The Shawnee National Forest is famous for its twice-yearly snake migration. In spring, snakes migrate out of the forest’s limestone bluffs and into LaRue Swamp. In the fall, the migration is reversed as the snakes come out of LaRue Swamp to spend the winter at the dry base of the limestone cliffs.
LaRue Swamp is on the west side of the road. The swamp is part of the Mississippi River basin. Here you will see species such as the cottonmouth snake, the southern leopard frog, and the bird-voiced tree frog. These animals are common in Mississippi and Louisiana but are not usually seen as far north as Illinois.
The limestone rock of the bluffs is more common to Missouri and Arkansas than the rest of Illinois. More than 405 million years ago, the bluffs were at the bottom of a vast sea called the Illinois Basin. There were seashells and coral in the Illinois basin. When the sea creatures died, they left behind skeletons made of calcium carbonate. Over millions of years, those skeletons became limestone rock.
To get to and from the bluffs, snakes must migrate across LaRue road every spring and fall. If you’re a snake, crossing the road is dangerous. In the cool early morning and evening hours, the black asphalt is relatively warm, and rather than crossing quickly, snakes and other cold-blooded creatures like to hang out. That is why so many snakes, frogs, toads, and turtles get hit by cars.
In 1972, the forest service made the decision to close LaRue Road for three weeks in the spring and three weeks in the fall in order for the snakes to migrate safely.
Now the Snake Road is closed from March 15 to May 15 in the spring and from September 1 to October 30 in the fall.
Snake enthusiasts and herpeto culturists also support closing the Snake Road to let the snakes migrate across it. Cars are prohibited, but people are welcome to walk the 2.6-mile Snake Road.
Herons and egrets also eat frogs and small snakes. Without snakes, these birds would be deprived of a food source, and we would be overrun by rodents. It’s something to think about before we run off to find a home or a club to end a snake’s life.