Nature Bulletin No. 420-A May 22, 1971
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
Contrary to popular belief, the Water Moccasin commonly known as
the "Cottonmouth" is the only poisonous water-loving snake in the
United States. It is a large, very thick-bodied snake with a chunky
head and a short tail that tapers very abruptly from the body. The
inside of its mouth is noticeably white and the moccasin, when
surprised, has a habit of rearing its head back, opening the mouth
wide, and beating its short tail back and forth in a vigorous steady
rhythm. It looks as mean and dangerous as it really is.
There is no danger of encountering a cottonmouth in Cook County. It
inhabits swampy areas, bayous and rivers along the Atlantic Coast and
the Gulf of Mexico from southern Virginia to Texas; and up the
Mississippi valley as far as southern Illinois. It will eat birds, small
mammals and the harmless water snakes but feeds principally on fish
and frogs, so the cottonmouth usually does not go far from water. It is
generally found on muddy banks of ponds, swamps or sluggish
streams, on partly submerged logs, or on low limbs of bushes and trees
overhanging such water areas.
Like most snakes, a cottonmouth will not attack if it can escape.
Walking along a bayou southeastern Missouri one time, a huge one
glided across the path, only three feet ahead of us, into the water.
Quietly paddling a dugout canoe through those bayous, moccasins
frequently dropped off of branches just in front of us, and swam away
beneath the surface to shelter, in a growth of cattails.
The cottonmouth, like the rattlesnakes and its close relative, the
copper head, is a pit viper. There is a deep pit, apparently a sense
organ, between each eye and the corresponding nostril. There are, of
course, two long hollow fangs at the front of the upper jaw, like
hypodermic needles, for stabbing its prey and injecting the venom. The
moccasin' s scales are keeled and rough. Its color may be dull olive,
sooty brown or almost black, with indistinct dark bands which
disappear in older snakes that become 4 or 5 feet long. The young,
from 7 to 12 in number, are born alive, bright brown and brilliantly
marked, with sulfur-yellow tails.
Our other water-loving snakes belong to the Water Snake Family, of
which there are a dozen species and several varieties in North
America: all of them with long tapering tails and all of them non-
poisonous. They are excellent swimmers that live in swampy places or
frequent the borders of rivers, creeks, lakes or ponds. Their food
generally consists of fishes, frogs, toads and crayfish, although some of
the smaller kinds also eat earthworms and slugs. Anglers believe that
they destroy gamefish and panfish but usually they capture only the
slower, less desirable "rough" fish or those that are diseased.
Largest, ugliest and meanest of them all is the Brown Water Snake or
"Water Rattle" found only in the South. Smallest is Kirtland's Water
Snake, never more than 20 inches long, first described by Robert
Kennicott here in Cook County where we also have the Graham's, the
Queen, and the Common or Banded Water Snakes. The later, wrongly
called a "water moccasin", has a thick body, dingy brown in color with
dark bands and blotches. Its belly is spotted with brown or red. Its
young, from 18 to 48 in number, are born alive like those of all the
other Water Snakes. It will flatten its head and body, strike viciously
when cornered, and may inflict a serious scratch but it is not
About wildflowers we say: "Love 'em and leave 'em". About snakes:
"Live and let live".
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Update: June 2012