Global Range: (200,000-2,500,000 square km (about 80,000-1,000,000 square miles)) The geographic range extends from southern New England to northern Florida, and west through the southern Great Lakes states and southern Iowa to southeastern Nebraska, eastern Kansas, central Oklahoma, western Texas, and the extreme portions of northern Coahuila and eastern Chihuahua (Conant and Collins 1991, Ernst and Ernst 2003, Campbell and Lamar 2004). Elevational range extends from near sea level to above 1,500 meters.
Overall, the species inhabits the Florida panhandle north to Massachusetts and west to Nebraska (Georgia Wildlife Federation 1999)
The Northern Copperhead (A. c. mokasen) inhabits northern Georgia and Alabama north to Massachusetts and west to Illinois.
The Southern Copperhead (A. c. contortrix) inhabits the Florida panhandle north to Southern Delaware and west to SE Missouri, SE Oklahoma and E Texas.
The Broad-banded Copperhead (A. contortrix laticinctus) ranges from northern Oklahoma to south-central Texas.
The Osage Copperhead (A. c. phaeogaster) lives in eastern Missouri to eastern Kansas and south to northeastern Oklahoma.
The Trans-pecos Copperhead (A. c. pictigaster) lives in west Texas.
Biogeographic Regions: nearctic (Native )
- Conant, R., J. Collins. 1998. A Field Guide to Reptiles and Amphibians Eastern/Central North America. New York: Houghton Mifflin Company.
Distribution: USA (Texas, E/C Oklahoma, E Kansas, Missouri, Arkansas, Louisiana, Mississippi, Alabama, Georgia, Florida, South Carolina, North Carolina, Tennessee, Kentucky, Virginia, West Virginia, S Illinois, S Indiana, S Ohio, Iowa, Pennsylvania, Maryland, New Jersey, Delaware, S New York, Connecticut, Massachusetts), Mexico (NE Chihuahua, N Coahuila) laticinctus: C/NC Texas, into C Oklahoma, north to Kansas mokasen: Massachussetts, Connecticut, SE New York, N New Jersey, Pennsylvania, Maryland, Delaware, Virginia, North Carolina, east to Indiana and Illinois. phaeogaster: Kansas, Missouri pictigaster: Texas, adjacent Mexico; Type locality.—Maple Canyon, Chisos Mountains, 5,200 feet elevation, Brewster County, Texas; Holotype: Chicago Acad. Sci. No. 4857.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
Average length of adult copperheads is 30 inches. They have an unmarked copper-colored head, reddish-brown, coppery bodies with chestnut brown crossbands that constrict towards the midline. Copperheads are thick-bodied and have keeled scales.
There is a temperature sensitive pit organ on each side of the head between the eye and the nostril. There is a single row of scales beneath the tail (Schmidt 1941, Tyning 1990).
Tails have no rattle (Ernst 1989).
Young copperheads are 7-10 inches long and grayer in color than adults. They have a sulfur yellow tipped tail, which fades with age and is lost by age 3 or 4.
Copperheads are sexually dimorphic in size. Males have longer tails than females and females grow to greater lengths (Tyning 1990).
The head of the Northern Copperhead is a red, copper color with the rest of its body being pinkish to gray-brown with a dark chestnut colored hourglass shaped pattern. The hourglass pattern is narrow on the top of its back and wider on its sides. It has elliptical pupils and facial pits between its eyes and nostrils (Ohio DNR 1999).
The underside, belly area, of the northern subspecies is dark (Schmidt & Davis 1941).
The southern copperhead subspecies is similar to the northern copperhead but the coloration is paler and the crossbands fail to meet at the midline. Also the belly of the southern subspecies is light in color (Schmidt & Davis 1941).
Broad-banded copperheads have bright coloration with a sharp contrast between the pattern and the ground color. The crossbands are very broad at the midline and always meet. The belly is dark (Schmidt and Davis 1941).
The osage copperhead is similar to those of the northern subspecies but the crossbands are often edged in white (Conant and Collins 1998).
