Photo by Christina Feng, Illinois Department of Natural Resources.

November 1, 2023

The Shawnee Hills Natural Division: An Ancient Landscape Supports Incredible Biodiversity

A graphic of Illinois highlighting the Shawnee Hills Natural Division located in the southern portion of the state.
The Shawnee Hills Natural Division. Illustration by Sarah Marjanovic.

When you think of the scenic beauty of Illinois, the Shawnee Hills naturally come to mind. One of 15 Natural Divisions, the rugged hill country of the Shawnee Hills Natural Division extends east to west across southern Illinois. Covering most of Hardin, Pope, Johnson and Union as well as parts of Jackson, Williamson, Saline and Gallatin counties, the Shawnee Hills Natural Division includes much of the Shawnee National Forest, one of the largest contiguous expanses of public land in Illinois, and an Illinois Wildlife Action Plan Conservation Opportunity Area, the Eastern Shawnee Hills.

Shawnee Hills Natural Division

This unglaciated land is defined by ancient sandstone and limestone cliffs and is the most heavily forested natural division in the state. An unparalleled diversity of landforms and habitats supports an abundance of species, including several Species in Greatest Conservation Need such as two state and federally endangered bats—the Indiana bat (Myotis sodalis) and gray bat (Myotis grisescens) –as well as the Illinois endangered Rafinesque’s big-eared bat (Corynorhinus rafinesquii) and the state threatened timber rattlesnake (Crotalus horridus).

A lush green forest with a waterfall tumbling down rock outcroppings into a stream that runs into the foreground.
Hikers can stop to enjoy a waterfall at Ferne Clyffe State Park located in the Greater Shawnee Hills Section of the Shawnee Hills Natural Division in Johnson County. Photo by Christina Feng, Illinois Department of Natural Resources.

For those not familiar with the area, the Shawnee Hills are divided into two sections, the Greater Shawnee Hills and the Lesser Shawnee Hills. While there are too many fantastic places to cover in one article, Christina Feng, Illinois Department of Natural Resources (IDNR) District Heritage Biologist, suggests Ferne Clyffe State Park as an excellent place to experience the Greater Shawnee Hills. Covering 2,430 acres, this site has impressive views throughout the park. There is Hawk’s Cave, one of Illinois’ largest shelter bluffs that can be viewed after hiking an easy 0.5-mile trail. There is a 100-foot waterfall on the Big Rocky Hollow trail. There is Round Bluff Nature Preserve. And there are plenty of recreational activities, including camping, picnicking, hiking, hunting, rock climbing and fishing. Ready to go? Ferne Clyffe is located on Illinois Route 37, just one mile south of Goreville and 12 miles south of Marion.

If you happen to visit Ferne Clyffe in the spring or early summer, be on the lookout for the Illinois threatened French’s shootingstar (Dodecatheon frenchii) while it is in bloom. This plant sports delicate, white flowers and is a habitat specialist that only grows along the shaded drip line of sandstone overhangs.

Community Types

Many of the rarest biological resources still to be found in Illinois are located in the Shawnee Hills Natural Division. In some cases, the bluffs, hills and steep-sided ravines of the Shawnee support the only known populations remaining in Illinois. The 2013 publication Natural Areas of the Shawnee National Forest provides beautiful images and detailed descriptions of the area and the main community types, of which a brief synopsis is provided here.

Upland Forest

A timber rattlesnake lies coiled up on sandstone rocks in Illinois. This snake is one of four venomous snake species found in Illinois.
The timber rattlesnake is one of four venmous snake species found in Illinois. It is currently on the Illinois threatened species list. Photo by Scott Ballard.

In the Shawnee Hills Natural Division, the dominant natural community is the upland forest, which historically was mainly comprised of oaks. In xeric (dry) sites post (Quercus stellata), scarlet (Quercus coccinea) and blackjack (Quercus marilandica) oaks reign, while in wetter sites you will find black (Quercus velutina), red (Quercus rubra) and white (Quercus alba) oaks mingled with shagbark (Carya ovata) and pignut (Carya glabra) hickories. In moist canyons, ravines and north-facing slopes, American beech (Fagus grandifolia), tulip poplar (Liriodendron tulipifera) and sycamores (Platanus occidentalis) rise above the understory.

Bottomland Forest

Here, only trees capable of withstanding periodic flooding can survive. In the bottomland forest, sugar maple (Acer saccharum), black walnut (Juglans nigra), pecan (Carya illinoinensis), silver maple (Acer saccharinum) and bur (Quercus macrocarpa), pin (Quercus palustris) and overcup (Quercus lyrate) oaks preside. The understory plant community often includes cardinal flower (Lobelia cardinalis), sedges, rushes and smartweeds.


This community of trees, grasses and forbs is fire dependent. Woodlands are characterized by an open canopy of “wolf trees”—highly branched, shorter growing trees with spreading limbs. In this community type, few shrubs are found, but little bluestem (Schizachyrium scoparium), woodland sunflower (Helianthus divaricatus) and asters (Aster sp.) abound. Prescribed fire is vital to restoring and maintaining this and other natural communities in the Shawnee Hills Natural Division.


