Avoiding Snakes: Nature's Evil Twins

Some species look alike, but guess wrong and you could have a harmful mistake on your hands.
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Some species look alike, but guess wrong and you could have a harmful mistake on your hands.

The snake flashed beneath the weeds and struck me just below the right knee with a whump! that felt like I'd been hit with a rubber hammer. Then just as quickly, it was gone, its patterned body blending into the leaf litter. I stood there, listening to my heart trying to pound its way out of my chest, wondering why I felt no pain. I checked my leg; no bite marks. My pants apparently deflected the fangs, if the snake had any. The reptile I watched glide away resembled a copperhead, but so do several harmless species of snakes that reside in my neck of the North Carolina Blue Ridge Mountains.

Did I come close to being bitten by a venomous snake? Because I didn't know what to look for back then, I'll never be certain. But I can tell you this: It was a long, careful hike back to the trailhead.

Nature is full of lookalikes, and while there's no great need to be able to distinguish a song sparrow from a chipping sparrow, the smart hiker knows how to tell the dangerous flora and fauna from the similar, safe ones. It can mean the difference between a pleasant trip and one on which your well-being is at risk.

Vipers

The United States harbors only two groups of venomous snakes: the somewhat rare coral snakes and the more common pit vipers, which include rattlesnakes, copperheads, and cottonmouths. Pit vipers are equipped with venom-injecting fangs and are so named for the tiny, heat-sensing pit located on each side of the head, between the eye and nostril. The pit helps them to locate prey.

Of course, if you see a snake with rattles, you know it's venomous. This simplifies matters in the West, where rattlesnakes are the only pit vipers. But in the eastern half of the country, rattleless cottonmouths and copperheads both bear markings akin to many harmless species.

To determine which variety you've encountered, look (at a comfortable distance, using binoculars) for a triangular head and other safe-or-sorry distinctions (see "Deadly Nuances," next page).

Water snakes in particular are easily mistaken for pit vipers. "Cottonmouths can look a lot like some water snakes," says Jeff Beane, curator of herpetology at the North Carolina Museum of Natural Sciences. Body language is a good clue. "Cottonmouths are poor climbers and are likely to form a tight circular coil on a stump or log just above water level. Water snakes usually hang draped over a branch in a tree or bush."

Also look at patterns. "The hourglass-shaped crossbands on a copperhead are narrow in the center of the back and wide along the sides," says Beane. "On a water snake, they're the opposite."

The temperamental cottonmouth lives only in the South, in or near water. Unlike most other rattleless snakes, the cottonmouth stands its ground when disturbed, displaying its gaping, white mouth. The range of the snake includes much of the eastern half of the United States in almost any kind of wooded habitat, usually near water. Keep an eye out around rocky hillsides in particular.

Deadly Nuances

Some deadly and benign snakes look alike, but a few clues will distinguish them.

    Pit viper
  • Broad, flat, arrow-shaped head
  • Distinctly narrowed neck
  • Heavy-looking body
  • Facial pits
  • Vertical pupil
    Non-venomous
  • Elongated, oval-shaped head
  • Less narrowed neck
  • Proportionately slender body
  • No facial pits
  • Round pupil

Coral Snakes

For years, biologists believed the resemblance between the coral snake, North America's most venomous reptile, and its harmless near-twins, the scarlet snake and scarlet king snake, was a classic case of mimicry. The impostors, scientists thought, adopted the coral's colorful bands as a survival mechanism. Predators that learned the hard way to avoid coral snakes would avoid scarlets, too.

But since a coral snake's bite invariably leads to death, there is no lesson to be learned, someone finally realized. So why, then, the uncanny similarity? "Nobody really knows," says herpetologist Beane.

Fortunately, we do know how to tell the snakes apart (see below).

A mnemonic device to help you distinguish the two is, "Red touching yellow, dangerous fellow." This rule of thumb holds true for both U.S. species of coral snake, the eastern and the Arizona or Sonoran. It doesn't always apply to similar snakes south of the U.S. border, however. And in the Arizona coral's Southwestern range, the harmless shovel-nose snake can also have adjacent red and yellow bands. To be safe, avoid them all.

Coral snakes live mostly underground or beneath natural objects. They surface to hunt only during the coolest times: evening for the Arizona species and early morning or late afternoon for the Eastern. Though furtive and rare, they possess venom more toxic than that of any other North American snake. Look before you reach under a rock or log.

Eastern coral snake:

Yellow and red bands are adjacent

Scarlet kingsnake:

Yellow and red bands don't touch