The belly of the Trans-pecos Copperhead is strongly patterned. Also there is a pale area located at the base of each broad crossband (Conant and Collins 1998).
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
- Ernst, C., R. Barbour. 1989. Snakes of North America. Fairfax, Virginia: George Mason University Press.
- Schmidt, K., D. Davis. 1941. Field Book of Snakes of the United States and Canada. New York: G.P. Putnams Sons.
Length: 135 cm
Comments: Copperheads are often in or near deciduous forest in hilly situations, usually in the vicinity of rock outcrops; they occur also on floodplains and at edges of swamps in the south and in mesic situations near water in the arid west. Hibernation generally occurs in dens among rocks, or in caves, animal burrows, under objects, in hollow logs or stumps, or in similar sites. Usually copperheads area in areas with abundant surface cover such as rocks, logs, stumps, or leaf litter. They are mainly terrestrial but sometimes climb into vegetation up to a few meters above ground. In the east at least, gravid females select rocky areas that are more open and have warmer soil temperatures than those used by nongravid individuals (Reinert, cited by Ernst 1992).
Habitat and Ecology
Copperheads prefer terrestrial to semi-aquatic habitats, which include rocky-forested hillsides and various wetlands (Tyning 1990). They have also been known to occupy abandoned and rotting slab or sawdust piles (Conant 1998).
Terrestrial Biomes: forest
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
May migrate up to several hundred meters (232-1183 m in Kansas) between winter den and summer range (Fitch 1960). Typically uses same den in successive years.
Comments: Opportunistic; diet includes small mammals, small snakes, lizards, amphibians, insects, and small birds (Fitch 1960, Ernst 1992). Gravid females usually do not eat. Apparently uses mainly a sit-and-wait foraging method.
The Copperhead is primarily a carnivore, as an adult eating mostly mice but also small birds, lizards, small snakes, amphibians and insects-especially cicadas (Conant and Collins 1998). The snakes are capable of swallowing prey that is several times larger than their own diameter. This is possible because they have a very flexible jaw and it has digestive juices that allow it to digest both bones and fur. Copperheads have fangs that inject its prey with a hemolytic venom (causes the breakdown of red blood cells) which subdues its prey, making it easy for the snake to swallow it. The copperhead seeks out its prey using its heat sensitive pits to detect objects that are warmer then its environment. This also enables them to find nocturnal mammalian prey (Ohio DNR 1999). Adult copperheads are primarily ambushers. When attacking large prey, the copperhead bites then releases immediately to allow the venom to take its effect then later tracks its prey. Whereas the smaller prey is held in its mouth until it dies (Ernst 1989). When the copperhead eats depends on the time of the year. They are most active April through late October, diurnal in the spring and fall, and nocturnal during the summer months (Ohio DNR 1999). When carrying young, some females will not eat at all because the embryos occupy so much of the body cavity. It has been found that some copperheads consume only eight meals in a single growing season. The only possible explanations for this could be due to a slow metabolism and/or difficulty finding prey ( Tyning 1990).
Young copperheads eat mostly insects, especially caterpillars, and use their yellow tipped tails to function as a worm-like lure to attract prey (Georgia Wildlife Federation 1999).
Known prey organisms
This list may not be complete but is based on published studies.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: > 300
Comments: This species is represented by a very large number of occurrences (subpopulations) (Campbell and Lamar 2004).
100,000 to >1,000,000 individuals
Comments: Adult population size is unknown but certainly exceeds 100,000.
Hibernates communally (especially in north) or singly. In Kansas, population density in fall was estimated at about 13/ha, with perhaps 2-4 times this many under optimal conditions; home range size was about 10 ha for males and 3.4 ha for females (Fitch 1960).
Life History and Behavior
Comments: Diurnal in spring and fall, mostly nocturnal in summer. Summer evening showers may stimulate activity. Active from April to late October or November in north (Fitch 1960). Active March to November or December in south; may emerge on warm days in winter. In eastern Texas, peak activity occurred April-July and September-October (Ford et al., 1991, Southwest. Nat. 36:171-177).
Status: captivity: 29.8 years.