Barrens are grassy openings in the forest found on rocky slopes that have only a thin layer of soil with some areas of exposed bedrock. The primary vegetation includes small, gnarled blackjack and post oaks. Prairie grasses such as little bluestem can spread freely there, and depending on when you visit, you can find blooms of blazing star (Liatris spicata), farkleberry (Vaccinium arboreum), Venus’ looking glass (Triodanis perfoliata), purple milkweed (Asclepias purpurascens), Indian pink (Spigelia marilandica) and New Jersey tea (Ceanothus americanus).

A sunny day at Collier Glade managed by the Illinois Nature Preserves Commission.
The Collier Limestone Glade is an Illinois Natural Areas Inventory Site located in the Lesser Shawnee Hills Section of the Shawnee Hills Natural Division in southeastern Hardin County. Photo by the Illinois Nature Preserves Commission.


Unlike barrens, glades consist primarily of exposed sandstone, shale or limestone bedrock, and the vegetation community is strongly influenced by the substrate type. These open areas showcase expanses of bedrock on the bluff tops and are typically surrounded by barrens and woodland communities. The trees are predominantly post and blackjack oak, although red cedar (Juniperus virginiana) is common in many unmanaged glades. In the glades you may find a multitude of prairie-associated grasses and forbs, including poverty oats grass (Danthonia spicata), prickly pear cactus (Opuntia humifusa) and glade coneflower (Echinacea simulata), or the ground may simply be covered with mosses and lichens. Species of interest that make their home in the glades include lichen grasshopper (Trimerotropis saxatilis), crane fly (Tipula sp.), small flower-of-an-hour (Phemeranthus parviflorus) and the olive hairstreak butterfly (Callophrys gryneus).


This community type is self-explanatory and boasts vertical rock faces. A student of nature might note that plant life on the north- and east-facing cliffs tends to be lusher than on the south- and west-facing cliffs. The sandstone cliffs support alumroots (Heuchera spp.), spleenworts (Asplenium spp.) and lichens in drier areas, and clubmosses (Lycopodiopsida spp.), wild hydrangea (Hydrangea arborescens) and partridgeberry (Mitchella repens) in wetter areas. Along the Ohio and Mississippi rivers, limestone cliffs are bejeweled with red columbine (Aquilegia canadensis), cleft phlox (Phlox bifida) and a profusion of ferns.

Caves and Springs

Prescribed fire is a vital tool of habitat management in the remaining glades of Illinois. A low ground fire helps restore plant diversity.
Prescribed fire is a necessary tool to prevent trees from shading out areas of vegetation that are reliant on high levels of light for germination and recruitment. Photo by the Illinois Nature Preserves Commission.

Cool and dark, caves lend an air of mystery to the region. Mostly limestone caves, these cool habitats are home to cave crickets (Ceuthophilus spp.), the state-threatened Shawnee Hills Cavefish (Forbesichthys papilliferus) and several bat species. Some caves hide streams and waterfalls within.

While swamps, seeps and springs are found in the Coastal Plain Natural Division, there are a couple of old springs at Ferne Clyffe near Boat Rock that were historically used as a permanent water source.

Habitat loss and fragmentation caused by historical logging and farming practices, encroachment by invasive species, and lack of fire have all taken a toll on the landscape. Conservation efforts and restoration practices including prescribed fire are a priority for a network of agencies and organizations in the region working to manage natural areas, encourage forest regeneration and improve wildlife habitat.

Hot Spot for Wildlife Research

Because of the biodiversity found there, the Shawnee Hills are a hot spot for wildlife researchers working to better understand the complex relationships between plants, animals, and habitat management. Previous OutdoorIllinois Journal articles have highlighted some of the ongoing work. Those interested in the movements of beavers (Castor canadensis) won’t want to miss reading about a study on radio tracking beaver conducted by the Cooperative Wildlife Research Laboratory at Southern Illinois University.

A gray fox stands in the grass looking towards the photographer.
The Illinois Department of Natural Resources considers the gray fox (Urocyon cinereoargenteus) to be a “watch list” species and studies are ongoing to understand how to better protect remaining populations in Illinois. Photo by the United States Fish and Wildlife Service.

Additionally, the IDNR has listed the gray fox (Urocyon cinereoargenteus) as a “watch list” species, meaning this is a species that has “poorly known distributions, status, trends or specific habitat needs in Illinois.” To address some of these data gaps, the Cooperative Wildlife Research Lab is conducting a multi-year study on gray fox ecology. They are interested in gray fox sightings. So, if you have seen one in Illinois recently, you can submit the sighting on their website.

In this issue, you can read about studies conducted by researchers from University of Illinois at Urbana-Champaign who are seeking to better understand whip-poor-wills ecology and behavior.

Visiting the Shawnee Hills

You could spend an amazing day appreciating the views at the Garden of the Gods, or you could spend an entire lifetime exploring all of the enchanting places and natural treasures of the Shawnee Hills Natural Division. Places with names like Cave-in Rock State Park, Bell Smith Springs, Giant City State Park and Fern Rocks Nature Preserve just to name a few. Wherever you choose to explore, be sure to visit throughout the year as each season brings new adventures for your senses and some stunning views.

Laura Kammin is a Natural Resources Specialist with the National Great Rivers Research and Education Center. She formerly held positions at Illinois-Indiana Sea Grant, University of Illinois Extension, Prairie Rivers Network and the Illinois Natural History Survey. She received her master’s degree in wildlife ecology from the University of Illinois, Urbana-Champaign.

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