From shrub swamp and open marsh, the Cooper Park trail leaves the boardwalk to enter a more mature stand of floodplain forest. This is one of the better places to see a prothonotary warbler—in season, of course. If there is one songbird that can be called a floodplain forest specialty, it is the cavity-nesting prothonotary warbler. The prothonotary warbler even seems to have an affinity for nesting in forests with standing water around the nest tree. Unable to create its own nest hole, the prothonotary warbler may use an old woodpecker hole excavated in a standing dead tree. Tree death due to flooding is a common occurrence along big rivers. It is another way that flooding can be looked upon as a normal part of a river’s yearly ecological cycle. House wrens and tree swallows also take advantage of the abundant dead trees in the floodplain forests. The declining Red-headed woodpecker is highly associated with floodplain forests for the same reason.
The trail continues through the forest and eventually leaves one of the two Registered Reserve units. To the east is a manicured picnic area; to the west is lower Peoria Lake. Before continuing on the trail, it is worthwhile to walk to the lake’s sandy shoreline to look for terns, gulls, double-crested cormorants, and waterfowl. Because the Illinois River valley is a major migratory flyway, a birder should be prepared for anything.
In recent years, American white pelicans have been using the river valley during migration; they may typically be seen leisurely soaring in great slow-moving flocks high over head or seriously following one another, first up a short way, and then down over invisible air waves, tracing sine waves across the sky. During appropriate times of the spring and fall migratory periods, seeing a low-flying osprey can almost be counted upon. Bald eagles are an absolute certainty during the winter months. Without mud flats in the immediate area, large numbers of shorebirds can be ruled out; but killdeer should be expected, and spotted sandpipers can sometimes be seen bobbing their tails along the margins of the lake or across fallen logs. From July through September astronomical numbers of swallows may be seen flying in every direction from just above the water to hundreds of feet in the air. With only a small degree of persistence, one may see cliff, barn, bank, northern rough-winged, and tree swallows, plus purple martins.
At lower Peoria Lake’s shoreline, the shining, tall buildings of downtown Peoria are clearly visible two miles away, as are the upscale condominiums and Key-West-like developments just outside the boundaries of Cooper Park. The gambling boat and hotel complex further down the shore add the Las Vegas touch. It is this view that underscores the significance of the sliver of undeveloped, wild land that is Cooper Park Wetlands.
The south unit of Cooper Park Wetlands Reserve begins at an area which was only very recently kept mowed and manicured. Now, however, the natural process of plant succession is being left to its own devices here, where young cottonwood and silver maple saplings, plus a few other species, are competing for dominance. This area will continue to change in structure and plant composition as the winners at competition for space, water, nutrients, and sunlight become the dominant individuals. Here, decurrent false aster once grew, but that stage, just after the mowing stopped, has long passed. Decurrent false aster is now elsewhere. Trees grow fast on the floodplain, though, so it will not be long before this thicket of saplings resembles more mature forests. Thicket-loving bird species such as the common yellowthroat, brown thrasher, and gray catbird will find appropriate habitats here for a few years—until the trees mature, when they will be forced to seek shrublands elsewhere. Change, of course, is the nature of succession.
The Cooper Park trail continues southward past the early successional woods into a more mature floodplain forest. Here as in other areas of the forest, one may take notice of piles of woody debris covering the forest floor in many places. Much of this wood has continually been piled and re-distributed by flood waters. It is not unusual for the entire trail system, including the boardwalk, to be covered in water during peak flood times during the spring. Park management policy includes leaving the woody debris piles in place because of the wildlife values such structures provide.
Turbid flood waters covering the trail at Cooper Park.
Before leaving the reserve’s southern entrance, the trail passes over another boardwalk system, which gives access to additional willow-shrub wetlands and forest. Bird communities here are similar to those already encountered, although subtle differences, due to slightly different habitat characteristics, become evident upon closer inspection.
A traveler on Illinois Route 116 intent upon the larger, more well-known natural attractions of Illinois might be more focused on getting as far away from gambling boats and pseudo-Floridian strip developments as quickly as possible. The stand of trees, at Cooper Park Wetlands, between the strip of businesses and the margins of lower Peoria Lake would quickly pass behind un-noticed. Cooper Park Wetlands, though, provides a good excuse to slow down, pull off the highway, and take a lazy hike for an hour or so. There are few better ways for adding balance to your life.
[Note: This story originally appeared in slightly different form in the fall 2002 issue of Illinois Audubon magazine, number 282.]
Special Note
: Cooper Park Wetlands is in the northwest corner of Tazewell County. Exit south from U.S. Route 24 on the east side of the Illinois River onto Illinois Route 116. Soon after the exit ramp, turn west onto the frontage road and continue west into the parking lot at Spindler Marina. The trail entrance to Cooper Park Wetlands is located at the southeast corner of the parking lot.In order to protect its natural features in perpetuity Cooper Park Wetlands was registered as an Illinois Land and Water Reserve. Activities in the registered area are strictly regulated by state law. More information is available by contacting the Illinois Nature Preserves Commission (One Natural Resources Way, Springfield, Illinois 62702-1271, telephone # 217-785-8686) or the Fon du Lac Park District (201 Veterans Drive, East Peoria, Illinois 61611, telephone # 309-699-3923).
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