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Frequently Asked Questions: Rattlesnakes

Also see Reptiles and Amphibians FAQ's

How do you tell if a snake is venomous?
How do I recognize a rattlesnake?
Does a rattlesnake stay in one area or move from place to place?
Do rattlers get a new rattle every year when they shed?
If someone is bitten by a rattlesnake, does this mean they're going to die?
What rattlesnakes are found around San Diego?
Is there any way I can keep snakes out of my yard?
I am nervous about being out where there are rattlesnakes. What should I do?
What temperature and time of day do snakes come out of hiding?
What do I do if I do get bitten by a snake? Or if my child does? Or my dog does?
Do rattlesnakes sting with their tongues? Their tails?
How do rattlesnakes reproduce?
What's a good book on rattlesnakes?

How do you tell if a snake is venomous?

First of all, if you don't know, leave it alone. Second, even if you do know, leave it alone. You can't tell if a snake is venomous just by looking at it unless you are familiar with the characteristics of different types of snakes. In the United States, there are 4 major types of venomous snakes: rattlesnakes, water moccasins, copperheads, and coral snakes. In other countries there are other kinds as well. But all snakes will bite if threatened. The vast majority of all snakebites, venomous or otherwise, occur when someone tries to capture a snake. Get a good field guide with color pictures, written for the area you are exploring or visiting, before you head out. Study it ahead of time, and learn the characteristics of the snakes you are likely to see.

How do I recognize a rattlesnake?

The main features of rattlesnakes include:

  • a broad, triangular head on a narrow neck
  • folding fangs
  • cat's-eye or elliptical pupils instead of round ones
  • usually a rattle at the end of the tail (though this may be missing or broken)

As you can see, picking out most of these characteristics requires being close to the snake. This is why we suggest that you leave any strange snake alone.

Does a rattlesnake stay in one area or move from place to place?

Rattlesnakes have home ranges, but they do not defend them as a territory. Generally, a home range is the area that an animal will spend most of its time acquiring resources and seeking mates. Rattlesnakes will not stand guard over them and fight other rattlesnakes for the control of an area. A rattlesnake will use a hole, or other refuge, as a place to rest, but when the resources are reduced (the rodents are eaten up) it will move on to greener and more rodent-filled pastures (but, within its home range). Because the density of rattlesnakes is dependent on the resources (how many hiding places and how many rodents), there generally aren't a whole lot of them in any one area. A countermeasure against rattlesnakes is to remove their food source and hiding places (exterminate the rodents from your yard and remove the hiding places, such as wood piles). If you live adjacent to a wilderness area, please leave the habitat untouched. The rattlesnakes are serving as nature's own way of controlling the native rodent populations.

Do rattlers get a new rattle every year when they shed?

Rattlers get a new rattle segment each time the snake sheds its skin which is normally about 3-4 times per year. Baby rattlesnakes are born with only one segment on their rattle called a button. The rattle is noiseless until the baby rattler sheds its skin for the first time and adds another segment to the button. The rattle makes noise when the segments click against each other. If the snake is able to find a fair amount of food and grow well, it will shed its skin as much as 4 times a year, each time adding a new segment. By using this as an estimate, one could gain a *rough* estimate of the snake's age in years. However, snake rattles do sometimes break off, due to wear and tear. And the number of times the snake sheds is variable according to conditions, so it would only be an estimate.

If someone is bitten by a rattlesnake, does this mean they're going to die?

No. Today, there are only a few cases of death as the result of a rattlesnake bite. The medical treatment of bites is greatly improved. A person bitten by a rattlesnake should make a full recovery without lasting effects provided that medical treatment is found immediately. Seek medical attention immediately. Visit the California Poison Control Center at San Diego's UCSD Medical Center for further information.

What rattlesnakes are found around San Diego?

In our area, the only venomous snakes are rattlesnakes. In the coastal and mountain regions of San Diego County there are three kinds: the Southern Pacific Rattlesnake (Crotalus viridis), the Southwestern Speckled Rattlesnake (C. mitchelli pyrrhus), and the Red Diamond Rattlesnake (C. ruber). In the desert is the Colorado Desert Sidewinder (C. cerastes).

Is there any way I can keep snakes out of my yard?

There is no substance that you could use to repel rattlesnakes that would not also have adverse effects on children, pets, and wildlife. Unfortunately, some people suggest lime powder (=caustic lye), but that is bad advice. It is quite caustic and can seriously injure children and animals -- including any wildlife that comes into contact with it. Some scam artists sell worthless substances (ropes, gels, powders) that they claim are snake deterrents. The truth is that there is no such substance.

You can try to discourage snakes by removing sources of food near your house. Try to keep the rodent population down by cleaning out prime rodent habitat: sheds, woodpiles, underbrush. Left alone, rattlesnakes help control the size of the rodent populations and are themselves preyed on by animals that you may like, including roadrunners.

Common sense is the best defense. Cultivate an attitude of alertness. The more you know about snakes and how they live, the more aware you will be of where you would expect to encounter them. Please read the next question and answer.

I am nervous about being out where there are rattlesnakes. What should I do?

Don't let your fear keep you from enjoying the outdoors. For all their fearsome reputation, rattlesnakes are quite shy and do not come after people. They will strike only in self-defense. If you can learn to behave in a way that does not frighten snakes, you will greatly reduce your chances of a confrontation.

Here are some common-sense suggestions:

If you will be hiking in a remote area, do not hike alone.

