It was about 6:45 a.m. on a bright, chilly morning in early May. We were walking between long rows of abandoned Army ammunition bunkers amid grassland that stretched for miles in every direction, quietly listening and looking, when a thrilling sound reached my ears: a thin, low “wolf whistle” that carried across the prairie. In this surreal setting, it was dreamlike, yet somehow belonged like nothing else.
I was at Midewin National Tallgrass Prairie helping with a U.S. Forest Service breeding bird survey, and the owner of this call was an Upland Sandpiper, one of the species we were here to find. Located south of Joliet and an hour’s drive from Chicago, Midewin was once home to the nation's largest munitions plant, which produced 5.5 million tons of TNT per week at its peak during World War II. Now, it’s the largest protected natural area in northeastern Illinois and one of the largest prairie restoration efforts east of the Mississippi River. The Wetlands Initiative has been partnering with the U.S. Forest Service to restore native prairie and wetland habitats here since 1997.
In a state where less than one-tenth of 1 percent of the original prairie habitat remains, Midewin’s vast size makes it a critical site to sustain populations of declining grassland birds like the Upland Sandpiper, Loggerhead Shrike, Grasshopper and Henslow’s sparrows, Bobolink, and others. Its 30 square miles provide the unbroken tracts of habitat these birds need to breed successfully in large numbers. Because Upland Sandpiper and Loggerhead Shrike are birds of special conservation concern—both are state-listed species in Illinois—the Forest Service holds surveys over two to three days each year specifically to monitor their populations, led by Forest Service ecologist Bill Glass.
It was my first time helping with the survey, and I joined bird survey veterans Fran Harty of The Nature Conservancy and Jason Zylka of the Forest Preserve District of Will County. We drove in Fran’s vehicle out to a remote part of Midewin’s east side, still closed to the public. We parked off the dirt road, then fanned out in an equidistant line across one end of a grassy field and began walking forward.
On the other side of a fencerow, another team of three people was doing the same. Because Upland Sandpipers are shy birds that hide in the tall grass, combing the fields is a good way to discover their presence. These preliminary surveys are followed by stationary “point-counts” in June, in which both sandpipers and other grassland birds are recorded (read an account of thesehere).
Upland Sandpipers are birds of the prairie, one of just a handful of North American shorebird species that feed and nest in dry grassland areas, rather than relying on watery or coastal habitat. The slim, light brown-patterned bird forages for insects on the ground, where it also prepares its scrape nest (a shallow depression in the ground). Once widespread across the Great Plains and upper Midwest, the Upland Sandpiper is now uncommon and has seen severe population declines across much of its range. While hunting has contributed to its decline, the primary concern today is habitat fragmentation due to the conversion of native grassland to agriculture both in the United States and in the sandpiper's winter home in South America.
Upland Sandpiper is now a species that Illinois birders consider themselves lucky to find. I had seen only one in the state once before, years ago. This unfamiliarity led me to ask Fran as we walked, “How do I tell an Upland apart from other sandpipers?” He replied simply, “Nothing else looks like it.”
This cryptic response soon made more sense to me when Jason called out, “Sandpipers!” and two thin-bodied, long-legged shorebirds flew overhead, apparently flushed by the other team. Their stuttering flight and profile are unique enough, but it was the distinctive behavior when I glimpsed them land near a bunker that clinched it: One bird held its wings above its head for a few moments after landing, like a person doing yoga or jumping jacks. Then, as I watched through binoculars, it folded its wings, ducked its head down, snuck into the high grass, and disappeared. That characteristic wolf whistle floated over to us on the wind, and then no sign of the birds remained.
We shared smiles. At least two “Uppies” were alive and well at Midewin. And it was clear that, despite participating in these surveys for more than 10 years each, this moment of discovery never gets old for Jason and Fran.
Jason Zylka has been involved with Midewin since 2000, four years after its designation as the first National Tallgrass Prairie, working as a seasonal employee there in 2000 and 2001 and then as a full-time biological technician for the next four years. He’s now a restoration ecologist with the Forest Preserve District of Will County, responsible for the various aspects of managing the district’s natural communities, but comes back to Midewin to help with the bird surveys whenever he can.
“I’m glad to be in a place where I can continue to contribute in some way,” said Jason. “It’s great to see how far the site has progressed since my first days there.”
Fran Harty’s history with Midewin goes back even further. He played a major role in the initial process in the 1990s of getting the decommissioned Army land designated and protected under the U.S. Forest Service system. Before that, he helped lead the first sandpiper surveys on the property together with Bill Glass in the mid-1980s to assess the site’s importance to unique bird species. Nearly 30 years later, the annual surveys continue to track the sandpiper’s numbers from year to year. In the first 10 years of the survey, there were about 200 sandpipers at Midewin, but they have been declining since then and the causes aren’t well understood.
