The Kirtland’s Warbler Has Recovered, But the Hard Work of Saving It Will Never Stop

Sustained management is the only way to prevent a population backslide once the bird sheds its endangered status later this year.

In 1967, under a precursor of the Endangered Species Act, 75 animal species became the first to receive federal protection as endangered. Some members of that freshman class, like the Bald Eagle, have since soared off the list after stunning recoveries. Others, like the California Condor, have made significant strides but remain fragile and listed. 

Somewhere in the middle perches the Kirtland’s Warbler. After bottoming out at 167 breeding pairs in 1974 and again in 1987, the spunky songbird’s numbers have grown steadily, thanks to rigorous, hands-on management. Its population—always naturally small—blew past the recovery goal of 1,000 pairs back in 2001, and today totals more than 2,300 pairs. 

Given that remarkable rebound, it’s no surprise that the U.S. Fish and Wildlife Service (FWS) last year proposed to take the species off the endangered list, and is expected to make that delisting official this summer or fall. But that doesn’t mean the hard work of protecting the bird is over. The reason the Kirtland’s Warbler remains listed nearly two decades after meeting its recovery goal is that it’s what biologists call a conservation-reliant species: If we ever stop managing forests to meet the bird’s particular habitat needs, it will again slide toward endangerment, or worse. 

In other words, when we humans hack away at their habitat, introduce invasive pests, or otherwise push conservation-reliant species to the brink, we put ourselves forever on the hook to save them, says Michael Scott, a retired University of Idaho wildlife biologist. “It’s like walking into an antique shop,” he says. “You break it, it’s yours.” 

While some threatened or endangered wildlife just need a helping hand and then bounce back on their own—ban DDT, and Bald Eagles rebound; eliminate non-native foxes from Aleutian Cackling Goose nesting islands, and the bird's numbers explode—those relatively simple cases are the exception, and conservation reliance is the rule. In a 2010 paper, Scott and colleagues concluded that 84 percent of species then listed under the Endangered Species Act would require ongoing management, even after official recovery goals are met. “The challenge created by the conservation reliance of threatened and endangered species is formidable,” they wrote.

If any species appears ready to meet that challenge, it’s the Kirtland’s Warbler—not due to its own traits or behaviors, but because of the passionate protectors in its corner. These university scientists, government wildlife experts, and nonprofit conservationists have long recognized that delisting, while a welcome sign of recovery, could put the species on shaky existential terrain. To build the bird a secure future, they’ve teamed up and put in place a plan to keep its numbers on the rebound. 

“This is a keystone management species that’s entirely conservation-reliant, and we have built a partnership that we believe will sustain this species and all the other species that rely on its management,” says Carol Bocetti, a biologist at California University of Pennsylvania who has been part of the warbler recovery effort for more than three decades. “That has certainly never been done before.”

A Precarious Perch   

One reason the Kirtland’s Warbler landed on the endangered list is nest parasitism by Brown-headed Cowbirds. The species—which moved into Kirtland’s breeding territory in the early 20th century after logging and land-clearing created new habitat—lays eggs in warbler nests and lets the endangered birds do the energy-draining work of raising cowbird chicks, which often outcompete their smaller nestmates and diminish overall reproductive success. To give the warblers a fighting chance, the FWS began trapping and euthanizing cowbirds in 1972. Emerging research suggests that the cowbird control may no longer be needed—perhaps because their own habitat has been dwindling in Michigan—but for now that work continues.

The more fundamental factor in the warbler’s decline, though, was habitat loss. The species nests on the ground in young jack pine forests, with almost the entire breeding-season population in northern Michigan and the rest in Wisconsin and Ontario. Historically, forest fires regularly scorched those sandy pine barrens, wiping out old trees and regenerating the large tracts of shrubby woods the birds need for breeding. But decades of fire suppression to protect property in the area led to a drastic decrease in the acreage burned each year, making proper habitat harder to find.

