The bird has come a long way. In the 1950s, there were fewer than 20 male Kirtland's warblers left, according to The Detroit Free Press. A management area was first established for the bird by the Michigan Department of Natural Resources in 1958 and it was listed nationally under the Endangered Species Preservation Act in 1966.

In 1971, two years before the Endangered Species Act was passed, there were only 201 singing males living in six counties of Michigan's Lower Peninsula, Science Magazine reported. In 2015, after nearly 50 years of conservation efforts, that number had risen to 2,383.

"This remarkable bird has a most impressive, exemplary success story that illustrates effective conservation and collaboration at work," Michigan Audobon Executive Director Heather Good said last year, as Science Magazine reported.

The warblers require a unique habitat that came with unique conservation challenges, as FWS explained:

Historically, wildfires were the most important factor for establishing the natural jack pine forests that Kirtland's warblers need for breeding habitat. Modern wildfire suppression greatly diminished the natural disturbance that once generated Kirtland's warbler breeding habitat. In the absence of wildfire, land managers had to take an active role in mimicking natural processes that regularly occurred within the jack pine ecosystem. This is primarily done through large-scale timber harvesting and human-assisted reforestation.

The warblers are also threatened by brown-headed cowbirds, which conservation groups work with the Forest Service to control.

Center for Biological Diversity Endangered Species Director Noah Greenwald said the warbler's recovery was a testament to the effectiveness of the Endangered Species Act, and a living argument against the Trump administration's recent changes weakening that legislation, finalized in August.

"This success story highlights the danger of the Trump administration's efforts to cripple laws protecting our wildlife and natural landscapes," Greenwald said in a press release. "Without the Endangered Species Act, the Kirtland's warbler might have vanished forever. Many other species will disappear if we don't stop Trump's efforts to gut conservation policies."

One of the arguments against the administration's changes is that they make it harder to protect species from the effects of the climate crisis, since they give the government wide leeway to interpret the phrase "foreseeable future." The Kirtland's warbler spends the winter in the Bahamas, meaning it could be threatened by sea level rise and more extreme storms like Hurricane Dorian, the Center for Biological Diversity pointed out.