Eastern Copperhead (Agkistrodon contortrix)

2/2/2021

Recognized Subspecies in VA: None
Size: 28 - 44 inches
Status: Least Concern

Description & Behavior

The Eastern Copperhead is a beautifully patterned snake; especially for its pattern to consist of mostly browns. Their bands are "hourglass-shaped" from above, and shaped like a chocolate kiss from the side. Many of these bands may be broken in the center of the back and slightly offset from the other half. Copperheads have short tails with black tips as adults, yellow/green tips as neonates (term for newly born specimens), and the gradien in between for young specimens. The top of their heads are generally slightly more orange than the body, hence the name, but variation does occur. This coloration forms a stark line behind the eye with the paler color on the side of the face. They have the classic pit viper head shape, one loreal heat pit (heat pits are located in the loreal scale) on either side, and of course hinging fangs. These are all common traits of the pit vipers, which is the subfamily the copperheads belong to.

Eastern Copperheads feed on a wide variety of prey items such as small rodents, shrews, lizards, large insects, and occasionally fish. These snakes often sit, concealed in the leaflitter, and wait for prey to come to them. The colored tail tip is often used as a caudal lure to draw in prey such as lizards. These snakes can be found by flipping, and they are why we often advise getting a good snake hook. We rarely use a snake hook for handling snakes, but we use them to flip debris so our hands are not too close to the concealed copperheads, black widows, or centipedes beneath. We often find them while road cruising wet nights, especially towards late August through October. Copperheads give live birth, often to 4-7 neonates; but litters of 21 neonates have been recorded.

Habitat

Known & Predicted Range

Eastern Copperheads generally like piles of debris, especially if they hold leaves. Log piles, rock piles, and leaf piles all are favorite places for copperheads. When copperheads do hang around human dwellings, they are hanging around similar setups. Piles of firewood, boards, leaves, tires, and generic junk mimics their favorite wild features, all while drawing prey. Their camouflage works best in areas of dappled light where there are lots of broad, dry leaves. This is mainly forest, but they like forest edge and cutovers as well. Even messy flower/shrub gardens make good habitat, and occasionally gardeners do get bitten on the hand when accidentally grabbing a copperhead while pulling leaves/dead stems.

Chicken coops and dog pens often draw rodents while offering snakes places to hide. It is best to keep these areas clean of debris that snakes and rodents can hide in if one wants to deter these animals from these high-traffic location. Ratsnakes will not eat copperheads, but will control rodent populations in places like chicken coops and sheds, lowering food options for copperheads. Kingsnakes such as Eastern Kingsnakes, Mole Kingsnakes, and Eastern Milksnakes will consume copperheads and Northern Black Racers will consume small copperheads. All of these snakes also control prey populations that would draw copperheads.

Similar Species

Several of our harmless, Virginia snake species will splay the back of their head in a defensive posture. Are they trying to mimic a copperhead? No, it just makes them look larger. Many snakes, like cobras and hognoses, have evolved upon this tactic to splay out most of their neck as well. Does it confuse people who equate a triangular head with a venomous snake? Yes. While pit vipers do have a very constant head-shape across the subfamily, they are not the only snakes to possess this.

Northern Watersnakes are quite often the victims of mistaken identity. They bare similar colors and even bands on part of their bodies. That said, they have larger, rougher scales and bands that widen in the center of the back. Watersnakes have long tails to aid in swimming and often labial bars (barring pattern on the scales on the lips). Juvenile Ratsnakes, such as Central and Eastern Ratsnakes as well as Cornsnakes get confused from time to time, but these snakes all have saddles instead of bands. Eastern Milksnakes and Mole Kingsnakes are also often persecuted for looking like copperheads, though they too are saddled. Many small, brown snakes get confused as well, but upon quick glance at this page, the differences should be rather clear. If it were not for the panic killing of all of the snakes listed above, we would have only included one similar species on this section: the Northern Cottonmouth.

Northern Cottonmouths are larger as adults, with larger heads than copperheads. Their patterns are quite similar, with the cottonmouth bearing a drabber, less contrasting pattern that almost looks pixelated more often than not. Cottonmouths have longer, dark tails and juveniles do bare a yellow/green caudal lure. Cottonmouths have dark mask, usually with a pale line along the lower edge.

Taxonomy & Phylogeny

For a long time, the Copperhead (Agkistrodon contortrix) was a species that contained four subspecies. These were the Northern Copperhead (A. c. mokasen), Southern Copperhead (A. c. contortrix), Osage Copperhead (A. c. phaeogaster), and Trans Pecos Copperhead (A. c. pictigaster). In 2008, Timothy Guiher and Frank Burbrink published a paper look at genetic work of the Copperhead and Cottonmouth and revised the taxonomy to reflect two distinct copperhead species, two cottonmouth species, and no subspecies in any of the new taxons. From this we now have the Broad-banded Copperhead (A. laticinctus) and the Eastern Copperhead. The holotype specimen (the museum specimen we use to represent the species) was an Eastern Copperhead, so that species kept the contortrix name. These two species are each other's closest living realities.

