Found a Snake Skin? Here's How to Tell Who Left It

What a shed keeps, and what it loses

It keeps:

• The shape and arrangement of every scale, including the belly and under-tail scales
• Texture. A ridge (keel) down the middle of a scale shows up clearly
• Scale counts, which are some of the most reliable ID features in snakes
• A faint, colorless "ghost" of the pattern. Bands and blotches show best on fresh sheds held up to light. Sheds from young snakes keep more pattern than adult sheds, and the back keeps pattern far better than the belly (Tsai & Mao 2017)

It loses:

• Color. Forget copper, black, red or green
• Pupil shape. The eye cap in a shed is a clear lens, so the "cat eye" test is useless
• True size. The skin stretches as the snake crawls out, so a shed runs on average about 11% longer than the snake that made it (Gray 2009). Girth gets stretched too
• Rattles. A timber rattlesnake shed does not include the rattle. It just ends in a blunt stub where the rattle starts

Keep that list in mind. Most bad shed IDs come from trusting color or length.

Before you start

The shed itself is harmless to handle. Wash your hands afterward like you would after any yard work.

A dry, crumpled shed is fragile. Soak it a few minutes in lukewarm water and it relaxes enough to unroll without tearing. Lay it flat on a dark surface, belly side up first. Use your phone's close-up or macro mode, and photograph before you start pulling things apart. The head and tail are the most useful parts, and the first to tear.

If it's in good shape, keep it in a zip bag and write the date and location on the bag. A shed is a real record of where a species lives.

Step 1: Flip it and look under the tail

This one step answers the venomous question.

Turn the shed belly up and follow the wide belly scales (ventrals) toward the tail. Where the body ends, there's one scale covering the vent, called the anal plate. Everything behind it is tail. Now look at the scales under the tail, the subcaudals:

• One single row, each scale running all the way across like the belly scales: pit viper. In Virginia that means a copperhead, cottonmouth or timber rattlesnake.
• A double row, paired like a zipper down the middle: harmless snake.

The Virginia Herpetological Society lists this single row under the tail as a feature shared by all three of Virginia's venomous snakes. For sheds, it's the most useful check you can make, and it works even when the head is missing.

Exceptions to know:

• Pit viper tails are not single all the way to the tip. VHS counts on Virginia snakes show copperheads with up to 17 paired scales near the tip (about 7 on average), and cottonmouths with 6 to 35 paired (about 20 on average), which can be half the tail. The scales right behind the vent are single in both. Judge by the first few scales after the anal plate, never the tip. A tail-tip fragment on its own can fool you.
• Tail torn off? You can't use this step. Move on to Step 2 and treat the result with caution.
• Single subcaudals are a reliable rule for Virginia sheds, not a universal law. Cardwell (2011) pointed out that a few harmless North American species elsewhere also have undivided subcaudals, which is why it shouldn't be used alone on a live snake. None of those occur in Virginia.
• This is a shed test. Never flip or pick up a live snake to check its tail.

Step 2: Feel the scales and check the anal plate

Two quick checks sort almost every Virginia snake into one of four groups.

Texture. Look at the back scales in good light, or run a fingertip along them. Keeled scales have a raised ridge down the center, like the keel of a boat, and feel rough. Smooth scales are flat and glossy. Ratsnakes have weak keels only along the middle of the back, so check the top, not just the sides.

Anal plate. Go back to the scale over the vent. Is it one solid scale (single), or split in two by a diagonal seam (divided)?

Every venomous Virginia snake lands in the same box: keeled with a single anal plate. That box also holds harmless gartersnakes and ribbonsnakes, which is exactly why Step 1 comes first.

Exceptions: The anal plate in mudsnakes and rainbow snakes varies between individuals. Ratsnake keels are faint enough that people call them smooth. And any snake can have an oddly split or fused scale, so if one feature disagrees with everything else, trust the majority.

Step 3: Count the rows across the middle of the back

This step separates the look-alikes, and it's easier than it sounds.

Go to the middle of the body, about halfway between head and vent. Start at the first small back scale touching a belly scale on one side. Count diagonally up and over the back, one scale at a time, until you reach the scale touching the belly on the other side. That's the midbody scale row count.

• Follow the natural slant of the rows. It's much easier than counting straight across.
• Virginia snakes almost always give an odd number. Got an even one? You skipped or double-counted. Count again a little further down.
• Count at midbody. Many snakes have more rows there than at the neck or near the vent, which is why guides list counts like "17-17-15."

