Bird Count, for more than 80 years, said its director, Geoff LeBaron.

Mr. Robbins observes a wood duck nesting box across the Patuxent River. (Katherine Frey/ The Washington Post)

“It is not an exaggeration at all to call him one of the giants of 20th century ornithology and bird conservation,” John Fitzpatrick, director of the Cornell Lab of Ornithology in Ithaca, N.Y., said in an interview.

[This humble scientist, a ‘national treasure,’ showed us how to understand birds]

Mr. Robbins said that his first conscious memory was of a display of mounted birds at the library in Belmont, Mass., where he was born Chandler Seymour Robbins on July 17, 1918. His father was a birder, and Chandler’s brother Samuel also grew up to be a noted ornithologist. Other family passions included, fortuitously, the opera; a pair of opera glasses doubled as Mr. Robbins’s first birding binoculars.

He received a bachelor’s degree in physics from Harvard University in 1940 and a master’s degree in zoology from George Washington University a decade later.

He declared himself a conscientious objector during World War II and joined the Civilian Public Service, work that eventually brought him to the Patuxent Research Refuge. After retiring in 2005, he continued field research until shortly before his death.

Washington, he observed, was an ideal region for birdwatchers because of its location along migration paths. A white-eyed vireo might be spotted en route from Mexico, or a ruby-throated hummingbird on the way from Panama, or a sooty shearwater from Tierra del Fuego.

“Just think — all the way from South America!” he once told The Washington Post, comparing the month of May to “the World Series of birding.”

He was senior editor of the “Atlas of the Breeding Birds of Maryland and the District of Columbia” but was most celebrated for his North American guide, first published in 1966 and known colloquially as the Golden Guide for the publishing series. Unlike predecessor guides, the book included a wealth of color images as well as maps of each bird’s breeding ground and migration path and a sonogram, or visual representation of its call.

His name did not appear on the cover.

“The astonishing thing about him is how modest he was,” said Laura Erickson, an author of birding books including National Geographic’s “Pocket Guide to the Birds of North America” and host of the radio show “For the Birds.”

“Every single bird field guide, just about, has the name of the author embedded in the title — the Sibley guide, the Crossley guide, the Kaufman guide,” she added. “He never wanted that kind of acclaim. In everything he did, he was the consummate government worker, working as part of a team and doing his darnedest to make sure all the work was absolutely scientifically straightforward and honest.”

His Breeding Bird Survey, the U.S. Geological Survey noted in an online obituary, exploited “Americans’ twin passions for birds and cars.” Trained volunteers across the United States and Canada set out on assigned 24.5-mile stretches of road. At half-mile increments, they stop for precisely three minutes to count every bird seen or heard.

Fitzpatrick described the bird survey as “the gold standard,” a “piece of genius . . . long before people were thinking very deeply about population trends.”

The survey allowed Mr. Robbins to draw attention to forest fragmentation caused by road construction and other development. He showed that when a forest is fragmented, species that dwell on the forest edge tend to grow, while those that thrive in the interior tend to decline.

His wife of six decades, the former Eleanor Cooley, died in 2008. Survivors include four children, Jane Robbins and Nancy Robbins, both of Beltsville, Md., Stuart Robbins of Laurel and George Robbins of Pittsfield, N.H.; two grandchildren; and eight great-grandchildren.

Mr. Robbins, a Laurel resident, died Columbia, Md., hospital of congestive heart failure and other ailments, said Jane Robbins.

Mr. Robbins was an unfancy man, turning down new binoculars in favor of the government-issue pair that had served him well for years. As he aged, he consented to one new device — a set of hearing aids. “I don’t want to hear people as much as I want to hear birds,” he told an interviewer for the Audubon Society.

He was credited with tagging well over 115,000 birds but named his favorite as the house wren, a plain brown creature that he loved, he told the Baltimore Sun, for its “amazingly high-pitched and intricate song.”