Eastern copperhead

{{short description|Species of reptile}} {{hatnote|Several terms redirect here. For other snakes commonly called "copperheads", see Copperhead (disambiguation).}} {{Speciesbox | image = Agkistrodon contortrix contortrix CDC-a.png | status = LC | status_system = IUCN3.1 | status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=Frost, D.R. |author-link=Darrel R. Frost |author2=Hammerson, G.A. |author2-link=species:Geoffrey A. Hammerson |author3=Santos-Barrera, G. |author3-link=species:Georgina Santos-Barrera |date=2007 |title=''Agkistrodon contortrix '' |volume=2007 |article-number=e.T64297A12756101 |doi=10.2305/IUCN.UK.2007.RLTS.T64297A12756101.en |access-date=12 November 2021}}</ref> | genus = Agkistrodon | species = contortrix | authority = (Linnaeus, 1766) | synonyms = {{collapsible list|bullets = true|title=<small>List</small> |''Boa contortrix'' <br />{{small|Linnaeus, 1766}} |''Scytale contortrix'' <br />{{small|— Sonnini & Latreille, 1801}} |''Scytale Cupreus'' <br />{{small|Rafinesque, 1818}} |''Scytale cupreus'' <br />{{small|— Say, 1819}} |''Tisiphone cuprea'' <br />{{small|— Fitzinger, 1826}} |[''Cenchris''] ''marmorata'' <br />{{small|F. Boie, 1827}} |''Acontias atrofuscus'' <br />{{small|Troost, 1836}} |[''Toxicophis atrofuscus''] <br />{{small|— Troost, 1836}} |''T''[''rigonocephalus''] ''cenchris'' {{small|Schlegel, 1837}} |''Trigonocephalus Contortrix'' <br />{{small|— Holbrook, 1838}} |''Trigonocephalus atro-fuscus'' <br />{{small|— Holbrook, 1842}} |''Cenchris contortrix'' <br />{{small|— Gray, 1842}} |''Cenchris atrofuscus'' <br />{{small|— Gray, 1849}} |''Agkistrodon contortrix'' <br />{{small|— Baird & Girard, 1853}} |''T''[''rigonocephalus''] ''histrionicus'' <br />{{small|A.M.C. Duméril & Bibron, 1853}} |''Ancistrodon contortrix'' <br />{{small|— Baird, 1854}} |''Agkistrodon contorting'' <br />{{small|Abbott, 1869}} ''(ex errore)'' |''Ancistrodon atrofuscus'' <br />{{small|— Cope, 1875}} |''Agkistrodon atrofuscus'' <br />{{small|— Yarrow, 1882}} |[''Ancistrodon contortrix''] Var. ''atrofuscus'' <br />{{small|— Garman, 1884}} |''Ancistrodon contortrix'' <br />{{small|— Boulenger, 1896}} |''Agkistrodon contortirix'' <br />{{small|Keim, 1914}} ''(ex errore)'' |''Agkistrodon mokasen cupreus'' <br />{{small|— Gloyd & Conant, 1938}} |''Agkistrodon contortrix contortrix'' <br />{{small|— Klauber, 1967}} |''Ancistrodon contortrix contortrix'' <br />{{small|— Schmidt, 1953}} }} | synonyms_ref = <ref name="McD99"/> | range_map = Copperhead distribution (Agkistrodon contortrix & A. laticinctus).jpg }}

The '''eastern copperhead''' ('''''Agkistrodon contortrix'''''),<ref>Moriarty, John J. (2017). ''Scientific and standard English names of amphibians and reptiles of North America north of Mexico with comments regarding confidence in our understanding''. 8th ed. Society Study Amphibians and Reptles [https://ssarherps.org/wp-content/uploads/2017/10/8th-Ed-2017-Scientific-and-Standard-English-Names.pdf Herpetological Circular 43].</ref> also known simply as the '''copperhead''', is a widespread species of venomous snake, a pit viper, endemic to eastern United States of America; it is a member of the subfamily Crotalinae in the family Viperidae.

The eastern copperhead has distinctive, dark brown, hourglass-shaped markings, overlaid on a light reddish brown or brown/gray background. The body type is heavy, rather than slender. Neonates are born with green or yellow tail tips, which progress to a darker brown or black within one year. Adults grow to a typical length (including tail) of {{convert|50|-|95|cm|in|0|abbr=on}}.

In most of the United States of America, the eastern copperhead favors deciduous forest and mixed woodlands. It may occupy 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.<ref name=":0">{{Cite news|url=https://nationalzoo.si.edu/animals/northern-copperhead|title=Northern copperhead|date=2016-04-25|work=Smithsonian's National Zoo|access-date=2017-06-29|language=en}}</ref> The eastern copperhead is known to feed on a wide variety of prey, including invertebrates (primarily arthropods) and vertebrates. Like most pit vipers, the eastern copperhead is generally an ambush predator; it takes up a promising position and waits for suitable prey to arrive.