Lifespan, longevity, and ageing
Most copulations occur in spring and late summer-early fall. Births occur mainly in August or September in most areas, but may occur as early as July or as late as November in some areas. In Kansas, individual females evidently give birth usually in alternate years, July-early October; males sexually mature in 2nd summer, most females in 3 years (Fitch 1960). In southern Texas, individual females may produce young in consecutive years (Vermersch and Kuntz, 1986, Snakes of south central Texas, Eakin Press, Austin). Litter size up to 21 (most often 4-8) in east and north, average of 5.3 in Kansas, usually not more than 3-4 in Trans-Pecos subspecies PICTIGASTER.
The life span of the copperhead is 18 years. Both sexes reach sexual maturity at 4 years when they are about two feet in length. However, Ernst (1989) notes that the age and size of maturity in the male copperhead is unknown. The breeding season is from February to May and from August to October. Females who breed in autumn can store the sperm until after she emerges from the overwintering site (Tyning 1990). The length of time that the sperm can be stored appears to differ depending on where it is being stored. If the sperm is stored in the cloaca, it only lasts a relatively short time, whereas if it is stored in the upper end of the oviducts in vascular tissues specialized as seminal receptacles it seems to last much longer (Ernst 1989). Copperheads have a gestation period of 3-9 months. They are a live-bearing snake, typically producing 2-10 young, where larger females produce larger broods. After birth, the female provides no direct care for the young (Tyning 1990).
Females are ovoviviparous. Eggs develop in the body of the female and hatch within or immediately after being expelled. They produce large, yolk-filled eggs and store the eggs in the reproductive tract for development. The embryo, during this time, receives no nourishment from the female, only from the yolk. The young are expelled in a membranous sac. At birth they weigh less than an ounce and are 7-10 inches in length (Ohio DNR 1999).
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; ovoviviparous
Average number of offspring: 6.
Average age at sexual or reproductive maturity (male)
Sex: male: 730 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 730 days.
Molecular Biology and Genetics
Statistics of barcoding coverage: Agkistrodon contortrix
Public Records: 0
Specimens with Barcodes: 2
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
IUCN Red List Assessment
Red List Category
Red List Criteria
No special status federally, however it is listed in the state of Massachusetts as endangered (Umass 1999).
IUCN Red List of Threatened Species: least concern
Global Short Term Trend: Relatively stable (=10% change)
Comments: Extent of occurrence, area of occupancy, and number of subpopulations probably are relatively stable; population size may be slowly declining (less than 10 percent over 10 years or three generations).
Global Long Term Trend: Increase of 10-25% to decline of 30%
Degree of Threat: Medium
Comments: No major threats are known. Locally, habitat loss, degradation, and fragmentation probably have resulted in declines in copperhead abundance.
Global Protection: Very many (>40) occurrences appropriately protected and managed
Comments: Many occurrences are in protected areas.
Relevance to Humans and Ecosystems
Comments: Venomous, and many humans are bitten each year (as a result of contact with immobile, unseen snakes), but the bite is almost never fatal (Ernst 1992).
- For other snakes commonly called "copperheads", see Copperhead.
Agkistrodon contortrix is a species of venomous snake endemic to North America, a member of the Crotalinae (pit viper) subfamily. The common name for the species is the copperhead. The behavior of Agkistrodon contortrix may lead to accidental encounters with humans. Five subspecies are currently recognized, including the nominate subspecies described here.
Adults usually grow to a total length (including tail) of 50–95 cm (20–37 in), although some may exceed 1 m (3.3 ft). Males are usually larger than females. 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 38–62/37–57 subcaudal scales in males/females. 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 there 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 2 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 there are 1–3 (usually 2) 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 2–2.5 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.
Common names for A. contortrix include: copperhead (snake), chunk head, death adder, highland moccasin, (dry-land) moccasin, narrow-banded copperhead, northern copperhead, pilot snake, poplar leaf, red oak, red snake, southeastern copperhead, white oak snake, American copperhead, southern copperhead, and cantil cobrizo (Spanish).
