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Every four years, ecologist Erin Victory walks among jack pine plantations grown on Michigan Department of Natural Resources (DNR) land. Along with other state employees and volunteers, she stops every 220 yards or so among the fragrant evergreens, listening for the staccato song of the Kirtland’s Warbler—one of the continent’s scarcest songbirds. Last year, those songs resounded among the trees less frequently. Surveys estimated just 1,477 breeding pairs in Michigan, where the vast majority of the warblers nest, down from 2,184 pairs in 2021. 

����’s a recent twist in what is often held up as a conservation success story. Kirtland’s Warblers, with their blue-gray heads and bright yellow bellies, are picky birds, nesting almost exclusively in young jack pine stands around 5 to 20 years old in small areas of Michigan, Wisconsin, and Ontario. Historically, natural fire cycles helped create these early successional habitats, opening up the canopy and renewing plant growth. But fire suppression, along with habitat loss and parasitic Brown-headed Cowbirds, devastated the warblers’ populations, landing them on the U.S. Fish and Wildlife Service’s first list of endangered species in 1967. At their lowest, population estimates fell to just 167 pairs.

To save the species, a team of conservationists that includes FWS, the U.S. Forest Service, the Michigan DNR, and nonprofits took dramatic measures. They trapped and euthanized cowbirds and cut down mature jack pines to make room for planting dense stands of saplings where the warblers could thrive. The plan worked: Kirtland’s Warbler numbers rebounded, and in 2019 the birds came off the Endangered Species list. But today, as the mosaic of managed stands ages, wildlife managers are seeing some population declines, says Victory, the Michigan DNR Kirtland’s Warbler coordinator. They’re experimenting with new ways to make jack pine forests hospitable for the warblers and keep their recovery going. “We're doubling down on our habitat management efforts to counteract that,” she says.

Part of the issue is that forest management plans, designed to work as a self-sustaining system, are not balanced right now, Victory says. The idea was that once the trees grew big enough, companies would harvest them for lumber, helping cover some of the costs of managing Kirtland’s Warbler habitat. Those areas could then be replanted, beginning the succession anew. However, sections of the forest are in a period of mismatch when trees are too old for the warblers to use but not big enough to sell as lumber.

To make space for new plantings, Kirtland’s Warbler managers have tried cutting down younger, midsize trees and chopping them into mulch or biomass. Researchers are separately experimenting with different habitat strategies on another 25 percent of the pine plantations—exploring how the songbirds fare in patches with different jack pine densities and areas with more red pines, where surprisingly some Kirtland’s Warblers have been spotted nesting in Wisconsin.

Eventually, they also hope to reintroduce fire to the landscape. Jack pines are adapted to fire; their cones open in extreme heat. But managers have scaled back their use of prescribed fire after a burn raged out of control in 1980, killing a Forest Service technician, destroying 44 homes and buildings, and charring 20,000 acres. As some community members remain wary of intentional fire, the Michigan DNR plans to invite public comment before possibly bringing more burns back.

����’s all part of the effort to keep fine-tuning their conservation plans, a method scientists call adaptive management. “Through that very evidence-based scientific process, [we can] figure out how to do things better,” says Nathan W. Cooper, a research ecologist at Smithsonian’s National Zoo and Conservation Biology Institute who has studied the Kirtland’s Warbler recovery efforts.

As the songbirds face new challenges like climatic shifts and potential threats to public lands, the work of keeping the birds around will have to evolve, too. “We're always going to have to manage for this species in order for them to persist on the landscape,” says Victory. “This is a legacy that we want to make sure we can pass down to next generations.”

This story originally ran in the Summer 2026 issue as “Fine-Tuning the Forest.” To receive our print magazine, become a member by .