Eastern Copperhead
Agkistrodon contortrix
Summary 6
Agkistrodon contortrix is a species of venomous snake, a pit viper, endemic to Eastern North America; it is a member of the subfamily Crotalinae in the family Viperidae. The common name for this species is the eastern copperhead. The generic name is derived from the Greek words ancistro (hooked) and odon (tooth), or fishhook. The trivial name, or specific epithet, comes from the Latin contortus (twisted, intricate, complex); which is usually interpreted to reference the distorted pattern of darker bands across the snakes back, which are broad at the lateral base but "pinched" into narrow hourglass shapes in the middle at the vertebral area. Five subspecies have been recognized in the past, but recent genetic analysis shows that A. contortrix and two of the subspecies are monotypic, while Agkistrodon laticinctus (formerly Agkistrodon contortrix laticinctus) and the fifth subspecies are a single distinct species (see subspecies table below).
Description 6
Adults grow to a typical length (including tail) of 50–95 cm (20–37 in). Some may exceed 1 m (3.3 ft), although that is exceptional for this species. Males are usually larger than females. Good-sized adult males usually do not exceed 74 to 76 cm (29 to 30 in), and females typically do not exceed 60 to 66 cm (24 to 26 in). In one study, males were found to weigh from 101.5 to 343 g (3.58 to 12.10 oz), with a mean of roughly 197.4 g (6.96 oz). According to a different study, females have a mean body mass of 119.8 g (4.23 oz). The maximum length reported for this species is 134.6 cm (53.0 in) for A. c. mokasen (Ditmars, 1931). Brimley (1944) mentions a specimen of A. c. mokasen from Chapel Hill, North Carolina, that was "four feet, six inches" (137.2 cm), but this may have been an approximation. The maximum length for A. c. contortrix is 132.1 cm (52.0 in) (Conant, 1958).
The body is relatively stout and the head is broad and distinct from the neck. Because the snout slopes down and back, it appears less blunt than that of the cottonmouth, A. piscivorus. Consequently, the top of the head extends further forward than the mouth.
The scalation includes 21–25 (usually 23) rows of dorsal scales at midbody, 138–157 ventral scales in both sexes and 38–62 and 37–57 subcaudal scales in males and females, respectively. The subcaudals are usually single, but the percentage thereof decreases clinally from the northeast, where about 80% are undivided, to the southwest of the geographic range where as little as 50% may be undivided. On the head are usually 9 large symmetrical plates, 6–10 (usually 8) supralabial scales, and 8–13 (usually 10) sublabial scales.
The color pattern consists of a pale tan to pinkish-tan ground color that becomes darker towards the foreline, overlaid with a series of 10–18 (13.4) crossbands. Characteristically, both the ground color and crossband pattern are pale in A. c. contortrix. These crossbands are light tan to pinkish-tan to pale brown in the center, but darker towards the edges. They are about two scales wide or less at the midline of the back, but expand to a width of 6–10 scales on the sides of the body. They do not extend down to the ventral scales. Often, the crossbands are divided at the midline and alternate on either side of the body, with some individuals even having more half bands than complete ones. A series of dark brown spots is also present on the flanks, next to the belly, and are largest and darkest in the spaces between the crossbands.
The belly is the same color as the ground color, but may be a little whitish in part. At the base of the tail are one to three (usually two) brown crossbands followed by a gray area. In juveniles, the pattern on the tail is more distinct: 7–9 crossbands are visible, while the tip is yellow. On the head, the crown is usually unmarked, except for a pair of small dark spots, one near the midline of each parietal scale. A faint postocular stripe is also present; diffuse above and bordered below by a narrow brown edge.
Several aberrant color patterns for A. c. contortrix, or populations that intergrade with it, have also been reported. In a specimen described by Livezey (1949) from Walker County, Texas, 11 of 17 crossbands were not joined middorsally, while on one side, three of the crossbands were fused together longitudinally to form a continuous, undulating band, surmounted above by a dark stripe that was 2.0–2.5 scales wide.
