Copper Head Snakes and Water Snakes
Identification of the venomous copperhead snake and the harmless northern banded water snake
In the Eastern US one of the biggest fears of homeowners and people who work or play outside near the water is venomous spiders and snakes. However, in fear of these creatures, other non-venomous and beneficial species are often misidentified and killed. Today's post is how to tell if a snake is a copperhead snake (Agkistrodon contortorix) or the harmless northern banded water snake (Nerodia sipedon). Both look similar, but they have some key differences.
Let's Begin with Copperheads....
Copperhead snakes are the most common venomous snake in the Eastern US. They are in the pit viper family (Crotalidae, pronounced Crow-tAl-a-day). They are also in the genus Agkistrodone (pronounced ag-kiss-trow-doe-ne), which includes the cottonmouth or water moccasin. It is a shy snake that is usually not aggressive and its bites are rarely fatal, though they can be painful.
POISONOUS VERSUS VENOMOUS
Animals that inject venom are called venomous, and not poisonous. You might have heard these terms used synonymously. There are no poisonous snakes only venomous snakes. Things that are poisonous can make you sick if you eat them. Animals that are venomous inject venom through fangs, stingers, or spines (like lion fish, sea urchins, spiders, and snakes). Venom serves as a way to help animals eat, subdue prey, and sometimes as a means of defense.
Poison is usually a defensive mechanism that prevents organisms from being eaten. Frogs, toads, salamanders, plants, mushrooms, and poison ivy are all poisonous. As usual, in nature, there is one exception which is an Asian snake, Rhabdophis tigrinus which eats poisonous toads. By ingesting the toads the snake becomes poisonous to eat. You can read the abstract in the US National LIbrary of Medicine, NIH paper if you'd like to know more.
Copperhead venom is hemolytic, which means that it functions by destroying red blood cells, causing hemorrhaging in animals. However, this same venom is being studied by researchers because it has properties that may be used to "paralyze" cancer cells to stop them from spreading. You can read more from from the Journal of the National Cancer Institute.
Here's a primer on how to tell venomous snakes from nonvenomous snakes.
1. Look at the head shape. Non-venomous snakes, with the exception of brown water snakes, have rounded heads, while venomous snakes have triangular heads.
2. There is a small and shiny cap of scales between the eyes, and over the nose of venomous snakes. Nonvenomous snakes have a smooth shiny cap that covers most of their head.
3. Venomous snakes have slit-eye pupils, like a cat, while nonvenomous snakes have round eyes. If you don't want to get close enough to the snake to see this, then take a photo with a long lens, and then look at it on your camera. Remember: "Round, safety is found," or "Eyeball is slit, you're gonna get bit (by the venomous snake)."
4.Venomous snakes also have a heat sensing pit between their nostril and eye. Nonvenomous snakes do not.
5. Venomous snakes have undivided scales from their vent (poop chute), down to the tip of their tail. Nonvenomous snakes have divided scales from the vent down. I know you're saying, hey, wait, I'm not getting that close! You don't have to. If you find a shed snake skin you can use it for identification.
6. Venomous snakes have movable fangs that can retract into their head. Nonvenomous snakes have fixed teeth.
WHERE TO FIND COPPERHEADS
They prefer woodland areas, round rocks or near streams and ponds, because there is plenty of prey and food in these locations. They mainly eat rodents and mice, though they will also eat voles, frogs, lizards, cicadas, birds and other insects if available.
They also tend to favor stones, garden walls, stone fences, compost piles, wood piles, and under building debris. They also like stone ledges and swampy low-lying areas. They may also den in large groups or hibernaculums starting in the fall, and continuing until February or March.
PICTURES OF COPPERHEAD SNAKES AND WHAT TO LOOK FOR
- See notes above about features of venomous snakes.
- Different color variations: from blackish to pink.
- Color varieties all have the characteristic copper head.
- All of them have bands that go across their bodies that usually look like hour glasses (10-18 bands usually).
- Cross-bands can look like hour glasses or Hershey kisses. In many cases the hour glass or "kiss" don't meet in the middle.