Saving the Kirtland’s Warbler has involved regenerating its required habitat—jack pine stands about 5 to 20 years old—by clear-cutting and replanting portions of the forest on a rotating basis across more than 210,000 acres of public land. Kirtland’s Warblers haven't been the lone beneficiaries of that work. The birds are emblematic members of an ecosystem built of blueberry bushes and fragrant sweet fern: large mammals like badgers and black bears, and avian species such as American Kestrel, Clay-colored Sparrow, and Upland Sandpiper. “If it weren’t for the management of this species, that ecosystem wouldn’t exist,” Bocetti says. 

Managers know they’ll need to maintain existing warbler habitat for the foreseeable future and add new tracts when opportunities arise. That’s why, in 2011, the Michigan Department of Natural Resources, the U.S. Forest Service, and the FWS signed an agreement committing the agencies to continue working together to conserve the species. And in 2015 they released a formal conservation plan detailing each agency’s ongoing responsibilities. 

Of course, that work costs money. As an endangered species, the Kirtland’s Warbler has been a priority for conservation funding. The mix of state and federal dollars devoted to the bird is complex and varies from year to year, and it’s difficult to say exactly how delisting will change that picture. But even with the benefit of Endangered Species Act programs it has sometimes been a challenge to acquire the necessary funding, and that struggle will only intensify after delisting. 

Securing the Future

To keep the species from losing ground will take about $376,000 per year in ongoing management, monitoring, and outreach costs, along with $2 million for research and other short-term projects, according to a business plan put together by the Kirtland’s Warbler Conservation Team, which was formed in 2016 as the long-term replacement for a recovery team established through the Endangered Species Act. The conservation team and others aim to raise roughly $7.5 million in endowment funds whose annual interest can cover those costs. 

The American Bird Conservancy has set up a fundraising portal for the bird, as has the Kirtland’s Warbler Alliance, which formed in 2013 under the umbrella of northern Michigan conservation group Huron Pines to raise money, educate the public, and otherwise support the bird’s ongoing protection. The Alliance is only now setting off on its own; it became incorporated as an independent nonprofit organization this spring, just launched a website, and is seeking funding to hire an executive director. 

Bill Rapai, a former journalist who wrote a book about the Kirtland’s Warbler and now chairs the Alliance board of directors, says he’s determined to build the funding stream and public support the warbler will need to thrive. “I don’t want to fail the species,” he says. “I don’t want to fail the people who have dedicated their careers—there are a lot of people who have come before me who put their heart and soul into this bird. Believe me, I am aware of that.”

So far, fundraising efforts have netted only a sliver of their goal. But they’re just getting underway, and Nat Miller, director of conservation for Audubon Great Lakes and a member of the conservation team’s long-term funding committee, says he’s confident that Audubon and others will raise what’s needed. Besides, Miller says, having built strong relationships over decades of shared endeavor, the agencies and organizations involved will do what it takes to save the species should any lean years lie ahead. “The Endangered Species Act, besides delivering dollars, has also stimulated the partnerships,” he says. “Collaboration is always hard work, but it builds a deep bench of support.”

For its part, Audubon Great Lakes is conducting outreach through its MI Birds program to build public awareness of the Kirtland’s Warbler and why it needs ongoing help. Michigan Audubon, meanwhile, works with the U.S. Forest Service to provide guided Kirtland’s Warbler tours that can deepen participants’ commitment to conserving the species. 

Through its International Alliances Program, Audubon also plays a lead role—along with the Bahamas National Trust and others on the Kirtland’s Warbler Conservation Team—in conserving the bird’s winter habitat in the Caribbean. “We want to make sure the wintering grounds are as protected as the breeding grounds,” Miller says.

Climate change makes protecting that winter habitat crucial. It ratchets up the risk that hurricanes, sea-level rise, or other hazards could devastate the species. The Kirtland’s Warbler may be in good shape today, but its population is small and clusters each non-breeding season on a handful of small islands in the Bahamas. There the tiny birds are vulnerable. But whatever threats they face, they do not face alone.