Spring 2001

Nearly a hundred nesting pairs of herons and a spectacular spring wildflower display are among the highlights at Indiana Dunes National Lakeshore

Indiana Dunes National Lakeshore

From mid-March through April of each year, a colony of great blue herons returns to their rookery at the Indiana Dunes National Lakeshore (IDNL) to nest. Around the same time, early ephemeral wildflowers begin to appear in the surrounding oak savannas, before the trees leaf out to soak up the summer sun.

The herons, numbering 98 nesting pairs last spring, have made their home on the eastern portion of the wet woods along the Little Calumet River for more than 60 years. They return to the region after wintering in the southeast and south central States. The rookery is closed to the public to protect the bird’s habitat, but visitors can observe them nesting from the trail along the south side of the river. This is best done in early spring while the trees are still budding and easier to see through.

The herons are concentrated on the east end of the woods, but the west end, dense with beech, tulip poplar, and maple trees, is best for viewing other species like kinglets, wood thrushes, woodpeckers, and warblers. Rarer sightings have included the pileated woodpecker and cerulean warbler.

Another rare species found in the oak savanna habitat near the rookery is the federally endangered Karner blue butterfly, which has not been recorded anywhere in Illinois since the early 1990s. It has some protected habitat in Wisconsin and Michigan, but the IDNL is its only known remaining habitat in Indiana. This is primarily because the Karner blue relies on a diet of wild lupine flowers, which thrive only in a healthy oak savanna. IDNL wildlife biologist Randy Knutson has conducted prescribed burns in the area to improve habitat and thus ensure the longevity of the Karner blue, as well as other species who rely on a healthy oak savanna for survival.

The 12,000-acre National Lakeshore, one of more than 380 national park sites run by the U.S. National Park Service, ranks fourth in plant diversity and represents a wide variety of plant communities: open beach, dune, lake, marsh, tamarack bog, forested fen, prairie, savanna, and several types of forest. Some spring wildflowers that bloom throughout the woods around the rookery include wild ginger, spring beauty, trout lily, Dutchman’s breeches, and, later in May, four varieties of phlox. Large-flowered and red trillium also make star appearances.

IDNL Natural Resource program manager John Kwilosz reports that several upland habitat restoration and fire management projects in the area have helped reestablish those wildflower species in recent years. Since the park was established in the 1960s, hundreds of former home sites, with their attendant lawn grasses, exotic shrubs and trees, and invasive weeds such as garlic mustard and purple loosestrife, have been removed and replaced with native prairie grasses and forbs.

Begin your visit at the Dorothy Buell Memorial Visitor Center, where maps, interpretive displays, wildlife information are available. Upcoming guided walks at the heron rookery include:

• Sundays, April 8 and April 15, 2001, 1:30-3 p.m.: "River Ramble" will focus on trout, nesting herons, and spring wildflowers.
• Sunday, May 13, 2001, 1:30-3 p.m.: "Wildflowers for Mom"

Meet at the parking lot on the east end of the heron rookery, 600 East Road. Call the Dorothy Buell Visitor Center for information on these programs or any other spring walks at (219) 926-7561 x244.

On Saturdays throughout the spring and summer, visitors are invited to join resource management staff in removing exotic vegetation from the park. the likely suspects include garlic mustard, purple loosestrife, black locusts, and sweet clover. Call in advance for information: (219) 926-7561 x337. — Lisa Phillips