After a storied 44-year career as a champion of some of Minnesota's most beloved and threatened wildlife, Carrol Henderson isn't going out quietly.

He's still got a full plate of projects, from advocating for ending the use of lead ammunition to creating a new trail for birders and wildlife watchers in northern Minnesota.

Henderson is retiring as head of the state Department of Natural Resources nongame wildlife program, which works to protect over 700 species including loons, osprey, eagles and turtles. It's a position he's held since the program was started in 1977.

In this photograph from 1987 Carrol Henderson collects trumpeter swan eggs from Alaska. Courtesy Carrol Henderson 1987

Although they might not know Henderson's name, most Minnesotans have probably encountered his outdoor advocacy in some form.

An author and photographer as well as a researcher, he led efforts to boost the populations of bald eagles, trumpeter swans and white pelicans across the state. He was behind the program that added a check-off box to Minnesota tax forms to support contributions to nongame wildlife conservation. The effort has raised more than $35 million for bees, butterflies, songbirds, frogs, turtles, bats and other wildlife since 1981.

Henderson was also among a group of researchers who spent seven years studying the effects of the 2010 Deepwater Horizon oil disaster on Minnesota's loons and pelicans that migrate to the Gulf of Mexico in the winter.

In an interview with MPR News Wednesday, he said the federal government is expected to release a plan within the next several weeks for helping migratory birds affected by the oil spill.

The researchers used radio implants and geolocators to track loons' movement and how deeply they dove into the water in search of food.

"We did find out that yes, they were going right to where the oil spill was," he said. "They go to the bottom, they feed on the bottom in the Gulf, maybe 120-130 feet deep. And that's where the crud would have settled."

The longtime bird watcher, Henderson also is involved in a proposal to create a birding and wildlife trail through northern Minnesota.

The Heart of the Bog trail, a designated route of roads and hiking trails, would extend from Duluth to Bemidji and then north to the Canadian border. Henderson said it would highlight some of the best places to spot birds and wildlife.

Henderson said the trail would help meet a growing demand for what he calls "nature tourism." While the number of hunters in Minnesota has declined, interest in wildlife photography, bird watching and other outdoor activities is on the rise, he said.

"Some of these communities that depend on a strong income from hunting activities and outdoor activities that are traditional, they need to latch onto this new rising star in our outdoor environment and say, 'We need to bring in some of these tourists who want to enjoy nature in the north country,'" he said.

Henderson also continues to promote efforts to encourage hunters and anglers to start using lead-free ammunition and fishing tackle. Lead ammunition breaks apart into tiny pieces, where it can poison bald eagles or other scavengers that eat animal remains left by hunters.

He estimates that at least 30 eagles die every year from eating lead-poisoned entrails.

"We have become so complacent and accepting of lead as a bullet that we don't think of consequences of what happens after we take our deer and leave the woods," Henderson said.