In another specimen, from Lowndes County, Alabama, the first three crossbands were complete, followed by a dark stripe that ran down either side of the body, with points of pigment reaching up to the midline in six places, but never getting there, after which the last four crossbands on the tail were also complete. A specimen found in Terrebonne Parish, Louisiana, by Ernest A. Liner, had a similar striped pattern, with only the first and last two crossbands being normal.
Behavior 6
Like all pit vipers, A. contortrix is generally an ambush predator; it takes up a promising position and waits for suitable prey to arrive. One exception to ambush foraging occurs when copperheads feed on insects such as caterpillars and freshly molted cicadas. When hunting insects, copperheads actively pursue their prey. Juveniles use a brightly colored tail to attract frogs and perhaps lizards, a behavior termed caudal luring (see video: [1]). In the Southern United States, they are nocturnal during the hot summer, but are commonly active during the day during the spring and fall.
Unlike other viperids, they often "freeze" instead of slithering away, and as a result, many bites occur due to people unknowingly stepping on or near them. This tendency to freeze most likely evolved because of the extreme effectiveness of their camouflage. When lying on dead leaves or red clay, they can be almost impossible to notice. They frequently stay still even when approached closely, and generally strike only if physical contact is made. Like most other New World vipers, copperheads exhibit defensive tail vibration behavior when closely approached. This species is capable of vibrating its tail in excess of 40 times per second— faster than almost any other non-rattlesnake snake species.
Distribution and habitat 6
It is found in North America; its range within the United States is in Alabama, Arkansas, Connecticut, Delaware, Northern Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, Nebraska, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia and West Virginia. In Mexico, it occurs in Chihuahua and Coahuila. The type locality is "Carolina". Schmidt (1953) proposed the type locality be restricted to "Charleston, South Carolina".
Unlike some other species of North American pit vipers, such as the timber rattlesnake and Sistrurus catenatus, A. contortrix has mostly not re-established itself north of the terminal moraine after the last glacial period (the Wisconsin glaciation), though it is found in southeastern New York and southern New England, north of the Wisconsin glaciation terminal moraine on Long Island.
Within its range, it occupies a variety of different habitats. In most of North America, it favors deciduous forest and mixed woodlands. It is often associated with rock outcroppings and ledges, but is also found in low-lying, swampy regions. During the winter, it hibernates in dens or limestone crevices, often together with timber rattlesnakes and black rat snakes. In the states around the Gulf of Mexico, however, this species is also found in coniferous forest. In the Chihuahuan Desert of West Texas and northern Mexico, it occurs in riparian habitats, usually near permanent or semipermanent water and sometimes in dry arroyos (brooks).
Conservation Status: 7
The copperhead is not a protected species in Texas and can be legally collected with a hunting license.
Fun Fact 8
Copperhead venom has compounds in it that may be useful for fighting cancer.
Sources and Credits
- (c) johnwilliams, some rights reserved (CC BY-NC), uploaded by johnwilliams
- (c) dw_ross, some rights reserved (CC BY), http://commons.wikimedia.org/wiki/File:20101204_1312.jpg
- (c) Ventus55, some rights reserved (CC BY-SA), http://commons.wikimedia.org/wiki/File:Agkistrodon_contortrix-AL.jpg
- TimVickers, no known copyright restrictions (public domain), http://commons.wikimedia.org/wiki/File:Agkistrodon_contortrix_phaeogaster_(2).jpg
- (c) Ronnie Richerson, all rights reserved, uploaded by Ronnie Richerson
- (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Agkistrodon_contortrix
- (c) Caleb Paul, some rights reserved (CC BY-SA), https://www.inaturalist.org/guide_taxa/776630
- (c) gburg2016, some rights reserved (CC BY-SA), https://www.inaturalist.org/guide_taxa/384145
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