As a common species within its range, it may be encountered by humans. Unlike other viperids, it often "freezes" instead of slithering away and fleeing, due to its habit of relying on excellent camouflage.<ref name=Allf>{{cite journal |last1=Allf |first1=Bradley C. |last2=Durst |first2=Paul A. P. |last3=Pfennig |first3=David W. |title=Behavioral Plasticity and the Origins of Novelty: The Evolution of the Rattlesnake Rattle |journal=The American Naturalist |date=October 2016 |volume=188 |issue=4 |pages=475–483 |doi=10.1086/688017 |pmid=27622880 |bibcode=2016ANat..188..475A }}</ref> Bites occur due to people unknowingly stepping on or near them.<ref name="Venomous Snakes">"[https://www.cdc.gov/niosh/topics/snakes/ Venomous Snakes]". National Institute for Occupational Safety and Health. Retrieved on November 10, 2008.</ref> Copperhead bites account for half of the treated snake bites in the United States.<ref>{{cite journal |last1=Mullins |first1=Michael E. |last2=Freeman |first2=William E. |title=Thromboelastometry (ROTEM) and thromboelastography (TEG) in copperhead snakebites: a case series |journal=Clinical Toxicology |date=September 2020 |volume=58 |issue=9 |pages=931–934 |doi=10.1080/15563650.2020.1713332 |pmid=31997668 }}</ref>

Five subspecies have been recognized in the past,<ref name="ITIS">{{ITIS|id=174296|taxon=''Agkistrodon contortrix ''|access-date=28 November 2006}}</ref> but recent genetic analysis has yielded new species information.

==Etymology== Its generic name is derived from the Greek words ''ankistron'' "hook, fishhook" and ''odon'', variant of ''odous'' "tooth".<ref>{{Cite web|url=https://www.inhs.illinois.edu/collections/herps/data/ilspecies/ag_contort/|title=Illinois Natural History Survey Agkistrodon contortrix|website=www.inhs.illinois.edu|access-date=2019-07-22|archive-date=2019-05-12|archive-url=https://web.archive.org/web/20190512073925/https://www.inhs.illinois.edu/collections/herps/data/ilspecies/ag_contort/}}</ref><ref>{{LSJ|a)/gkistron|ἄγγιστρον}}, {{LSJ|o)dw/n|ὀδών}}, {{LSJ|o)dou/s|ὀδούς|ref}}.</ref> 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 snake's back, which are broad at the lateral base, but "pinched" into narrow hourglass shapes in the middle at the vertebral area.<ref name="C&L04">Campbell JA, Lamar WW (2004). ''The Venomous Reptiles of the Western Hemisphere''. Ithaca and London: Comstock Publishing Associates. {{ISBN|0-8014-4141-2}}.</ref><ref>Lemos Espinal, J.A., G.R. Smith, J.R. Dixon, and A. Cruz. (2015). ''Amphibians and Reptiles of Sonora, Chihuahua, and Coahuila, Mexico''. Distrito Federal, Mexico. {{ISBN|978-607-8328-27-7}}.</ref>

==Description== Adults grow to a typical length (including tail) of {{convert|50|-|95|cm|in|0|abbr=on}}. Some may exceed {{convert|1|m|ftin|abbr=on}}, although that is exceptional for this species.<ref>Ernst, Carl H.; Barbour, Roger W. (1989). ''Snakes of Eastern North America''. Fairfax, Virginia: George Mason University Press. {{ISBN|978-0913969243}}.</ref> Males do not typically exceed {{convert|74|to|76|cm|in|frac=2|abbr=on}} and weigh from {{convert|101.5|to|343|g|oz|frac=16|abbr=on}}, with a mean of roughly {{convert|197.4|g|oz|frac=16|abbr=on}}.<ref>{{cite journal|author=Schuett GW|author-link=species:Gordon W. Schuett |author2=Grober MS|year=2000|title=Post-fight levels of plasma lactate and corticosterone in male copperheads, ''Agkistrodon contortrix'' (Serpentes, Viperidae): differences between winners and losers|journal=Physiology & Behavior|volume=71|issue=3|pages=335–341|doi=10.1016/s0031-9384(00)00348-6|pmid=11150566|s2cid=10137506}}</ref> Females do not typically exceed {{convert|60|to|66|cm|in|frac=2|abbr=on}},<ref>Palmer, William M.; Braswell, Alvin L. (1995). ''Reptiles of North Carolina''. Chapel Hill and London: University of North Carolina Press. {{ISBN|978-0807821589}}.</ref><ref>Stejneger, L (1895). ''The Poisonous Snakes of North America''. Washington, District of Columbia: United States Government Printing Office.</ref> and have a mean body mass of {{convert|119.8|g|oz|frac=64|abbr=on}}.<ref>{{cite journal |last1=Shine |first1=Richard |title=Relative Clutch Mass and Body Shape in Lizards and Snakes: Is Reproductive Investment Constrained or Optimized? |journal=Evolution |date=1992 |volume=46 |issue=3 |pages=828–833 |doi=10.1111/j.1558-5646.1992.tb02088.x |pmid=28568652 |jstor=2409650 }}</ref> The maximum length reported for this species is {{convert|134.6|cm|in|frac=16|abbr=on}} 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&nbsp;cm), but this may have been an approximation. The maximum length for ''A. c. contortrix'' is {{convert|132.1|cm|in|frac=16|abbr=on}} (Conant, 1958).<ref name="C&L04" /> {{Multiple image | image1 = Kupferkopf-02.jpg | image2 = Agkistrodon contortrix qtl1.jpg | direction = vertical | total_width = 200 | footer = Head closeup, showing dilated and constricted pupils }}