Expect a row or two of individual variation either way.

Put Steps 2 and 3 together and the field shrinks fast. Keeled, divided plate, 17 rows: brownsnake, rough earthsnake or rough greensnake. Smooth, divided plate, 17 rows: almost certainly a black racer.

Step 4: Use size, body shape, place and pattern

Now bring in the softer clues.

• Length. Knock about 10% off the shed length for a rough body length. A 4-foot shed rules out every small species, but a short shed proves nothing, since big species start small.
• Belly scale width. It stretches less than overall length and hints at body shape. Wide belly scales on a long shed suggest a heavy snake like a ratsnake or watersnake. Narrow ones fit a slender racer.
• Where you found it. Range does a lot of work in Virginia. Cottonmouths are a southeastern Virginia snake. Timber rattlesnakes live mostly in the mountains, with a small population in the far southeast. Around Richmond, the copperhead is the only venomous snake you need to rule in or out.
• Habitat. A shed in an attic, barn rafter or high in a shrub points to a climber like the eastern ratsnake. One at a creek edge fits a watersnake.
• Pattern ghosts. Hold the shed up to a window. A copperhead's bands are wide on the sides and pinched over the spine (the hourglass). A young ratsnake's blotches are widest across the back. Adult ratsnake sheds can still show faint traces of the juvenile blotches even when the snake looks solid black.

Step 5: If you have the head, check the face

Head scales separate close relatives, but they're the hardest part to read because the head is usually crumpled or torn. Photograph it before you try to unfold it. You may only get one look.

• Loreal scale. A small scale on the side of the face, between the nostril scale and the scales in front of the eye. Copperheads have one. Cottonmouths don't. Handy in southeastern Virginia, where both live.
• Top of the head. A timber rattlesnake has many small scales on top of its head. Copperheads and cottonmouths have large plates there, like most harmless snakes.
• The nose. An upturned, pointed snout scale means an eastern hog-nosed snake. Four small scales across the top of the snout instead of two points to the very rare pinesnake.

The comparison most Virginians actually need

Most shed calls in central Virginia come down to one question: copperhead or ratsnake?

If the tail shows a double row, you can stop worrying. That's the case for most sheds people find around Henrico homes.

A few traps

• "It's huge, so it must be dangerous." Shed length is stretched and unreliable, and Virginia's biggest snake is the harmless eastern ratsnake.
• "I can see the pupils." You can't. The eye cap is clear.
• Pet escapes. A shed with far more tiny, smooth scale rows than any native snake is probably an escaped pet, like a ball python. Native rules don't apply.
• Old, weathered sheds. Sheds dry, fade and shred fast in sun and wind. If the key features are gone, the honest answer is "unknown."
• A shed is old news. It tells you a snake was there, not that it's there now. Many move on after shedding.

Still not sure?

Send clear close-ups of the belly near the vent, the under-tail scales, a midbody section of the back, and the head if you have it. Include where you found it.

Free, anywhere in Virginia. Prefer to talk? Call (804) 404-5594. We answer as soon as we can.

And if it turns out to be a copperhead, that's not a reason to panic or grab a shovel. It's a reason to wear gloves when you move the woodpile and to watch where you put your hands and feet. Snakes that are left alone rarely bite.

Sources and further reading

• Virginia Herpetological Society. Species accounts for the copperhead, cottonmouth, rainbow snake, mudsnake, pinesnake and milksnake; Snake Identification Guide and Copperhead look-alikes
• Tsai, T.-S. & Mao, J.-J. (2017). Species identification of shed snake skins in Taiwan and adjacent islands. Zoological Studies 56:38
• Gray, B.S. (2009). The Serpent's Cast: A Guide to the Identification of Shed Skins from Snakes of the Northeast and Mid-Atlantic States. Center for North American Herpetology
• Cardwell, M.D. (2011). Recognizing dangerous snakes in the United States and Canada: a novel 3-step identification method. Wilderness & Environmental Medicine 22:304-308
• Ernst, C.H. & Ernst, E.M. (2003). Snakes of the United States and Canada. Smithsonian Books
• University of Georgia. Natural History Series: Copperhead
• Durso, A.M. (2012). Identifying snake sheds, part I, part II, part III. Life is Short, but Snakes are Long. Worked examples from Florida and Utah