On its yearly journey from Canada to Central America, the green-winged teal stops in southern Illinois.

The teal is a duck that breeds in the northern parts of North America, but spends its winters far south of its breeding range. It prefers shallow ponds, especially ones with lots of emergent vegetation, which makes the Shawnee a perfect stopover for migrating teals. The teal is one of 237 bird species accommodated by the unique blend of habitats in the Shawnee National Forest, said Michael Eichholz, assistant professor of zoology at Southern Illinois University Carbondale.

The forest offers homes for animals that came east from the Ozark Mountains, west from the Smoky Mountains, north from the southern swamplands and south from the rolling prairies, he said. Five distinct ecological divisions lie within the boundaries of the forest, a collision of habitats found nowhere else in Illinois.

Steve Widowski, a Forest Service wildlife biologist, has made a living for the past 30 years from understanding the forest’s rich biological culture.

“The Shawnee is at a location where east meets west, north meets south, and so we have a lot of these influences,” Widowski said, citing botanical and geographical variety in the 284,000 acres of designated forest. “On the west side of the forest in particular, we have Mississippi River floodplain, bottomland forest, coming right next to upland forest, Illinois Ozark forest … a lot of diversity in a small location there.”

And with more than 500 vertebrate species to consider, Widowski stays busy.

Those include more than 47 reptiles, 32 amphibians and 112 fish, according to the forest’s 2006 Land and Resource Management Plan.

Of particular concern are the federal threatened and endangered species that live within the forest, Widowski said. Special attention is required for the least tern, Indiana bat, pallid sturgeon and an assortment of mussels with colorful names – the fanshell, fat pocketbook, pink mucket and orange-footed pimpleback.

Additionally, another 43 are state threatened and endangered species.

“It’s all these different groups of animals that have adapted to very specific kinds of habitat all converging in southern Illinois because the ranges all just happen to converge right together,” Eichholz said.

Because of their position, the wetlands of the Shawnee are particularly crucial for the teal and many other migratory birds, Eichholz said. Located halfway between the winter and summer homes of most of those animals, and fortified with an abundance of food sources, the wetlands provide an ideal stopping place for the birds to rest, feed and prepare to breed.

Without a stopping place in the Shawnee, many of those bird species would see a dramatic population decrease, Eichholz said.

The Shawnee provides an ideal habitat for other creatures as well. Hundreds of non-migratory bird species abound, such as wild turkey, quail and the great blue heron. Whitetail deer are flourishing, while other species such as beaver, fox and bobcat can be found by looking closely.

The Shawnee provides an ideal habitat for other creatures as well. Hundreds of non-migratory bird species abound, such as wild turkey, quail and the great blue heron. Whitetail deer are flourishing, while other species such as beaver, fox and bobcat can be found by looking closely.

The Shawnee’s distinct terrain plays a crucial role in maintaining the area’s biodiversity. The most obvious example of this role might be the biannual snake migration, when thousands of reptiles and amphibians travel between the nearly 400 ft.-high LaRue-Pine Hills bluffs and the adjacent swampland.

Triggered by changes in ground temperature, the migration between winter and summer habitats takes the snakes from fissures high in the bluffs to lowland swamps and slough areas. Approximately 66 percent of Illinois’ amphibians and 59 percent of the state’s reptiles live in this area, making the migration a major event for both amateur and professional herpetologists from around the country.

The Forest Service closes 2.5 miles of “Snake Road” to vehicle traffic between March 15 and May 15 and again from September 1 to October 31.

“It’s probably the only place in the country where a road is closed for reptile and amphibian migrations,” Widowski said.