New knowledge about the natural world doesn't always come easily. It often must be hard-won through close observation, experimentation, and sometimes even a crisis. Over the 75 years that Minnesota Conservation Volunteer has been publishing, natural resource managers have expanded their understanding of the state's wild places and creatures, including bald eagles.

When the first issue of the magazine, then called the Conservation Volunteer, came out in October 1940, a new U.S. law had just come onto the books in June. Before that time, eagles and other raptors were seen as competitors for fish and game or as "chicken hawks" that preyed on farm fowl. They were often shot on sight as vermin. But finally, the federal government had drawn a line with the national bird. "Under terms of federal law, bald eagles are protected in Minnesota," reported a March 1941 news item in the magazine. "Outlaw killing is punishable by a fine of $500, one year's imprisonment, or both."

The Conservation Volunteer worked to remind readers of the new law and to help change the prevailing mindset about raptors. "Our National Emblem Is Angry," read one headline in 1942. Minnesota soon enacted protections of its own: The 1945 Legislature passed a bill protecting 17 of Minnesota's 20 species of eagles, hawks, and vultures.

In 1946 Walter Breckenridge, curator of the museum of natural history at the University of Minnesota, enlightened readers about the role of each species in its environment—foreshadowing a holistic approach that would come to be known as ecosystem-based management. "As we survey the different species of hawks, we find each one fitting into a niche in Nature's program that is different from the others," he wrote. "It is our hope that shooters throughout the state … will give up hawk shooting entirely in the future."

Despite new laws and a gradual shift in public attitudes, bald eagles remained an uncommon sight, not only in Minnesota but also across the continental United States. And their numbers were going down. "Kenneth D. Morrison of New York City, editor of Audubon Magazine, and formerly editor of the Conservation Volunteer, recently said bald eagles have decreased alarmingly over most of their range," a magazine news brief reported in 1955. "There are probably fewer than 5,000 bald eagles left alive in the United States outside of Alaska," informed another in 1962.

Illegal shooting was still being fingered as a key culprit, but in reality something else was going on—something more invisible and insidious. In 1962 the book Silent Spring by Rachel Carson startled the public by calling attention to the toxic effects of DDT, a synthetic chemical that was being widely used as a pesticide. The Volunteer story "A Potpourri on Pesticides" in 1965 drew connections between Carson's work and new research that implicated DDT in eagle population declines. By 1968 the connection had become even clearer: DDT had been found to weaken eagles' eggshells, thus limiting their ability to reproduce. The United States banned its use in 1972.

Even with DDT out of the picture, other pollutants came to light. "The Case of the Poisoned Eagles" (Nov.–Dec. 1981) by the DNR's Carrol Henderson reported on a study by the agency's new Nongame Wildlife Program. It found that some eagles at Lac qui Parle Wildlife Refuge in western Minnesota were being poisoned by lead in the waterfowl they ate. In the Sept.–Oct. 1986 issue, Roger Holmes, then chief of DNR Wildlife, wrote: "Minnesota will, beginning in 1987, prohibit lead shot for all waterfowl hunting statewide."

In the 1970s and '80s, as eagles made their way back from the DDT-induced population crash, Minnesota had an important role to play. Chippewa National Forest had been one of the birds' strongholds in the Lower 48. Volunteer stories written by U.S. Forest Service wildlife biologist John Mathisen described the annual surveys of the forest's eagle population, which had begun in 1963.

By 1987 DNR nongame wildlife specialist Joan Galli could confidently state that "Minnesota is home to the largest population of nesting bald eagles in the lower 48 states." In 1993 the magazine cited wildlife researchers' predictions of 600 pairs by the year 2000. Even that optimism was exceeded: According to a statewide analysis by the DNR, Minnesota had more than 1,300 pairs by 2005.

While we know more than ever about Minnesota's eagles, there are still challenges to meet. Eagles are susceptible to lead poisoning from gut piles left by deer hunters using lead shot. "The Case for Copper" (Sept.–Oct. 2013) explained the situation.

Today, the bald eagle is—it's still surprising to say—a rather common sight in Minnesota, especially along the Mississippi River in the state's southeast. There it has spawned tourism centered on the education-based National Eagle Center in Wabasha.

To follow an eagle story right up to the present second, check out the live feed from the nest of a metro-area eagle.