- Often the outer edges of the "kiss" are also darker.
- Adults can be 2-4 ft. long.
- Thickish stout snakes.
- Belly is the same color as the ground usually.
TYPES OF COPPERHEADS IN THE EASTERN US
There are two subspecies of copperhead in the Eastern US, the Southern copperhead (Agkistrodon contortrix contortrix) and the Northern copperhead (Agkistrodon contortrix mokasen). The main difference is in their range, from the Northern to Southern US, though there is some overlapping around the Appalachian mountain region.
It's difficult to make any generalizations about color patterns between Northern and Southern, since they are very close.
PICCTURES OF BABY COPPERHEAD SNAKES
Female copperhead snakes are ovoviviparous, meaning that they carry their eggs in their bodies, until the eggs are ready to hatch, and then they release the eggs and the young hatch out immediately. The young copperheads are easy to tell apart from nonvenomous species because they have a very lemony yellow tail, which they keep until they're over about a year old.
Tail coloring, or caudal coloring as it's known to scientists, is thought to be for caudal luring. This means that the juvenile snakes wriggle the little yellow tip in the leaves, making it look like food for insects, birds, mice, or other creatures, that then become food for the snake when they approach. This is not uncommon in pit vipers.
Not that you ever want to get close enough to tell, but the males have been proven to have slightly longer tongue tines than females during the breeding season. This is because the males have to use their tongues to "scent" where the female is. They literally smell her out. Having a long tongue is helpful for this. Check out the paper in the Journal of Zoology to learn more.
COMPARING WATER SNAKES TO COPPERHEADS
Now that you have a working idea of what a copperhead looks like, I want to defend my friend the common water snake, sometimes called the banded water snake.
Banded water snakes are harmless, nonvenomous fish eaters. Like the copperhead, they hunt along water edges, rocks, under logs, etc. They also have a similar diet, though the water snakes tend to eat more minnows, crayfish, salamanders, etc. In our region they swim both in fresh and brackish water. Both copperheads and water snakes can swim well.
It's easy to get the two confused, and many, many water snakes have been killed by mistake. Take a look at the pictures below. You can see that the water snake has a wide variation of color patterns, just like the copperhead; however, they do not have hour glass shaped bands, and they have the physical characteristics of nonvenomous snakes (eyes, head scale pattern, vent scales, eye etc.). Their bands go all the way across and are usually much thicker than the hourglass or Hershey kiss of copperheads.
The main confusion between water snakes and copperheads comes from their head shape and coloration. Unfortunately, they are very close to each other, and there is a great deal of variety. Unlike most nonvenomous snakes the water snake also has a triangular head.
If you're not sure which snake is which, then leave them both alone. If they are not an immediate threat to people or pets, just leave the area, and try to avoid them. These snakes are an important part of the food web, helping to control pest populations and keep the balance of other organisms. They are shy, and really want to avoid you too!
FOR THE CURIOUS: COPPERHEAD BITES
Copperheads are solenoglyphous, meaning that the fang size is directly proportional to the snake's size. The bigger the snake, the bigger the fangs! However, hatchling copperheads do have functioning fangs that can release venom that is just as toxic as the adults.
I'm not going to go into the details of copperhead bites and how to treat them here. If you want to know more, there's plenty of information available through the Center for Disease Control (CDC) and other. Here are a few websites:
WATER SNAKE V. COPPERHEAD SNAKE QUIZ
Are you ready to see if you could pass the watersnake v. copperhead quiz? I'll show you pictures below, see if you can guess correctly. Answers are at the bottom of the page.
- A: water snake
- B: water snake
- C: copperhead
- D: water snake
- E: copperhead
- F: water snake
- G: copperhead
Here are some copperhead and water snake resources you may find interesting:
- Copperheads, Wild About Snakes, by Melanie Howard (ages 8-14 yrs)
- Copperhead Snakes, by Mary Dunn (ages 5-8 yrs)
- Peterson Guide to Reptiles and Amphibians (Field Guide for All Ages)