Always wear sturdy shoes (not sandals, jellies or flip-flops) with socks when you are out walking in grassy or rocky areas. Don't allow children to run outside barefoot or in open-toed shoes.

Don't ever put your hands or feet anywhere you aren't looking. Don't put your hands on rocks or branches over your head, and don't put your hands or feet under anything. Snakes usually pick up the vibrations of feet and walking sticks and get out of the way, but sometimes do not.

Walk, don't run, especially in unfamiliar, grassy, brushy, or rocky areas. Never let a dog run loose; always keep a dog leashed no matter how good it normally is. Running means that you may surprise a snake (and they don't like surprises), and dogs are fascinated with rattlesnakes and will not leave them alone. A large snake can easily kill a small dog.

If you have to turn over a rock or log, turn it toward you, keeping your hands on your side of the log, not reaching over it. If it's in your path, walk around it; don't step over it (a snake might be lying on the other side).

Don't try to catch snakes. This may sound obvious, but most snakebites happen this way. Wild snakes do not make good pets and should never be killed. The only good reason to try to catch a wild snake is to move it out of harm's way to a safer place, and this should only be done by someone with knowledge and training. Don't tease snakes by throwing rocks or cornering them.

What temperature and time of day do snakes come out of hiding?

Rattlesnakes, like all reptiles, cannot regulate their own body temperature, so they are less active during cool times than during warm ones. They can come out at any time, day or night, if it's warm enough for them to be active. Generally, they tend to stay in when it's much below 50 degrees F, and the cooler it gets the harder they are to find out. They are unable to be active in very cold temperatures and can easily freeze to death if they are not protected by a hole or other shelter. In very hot weather (say, over 100 degrees F), they can easily overheat and die if they cannot find a cool place (such as a shaded rock or bush). This is called behavioral thermoregulation: the snake can't internally moderate its body temperature, but it selects sites that will help it do so externally.

Rattlesnakes and all the other pit vipers depend on finding their prey by a sort of heat radar (mammals tend to be warmer than their air around them except in very hot weather). Since they primarily eat rodents, and since rodents are largely nocturnal foragers, rattlesnakes can and do hunt at night when the cooler air makes the heat image of the mammal stand out from its surrounding environment. If it's been a lean year, you may find rattlesnakes out all the time as they try to find enough prey to survive.

So it's temperature, not time of day, that determines how active a rattlesnake is. In southern California, we don't have that much of a temperature differential between winter and summer, so you could see rattlesnakes at just about any time (though they do get torpid in the cooler months of January and February). In more northern areas, they will actually stay torpid for months at a time in cold weather. Torpor helps the snake conserve its resources until things warm up and it can hunt again. Reptiles do not go into true hibernation. The short version is: if it's warm enough, the snakes will be out, no matter what time of day or year it is.

What do I do if I do get bitten by a rattlesnake? Or if my child does? Or my dog does?

Do not panic. First, take a deep breath. Let your adrenaline rush subside a little before you act. A rattlesnake bite will leave two well-defined puncture marks and there will be an immediate, lasting pain. If you are unsure if the snake is a poisonous species, treat it as a medical emergency anyway.

If you have been bitten by a rattlesnake, it is important to get help as soon as possible. Call 911 for medical assistance. The best treatment for a rattlesnake bite is to seek medical treatment immediately. Get to a hospital emergency room as soon as possible. If someone else has been bitten, keep that person calm and transport them to the hospital immediately. Call 911 if the medical condition of the person is severe. Don't chase the snake. The antivenin treatment for a rattlesnake bite does not require knowing what species of rattlesnake it is. In the southern California area, the only poisonous snakes are rattlesnakes. Therefore, the emergency medical staff should be able to identify the characteristics of a bite without knowing exactly what kind of snake it is.

We repeat: GET HELP.

Do not apply a tight, constricting tourniquet.

Do not cut the bite area.

Do not ice the bite area.

Do not attempt to suck out the venom with your mouth.

Do not give alcohol to the bitten person.

Seek medical attention immediately. Visit the California Poison Control Center at San Diego's UCSD Medical Center for further information.

Do rattlesnakes sting with their tongues? Their tails?

Snakes do not sting, lick, or poison with their tongues. The tongue is a super-sensitive organ that permits the snake to make sense of its surrounding by combining taste and scent cues.

Rattlesnakes rattles are used only for making noise.

How do rattlesnakes reproduce?

Snakes reproduce pretty much the way all other vertebrates do. They are all either male or female, though it may be hard to tell which is which unless you're trained at telling the difference, or unless you see the snakes in the act of mating. The male has two organs called hemipenes, which are positioned side by side, and either can be used when mating with the female. Although many kinds of snakes are oviparous (lay eggs), rattlesnakes are ovoviviparous -- the female retains the eggs in her body until they hatch and the young emerge alive. Baby snakes are ready to go as soon as they are hatched or born. There is little to no parental care of the newborn snakes.

What's a good book on rattlesnakes?

Rattlesnakes: Their Habits, Life Histories, and Influence on Mankind, by Laurence M. Klauber, abridged by Karen Harvey McClung. University of California Press, Berkeley. 1982. ISBN 0-520-04038-4 This book is an abridgment of Klauber's authoritative two-volume work. It is scientifically accurate, yet lively and nontechnical enough to be readable by the general public. It may be purchased through

Answers from various sources.
Reviewed by Bradford Hollingsworth, Department of Herpetology,
and Margaret Dykens, Research Library

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