Information About Identifying the Snakes of North America

Copperhead vs Cottonmouth Snake

Both the Copperhead and Cottonmouth (Water Moccasin) are heavy-bodied aquatic snakes. Both are venomous pit vipers with big fangs and potent venom. They look somewhat similar. Here are the main things to know regarding the differences between these two snakes:

Appearance: The Cottonmouth is usually larger and heavier. The Cottonmouth is definitely darker - it is more of a brown, and the Copperhead is more of a tan/pink or copper color. Cottonmouths tend to darken and the pattern fades with age, and old Cottonmouths can look almost black, or chalky dark gray. Copperheads tend to maintain their pattern throughout life. But a picture is worth a thousand words. I have several photographs of both species below, so study them carefully.

Range: The Cottonmouth is more southern, and the Copperhead range is more eastern and extends further north. Both are found primarily in water areas - in the south, Cottonmouth just love swamps, more than big, clear lakes. Copperheads are more likely to be found on dry land, but Cottonmouth really stick to water. Look at the below photos for a better idea of the range. A lot of it overlaps.

Venom Potency: Both have potent cytotoxic venom that dissolves tissue. But the Cottonmouth bite is far more severe. A Copperhead bite is almost never fatal to an adult. Maybe a little kid or pet. But an adult Cottonmouth can kill an adult human, because it delivers enough venom of stronger proteins that break down more tissue and blood cells, and can cause systemic bleeding that can kill a person. Either way, you don't want to be struck by either, so if you see either snake, just back away! Never EVER attempt to catch or kill either of these snakes. 90% of snakebites from these species occur when people mess with them and try to kill them or catch them (remember, they can still strike after you think they are dead).

If you live in an area of the country where both species of snake live, your best bet for really telling the difference is to look at a lot of photographs of the two snakes. Click the below photos for large images that you can scroll through to really get it set in your mind what the differences are in appearance.

Click the below photographs for high-resolution photos of Cottonmouths:

Click the below photographs for high-resolution photos of Copperheads:

The Copperhead (Agkistrodon Contortrix) and the Cottonmouth (Agkistrodon Piscivorus) are snakes that are quite remarkable in their ability to swim in the water, and is also two of the most commonly misidentified snakes in the United States. These species are also two of the most feared species because of a reputation for being quite an aggressive species and the ability to deliver a dangerous bite. There are many different regional and quirky names given to these species, including true water viper, Troost’s Moccasin, water pilot and the mangrove rattler.

Appearance And Diet
The size of the Cottonmouth and Copperhead can vary significantly depending on the age of the snake, with most examples being over three feet in length, while the largest males can sometimes get to nearly six feet in length. One of the distinct features of the water moccasin is that its head is broad and narrows to connect to the rest of the body. The coloration of these snakes is patchy among younger snakes, and can include colors such as olive, green, brown and tan, but this will darken significantly as the snakes get older, with most adult snakes being almost entirely black. The name Cottonmouth actually comes from the inside of the mouth of the snake, which is a distinct white color. The Copperhead is so named because of the copper color it carries.

Because these snakes tend to spend much of their time in the water, the prey of the cottonmouth will often include a high proportion of fish and frogs. However, those living in swampy areas or rivers will often have a broader diet including small mammals and birds than those snakes that live on the coast. When hunting the Water Moccasin and Copperhead will usually strike and hold its prey in its jaws until it stopped moving before consuming it.

Identifying The Cottonmouth vs. Copperhead
Because there are so many people who are scared that any snake they find near water is a Cottonmouth or Copperhead, it is worth noting some of the differences between this species and other harmless water snakes. One of the first differences is that the Cottonmouth and Copperhead will usually have a larger and broader head than other species of water snakes. Another difference is that when it is in the water, the Cottonmouth will tend to swim on the surface, while other water snakes tend to be less buoyant and swim below the surface. When confronted by people, the Water Moccasin has a distinct defense mechanism unless it can escape, and this is to wrap its body into a coil, and open its large white mouth to ward off the threat.

As with any snake, it is worth avoiding it where possible, but it is the fear of the nasty bite of this species that causes the killing of many harmless water snakes every year.

Behavior And Habitat
The Cottonmouth and Copperhead are snakes that have developed a fearsome reputation for being aggressive, but in all studies made of the species this isn’t entirely true. Where possible, the snake will always look for an escape route, and in some cases it will lunge past the perceived threat if it lies between the snake and the water where it can make its escape. However, if escape is not possible, and the defense mechanism of coiling doesn’t ward off the threat, then it will strike. The exception to this rule can be among male snakes during mating season where they can be a little more aggressive in defense of their territory.

In terms of the habitat, the Water Moccasin can be found near many bodies of water such as lakes, marshes, streams and the sea, but studies have shown that it prefers shallow warmer water where possible. Although it is generally found near water, there are some examples of the Cottonmouth and Copperhead living in a woodland habitat that was quite some distance from the nearest stream. Like many snakes the Water Moccasin can be found across much of the south eastern states, but also has a significant population in the central states too.

Reproduction And Growth Cycle
Although the mating does depend on the climate, the majority of these snakes will be mating during late spring through May and June, with the female giving live birth to litters of around six to ten snakes in late August and September. These young snakes are usually between six and ten inches in length, and the tips of their tails are either yellow or gray in color.

The young Water Moccasin and Copperhead will grow quickly for the first two years, reaching sexual maturity after around two years. They are generally solitary snakes and the young snakes do use their colored tail tips as a bait to attract small frogs which they will then pounce upon. The females will generally be able to breed every two to three years, and these snakes have a life span of up to ten years in the wild.

Here are some of my other snake info pages:
Guide to Florida's Venomous Snakes
Eastern Diamondback Rattlesnake
Eastern Coral Snake
Water Moccasin a.k.a. Cottonmouth
Pygmy Rattlesnake
Timber Rattlesnake

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My page about The Venomous Snakes of Florida - with many photographs and info.
Read my article about How to Identify Snakes - is the snake you saw dangerous or safe?
Here's my page about Snake Bite First Aid Treatment - how to tell if it was venomous.
Here's my advice about How to Kill Snakes - practical advice to best protect you.

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