Western Cottonmouth (Agkistrodon piscivorous leucostoma)

     The Western Cottonmouth (Agkistrodon piscivorous) or water moccasin is one of the venomous snakes residing in north central Texas.  Although it does occur in the Dallas and Fort Worth area it is rarely seen by most.  Instead most individuals misidentify the harmless water snake as a cottonmouth.  Cottonmouths are distinctive looking snakes that normally range between  two and three feet in length.  Cottonmouths posses a flat and broad head, upturned snout, a heat sensing pit between the eye and nostril, vertically oriented pupils (cat-like eyes), a thick body and slender tail.  Adults have a base coloration of buff to dark brown with irregular darker cross-bands across the back that may vary from  brown to black.  A pale stripe extends from behind the eye to the back of the head. This later becomes suffused with the rest of the coloration of the body as the snake matures.  A second white stripe extends from beneath the eye to the corner of the jaws.  The ventral surface is somewhat variable with a yellowish base coloration and irregular brown to dark gray blotches.  Closer to the tail, the dark ventral blotches become more concentrated.  The scales are keeled and the anal scale is undivided. 

     Newborn specimens posses a bright to faded yellow tail tip which is used to lure prey such as frogs within striking distance.  The tail tip changes to greenish yellow in sub adults and then to black at the onset of maturity.  Newly born cottonmouths do not resemble the adults until they reach maturity.  Until then, the juveniles have a strong resemblance to young copperheads.

     Throughout their range in Texas, cottonmouths are affiliated with virtually every type of aquatic environment.  This includes coastal marshes, swamps, slow moving streams, lakes, ponds, and rivers.  They are opportunistic predators and are known to consume a wide range of prey items including: fish, salamanders, frogs, turtles, other snakes (most often water snakes), birds and their eggs, and small mammals.  Cottonmouths have even been found consuming road kill including one instance where a specimen was seen feeding on pieces of a hog that had been killed by an automobile.

     Whenever alarmed, cottonmouths vibrate their tails and squirt a strong smelling musk.  The musk is ejected from glands situated near the cloaca and presumably can serve as a deterrent to predators.  Upon the approach of a human, many cottonmouths will flee and seek the shelter of the water.  However, these snakes occasionally remain motionless, presumably this is an attempt to hide by blending into the surrounding environment.  However, it is the open mouth warning displayed by this snake that afforded its common name cottonmouth.

     Females typically reach maturity when two to three years old. Courtship and mating normally takes place during the spring, but reproductive activity has been documented throughout this snakes period of activity.  Gestation requires 160-170 days and the female gives birth to as many as 16 young in September. Female cottonmouths can store sperm in their oviducts for several months.

     Cottonmouths can deliver a painful and medically significant bite.  However, this snake does not pose a serious health risk to humans.  In the United States one person per year dies from the bite of a cottonmouth.  For more information regarding the first aid of venomous snake bite click here.

 

Can you find the cottonmouth in this photograph from Anderson County, Texas?

Photograph by Carl J. Franklin

                         

This specimen from Franklin County, Texas demonstrates how the cottonmouth's common name was earned.  Notice how the cottonmouth flattens its body when threatened.

Photograph by Carl J. Franklin

 

                             

Notice the ventral and dorsal coloration of this sub adult specimen from Palo Pinto County, Texas.

Photograph by Carl J. Franklin

 

 

 

                                               

Like all snakes, the cottonmouth uses its tongue to receive and interpret important information regarding its environment such as the location of prey and predators.

Photograph by Carl J. Franklin

 

 

Another view of a sub adult specimen from Texas: Palo Pinto, County.  Note that the pupils do not appear cat-like.  This is because the photograph was taken at night.

Photograph by Carl J. Franklin

 

 

Adult specimen from Texas: Palo Pinto, County.  Note the vertical or cat-like pupils on this specimen which was photographed during the day.

Photograph by Carl J. Franklin