Wilderness Underfoot: Our rare poisonous snakes

StoryImage( ‘/Images/Story//Auto-img-11200659339921.jpg’, ”, ‘The Eastern massasauga rattlesnake – Sistrurus catenatus is the only poisonous snake found this far north in Illinois. It is extremely rare throughout the state.’);
StoryImage( ‘/Images/Story//Auto-img-11200659891278.jpg’, ”, ‘The timber rattlesnake – Crotalus horridus is a threatened species in Illinois. It occurs in the southern third of the state, and up along the Illinois and Mississippi rivers.’);
StoryImage( ‘/Images/Story//Auto-img-11200660271277.jpg’, ”, ‘The copperhead – Agkistrodon contortrix is found in the lower third of the state. It is abundant in the Shawnee Hills and on the bluffs of the Mississippi River.’);
StoryImage( ‘/Images/Story//Auto-img-1120066078598.jpg’, ”, ‘The cottonmouth (or water moccasin) – Agkistrodon piscivorus is found only in the extreme southern tip of Illinois. A common misconception is that any snake sighted in the water is a water moccasin – not very likely in our region! There are plenty of nonpoisonous water snakes throughout Illinois.’);

Chances are you won’t ever come upon a poisonous snake in this region of Illinois

Most reports of poisonous snakes here are due to mistaken identity, but even so, avoiding any snake you can’t accurately identify as harmless is a good practice. And even nonpoisonous snakes will hiss, bite, and defecate on you if handled or annoyed.

Of the four poisonous snakes that live in Illinois, only one of them – a rattlesnake called the Eastern massasauga – occurs this far north. The snake has infrequently been reported in DeKalb County and in the counties near Lake Michigan.

Like many nonpoisonous snakes, the massasauga was once widespread throughout the state, but its numbers have declined due to agriculture and other development in its habitats. The snake inhabited old fields, savannas, floodplain forests, marshlands and bogs. Now its distribution around the state is sparse. One remaining population of this snake inhabits Allerton Park near Champaign.

Illinois’ other poisonous snakes are the timber rattlesnake, the copperhead, and the cottonmouth (also known as the water moccasin). All of the poisonous snakes here are pit vipers – possessing tubular fangs for delivering venom and heat-sensing pits between each eye and nostril.

According to a report for the Illinois Poison Center (IPC), poisonous snakes in our state are not aggressive and bite only when stepped on, picked up, or cornered. More than half of all snakebites happen when someone is intentionally handling a poisonous snake. Children, intoxicated individuals, and snake handlers are the most frequent victims. About 20 percent of poisonous snakebites are “dry” – that is, they don’t deliver any poison. Deaths from snakebites in North America typically total less than 15 per year.

From the June 29-July 5, 2005, issue

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