Poisonous Snakes in Illinois -- Questions and Answers
Nature Bulletin No. 540-A October 19, 1974
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
POISONOUS SNAKES IN ILLINOIS -- QUESTIONS AND ANSWERS
Q. Are poisonous snakes found in Illinois ?
A. Yes. Four kinds are native -- the Copperhead, the Water Moccasin or
Cottonmouth, the Timber Rattlesnake, and the Massasauga or Swamp
Rattler. All are uncommon or rare and are seldom seen.
Q. Where are they found ?
A. The copperhead is restricted to the southern half of the state where it
inhabits certain rocky wooded hillsides. The water moccasin is found
only along the big rivers and bottomland swamps of extreme southern
Illinois. The timber rattler is mainly limited to the wilder areas of rocky
bluffs along the Mississippi and Illinois rivers. The massasauga has a
spotty distribution in swampy or prairie regions.
Q. Do any of them live in Cook County ?
A. Yes. A few massasaugas are native in northeastern Cook County.
The common water snakes of this region are not "water moccasins. .
Q. How do these differ from native harmless snakes ?
A. They have a pair of hollow, hypodermic-like fangs hinged to the roof
of the mouth. The pupil of the eye is a vertical slit, as in a cat, instead of
round or oval. All belong to the group known as pit vipers, so-called
because they have a sensory pit between the eye and the nostril which
helps them detect warm-blooded prey. Their heads are distinctly
Q. How do these snakes produce young? Do they lay eggs ?
A. No. All four species give birth to living young, usually less than a
dozen at a time. At first, young copperheads and moccasins have bright
yellow worm-like tails which may serve as bait to attract prey. Young
rattlesnakes have merely a "button" on the end of the tail and cannot
Q. Does the number of rattles show the age of a rattler ?
A. No. Rattlesnakes shed their skins about three times a year and add a
new rattle at each molt. Also, rattles are frequently lost so that older
snakes seldom have a complete set.
Q. How far can one of these poisonous snakes strike ?
A. From a coiled position they seldom strike more than half of their
Q. How big are these snakes ?
A. Adult copperheads average about 30 inches in length; moccasins, 36
inches; massasaugas, 22 inches; and the timber rattler, 40 inches. The
copperhead has about the same body proportions as many harmless
snakes, but the moccasin is very heavy-bodied with a short stubby tail.
The two species of rattlers are intermediate in build.
Q. What do these snakes eat?
A. All eat small rodents, and occasionally birds, which they kill with
their fangs. To these the copperhead adds large insects and their larvae.
The massasauga occasionally eats frogs but the moccasin's diet is
mostly fish and frogs. The timber rattler preys on rats, ground squirrels
and young rabbits.
Q. What are the best precautions against snake bite ?
A. Education. Learn to recognize these poisonous snakes in zoos or
museums. When in "snake country, " watch where you step, or reach
with your hands, or sit down. Do not handle poisonous snakes. Many
professional snake men eventually get bit. If bitten, keep your head. Do
not experiment with home remedies.
Go to a physician promptly.
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Update: June 2012