The Endangered Species Act’s latest success story is a photogenic bird with a bright yellow chest, a gray-blue back and wings, and an intricate, pulsing lilt of a song.
Three decades ago there were only about 200 singing male Kirtland’s warblers left in the world.
And their picky breeding habits — they only build nests under the boughs of young jack pines in Michigan’s northernmost forests — didn’t exactly give them many habitat options.
That’s because government fire-suppression policies throughout the 20th century disrupted the jack pine life cycle.
Today, thanks to a coordinated forest-management program between federal, state and nonprofit agencies, the population of this Michigan-native songbird has skyrocketed to thousands of breeding pairs — double the goal set by government wildlife managers.
As a result, the Kirtland’s warbler is off the endangered list — and birdwatching tourists with money to spend are flocking to the region.
Yet the Warbler’s persnickety life cycle and the ongoing impacts we humans have on its habitat means that the battle for survival is far from over.
Fire suppression at fault
Previously, natural fire patterns would clear out overgrown jack pines, and also cause pine cones to burst open, enabling the forest to regenerate, and providing the Kirtland’s warbler with healthy housing stock of young trees with exactly the right height and density the bird required.
But the impacts of America’s westward expansion took their toll, with fire suppression resulting in larger, older, more dense jack pine forests that were inhospitable to the warbler.
To add insult to injury, the widespread extermination of bison in the Great Plains forced the more adaptive brown-headed cowbird — which formerly fed on seeds embedded in bison dung — to find new habitat across North America.
Unfortunately for the Kirtland’s warbler, the cowbird is also a parasite, and when it moved into those Michigan jack pine forests, it took to kicking the eggs out of warbler nests, and laying its own there instead.
Logging to the rescue?
Today, the jack pine forests of Michigan’s Lower Peninsula region are logged in a multi-year rotation that replicates the effects of historic fire cycles — and the cowbirds are being euthanized and effectively kept at bay.
The timber industry is playing along because it has found a market for the larger, mature jack pines that are scorned by the warbler.
Some experts are concerned that the warbler, which migrates south to overwinter in the Bahamas, may be affected by the impacts of climate change, including rising sea levels and devastation from increasingly severe hurricane seasons.
Conservationists are so concerned about this that the American Bird Observatory has financed a science position in the Bahamas to monitor climate-related impacts on the warbler.
But so far the bird is doing so well — and even bucking a nationwide trend of massive bird die-offs — that Michigan is now enjoying the economic benefits of guided bird tours and Kirtland’s warbler conventions.