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Northern Water Snake vs Copperhead

Northern Water Snake vs Copperhead

Northern Water Snake and Copperhead snakes have some similarities, but are ultimately completely different. One is venomous while the other isn’t.

Northern Water Snakes (Nerodia sepidon – nero meaning “flowing” or “liquid” and dia meaning “through”) are non venomous swimming serpents and one of the most common snakes in the eastern United States.

Unfortunately, people sometimes kill these snakes after mistaking them for the venomous Copperhead snake (Agkistrodon contortorix) which can also be commonly found. Even newly hatched Copperheads have fully functional fangs capable of injecting venom.

An easy way to differentiate between these two species is by looking at their patterns.

Copperheads have an hourglass-like pattern that renders them virtually invisible in their preferred habitat of a leaf littered forest floor. 

Northern Water Snakes on the other hand have a bulb-shaped pattern that widens in the center and  makes for good camouflage in their watery environments.

Adding to the difficulty of properly identifying the snakes is the similarities in some of young and juvenile snakes. Again, focusing on the pattern and not the color will help you in seeing how different they are.

Quick Reference Section

Other differences

1. Coloration

Northern Water Snake In Coil
Northern Water Snake In Coil

Northern Water Snakes can vary in color, some are more red than brown, some are very dark, some are very dull, but the pattern remains the same.

Juveniles colors are more vivid. As they get older, their pattern will change to a solid dark color. This ranges from brown to black to deep reddish-purple until the pattern can barely be seen.

Their bellies also vary, ranging from a more common cream color to orange.

individual Northern Water Snakes may look different in water than on land. As their scales dry, the colors will appear more uniform and will be harder to see.

Copperhead in coil
Copperhead in coil

Young Copperheads are more grayish in color than adults and possess bright yellow or greenish yellow tail tips. This color fades after about a year.

Copperheads bellies are whitish, yellowish or a light brownish, stippled or mottled, with brown, gray or blackish, often large, paired dark spots or smudges along sides.

These snakes get their name from their copper-red heads, according to the biology department at Pennsylvania State University.

2. Head Shape

Copperhead Snake
Copperhead Snake on pavement
Northern Water Snake in Wisconsin
Northern Water Snake on log

Copperhead’s heads are arrow-shaped or more broad than the Northern Water Snake.

3. Pupil Shape

In Copperheads, the pupils are slit-shaped (like cat eyes), and their irises are usually orange, tan or reddish-brown, while the Northern Water Snakes pupils are round.

4. Habitats

Copperheads are typically found in different habitats than Northern Water Snakes.

Northern Water Snake
Northern Water Snake

Northern Water Snakes never stray more than two or three hundred yards from water. This means that they can be frequently spotted at recreational water sources like swimming holes or waterfalls.

Copperhead snake (agkistrodon-contortrix)
Copperhead snake (agkistrodon-contortrix)

Copperheads, like Northern Water Snakes, swim and can also be found near water across the region.

However, Copperheads prefer woodland areas, round rocks or near streams and ponds. The main reason is because there is plenty of food for them in these areas.

They also tend to favor stones, garden walls, stone fences, compost piles, wood piles, and under building debris.

As mentioned above their respective patterns are consistent with their habitats and serve as camouflage.

5. Social Habits

Male and female Copperhead snake
Male and female Copperhead snake

Northern Water Snakes are only social during fall and spring. They have been observed coiled together, basking in the sun. In the warmer months, they tend to remain alone and are found on overhanging branches, walkways, and cattail stems.

Copperheads are semi-social snakes. While they hunt alone, they usually hibernate in communal dens and often return to the same den every year.

6. Eating habits

Copperhead snake with tongue out
Copperhead snake with tongue out

Northern Water Snakes hunt along freshwater shorelines and swim in shallow water in order to capture small aquatic life.

They feed heavily on fish and amphibians, but have also been recorded eating northern cricket frogs, toads, southern leopard frogs, bullfrog tadpoles, and spring peepers.

They will also eat mammals or birds if they can find and catch them.

Copperheads are primarily ambush hunters, subduing their prey with venom and swallowing them whole.

They feed on a range of animals including mice, small birds, lizards, small snakes, amphibians and insects (especially cicadas).

7. Sleep Habits

Two water snakes hiding in rocks
Two water snakes hiding in rocks

In summer, Copperheads are primarily nocturnal. From April to late October they are diurnal.

They hibernate over the winter, from November to April, but come out on warmer days to bask in the sun.

On the other hand, Northern Water Snakes are more active in the day and at night.

8. Reproduction

Both Copperheads and Water Snakes are ovoviviparous, which means that eggs incubate inside the mother’s body and live young get born in late summer or early autumn.


close up of northern water snake head
close up of northern water snake head

1. Even if the terms “poisonous” and  “venomous”  are used synonymously, they are not the same. Animals that inject venom are called venomous, and not poisonous.

Therefore, there are no poisonous snakes only venomous snakes.

Snakes that are venomous like the Copperheads, inject  venom that serves as a way to subdue their prey, and as a means of defense, while poison  is usually a defensive mechanism that prevents organisms from being eaten.

2. A Copperheads venom is also hemolytic, meaning that it functions by destroying red blood cells, causing hemorrhaging in animals.

Something unexpected from the use of venom is that it is currently being studied by researchers. They believe it has properties that could be used to “paralyze” cancer cells and to stop them from spreading.

You can read more from from the Journal of the National Cancer Institute.

3. The ADW explains that when attacking large prey, Copperheads bite their victim, and then release it. They let the venom work, and then track down the prey once it has died.

Cottonmouth vs. Water Snakes: How To Spot The Difference! (ft. Life’s Wild Adventures)

The below video gives a really good explanation about the differences between the Northern Water Snake, Copperheads, and as a side note the Yellow Belly Water Snake.


Copperheads, like Northern Water Snakes, swim and can be found near water. Copperheads will be a bit bulkier of snake and will show the white of their mouth when they feel threatened.

Water Snakes on the other hand will flatten their head to mimic a copperhead, but don’t usually open their mouth wide.

These snakes are defensive in nature, but in general just want to be left alone, so won’t be chasing you if you encounter them.

If you do get bitten by a copperhead, their venom is relatively mild and their bites are rarely fatal for humans.

At the same time, Northern Water Snakes, even if non-venomous,  have strong bites, which can leave deep cuts. As a precaution you should consult your doctor for proper care.

Lastly they can also release a powerful-smelling musk from their tail, or eject fecal matter as other defense mechanisms.

Let us know in the comments below if you have anything to add or have some other questions or comments.  

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Chris Jordan

Wednesday 29th of September 2021

A Northern Water snake has a small triangular head that doesn't look much different than its neck. A Copperhead has a large, broad head that looks much larger than its neck.