A March 2021 Field Note by Vera Leopold, TWI Grants Manager/Development Associate and resident birder
A misty spring morning rises over the marsh. A pair of Virginia Rails starts up a strident squawking somewhere in the cattails. A Pied-billed Grebe slips silently beneath the surface of the water. Swamp Sparrows sing their clear trills around the vegetation’s edges. And a semi-truck rumbles by on the nearby road.
This wetland scene takes place not in a remote wilderness area but at a remnant site in the Calumet region on Chicago’s Southeast Side. For the past five years, the Wetlands Initiative has been bringing back healthy habitat at the 113-acre Indian Ridge Marsh North parcel in partnership with Audubon Great Lakes and the Chicago Park District. And since 2017, I’ve been conducting surveys at Indian Ridge Marsh to detect the presence of secretive marsh birds as part of Audubon Great Lakes’ Marsh Bird Monitoring Program.
Vera Leopold taking a selfie at Indian Ridge Marsh.
The Calumet region, which stretches across southeast Chicago and northwest Indiana, was once a vast, rich wetland system that supported huge numbers of birds and other wildlife. A diversity of wetland birds continued to thrive here up until the 1990s. Unfortunately, the Calumet’s transformation into an industrial corridor disrupted the marshes’ natural, dynamic water-level fluctuations. A dramatic decline in habitat quality resulted, soon followed by the disappearance of marsh birds at many of the remaining sites they once frequented.
Now, through collaborative on-the-ground restoration, TWI and others are working to bring back the healthy hemi-marsh wetlands on which these birds rely. Audubon Great Lakes devised the monitoring program to assess how successful our conservation efforts are over time.
Special techniques are needed to effectively count marsh birds—they’re called “secretive” for a reason! Many wetland-dependent species such as rails and bitterns spend nearly all their time hidden in dense vegetation, and that’s also where they nest. A sharp-eyed observer might get lucky and see one emerge at dawn or dusk, when the birds tend to be most active. Otherwise, you could visit a wetland many times and never know they’re there.
To overcome this challenge, Audubon Great Lakes has deployed a standardized protocol developed by the U.S. Fish and Wildlife Service that uses a Bluetooth speaker to broadcast recordings of certain species’ calls over the marsh at maximum volume. Marsh birds that are on their breeding territory will often respond with calls of their own, announcing their presence. Volunteers receive training in identifying 18 species by sight and recognizing their calls; these species are the focus of the monitoring program. Then volunteers are assigned one or more wetland sites to cover, visiting a series of points at each site starting at dawn. Monitors conduct surveys a total of three times between May 1 and June 15. Because TWI is restoring Indian Ridge Marsh, I was able to score it as my survey site.
Indian Ridge Marsh at dawn, with the bird-call speaker in the foreground (click to enlarge). Photo by Vera Leopold/TWI.
A marsh-bird surveying adventure starts with a gear check the night before. In addition to the Bluetooth speaker, compass, and clipboard provided by Audubon Great Lakes, I put out my rubber boots, waterproof pants, binoculars, granola bars, and water bottle. Then it’s out of bed in the dark to drive to Indian Ridge Marsh and arrive at the first point ready to count, ideally 30 minutes before sunrise around 5:00.
I stand at the point for five minutes, quietly listening and looking. Then I play the recordings of five targeted marsh birds with a minute-long break between each species. I note on my data sheet the birds I detect, with their direction, estimated distance, and type of call. Between surveys, I walk swiftly to the next point to complete all nine points at Indian Ridge Marsh within three hours of sunrise, when the birds are most active.
When the speaker gets a response from a live bird, it’s like magic. More than once after playing the “wipeout” call of the state-endangered Common Gallinule, its raucous laughter emerged in answer from a patch of cattails not far from where I was standing. Rails can be especially territorial and sometimes walk right up to investigate. One spring, a Sora—a type of small rail with a stubby, candy corn–colored bill—called back from less than 10 feet away in the reeds and then popped out to get a better look at the Bluetooth speaker.
One of the Virginia Rails seen at Indian Ridge Marsh in 2020 (click to enlarge). Photo by Vera Leopold/TWI.
An even more thrilling encounter happened in June of 2020. Along 116th Street at the north end of the site, TWI has cleared invasive phragmites, removed trash that had been dumped, and planted native seed and plugs in past years. And just a few months earlier, the Chicago Park District had used an earth-moving contractor to restore a more natural sloping shoreline there. Shortly after I reached my point, I heard the sharp squeaking of a Virginia Rail close by and spotted it walking around in the shallow water in plain view. When the Virginia Rail recording played, the bird gave its “grunt” call in unison with an unseen second bird in the newly reestablishing native vegetation nearby—likely a pair defending their nesting territory! Though habitat restoration is not yet complete, the birds already appear to be responding.
Bird surveying in the Calumet region isn’t like other monitoring I’ve done in rural and remote areas. Sometimes I have to pause my stopwatch and wait for a train to go by on the adjacent track. Or wait for the clanging bell to cease as the bridge over the Calumet River is raised for a barge to pass through. The traffic noise along Torrence Avenue tends to get louder as the morning progresses.
Despite the urban setting, wildlife is always present at Indian Ridge Marsh. A harmless garter snake once greeted me, curled around dead phragmites stalks with impressive camouflage. I’ve seen a turtle laying eggs along the path. Herons and egrets flush as I walk between points; a resident kingfisher gives a rattling call from a nearby branch; sometimes a Bald Eagle watches me from atop a dead cottonwood tree. Even after all the man-made changes to this wetland area, it still has value for birds and wildlife and for the surrounding communities. And as restoration progresses, the habitat will only continue to improve.
A garter snake coiled among the dead phragmites. Photo by Vera Leopold/TWI.
With several years of data now in hand from me and other monitors, this spring Audubon Great Lakes released a new Marsh Bird Data Hub—an exciting tool to visualize how rare marsh birds are benefiting from wetland restoration and conservation efforts across the Calumet region. Monitoring data on the 18 focal bird species is fed into the hub from 32 wetland sites across the Calumet, in both Illinois and Indiana.
The Marsh Bird Occupancy Dashboard, accessible to anyone who visits the data hub website, can be manipulated to show trends from 2017 through 2020 for different Calumet sites and each focal species. The dashboard can also be filtered to display the likelihood that certain species are present at a specific wetland site. At Indian Ridge Marsh, for example, I can see that the likelihood of “occupancy” is increasing over time for Blue-winged Teal, Common Gallinule, Least Bittern, Marsh Wren, Pied-billed Grebe, and Virginia Rail. The pair of rails I recorded in spring of 2020 are part of a resurgence of that species and others across the Calumet region, bringing hope for the future of these valuable urban wetlands and their biodiversity.
Meanwhile, the Marsh Bird Monitoring Program is continuing in 2021 and they’re seeking new volunteers. I share a sentiment I recently heard during a webinar with fellow marsh-bird monitors: No matter what the morning brings, you never regret being out in a wetland at sunrise.
Discover the marsh birds of Illinois and Indiana and hear their calls here.
Sign up here to become a volunteer for the Marsh Bird Monitoring Program.