It is found in the United States in the states of Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Ohio, Oklahoma, Maryland, Massachusetts, Mississippi, Missouri, New Jersey, New York, North Carolina, 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 Crotalus horridus and Sistrurus catenatus, Agkistrodon contortrix has not reestablished itself north of the terminal moraine after the last glacial period (the Wisconsin glaciation), except it is found in southeastern New York State and southern New England, an area north of Long Island (the terminal moraine of the Wisconsin glaciation).
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, in 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).
This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001). Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2007.
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: ). In the southern United States, they are nocturnal during the hot summer months, but are commonly active during the day during the spring and fall.
Like most North American viperids, these snakes prefer to avoid humans and, given the opportunity, will leave the area without biting. However, unlike other viperids they will often "freeze" instead of slithering away, and as a result many bites occur from 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 will frequently stay still even when approached closely, and will generally strike only if physical contact is made.
Roughly 90% of its diet consists of small rodents, such as mice and voles. They have also shown fondness for large insects and frogs, and though highly terrestrial, have been known to climb trees to gorge on emerging cicadas.
A. contortrix breeds in late summer, but not every year: sometimes a female will produce young for several years running, then not breed at all for a time. They give birth to live young, each of which is about 20 cm (7.9 in) in total length. The typical litter size is 4 to 7, but there can be as few as one, or as many as 20. Their size apart, the young are similar to the adults, but lighter in color, and with a yellow-marked tip to the tail, which is used to lure lizards and frogs.
Although venomous, these snakes are generally not aggressive and bites are rarely fatal. Copperhead venom has an estimated lethal dose of around 100 mg, and tests on mice show its potency is among the lowest of all pit vipers, and slightly weaker than that of its close relative, the cottonmouth. Copperheads often employ a "warning bite" when stepped on or agitated and inject a relatively small amount of venom, if any at all. "Dry bites" involving no venom are particularly common with the copperhead, though all pit vipers are capable of a dry bite.
Bite symptoms include extreme pain, tingling, throbbing, swelling, and severe nausea. Damage can occur to muscle and bone tissue, especially when the bite occurs in the outer extremities such as the hands and feet, areas in which there is not a large muscle mass to absorb the venom. A bite from any venomous snake should be taken very seriously and immediate medical attention sought, as allergic reaction and secondary infection are always possible.
The venom of the southern copperhead has been found to hold a protein called "contortrostatin" that halts the growth of cancer cells in mice and also stops the migration of the tumors to other sites. However, this is an animal model, and further testing is required to verify safety and efficacy in humans.
Although technically the antivenin CroFab could be used to treat an envenomation, it is usually not administered for copperheads, as the risk of complications of an allergic reaction to the treatment are greater than the risk from the snakebite itself in most cases. The antivenin can cause an immune reaction called serum sickness, which can consist of bouts of flu like symptoms for 1-12 months. Pain management, antibiotics, and medical supervision in the case of complications is usually the course of action. In 2002, an Illinois poison control center report on the availability of antivenin stated it used 1 Acp to 5 Acp depending on the symptoms and circumstances. The symptoms of a mild envenomation include swelling of the hand, mild cellulitis, and respiratory distress. The symptoms of a moderate envenomation would include swelling of the hand, vomiting, mild bleeding, ecchymosis, diaphoresis, sinus tachycardia, and hypotensia.