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.&nbsp;piscivorus''. Consequently, the top of the head extends further forward than the mouth.<ref name="G&C90">Gloyd HK, Conant R (1990). ''Snakes of the'' Agkistrodon ''Complex: A Monographic Review''. Society for the Study of Amphibians and Reptiles. LCCN 89-50342. {{ISBN|0-916984-20-6}}.</ref>

The escalation 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.<ref name="C&L04"/>

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.<ref name="G&C90"/>

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 had a similar striped pattern, with only the first and last two crossbands being normal.<ref name="G&C90"/>

==Distribution and habitat== The eastern copperhead is found in North America; its range within the United States is in Alabama, Arkansas, Connecticut, Delaware, District of Columbia, 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".<ref name="McD99">McDiarmid RW, Campbell JA, Touré TA (1999). ''Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1''. Washington, District of Columbia: Herpetologists' League. {{ISBN|1-893777-00-6}} (series). {{ISBN|1-893777-01-4}} (volume).</ref>

Unlike some other species of North American pit vipers, such as the timber rattlesnake and massasauga, the copperhead has mostly not re-established itself north of the terminal moraine after the last glacial period (the Wisconsin glaciation),<ref>Anonymous. (year?). ''Copperhead Snake, Life History Notes''. Ohio Division of Wildlife. Publication 373 (399).</ref> though it is found in southeastern New York and southern New England, north of the Wisconsin glaciation terminal moraine on Long Island.

Historically, kingsnakes have been major copperhead predators. Recent copperhead abundance has been linked to declining kingsnake populations in those areas.<ref>{{Cite journal |last=Steen |first=David A. |last2=McClure |first2=Christopher J. W. |last3=Sutton |first3=William B. |last4=Rudolph |first4=D. Craig |last5=Pierce |first5=Josh B. |last6=Lee |first6=James R. |last7=Smith |first7=Lora L. |last8=Gregory |first8=Beau B. |last9=Baxley |first9=Danna L. |last10=Stevenson |first10=Dirk J. |last11=Guyer |first11=Craig |date=2014-03-01 |title=Copperheads are Common when Kingsnakes are Not: Relationships Between the Abundances of a Predator and One of their Prey |url=https://bioone.org/journals/herpetologica/volume-70/issue-1/HERPETOLOGICA-D-13-00064/Copperheads-are-Common-when-Kingsnakes-are-Not--Relationships-Between/10.1655/HERPETOLOGICA-D-13-00064.full |journal=Herpetologica |volume=70 |issue=1 |pages=69 |doi=10.1655/HERPETOLOGICA-D-13-00064 |issn=0018-0831|url-access=subscription }}</ref>

Eastern copperheads are habitat generalists which are species able to survive in different habitats (fragmented and unfragmented).<ref name=":1">{{cite journal |last1=Novak |first1=Megan V. |last2=Crane |first2=Derek P. |last3=Bell |first3=Lindsey |last4=Keiner |first4=Louis |last5=Gatto |first5=Caitlin R. |last6=McNabb |first6=Christian T. |last7=Parker |first7=Scott L. |title=Spatial Ecology of Eastern Copperheads in Fragmented and Unfragmented Habitats |journal=Journal of Herpetology |date=14 February 2020 |volume=54 |issue=1 |page=97 |doi=10.1670/18-146 }}</ref> 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.<ref name=":0" /> 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).<ref name="C&L04" /> Habitat fragmentation has been found to impair Eastern Copperhead access to feeding, brumation, and reproduction sites.<ref name=":1" /> In a tracking study, copperheads studied in fragmented areas never left the area they were first caught in.<ref>{{Cite journal |last=Novak |first=Megan V. |last2=Crane |first2=Derek P. |last3=Bell |first3=Lindsey |last4=Keiner |first4=Louis |last5=Gatto |first5=Caitlin R. |last6=McNabb |first6=Christian T. |last7=Parker |first7=Scott L. |date=2020-02-14 |title=Spatial Ecology of Eastern Copperheads in Fragmented and Unfragmented Habitats |url=https://bioone.org/journals/journal-of-herpetology/volume-54/issue-1/18-146/Spatial-Ecology-of-Eastern-Copperheads-in-Fragmented-and-Unfragmented-Habitats/10.1670/18-146.full |journal=Journal of Herpetology |volume=54 |issue=1 |pages=97 |doi=10.1670/18-146 |issn=0022-1511|url-access=subscription }}</ref>

==Conservation status== This species is classified as least concern on the IUCN Red List of Threatened Species (v3.1, 2001).<ref name="iucn status 12 November 2021" /> This means that relative to many other species, it is not at risk of extinction in the near future. The population trend was stable when assessed in 2007.<ref name="ICUN-31">{{Redlist CC2001|date=13 September|year=2007}}</ref> Their venom has potential medicinal value to humans.<ref name="VanDeWalle EASTERN COPPERHEAD">{{cite book |last1=VanDeWalle |first1=Terry |chapter=EASTERN COPPERHEAD Agkistrodon contortrix (Linnaeus) 1766 VENOMOUS |pages=299–306 |doi=10.2307/j.ctv2nwq90n.38 |jstor=j.ctv2nwq90n.38 |title=The Natural History of the Snakes and Lizards of Iowa |date=2022 |publisher=University of Iowa Press |isbn=978-1-60938-837-9 }}</ref>{{How|Please explain.|date=May 2024}}

==Behavior== In the Southern United States, copperheads 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.<ref name="Venomous Snakes"/> 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. Eastern Copperheads are more likely to either remain in crypsis or flee in the presence of a human rather than display defensive behavior.<ref>{{Cite web |title=https://pascal-swu.primo.exlibrisgroup.com/discovery/fulldisplay?&context=PC&vid=01PASCAL_SWU:SWU&search_scope=MyInst_and_CI&tab=Everything&lang=en&docid=cdi_doaj_primary_oai_doaj_org_article_d4e85230a2a74dd6a3469285741c5ce5 |url=https://pascal-swu.primo.exlibrisgroup.com/discovery/fulldisplay?&context=PC&vid=01PASCAL_SWU:SWU&search_scope=MyInst_and_CI&tab=Everything&lang=en&docid=cdi_doaj_primary_oai_doaj_org_article_d4e85230a2a74dd6a3469285741c5ce5 |access-date=2026-04-21 |website=pascal-swu.primo.exlibrisgroup.com |language=en}}</ref> Generally nonaggressive, will only strike if threatened as a last resort.<ref>{{Cite journal |last=Stratton |first=J. Benjamin |last2=Richter |first2=Stephen C. |date=2025-01-17 |title=Individual capture history affects site use and defensive behavior of foraging eastern copperheads at a recreational site |url=https://link.springer.com/article/10.1007/s00265-025-03562-y |journal=Behavioral Ecology and Sociobiology |language=en |volume=79 |issue=1 |page=16 |doi=10.1007/s00265-025-03562-y |issn=1432-0762|doi-access=free }}</ref> 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.<ref name=Allf/>

==Diet and feeding behavior== thumb|278x278px|Copperhead swallowing a cicada. [[File:Eastern Copperhead, Nantahala Dr, Durham, NC 27713 imported from iNaturalist photo 297973634.jpg|thumb|Eating a DeKay's brown snake]] The eastern copperhead is a diet generalist and is known to feed on a wide variety of prey, including invertebrates (primarily arthropods) and vertebrates. A generalized ontogenetic shift in the diet occurs, with juveniles feeding on higher percentages of invertebrates and ectotherms, and adults feeding on a higher percentage vertebrate endotherms. Both juveniles and adults, though, feed on invertebrates and vertebrates opportunistically. The diet is also known to vary among geographic populations.<ref name="G&C90"/>{{rp|128–130 p.}}<ref name="C&L04"/>{{rp|254–255 p.}}<ref name="Ernst & Ernst 2011">Ernst, Carl H. and Evelyn M. Ernst. (2011). ''Venomous Reptiles of the United States, Canada, and Northern Mexico'', Volume 1. The Johns Hopkins University Press. Baltimore, Maryland. {{ISBN|0-8018-9875-7}}</ref>{{rp|181–184 p.}}

Studies conducted at various locations within the range of the eastern copperhead (''A. contortrix''), including Tennessee,<ref>{{cite journal|url=https://friendsofthecumberlandtrail.org/wp-content/uploads/2009/11/im3511_20091103_114214.pdf|author=Garton, J.S. and Dimmick, R.W. |year= 1969|title=Food habits of the copperhead in middle Tennessee|journal=Journal of the Tennessee Academy of Science|volume= 44|pages=113–117|archive-url=https://web.archive.org/web/20160528033659/https://friendsofthecumberlandtrail.org/wp-content/uploads/2009/11/im3511_20091103_114214.pdf |archive-date=2016-05-28 }}</ref> Kentucky,<ref>{{cite journal|author=Bush, F.M. |author-link=species:Francis M. Bush |year=1959|title=Foods of some Kentucky herptiles|url=https://archive.org/details/sim_herpetologica_1959-06-02_15_2/page/72 |journal= Herpetologica|volume= 15|pages= 73–77}}</ref> Kansas,<ref>Fitch, H.S. (1982). [https://biosurvey.ku.edu/resources-snake-community-prairie-woodland-habitat-northeastern-kansas "Resources of a snake community in prairie-woodland habitat of northeastern Kansas", pp. 83-97 in N. Scott, Jr. (ed.), ''Herpetological communities''. U.S. Fish and Wildlife Service, Wildlife Research Report, 13.] {{Webarchive|url=https://web.archive.org/web/20211009174701/https://biosurvey.ku.edu/resources-snake-community-prairie-woodland-habitat-northeastern-kansas |date=2021-10-09 }}</ref> and Texas,<ref>{{cite journal|author=Lagesse, L.A. and Ford, N.B. |year= 1996|title=Ontogenetic variation in the diet of the southern copperhead, ''Agkistrodon contortrix'', in northeast Texas|url=https://www.researchgate.net/publication/286891576|journal= Texas Journal of Science|volume= 48|pages= 48–54}}</ref> identified some consistently significant prey items included cicadas (''Tibicen''), caterpillars (Lepidoptera), lizards (''Sceloporus'' and ''Scincella''), voles (''Microtus''), and mice (''Peromyscus''). Accounts of finding large numbers of copperheads in bushes, vines, and trees seeking newly emerged cicadas, some as high as 40 feet above ground, have been reported from Texas by various herpetologists.<ref name="G&C90"/>{{rp|130 p.}}<ref>{{cite journal|author=Curtis, Lawrence|year= 1949|title=The snakes of Dallas County, Texas|journal= Field & Laboratory|volume= 17|pages= 5–13}}</ref><ref name="Werler & Dixon. 2000">Werler, John E. and James R. Dixon. (2000). ''Texas Snakes: Identification, Distribution, and Natural History''. Austin, Texas: University of Texas Press. {{ISBN|0-292-79130-5}}</ref>{{rp|347–348 p.}}

Other items documented in the diet include various invertebrates, e.g. millipedes (Diplopoda), spiders (Arachnida), beetles (Coleoptera), dragonflies (Odonata), grasshoppers (Orthoptera), and mantids (Mantidae), as well as numerous species of vertebrates, including salamanders, frogs, lizards, snakes, small turtles, small birds, young opossums, squirrels, chipmunks, rabbits, bats, shrews, moles, rats, and mice.<ref name="C&L04"/>{{rp|254–255 p.}}<ref name=" Ernst & Ernst 2011" />{{rp|181–184 p.}}

{{Easy CSS image crop|Image=Eastern Copperhead imported from iNaturalist photo 151862798 on 3 December 2024.jpg|desired_width=250|align=right|caption=Eating a northern slimy salamander|crop_left_perc=15|crop_right_perc=25|crop_top_perc=25|crop_bottom_perc=10}}

Like most pit vipers, the eastern copperhead 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.<ref>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. {{ISBN|978-0972015400}}.</ref> They possess facial pit organs which is a complex infrared-imaging system that allows accurate and precise strikes on potential prey.<ref>Van Dyke, J. U., & Grace, M. S. (2010). The role of thermal contrast in infrared-based defensive targeting by the Copperhead, Agkistrodon Contortrix. Animal Behaviour, 79(5), 993–999. https://doi.org/10.1016/j.anbehav.2010.01.012 </ref> Juveniles use a brightly colored tail to attract frogs and perhaps lizards, a behavior termed caudal luring (see video: [https://web.archive.org/web/20110823183247/http://open2it.com/videos/62-animal-behavior/160-caudal-luring-in-the-copperhead.html]). Sight, odor, and heat detection are used in locating prey, although after the prey has been envenomated, odor and taste become the primary means of tracking. Smaller prey items and birds are often seized and held in the mouth until dead, while larger prey items are typically bitten, released, and then tracked until dead. Copperheads occasionally feed on carrion. Gravid females typically fast, although some individuals occasionally take small volumes of food.<ref name="C&L04" />{{rp|254–255 p.}}<ref name="Ernst & Ernst 2011" />{{rp|181–184 p.}} An individual may eat up to twice its body mass in a year. One study found an individual that ate eight times during an annual activity period, totaling 1.25 times its body mass.<ref>Schoener, T.W. (1977). "Competition and the niche". pp. 35-136. '''''In'':''' Gans, C. and D.W. Tinkle (eds.) (1977). ''Biology of the Reptiles, Volume 7''. New York: Academic Press.</ref>

Predators of the eastern copperhead are not well known, but may include owls, hawks, opossums, bullfrogs, and other snakes, including the Kingsnake.<ref>{{Cite journal |last=Steen |first=David A. |last2=McClure |first2=Christopher J. W. |last3=Sutton |first3=William B. |last4=Rudolph |first4=D. Craig |last5=Pierce |first5=Josh B. |last6=Lee |first6=James R. |last7=Smith |first7=Lora L. |last8=Gregory |first8=Beau B. |last9=Baxley |first9=Danna L. |last10=Stevenson |first10=Dirk J. |last11=Guyer |first11=Craig |date=2014 |title=Copperheads are common when kingsnakes are not: relationships between the abundances of a predator and one of their prey |url=https://research.fs.usda.gov/treesearch/46211 |journal=Herpetologica. 70(1): 69-76 |language=en |volume=70 |pages=69–76}}</ref> They will use anti-predatory behaviors to discourage predators. These include: move away or flee, musking, tail vibrating, mouth gaping, or curling up into a camouflage pile.<ref name="VanDeWalle EASTERN COPPERHEAD"/><ref>{{cite thesis |id={{ProQuest|2853734219}} |last1=Stratton |first1=James Benjamin Postal |date=2023 |title=Individual Capture History Affects Site Use and Defensive Behavior of Foraging Eastern Copperheads at a Recreational Site }}{{pn|date=April 2024}}</ref>

==Reproduction== {{Easy CSS image crop|Image=Eastern copperhead - Agkistrodon contortrix (42669143530).jpg|caption=Juvenile in Missouri, showing the characteristic yellow tail of juveniles|align=right|desired_width=250|crop_right_perc=10|crop_left_perc=20|crop_bottom_perc=20|crop_top_perc=10}} Eastern copperheads breed in late summer, but not every year; sometimes, females produce young for several years running, then do not breed at all for a time. Mating is sometimes preceded by male combat.<ref>{{cite journal |last1=Smith |first1=C. F. |last2=Schuett |first2=G. W. |last3=Schwenk |first3=K. |title=Relationship of plasma sex steroids to the mating season of copperheads at the north-eastern extreme of their range |journal=Journal of Zoology |date=April 2010 |volume=280 |issue=4 |pages=362–370 |doi=10.1111/j.1469-7998.2009.00669.x }}</ref> In male combat, losing experience had a greater effect than SVL in winning access to females.<ref>{{Cite journal |last=Schuett |first=GORDON W. |date=1997-07-01 |title=Body size and agonistic experience affect dominance and mating success in male copperheads |url=https://www.sciencedirect.com/science/article/abs/pii/S0003347296904170 |journal=Animal Behaviour |volume=54 |issue=1 |pages=213–224 |doi=10.1006/anbe.1996.0417 |issn=0003-3472|url-access=subscription }}</ref> Females give birth to live young, each of which is about {{convert|20|cm|in|0|abbr=on}} in total length. The typical litter size is four to seven, but as few as one, or as many as 20 may be seen. Females are capable of storing sperm for up to a year.<ref>Jordan, M. A., Perrine-Ripplinger, N., & Carter, E. T. (2015). An independent observation of facultative parthenogenesis in the Copperhead (agkistrodon contortrix). Journal of Herpetology, 49(1), 118–121. https://doi.org/10.1670/14-017 </ref> Their size apart, the young are similar to the adults, but lighter in color, and with a yellowish-green-marked tip to the tail, which is used to lure lizards and frogs.

''A. contortrix'' males have longer tongue tie lengths than females during the breeding season, which may aid in chemoreception of males searching for females.<ref>{{cite journal |last1=Smith |first1=C. F. |last2=Schwenk |first2=K. |last3=Earley |first3=R. L. |last4=Schuett |first4=G. W. |title=Sexual size dimorphism of the tongue in a North American pitviper |journal=Journal of Zoology |date=April 2008 |volume=274 |issue=4 |pages=367–374 |doi=10.1111/j.1469-7998.2007.00396.x }}</ref>

===Facultative parthenogenesis=== Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. ''A. contortrix'' can reproduce by facultative parthenogenesis, that is, they are capable of switching from a sexual mode of reproduction to an asexual mode.<ref name=Booth>{{cite journal |last1=Booth |first1=Warren |last2=Smith |first2=Charles F. |last3=Eskridge |first3=Pamela H. |last4=Hoss |first4=Shannon K. |last5=Mendelson |first5=Joseph R. |last6=Schuett |first6=Gordon W. |title=Facultative parthenogenesis discovered in wild vertebrates |journal=Biology Letters |date=23 December 2012 |volume=8 |issue=6 |pages=983–985 |doi=10.1098/rsbl.2012.0666 |pmid=22977071 |pmc=3497136 }}</ref> The type of parthenogenesis that likely occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote. This process leads to genome-wide homozygosity, expression of deleterious recessive alleles, and often to developmental failure (inbreeding depression). Both captive-born and wild-born ''A. contortrix'' snakes appear to be capable of this form of parthenogenesis.<ref name=Booth />

==Venom== Although venomous, eastern copperheads are generally not aggressive and bites are rarely fatal.<ref name="Walker470">{{cite journal |last1=Walker |first1=Patrick J. |last2=Morrison |first2=Ray L. |title=Current Management of Copperhead Snakebite |journal=Journal of the American College of Surgeons |date=April 2011 |volume=212 |issue=4 |pages=470–474 |doi=10.1016/j.jamcollsurg.2010.12.049 |pmid=21463771 }}</ref> Copperhead venom has an estimated lethal dose around 100&nbsp;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.<ref>{{Cite journal|last1=Cox|first1=Robert D.|last2=Parker|first2=Christina S.|last3=Cox|first3=Erin C. E.|last4=Marlin|first4=Michael B.|last5=Galli|first5=Robert L.|date=December 2018|title=Misidentification of copperhead and cottonmouth snakes following snakebites|journal=Clinical Toxicology|volume=56|issue=12|pages=1195–1199|doi=10.1080/15563650.2018.1473583|pmid=29792342|s2cid=43975773}}</ref> 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.<ref>{{Cite web|date=16 March 2021|title=Copperhead Fact Sheet|url=http://www.worldanimalfoundation.net/f/copperhead.pdf|access-date=16 March 2021|website=World Animal Foundation}}</ref> The fangs of dead pit vipers are capable of delivering venom in amounts that necessitate the use of antivenom.<ref>{{cite journal |last1=Emswiler |first1=Michael P. |last2=Griffith |first2=F. Phillip |last3=Cumpston |first3=Kirk L. |title=Clinically Significant Envenomation From Postmortem Copperhead (Agkistrodon contortrix) |journal=Wilderness & Environmental Medicine |date=March 2017 |volume=28 |issue=1 |pages=43–45 |doi=10.1016/j.wem.2016.09.007 |pmid=27876196 |doi-access=free }}</ref>

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 a large muscle mass is not available to absorb the venom. A bite from any venomous snake should be taken very seriously and immediate medical attention sought, as an allergic reaction and secondary infection are always possible.<ref>{{Cite web|title=Copperhead {{!}} CS Mott Children's Hospital {{!}} Michigan Medicine|url=https://www.mottchildren.org/health-library/th1317|access-date=2021-03-16|website=www.mottchildren.org}}</ref>

The antivenom CroFab is used to treat copperhead envenomations that demonstrate localized or systemic reactions to the venom. As many copperhead bites can be dry (no envenomation), CroFab is not given in the absence of a reaction (such as swelling) due to the risk of complications of an allergic reaction to the treatment.<ref>{{Cite journal|url=https://www.annemergmed.com/article/S0196-0644(02)93334-2/fulltext|doi=10.1067/mem.2002.124450|title=Rational use of crotalidae polyvalent immune Fab (Ovine) in the management of crotaline bite|year=2002|last1=Yip|first1=Luke|journal=Annals of Emergency Medicine|volume=39|issue=6|pages=648–650|pmid=12023708|doi-access=free|url-access=subscription}}</ref> The antivenom can cause an immune reaction called serum sickness. Pain management, tetanus immunization, laboratory evaluation, and medical supervision in the case of complications are additional courses of action.<ref>{{EMedicine|article|771329|Copperhead and Cottonmouth Envenomation}}</ref> In 2002, an Illinois poison control center report on the availability of antivenom stated it used 1 Acp to 5 Acp depending on the symptoms and circumstances. Antivenom use however may not be necessary in the majority of cases, A study that analyzed 88 copperhead bite victims reported that all the victims survived and none required antivenom.<ref name="Walker470" />

=== Research === The venom of the southern copperhead has been found to hold the protein ''contortrostatin'' that halts the growth of cancer cells in mice and also stops the migration of the tumors to other sites.<ref>{{Cite journal|title=Snake Venom Protein Paralyzes Cancer Cells|first=Robert |last=Finn|year=2001|journal= Journal of the National Cancer Institute|volume=93|issue=4|pages=261–262|doi=10.1093/jnci/93.4.261|pmid=11181769|doi-access=free}}</ref> However, this is an animal model, and further testing is required to verify safety and efficacy in humans.<ref>{{Cite journal|title=The role of contortrostatin, a snake venom disintegrin, in the inhibition of tumor progression and prolongation of survival in a rodent glioma model|vauthors=Pyrko P, Wang W, Markland FS, Swenson SD, Schmitmeier S, Schönthal AH, Chen TC |year=2005|journal=J. Neurosurg. |volume=103 |issue=3 |pages=526–537 |pmid=16235686 |doi=10.3171/jns.2005.103.3.0526}}</ref>

==Subspecies==

This species was long considered to contain five subspecies listed below, but gene analysis suggests that ''A. c. laticinctus'' represents its own distinct species, while ''A. c. mokasen'' and ''A. c. phaeogaster'' are regional variants of ''A. c. contortrix'', and ''A. c. pictigaster'' is a regional variant of ''A. c. laticinctus''.<ref name="Burbrink & Guiher (2014)">{{cite journal |last1=Burbrink |first1=Frank T. |last2=Guiher |first2=Timothy J. |title=Considering gene flow when using coalescent methods to delimit lineages of North American pitvipers of the genus Agkistrodon: Agkistrodon Species Delimitation |journal=Zoological Journal of the Linnean Society |date=February 2015 |volume=173 |issue=2 |pages=505–526 |doi=10.1111/zoj.12211 |doi-access=free }}</ref>

Five subspecies have been recognized in the past,<ref name="ITIS"/> but recent genetic analysis shows that ''A c. contortrix'' and two of the subspecies are monotypic, while ''Agkistrodon laticinctus'' (formerly ''Agkistrodon contortrix laticinctus'') and the fifth subspecies are a single distinct species.

{|cellspacing=0 cellpadding=2 border=1 style="border-collapse: collapse;" !bgcolor="#f0f0f0"|Previous taxonomy<ref name="ITIS"/><ref name="G&C90"/> !bgcolor="#f0f0f0"|Current taxonomy<ref name="Burbrink & Guiher (2014)" /> !bgcolor="#f0f0f0"|Geographic range<ref name="Burbrink & Guiher (2014)" /> |- |Southern copperhead ''Agkistrodon contortrix contortrix''

(Linnaeus, 1766) |Eastern copperhead ''Agkistrodon contortrix''