The copperheads are the outgroup to the Agkistrodon, with cottonmouths and cantils (a group of Central America that are very easy to tell are closely related to these snakes) are closer related to one another than they are the Copperhead. This genus makes a very nice, clean phylogeny ignoring the species level debates within each group.

Venom

We should note: Eastern Copperheads are relatively shy snakes, opting to stay away from humans typically. Occasionally, as these snakes are quite numerous in most of the state, humans and copperheads do cross paths. It is very likely that most of the time, we humans never know we walked by the copperheads we cross paths with. These snakes are not aggressive animals. They do not want to bite you. They just want to live. Everytime copperheads (or even cottonmouths and rattlesnakes) encounter humans in a negative way, the humans walk away. The snakes however are usually not so lucky. Snake venom is a very poor defence mechanism. Animals that use venom for defence either have very powerful, fast acting venoms for causing localized pain (like wasps) or wicked deliverance devices that are just as dangerous as the venom (like stingrays). Snakes have evolved venom for killing prey quickly. For copperheads, this is mice, shrews, lizards and other similarly sized items. A small mouse weighs about 20 grams. A 150 pound human weighs ~68,040 grams; 3,402 times more than that ideal, prey-sized mouse. This venom is not formulated to kill a human. These snakes bite humans because they feel like they have no choice left. Maybe it trains predators to fear other similar snakes, but that does not save that snake; and a copperhead is not thinking about how a human perceives other snakes when it is being stepped on.

Copperheads bites are very rarely fatal. From 1989 to 2019 Copperhead bites amounted to five human fatalities. This has to be balanced with the fact this species accounts for 39% of snake bites in the US and there are typically 2,000 - 3,000 copperhead bites documented each year. If we just use 2,500 as a base line, copperheads kill 1 in 15,000 people they bite.

Copperhead bites generally yield too little venom to threaten most people. An average bite yields 40-70 milligrams of venom and the LD50 (general dose that could kill 50% of the population studied) is around 100 for humans. Despite common myths, baby snakes are no

Rough chart to show average yield vs a fatal dose for Copperhead venom

more dangerous than adults. We can dispute this with math. Tiny snakes have tiny venom glands. Large snakes have large venom glands. We like to use the analogy of a 12 oz. drinking glass and a 1.5 oz. shot glass. If one spills a whole shot glass of grape juice on the carpet, is that more or less of a mess than spilling 1/3rd of the standard drinking glass? Data also suggests that neonates do not need to "learn to control their venom yields" as it seems to be instinctual. Juveniles are more nervous, so maybe the chance of a dry bite is lower, but there is no evidence that neonates give larger doses in any research.

While death is not a major concern, the venom is incredibly painful. The venom is primarily hemotoxic, destroying tissues and the walls of blood vessels and the intense swelling causes massive pain. There is a group of Australian elapids in the genus Austrelaps, which are often called "Copperheads", and their venom is neurotoxic, often leading to confusion. Furthermore, many rattlesnakes pack a neurotoxic venom.

This venom does pose a significant threat to dogs particularly. It is estimated that around 50,000 dogs are bitten annually. Deaths are rare, but some estimates suggest ~5% mortality rate amongst dogs. The issue is that dogs are frequently bitten on the muzzle, tongue, or face as they use their mouths to pick up the snakes or push their noses forceable into the snake trying to figure out what they are smelling. They swell from the venom like humans do, but swelling that close to the airway is a much larger threat. It is best for one to keep their dog on a six-foot lead when hiking, and many parks require you do this anyways. This will not just protect the dog from snake bites, but it will protect them from skunks, other wildlife, poisonous items your dog may try to eat (mushrooms, baits, items that other people dropped), and protect wildlife from dogs.

We generally fear venom, but venom is valuable for human research. The active compound in Ozempic for example was originally found in the venom of the Gila Monster. Similarly, studies have been done on copperheads and contortrostatin is a protein that has recently caught the eye of medical research. It has been shown to impact breast cancer by binding to integrin receptors, blocking cancer cell adhesion, and inhibiting tumor growth and angiogenesis. This protein was discovered in the venom of the copperhead, hence the name.

Remember, the snake is not on your turf. The Agkistrodon lineage evolved in eastern North America between 5-10 million years ago. This was way before modern humans even existed, much less roamed North America. Copperheads are a fact of life here in Virginia and killing them does not solve your problems. Managing one's yard to discourage copperheads is recommended, just as one would for flooding if they lived in a flood-zone. Even doing this does not mean one may not see a copperhead occasionally that is trying to cross their yard while looking for a good spot to hunt, but it hopefully will not hang around. Use caution in copperhead country, respect wildlife, and you will likely never have an issue.