The Age of Humans The Age of Humans

This Bird Didn’t Start the Fires, But It May Need Them to Survive

An endangered bird once threatened by humans now relies on us for its survival

The Kirtland's warbler needs humans to cut and replant the trees it nests in. Without this work, the species' painstaking recovery from less than 1,000 males to over 2,000 could be erased. (Joel Trick, USFWS)
smithsonian.com

Two hundred years ago, the Kirtland’s warbler had its pick of the jack pine forest when it came to choosing nesting grounds. Regular wildfires sweeping through the sandy forests of Michigan, where the majority of these birds still nest, kept the trees not too tall and not too short—just the way the warbler liked them.

Then humans moved to town, bringing with them an advancement that was great for civilization but not so great for this bird’s habitat: the ability to control fire.

“It’s a very specific habitat they need that historically was managed by naturally occurring fires,” says Jonathan Lutz, executive director of Michigan Audubon, which bears the iconic bird as its logo. “Now we have to mimic those historic conditions.”

The “we” refers to the state and federal agencies that, since the bird landed on the endangered species list in the mid-1970s, have been selectively logging, seeding, replanting and occasionally burning the jack pines to simulate their natural growing conditions while avoiding fires that could threaten the homes and lives of nearby residents.

This labor-intensive management system is now the norm on 150,000 acres of public land in Michigan set aside as warbler habitat. Each breeding pair of warblers prefers to have six to ten acres for its nesting territory, though the birds will make do with less if the forest is just right.

While painstaking, such careful human management—which includes regularly removing the cowbirds that take over warblers’ nests—appears to be working.

The initial recovery plan developed in 1976 established a goal of counting 1,000 pairs of warblers per year in their known range, which extends slightly beyond Michigan’s borders into Wisconsin and Ontario.

This year, the annual count of singing males in June came in at a whopping 2,365. What started as a hesitant sense of success for the bird’s champions in 2002, the first year the number of males came in above 1,000, has steadily climbed to a triumphant trill—one that could soon culminate in the bird no longer being considered endangered.

“It’s an exciting thing to think that, in my career, we’ve been able to go from not a lot of Kirtland’s warblers to potentially taking them off the [endangered species] list,” says Christie Deloria, a fish and wildlife biologist with the U.S. Fish and Wildlife Service who’s been working with the warbler for 20 years.

But removing the bird’s name from the list is not as easy as it might sound. Though these birds have found a way to survive in a post-wildfire habitat, their livelihoods depend on ongoing human intervention to keep parasitic cowbirds at bay and to artificially maintain a young jack pine forest.

In other words, Kirtland’s warblers are not ready for the training wheels to come off entirely. This leaves them in new territory as a so-called conservation reliant species. The bird once threatened by humans’ interaction with its environment now cannot survive without human intervention.

Just 30 species—or about 1 percent of those originally listed as endangered—have been taken off the list and are considered “recovered.” Of the remainder, one analysis found that 84 percent are conservation reliant.

“It’s become a managed system, so it’s a managed species,” Dan Kennedy, endangered species coordinator for Michigan Department of Natural Resources, says of the Kirtland’s warbler. “Unless we come up with a way to put fire on the ground over large areas safely, we are going to be planting young jack pine for quite a while.”

So why not just let the forests burn, like the good ol’ days? Deloria says many of the agencies involved with maintaining warbler habitat are gun-shy about using prescribed burns, and for good reason.

A controlled burn officials set in 1980 suddenly went wild, destroying 44 homes and buildings and killing a firefighter who tried to tame the blaze. Now, when large-scale burning comes up as a back-to-nature solution, so does the Mack Lake Wildfire.

“We have to put human and property safety first,” says Kennedy.

While the U.S. Forest Service and DNR use some burning to clear older jack pines and foster new ones, “it’s never going to be the answer for Kirtland’s warbler,” Deloria says. “It can be used, but we have to keep the other tools in the toolbox, such as cutting trees and replanting them.”

These tools, as one might imagine, use more time and resources than a box of matches. But if these agencies can find the funding (around a half-million dollars annually) and communal willpower to sustain this species in perpetuity, they could set the stage for other conservation-reliant species ready to be weaned from endangered status.

For starters, each of the agencies involved have committed to maintaining the bird’s habitat and protections regardless of its endangered status. But some of the funding for that work leaves with the “endangered” title.

A Friends of the Kirtland’s Warbler nonprofit was launched to fill the gap, raising funds for the bird’s future among its devoted followers; it helps that Michiganders love their warbler.

“We have, as human beings, a responsibility to maintain these populations,” Deloria says, “because what happens to them eventually happens to us.”

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