(Linnaeus, 1766) |style="width:40%"|The United States: east Texas, east Oklahoma, extreme eastern Kansas, and extreme southeastern Nebraska, eastward to the Atlantic coast; north to extreme southeast Iowa, southern Illinois, southern Indiana, southern Ohio, Pennsylvania, southeast New York, Massachusetts, and parts of Connecticut; absent from southern Georgia and the Florida Peninsula. |- |Broad-banded copperhead ''Agkistrodon contortrix laticinctus''

Gloyd & Conant, 1934 |Broad-banded copperhead ''Agkistrodon laticinctus'' Gloyd & Conant, 1934 |In the United States from eastern Kansas, southwest through central Oklahoma, central and Trans-Pecos, Texas and neighboring areas of northern Chihuahua and Coahuila, Mexico. |- |Northern copperhead ''Agkistrodon contortrix mokasen''

Palisot de Beauvois, 1799 |Eastern copperhead ''Agkistrodon contortrix'' |The United States, in southern Illinois, extreme northeastern Mississippi, northern Alabama, northern Georgia northeast to Massachusetts, the Appalachian Mountain region and associated plateaus |- |Osage copperhead ''Agkistrodon contortrix phaeogaster''

Gloyd, 1969 |Eastern copperhead ''Agkistrodon contortrix'' |The United States, in eastern Kansas, extreme southeastern Nebraska and a large part of Missouri |- |Trans-Pecos copperhead ''Agkistrodon contortrix pictigaster''

Gloyd & Conant, 1943 |Broad-banded copperhead ''Agkistrodon laticinctus'' |The Trans-Pecos region of western Texas and adjacent areas of northern Chihuahua and Coahuila, Mexico. |- |}

==Gallery== <gallery mode="packed" heights="150"> File:CopperheadInLeavesCU.JPG|Eastern copperhead, ''A. contortrix'', at the southern limit of its range, in Liberty Co., Florida, camouflaged in dead leaves. File:Copperhead (Agkistrodon contortrix) photographed in Liberty Co., Texas. W. L. Farr.jpg|Eastern copperhead (''Agkistrodon contortrix'') from Liberty Co., Texas (30 March 2007). File:Southern Copperhead.JPG|Eastern copperhead (''Agkistrodon contortrix'') from Georgetown Co., South Carolina (23 August 2013). File:Osage Copperhead (Agkistrodon contortrix phaeogaster) (16426738014).jpg|Eastern copperhead (''Agkistrodon contortrix'') Jefferson Co., Missouri (5 April 2015: 67&nbsp;°F) were previously classified as "Osage copperhead" (''Agkistrodon contortrix phaeogaster''). File:Nördlicher Kupferkopf.JPG|Eastern copperhead (''Agkistrodon contortrix'') Westchester County, New York (May 2002). Northern populations, typically darker, were previously classified as ''A. c. mokasen''. File:Agkistrodon contortrix-DS-2.JPG|View of the ventral, or belly, pattern of a copperhead. </gallery>

==References== {{Reflist}}

==Further reading== {{refbegin}} *Behler JL, King FW (1979). ''The Audubon Society Field Guide to North American Reptiles and Amphibians''. New York: Alfred A. Knopf. {{ISBN|0-394-50824-6}}. (''Agkistrodon contortrix'', pp.&nbsp;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.&nbsp;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.&nbsp;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.&nbsp;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.&nbsp;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.&nbsp;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.&nbsp;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, differentiis, synonymis, locis. Tomus I. Editio Duodecima, Reformata.'' Stockholm: L. Salvius. 532 pp. (''Boa contortrix'', new species, p.&nbsp;373). (in Latin). *{{cite journal|author=Livezey RL|year=1949|title=An aberrant pattern of ''Agkistrodon mokeson austrinus ''|url=https://archive.org/details/sim_herpetologica_1949-07-01_5_4/page/92|journal=Herpetologica|volume=5|page=93}} *Morris PA (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.&nbsp;110–114, 181). *Powell R, Conant R, Collins JT (2016). ''Peterson Field Guide to Reptiles and Amphibians of Eastern and Central North America, Fourth Edition''. Boston and New York: Houghton Mifflin Harcourt. xiv + 494 pp., 207 Figures, 47 color plates. {{ISBN|978-0-544-12997-9}}. (''Agkistrodon contortrix'', pp.&nbsp;436–437, Figure 197 + Plate 45). *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.&nbsp;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.&nbsp;198–199). *Wright AH, Wright AA (1957). ''Handbook of Snakes of the United States and Canada''. Ithaca and London: Comstock Publishing Associates. 1,105 pp. (in two volumes). (''Ancistrodon contortrix'', pp.&nbsp;903–916 + Figures 259, 261–263 + Map 64). *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.&nbsp;109, 156). {{refend}}

==External links== {{Commons}} {{AmCyc Poster|Copperhead}} * {{NRDB species|genus=Agkistrodon|species=contortrix|date=9 August|year=2007}} *[https://www.iowaherps.com/species/agkistrodon_contortrix Copperhead] on Reptiles and Amphibians of Iowa

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contortrix Category:Fauna of the Southeastern United States Category:Reptiles of the United States Category:Reptiles of Mexico Category:Venomous snakes Category:Articles containing video clips Category:Animal taxa named by Carl Linnaeus Category:Reptiles described in 1766 Category:Least concern biota of the United States