“They’re now down to fewer than 10 birds,” said Bill Glass of the Forest Service. “But the habitat is there and we are increasing their habitat, so we’re not sure what the problem is. It could be something going on [in their wintering grounds] in South America or on migration; it could be the presence of invasives at Midewin, which we’re working to manage. I suspect it’s a number of factors and not just one thing.”
From the sandpiper search, we moved on to driving along old fencerows, looking for shrike nests. Loggerhead Shrikes are black, white, and gray patterned predatory songbirds that behave somewhat like hawks. They hunt over grassland and shrubland from conspicuous perches, catching and eating grasshoppers and other insects, lizards, rodents, and even birds as large as themselves. One of their nicknames, butcherbird, is earned by shrikes’ somewhat macabre behavior of impaling their dead prey on thorns or barbed wire for easier eating. They sometimes store prey in these caches or “larders” for later.
Like Upland Sandpipers, Loggerhead Shrike populations have declined sharply in the upper Midwest, although they’re still fairly common in the southern and western United States. Midewin is one of the few places in Illinois where a healthy population of nesting shrikes persists; unlike the sandpipers, their numbers are doing well here and may even be increasing. The shrikes typically build their nests just a few feet off the ground in dense shrubs and trees with many trunks, the thornier the better. The goal of the surveys is to count shrikes, flag the locations of their nests, and record the number of eggs if possible.
In addition to the annual surveys, a researcher, Dr. Amy Chabot, is working with Forest Service staff to study shrikes and their nests at Midewin. Funding for this year’s shrike research is provided through a grant to The Nature Conservancy from the National Fish and Wildlife Foundation. As part of broader studies of shrike populations across eastern North America, she’s interested in determining whether the shrikes seen at Midewin from year to year are the same birds returning from migration or different ones and, if different, where they are coming from. Consequently, she’s been banding shrikes at Midewin and studying their genetics.
Dr. Chabot is also helping the Forest Service study shrike nest predation at Midewin, which seems unusually high, by setting up automatic cameras near nests. Because Brown Thrashers are abundant nesters at Midewin and use similar locations, we also were asked to flag and record data on thrasher nests when we found them.
Well-versed in this nest-finding work, Jason and Fran scanned the fencerows with sharp eyes and were able to pick out bird nests in spots that to my eyes looked like just another clump of branches and vegetation. Once we found a nest, we quickly inspected it to see if it was occupied and determine if it belonged to a shrike, thrasher, or some other bird species. Using the very advanced tool of a small mirror on a pole, we could peer into the nest to check for eggs with minimal disturbance.
While the three of us didn’t find any shrike nests on this particular day, we did locate a number of active thrasher nests (usually with the handsome, rusty-brown parents keeping a close watch nearby), and I once used the mirror to discover a clutch of sky-blue American Robin eggs. Other groups saw adult shrikes, while we had to settle for the occasional sighting of a lookalike Northern Mockingbird. The striking black-and-white pattern in the mockingbird’s wings when they fly by gets your heart rate going, as Jason put it, at first making you think it’s a shrike.
Midewin is a landscape in transition, and other relics of its history—aside from the massive concrete bunkers—were in evidence on our route. We passed strings of telephone poles leading to nowhere and reconnoitered with the other teams near a small ghost town of abandoned and slowly crumbling buildings: infrastructure still to be removed from the arsenal days.
Cattle ranchers also still have grazing leases on portions of Midewin (they keep grasses short, benefitting Upland Sandpipers and certain other grassland bird species). At some survey points, an extremely curious bovine audience watched our every move. Other times, while driving, we had to slow to a crawl to wait for cows to leave the road. “You can’t stop all the way,” warned Fran, “or they’ll come up to the car and slime you.” Apparently, some cows can’t resist licking a shiny, probably bug- and salt-covered vehicle.
In total over two days of surveys, the teams found six Upland Sandpipers and eight shrike nests. While we had just two target species on this survey, Midewin is full of other birdlife. As we searched, we were surrounded by the songs of Grasshopper Sparrows, Dickcissels, and Eastern Meadowlarks. In all, I counted nearly 30 other species over my five-hour surveying adventure. Midewin truly is a haven not just for the rarest Illinois species, but for other birds and wildlife that need this huge site and others like it in order to stay common in our state.
Why does it matter whether the Uppies and shrikes are doing well at Midewin? Ecologically speaking, they are essential parts of complex prairie ecosystems, which likely won’t function as well if any species are missing. Put less scientifically, they simply belong here. Our Prairie State without the wolf whistle of the Upland Sandpiper or the black-and-white flash of a hunting Loggerhead Shrike wouldn’t be the same; would be diminished. As restoration efforts progress at Midewin, hopefully greater numbers of these special birds will thrive in Illinois.
For more information:
Learn more about TWI’s restoration work at Midewin National Tallgrass Prairie:
Hear the call of the Upland Sandpiper:
Learn more fascinating facts about the Loggerhead Shrike: