SNAKES AND QUESTIONS ARRIVE IN THE SPRING: PART II

by Whit Gibbons

April 20, 2014

In last week's column, I noted that as snakes begin to make their appearance in the spring, I receive an increasing number of questions about them. Here are a few more.

Q. On your webpage srelherp.uga.edu/snakes/ you say the eastern diamondback rattlesnake and the canebrake rattler have the same genus (Crotalus).

Why, then, does the pygmy rattlesnake have a different genus name (Sistrurus)? Is it not a true rattlesnake? And what is a rattlesnake, anyway - other than a snake with rattles on its tail?

A. "Rattlesnake" is a term that refers to any of the several species of snakes that have a string of segments (the rattle) at the end of the tail; they acquire a segment each time they shed their skin.

Most rattlesnakes belong to the genus Crotalus, but two species (the pygmy rattler of the Southeast and the massasauga, found in the Midwest and as far north as southern Canada) have head scale configurations that are different from the other rattlesnakes.

Scientists consider these two species in the genus Sistrurus to be more closely related to each other than to any of the species in the genus Crotalus.

Q. What purpose do the snake's rattles serve? Is it the obvious one - scaring predators away - and if so, what predators does it work on? Aren't rattlers at the top of their food chain?

A. Many large, terrestrial snakes vibrate their tails when threatened by a predator (or person) and debate continues among herpetologists about the function of the rattles. Having them certainly ensures that the snake will get your attention.

All snakes, including rattlers, are at the top of the food chain in being carnivorous. But they can be eaten by other predators, such as raccoons, foxes, coyotes, and bobcats, and a rattling snake might make a mammal predator have second thoughts.

Also, it has been proposed that in the western species rattling was adaptive in keeping buffalo or other hoofed animals from stepping on the snake.

An additional hypothesis that has been proposed is that rattles are sometimes used as a lure for small mammals that can be attracted to a clicking sound like an insect might make.

Q. Do king snakes really keep other snakes away?

A. Common kingsnakes, a species found across the continent from the Atlantic in the Southeast to the Pacific in California, are immune to the venom of pit vipers (copperheads, cottonmouths, rattlesnakes) and have been documented to eat them.

If they encounter a pit viper in the wild and it is small enough to eat, the kingsnake will bite it, kill it by constriction, then swallow it whole.

So, when kingsnakes and pit vipers of any kind are found in the same area, the former probably reduce the numbers of the latter. However, migrant pit vipers can wander into an area and go a long time without encountering a kingsnake that will eat them.

Q. I am afraid of snakes being around where I live and have looked into a bunch of different chemicals on the Internet that claim to keep snakes away. Some of them are mothballs, lime, soil acidifier, and sulfur.

Commercial products designed specifically for the purpose of repelling snake, supposedly after studies have been conducted, are also available.

A. I get asked about snake repellents quite often. So far I have found no evidence that snakes outdoors can be deterred by any of the chemicals you mention or by any commercial product touted to ward off snakes.

If enough mothballs, sulfur, or other foul-smelling chemical was used to keep snakes away, I doubt that any normal person would want to remain in the vicinity.

A study that is sometimes cited regarding snakes that avoided certain chemicals was based on snakes held in a tightly enclosed area, not outdoors.

As far as I know, no effective snake repellent exists - they all reside, as it were, in the realm of the snake oil salesman.

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