In Chicago, Controlled Fires Are Helping to Restore Crucial Bird Habitat

The burns, conducted by Audubon Great Lakes and others, stave off invasive plants while spurring new growth at sites across the region.

On a mild Monday in February, a 30-acre patch of common reed sways in the winter breeze at Indian Ridge Marsh in Southeastern Chicago. A colony of Black-crowned Night-Herons once built a rookery at Indian Ridge Marsh, and the herons’ lingering presence prevented the U.S. Army Corps of Engineers from touching this plot of land in 2011, when the agency restored the surrounding 150 acres of former steel-industry dumping grounds. But that was before the reeds, known as phragmites, grew taller, the thicket became denser, the water rose higher, and the last herons left. The parcel is now ripe for restoration. But first the land needs fire. 

As the restoration crew sprays gouts of flaming fuel over the grasses, the plants crackle and the smell of diesel and campfire permeates the air. This conflagration is one of the critical moments in habitat restoration for Indian Ridge. Before the steel mills and factories transformed the Calumet region into an industrial zone studded with rusting hulks and debris-choked ponds, this area teemed with wetlands, rivers, and forest. Now, after decades of neglect, the Chicago Park District, Audubon Great Lakes, and the nonprofit Wetland Initiative, among others, are working together to restore the area and provide somewhere for migratory birds to rest, refuel, and reproduce.

Today the biggest threat to existing wetlands in the Calumet are invasive plants like phragmites and narrowleaf cattail. As they take over, the weeds suffocate native species like lake sedge, making conditions intolerable for marsh birds that include the Common Gallinule and Least Bittern—species that used to thrive here. Unlike many native grassland and forest plants that evolved with wildfires, the invasive plants do not tolerate fire well; maintaining a healthy ecosystem means applying herbicides and then burning the property every year. The flames will not only help knock the plants back, but they will also encourage native plants to sprout, “bringing seeds out of their slumber,” says Daniel Suarez, who leads the site’s field crew for Audubon Great Lakes.

History shows the marsh system here can be prime real estate for the birds, whose populations are plummeting due primarily to habitat loss. Audubon Great Lakes, with the help of longtime birder Walter Marcisz, has been compiling data on how a variety of birds have fared over time at Indian Ridge. In the 1990s, says Marcisz, "my impressions were, ‘Boy, is this a great place.’” Gradually marsh-bird populations declined until the birds were basically all gone. Only recent restoration efforts have brought them back in small numbers.

The more land the team of conservationists burns and restores—as Audubon is already doing at nearly 30 marsh, forest, and grassland sites across the Chicago region—the more likely it is that the species will recover. As a 2016 study on grassland birds in Illinois revealed, populations of grassland-dependent Henslow’s Sparrows have plateaued everywhere in the state except Chicago, where their numbers are increasing. “We’ve lost a lot of places in Chicago,” says Nat Miller, Audubon Great Lakes director of conservation and co-author of the 2016 study, as he walks along what will be a trail for visitors of Indian River Marsh. But even with a history of heavy industrial use, he says, “these open areas can be good habitat.” As the flames reduce the brush to ash across the restoration site, and the smoke dissipates in the wind, the rebirth of marsh has already begun. 

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