|Subspecies||Taxon author||Common name||Geographic range|
|A. c. contortrix||(Linnaeus, 1766)||Southern copperhead||The United States, in the lower Mississippi Valley and the states bordering the Gulf of Mexico, from eastern Texas and southeastern Oklahoma to southern Illinois, on the South Atlantic Coastal Plain from the Florida panhandle to South Carolina|
|A. c. laticinctus||Gloyd & Conant, 1934||Broad-banded copperhead||The United States, from south-central Texas (Victoria to Frio Counties), north through central Oklahoma to the extreme south of Cowley County, Kansas.|
|A. c. mokasen||Palisot de Beauvois, 1799||Northern copperhead||The United States, in southern Illinois, extreme northeastern Mississippi, northern Alabama, northern Georgia northeast to Massachusetts, the Appalachian Mountain region and associated plateaus|
|A. c. phaeogaster||Gloyd, 1969||Osage copperhead||The United States, in eastern Kansas, extreme southeastern Nebraska and a large part of Missouri|
|A. c. pictigaster||Gloyd & Conant, 1943||Trans-Pecos copperhead||The United States, in western Texas from the vicinity of the Pecos and Devils Rivers to the counties of Jeff Davis and Presidio, Mexico, in northern Chihuahua and Coahuila|
|Broad-banded copperhead||Southern copperhead||At the St. Louis Zoo|
|Copperhead crossing river in|
|Southern copperhead in|
Covington, Georgia, at Bert
Adams Scout Reservation
|Southern copperhead, near|
a cicada (in Arkansas)
consuming cicada (Arkansas)
|Southern copperhead close|
up (in Arkansas)
In popular culture
- During the American Civil War, the leading Peace Democrats were called Copperheads.
- In the movie, Copperhead a small town in the Wild West is attacked by thousands of copperheads.
- In 2010, small arms maker SIG Sauer named a limited edition .380 ACP pistol the P238 Copperhead.
- A villain of Batman's rogue's gallery is a snake-like assassin named Copperhead.
- List of crotaline species and subspecies
- Crotalinae by common name
- Crotalinae by taxonomic synonyms
- McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
- "Agkistrodon contortrix". Integrated Taxonomic Information System. Retrieved 28 November 2006.
- Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Ithaca and London: Comstock Publishing Associates. 870 pp., 1500 plates. ISBN 0-8014-4141-2.
- Gloyd HK, Conant R. 1990. Snakes of the Agkistrodon Complex: A Monographic Review. Society for the Study of Amphibians and Reptiles. 614 pp., 52 plates. LCCN 89-50342. ISBN 0-916984-20-6.
- Wright AH, Wright AA. 1957. Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates. (7th printing, 1985). 1,105 pp. (in two volumes) ISBN 0-8014-0463-0. (Ancistrodon contortrix, pp. 903-916 + Figures 259, 261-263 + Map 64).
- U.S. Navy. 1991. Poisonous Snakes of the World. United States Government. New York: Dover Publications Inc. 203 pp. ISBN 0-486-26629-X.
- Anonymous. (year?). Copperhead Snake, Life History Notes. Ohio Division of Wildlife. Publication 373 (399).
- Agkistrodon contortrix at the IUCN Red List. Accessed 13 September 2007.
- 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 13 September 2007.
- Reiserer RS. 2002. "Stimulus control of caudal luring and other feeding responses: A program for research on visual perception in vipers". pp. 361-383. In Schuett GW, Höggren M, Douglas ME, Greene HW (editors). 2002. Biology of the Vipers. Eagle Mountain, Utah: Eagle Mountain Publishing. 580 pp. ISBN 978-0972015400.
- "Venomous Snakes". National Institute for Occupational Safety and Health. Retrieved on November 10, 2008.
- Smith CF, Schwenk K, Earley RL, Schuett GW. 2008. Sexual size dimorphism of the tongue in a North American pitviper. Journal of Zoology 274 (4): 367-374.
- Finn, Robert (2001). "Snake Venom Protein Paralyzes Cancer Cells". J. National Cancer Institute 93 (4): 261–262.
- Pyrko P, Wang W, Markland FS, Swenson SD, Schmitmeier S, Schönthal AH, Chen TC (2005). "The role of contortrostatin, a snake venom disintegrin, in the inhibition of tumor progression and prolongation of survival in a rodent glioma model". J. Neurosurgery 103 (3): 526–537. doi:10.3171/jns.2005.103.3.0526. PMID 16235686.
- http://www.emedicine.com/emerg/topic539.htm emedicine.com
- Sig Sauer product page for P238 Copperhead (archived copy of expired page).
- Behler JL, King FW. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. ISBN 0-394-50824-6. (Agkistrodon contortrix, pp. 683-684 + Plates 649-652, 655).
- Boulenger GA. 1896. Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the ... Viperidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiv + 727 pp. + Plates I-XXV. (Ancistrodon contortrix, pp. 522-523).
