Spring 1998

Rookery's nesting birds include great blue herons, black-crowned night herons.

Will County, Illinois

Through the fall and winter, the Lake Renwick Heron Rookery is a quiet place, closed to the public because there just isn't much to see. But that changes come spring, and the preserve harbors some of Chicago's most spectacular summertime sights, with performances by thousands of herons, egrets, and other endangered and threatened wading birds. Visitors are welcomed on Saturday and Wednesday mornings throughout the season.

A number of raptors and water-loving birds visit Lake Renwick, but the nesting birds have given this site its regional renown. The large great blue herons, standing four feet tall, are the state's most common heron. Great egrets and double-crested cormorants are both on the state's threatened species list. Less common at Lake Renwick are the state-endangered black-crowned night herons. Typically nocturnal birds, they appear only occasionally during the day. Lake Renwick also hosts small number of cattle egrets, a plentiful species typically found in prairies and pastures, not wetlands.

Migrating herons start to arrive from the south in March; other birds soon follow, jousting for prime nesting spots. (Each species prefers a different nesting height, so there is no inter-species fighting: great blues, for instance, take the top of the trees, while night herons prefer the bottom.) The preserve remains closed during this period to foster nesting success. The Rookery opens to the public the first weekend in May.

Lake Renwick itself occupies most of the preserve's 320 acres. From the visitor's center, a quarter-mile walk leads to the shoreline viewing platforms, 750 feet from the two main nesting islands. It's a spectacular sight. The islands and the far shore are covered by birds in constant movement, wading along the shoreline, diving for fish, and taking off and landing from all directions. June is particularly exciting, when newborn chicks test their wings and learn to fly. The preserve provides tripod-mounted viewing scopes, or bring your own binoculars and telephoto lenses.

The out-migration starts as early as July, when some birds head north to fatten the chicks and shape up before heading south for winter. Other birds take off in August; by the end of the month, the rookery is all but empty again, and it closes to visitors for the winter.

Like many lakes in the Chicago area, Renwick started near the turn of the century as a gravel quarry. Springs turned it into a wetland, which has long attracted birds; some reports say herons have been nesting at the site since the 1930s. When the quarry closed in 1983, conservationists campaigned to preserve the site. In 1990, the Will County Forest Preserve District and the Illinois Department of Natural Resources acquired the land; it's now an official state nature preserve (dedicated in 1992), operated by the Forest Preserve District.

The Rookery is open to the public just two mornings per week, from the first weekend in May until the end of August. On Saturdays it's open from 8 until noon; volunteers staff the visitor's center and guides conduct short interpretive programs at 9, 10 and 11a.m. The rookery opens at 10 AM on Wednesday mornings for a one-hour visit; if no visitors are there at 10, the staff closes it back up. As a state nature preserve, picnicking, pets, and recreational activities are prohibited. For more information, call the Will County Forest Preserve District at (815) 727-8700.

— Chris Larson