George Bird Grinnell (1849–1938), Birdie to his friends, was a man of parts, one of those Victorian-era fellows who knew a little bit about everything, a lot about some things, and just about everyone who was worth knowing at that time. He grew up the child of privilege in New York City, but, like his friend Theodore Roosevelt, he wanted to toughen up and see the world. He was an indifferent student who got into Yale and hung on, eventually gathering the intellectual self-discipline to earn a doctorate in the new field of paleontology. He founded things, and he got things done, and he lived a long life gathering knowledge and harboring secrets.

Without Grinnell, who came within a hair’s breadth of accompanying George Armstrong Custer to his destiny at the Little Big Horn, there may not have been a Yellowstone National Park, a Denali/Mount McKinley National Park, a Glacier National Park, or a system of national parks to begin with. Without him, many 19th-century Plains Indians would never have had their thoughts and lives recorded for posterity. Without Grinnell, there might have been no Audubon Society, no Bronx Zoo. Without him, it’s conceivable that the American bison could have gone extinct.

So why don’t we know him better?

That’s a question that underlies the new biography Grinnell: America’s Environmental Pioneer and His Restless Drive to Save the West, whose 600 pages are full to bursting with all of its subject’s accomplishments. Its author, John Taliaferro—his name, Italian by way of Virginia, is pronounced Toliver—is no stranger to big places (he lives in Texas and Montana) or big subjects, with previous books ranging from a biography of the noted diplomat and politician John Hay to one on Edgar Rice Burroughs, chronicler of imagined life on Mars and in the African jungle. “Who was this guy? That’s what I asked myself when I first started noticing Grinnell’s name popping up,” Taliaferro tells Kirkus from his Austin home. “He should be a household word, but instead he’s barely known.”

There were many things that drew Taliaferro to Grinnell, from his wide-ranging interests to his work in conservation. Among other things, Taliaferro credits Grinnell with helping set aside large tracts of land in Montana aside, having “early on recognized their beauty, their resources, their people, and their potential.” Moreover, he says, “I was fascinated by Grinnell as a new kind of person, an Easterner who essentially commuted back and forth to the West after the transcontinental railroad was completed, reinventing himself as he traveled.”

The task of any biographer, Taliaferro holds, is to figure out somewhere in the process “what the person really knows about himself or herself.” In the case of Grinnell, there was an abundance of ambition: He wanted to be a second Audubon, perhaps, and certainly a famed pioneer of the unexplored country. There were matters that he took pains not to acknowledge or reveal, including what appears to be the strong possibility that he was a gay man in a time when being so invited imprisonment at worst and shaming and shunning at best.

And then there were the matters about which he went against the grain, including an on-the-way-to-being-enlightened view of Native Americans whom his generation robbed of their homelands and cultures. As Taliaferro writes, while we today would regard some of his ideas as paternalistic and perhaps even downright racist, his “attitude toward Indians, as a race, as tribes, as individuals, was forever evolving.” Certainly he did not believe, as did his friend Teddy Roosevelt, that Native Americans were natural enemies deserving of extinction, and he wrote perceptive books on several tribes, including the Cheyenne who had fought against his old boss, Custer, on the Montana prairie.

Taliaferro took six years to write his biography, the first devoted wholly to the naturalist and explorer, retracing his steps and working his way along the many tracks that made up Grinnell’s life. To name just one daunting task, it took Taliaferro a full year to read the thousands on thousands of pages of Grinnell’s surviving correspondence. “He did so much good in the world, driven, of course, by a sense that he knew what was best,” Taliaferro says. “I hope I do him justice.” Readers with an interest in conservation, the environment, animals, parks, Native American history, philanthropy, 19th-century characters, and a dozen other subjects will be delighted to discover that he does George Bird Grinnell justice indeed.

Gregory McNamee is a contributing editor.