- Conant R. 1975. A Field Guide to Reptiles and Amphibians of Eastern and Central North America, Second Edition. Boston: Houghton Mifflin. xviii + 429 pp. + Plates 1-48. ISBN 0-395-19979-4 (hardcover), ISBN 0-395-19977-8 (paperback). (Agkistrodon contortrix, pp. 226-228 + Plate 34 + Map 174).
- Conant R, Bridges W. 1939. What Snake is That? A Field Guide to the Snakes of the United States East of the Rocky Mountains. (with 108 drawings by Edmond Malnate). New York and London: D. Appleton-Century. Frontispiece map + viii + 163 pp. + Plates A-C, 1-32. (Agkistrodon mokasen, pp. 136-139 + Plate 27, Figures 79-81).
- Gloyd HK. 1934. Studies on the Breeding Habits and Young of the Copperhead, Agkistrodon mokasen Beauvois. Papers Michigan Acad. Sci. 19: 587-604, 2 figures, 3 plates.
- Holbrook JE. 1838. North American Herpetology; or, A Description of the Reptiles Inhabiting the United States [First edition]. Vol II. Philadelphia: J. Dobson. (E.G. Dorsey, printer). 130 pp. + Plates I-XXX. (Trigonocephalus contortrix, pp. 69-72 + Plate XIV).
- Holbrook JE. 1842. North American Herpetology; or, A Description of the Reptiles Inhabiting the United States [Second edition]. Vol. III. Philadelphia: J. Dobson. (E.G. Dorsey, printer). 128 pp. + Plates I-XXX. (Trigonocephalus contortrix, pp. 39-42 + Plate VIII).
- Hubbs B, O'Connor B. 2012. A Guide to the Rattlesnakes and other Venomous Serpents of the United States. Tempe, Arizona: Tricolor Books. 129 pp. ISBN 978-0-9754641-3-7. (Agkistrodon contortrix, pp. 93-103).
- Jan G, Sordelli F. 1874. Iconographie générale des Ophidiens, Quarante-sixième livraison. Paris: Baillière. Index + Plates I-VI. (Trigonocephalus contortrix, Plate V, Figure 1). (in French).
- Linnaeus C. 1766. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, diferentiis, synonymis, locis. Tomus I. Editio Duodecima, Reformata. Stockholm: L. Salvius. 532 pp. (Boa contortrix, new species, p. 373). (in Latin).
- Livezey RL. 1949. An aberrant pattern of Agkistrodon mokeson austrinus. Herpetologica 5: 93.
- Morris, Percy A. 1948. Boy's Book of Snakes: How to Recognize and Understand Them. A volume of the Humanizing Science Series, edited by Jaques Cattell. New York: Ronald Press. viii + 185 pp. (Agkistrodon contortrix, pp. 110-114, 181).
- Schmidt KP, Davis DD. 1941. Field Book of Snakes of the United States and Canada. New York: G.P. Putnam's Sons. 365 pp. (Agkistrodon mokasen, pp. 283-285 + Plate 30).
- Smith HM, Brodie ED Jr. 1982. Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. ISBN 0-307-13666-3 ("limp"), ISBN 0-307-47009-1 (hardcover). (Agkistrodon contortrix, pp. 198-199).
- Zim HS, Smith HM. 1956. Reptiles and Amphibians: A Guide to Familiar American Species: A Golden Nature Guide. New York: Simon and Schuster. 160 pp. (Ancistrodon contortrix, pp. 109, 156).
Names and Taxonomy
Comments: Keratin biochemistry suggests that New World members of genus Agkistrodon may not be monophyletic (if such genera as Deinagkistrodon and Calloselasma are recognized as valid) (Campbell and Whitmore 1989). See Chiasson et al. (1989) for information on scale morphology and its implications concerning relationships among Agkistrodon and closely related genera. According to Crother et al. (2008), evidence from MtDNA data suggests that this single species may be composed of multiple independently evolving lineages not concordant with traditional subspecific designations (Guiher and Burbrink, pers. comm.).