The Highly Venomous Timber Rattlesnake Is an American Icon

By: Mark Mancini  | 

timber rattlesnake
Timber rattlesnakes (Crotalus horridus) are extremely dangerous, with venom that passes through a set of hollow fangs in a mouth with a built-in hinge mechanism. Wikimedia Commons (CC BY 2.0)
[It] occurred to me that the Rattle-Snake is found in no other quarter of the world besides America, and may therefore have been chosen, on that account, to represent her.
Benjamin Franklin

Franklin penned those words in a 1775 letter to the Pennsylvania Journal. By then, he had a well-known affinity for a particular type of rattler: Crotalus horridus, or the timber rattlesnake.

Just like Franklin implied, rattlesnakes are native to the Americas. There are around 30 living species, which range as far south as Argentina and as far north as Canada.

If it's the timber rattlesnake you're after, visit the continental U.S.

From craggy New Hampshire to sunburnt Texas, 27 states have populations of tail-buzzing timber rattlers. Crotalus horridus is a very widespread species, in other words. Yet across many parts of this country, timbers aren't nearly as common as they used to be.

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Know Your Rattlers

Another name for the timber rattlesnake is the "banded rattlesnake." It fits; these reptiles have dark bands overlaying a backdrop of scales that's lighter in color. Individual snakes can look black and gray or they can have a brown-on-tan complexion.

The namesake "rattle" is made of shed skin. A newborn baby's tail is tipped with a scaly lobe called a "pre button." This is lost once the animal sheds its skin for the first time. At that point, the pre button will be replaced by a "button" — a knob of old skin which becomes the first segment in the snake's rattle.

New segments are added on during later sheds. Because of the way these things interlock, the reptiles can produce an audible "buzz" by shaking their tails. The sound sends a message of warning to other animals that get a little too close for comfort.

Timber rattlers are the largest venomous snakes in New York, Tennessee and a few other states; adults can grow 34 to 60 inches (90 to 152 centimeters) long.

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Eyes and Pits

Their heads are vaguely triangular, with vertical pupils set in lidless eyes. Between those eyeballs and the snakes' nostrils, there are two sensory pits capable of detecting infrared radiation, or IR.

All rattlesnakes share this feature. And for good reason: Every animal on the planet gives off invisible IR. However, even in total darkness, the facial "pits" can locate the source of this radiation — which the snakes perceive as heat.

So if, say, a warm-bodied mouse wanders past a rattlesnake at the stroke of midnight, it might be out of luck. Armed with the pit organs, the reptile could theoretically locate this tasty morsel, despite poor lighting conditions.

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A Striking Image

Rattler venom passes through a set of hollow fangs with their own built-in hinge mechanisms. The special teeth can swing forward and jab a nearby target when the snake means business. Then as the jaws close, both fangs are pulled backwards.

As for the actual venom, it's a mixture of toxins. Some of them, called "neurotoxins," impair the target's nervous system. Others (i.e., "hemotoxins") do a number on things like red blood cells and the general blood-clotting process.

The exact content of timber rattler venom may vary from one specimen to the next.

As noted in "America's Snake: The Rise and Fall of the Timber Rattlesnake" by nature writer Ted Levin, the venom of this species has been divided "into four main types ... which vary geographically from virulent to weak, a distinction likely the result of populations having been isolated for scores of centuries in temperate refuges during the Ice Age."

Hence, some timber rattlesnakes — including many in the deep South — carry a more neurotoxic brand of venom than others do.

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Forest Creatures

Timber rattlers are cut out for life in deciduous forests, ecosystems dominated by hardwood trees that lose their foliage once a year.

For food, Crotalus horridus turns to small mammals — like mice, rats, voles, chipmunks and rabbits — as well as birds, amphibians and other reptiles.

The species gives birth to live young in August and September. As the winter approaches, timbers hole up in dens, with rock crevices being popular lodgings. Several of these rattlers may hibernate together inside the same den throughout the coldest months of the year.

In the springtime, they migrate away from these shelters. Using chemical trails left behind by other individuals, a timber rattlesnake can relocate the same den every winter.

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United Snakes of America

Timber rattlesnakes were some of the first venomous reptiles that the British encountered in North America. And it didn't take too long for them to emerge as political symbols.

In a 1751 article titled "Rattle-Snakes for Felons," Benjamin Franklin slammed the United Kingdom for sending convicted criminals to its 13 American colonies. To get even, he proposed shipping live rattlesnakes back to London.

"Rattlesnakes seem the most suitable returns for the human serpents sent by our mother country," Franklin opined.

Clearly, he was joking. But Franklin grew to appreciate the timber rattlesnake and see it as a mascot of sorts for the emerging United States. He wasn't alone; in 1776, the U.S. Navy's first commander-in-chief started flying a yellow flag bearing a rattler and the slogan "Don't Tread on Me."

Named the "Gadsden Flag" after its original designer, South Carolina's Christopher Gadsden, this distinctive (and polarizing) banner is still widely used more than two centuries later.

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The Road Ahead

In the United States, your chances of getting killed by a rattlesnake — any rattlesnake — are statistically slim. That said, in the event of a bite, get to a hospital as soon as you can. (If possible, photograph the actual snake for identification purposes.)

When rattlers bite people, it's often a response to inappropriate handling. Give these reptiles their space and they can make great neighbors. Research published in 2013 suggests timber rattlesnakes may be doing us a huge favor by eating certain rodents which are known to spread Lyme disease.

Unfortunately, Crotalus horridus has seen better days as a species.

Timber rattlers have gone locally extinct in Michigan, Maine, Rhode Island and Delaware over the years. Meanwhile, there's only a single breeding population of them left in the entire state of New Hampshire.

Habitat loss, persecution by fearful humans and the overcollection of wild snakes for the pet trade have all contributed to this decline. So has the rise of Snake Fungal Disease (SFD), an infectious disorder that can lead to blisters, clouded eyes and life-threatening skin lesions.

Slow maturity rates aren't helping. Timber rattlers can live into their thirties, but some females don't start reproducing until age 10. After she's given birth to her first litter, a mother timber might not have another one for three to five more years — or ever, really.

Today, the timber rattlesnake is considered "endangered" or "threatened" in 12 states. Conservationists around the country are working hard to secure a brighter future for this great American serpent.

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