GRAND RAPIDS, Mich. (WOOD) — A wildfire in northern Michigan may have an outsized impact on a threatened species: the Kirtland’s warbler. Whether the impact is a positive or negative remains to be seen.

The Wilderness Trail Fire torched more than 2,400 acres east of Grayling this June — including a key stretch of jack pine forest that serves as one of the few hot spots for the once-endangered bird. Bill Rapai, the executive director for the Kirtland’s Warbler Alliance, said there’s no way for environmental agencies to track whether any birds died in the fire but that nests were certainly lost.

“It burned through nesting habitat. As a matter of fact, it burned through habitat that I helped plant in 2014,” Rapai told News 8. “We know there were adult Kirtland’s warblers that had built nests and laid their eggs and were raising their young there, and those were lost in the fire.”

Rapai said the birds would have fled the area. While it may still be early enough in the season for the warblers to make new nests and have another clutch of eggs, there were certainly losses.

“The 2021 census (found) there were at least 18 singing males in that area. So if you assume that each singing male had a mate, we had 18 nests,” Rapai estimated. “Let’s say each nest had four to five eggs. So we potentially lost a good deal of birds.”

The good news is the Kirtland’s warbler population is strong enough now to survive an event like this wildfire.

“There are enough Kirtland’s warblers across the landscape. There are Kirtland’s warblers as far west as Kalkaska. There are some over toward the Tawas area. It’s not like this was a major portion of the Kirtland’s warbler’s population. It’s not a blow that we can’t recover from,” Rapai said.

A male Kirtland’s warbler is perched in a jack pine tree. (Courtesy Vince Cavalieri/USFWS)

That wasn’t always the case. The Kirtland’s warbler was included in the U.S. Fish and Wildlife Service’s first federal Endangered Species List in 1967, primarily because it fell victim to an invasive bird — the brown-headed cowbird.

“(The brown-headed cowbird) pretty much wandered into Michigan after the state was lumbered in the late 19th and early 20th centuries. It found the Kirtland warbler’s nest and said, ‘Hey, here’s a new nest that we can lay our eggs in,’” Rapai explained. “The brown-headed cowbird lays its eggs in another bird’s nest and then just wanders off and lets that host species raise the bird. … Then the brown-headed cowbird (chick) will out-compete the Kirtland’s warblers (chicks). They will eat all of the food. They will push the Kirtland’s warblers out of the nest.”

The other key reason for the warbler’s decline: human intervention to prevent wildfires. Kirtland’s warblers like to nest in the sandy soil beneath young jack pine trees. As the trees grow older, the lower branches die off and expose the nests. By interrupting the natural cycle of regeneration triggered by wildfires, the Kirtland’s warbler lost a lot of habitat.

A map of the Kirtland’s warbler range, limited to parts of Michigan, Wisconsin, Minnesota and Canada. (Courtesy Cornell Lab of Orinthology)

“This bird limped along for a long, long time. And once we finally figured out that secret sauce, once we finally figured out what it would take to see that population begin to grow, that’s when it began to take off and we knew that the species was going to be safe,” Rapai said.

The Kirtland’s warbler was removed from the federal endangered species list in October 2019, but it is still listed as a threatened species in Michigan by the Department of Natural Resources. In addition to stretches across northern Michigan and the Upper Peninsula, the warbler can also be found in pockets of forest across Minnesota, Wisconsin and Canada.

According to Rapai, the DNR is still formalizing its plan for how to best repair the forest lost in the Wilderness Trail Fire, but it appears it will be as hands off as possible. Rapai said the key will be the age of the remaining trees.

“There are some areas where there are more mature trees that are able to produce cones. There, they will just let those cones naturally repopulate the jack pine population,” he explained. “In the areas where the trees are younger, too young to create cones, the DNR is going to have to go through those areas and replant.”

There is a silver lining to the wildfire that could actually benefit the bird. Rapai believes it will actually help correct the balance between healthy and aging forests.

“There will be some bonus acreage created by this,” he said. “That’s going to be good, especially because we know that we were kind of heading into a little bit of a habitat shortfall. … The number of acres that get planted for the Kirtland’s warbler had fallen behind a little bit. (We will take) every little acre that we can add to this.”