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Are Baby Rattlesnakes the Most Dangerous Biters?

by Tony Iwane on May 01, 2018

neonate rattlesnake
A neonate western rattlesnake (Crotalus oreganus), showing only one button on its rattle. (Photo by Zach Lim)

Is it true that the bite of a baby rattlesnake is more dangerous than the bite of adult rattlesnake?

With warm spring temperatures finally settling in throughout the Bay Area, snakes of all kinds are active, including the only local species that poses any significant health risk to humans, the western rattlesnake (Crotalus oreganus). Having spent the winter denned-up in their hibernacula, these vipers are now on the move to their hunting and mating grounds, and as one recent rattlesnake bite on Mount Tam illustrates, more likely to encounter us humans.

According to reports, the snake involved in that incident was approximately nine to twelve inches in length, indicating that it was young. And this, of course, brings up the oft-repeated conventional wisdom that the bite of a young rattlesnake is more dangerous than the bite of an adult rattlesnake. While that is a tempting “fun fact” to repeat in conversation due to its inherent counterintuitiveness, is there any truth to this common belief?

“The story that juvenile rattlesnakes are more dangerous is simply folklore,” says Greg Pauly, a herpetologist at the Natural History Museum of Los Angeles County. The explanations that come with this belief generally follow two lines of reasoning: first, that the young rattlers can’t control the amount of venom they inject meaning they will inject everything they have; and second, that adult rattlers are more experienced and won’t “waste” their venom when giving a defensive bite — meaning they more often inject less venom or give a “dry” bite without any venom.

In the first case, even if it is true that young rattlers cannot control their venom (some studies show that they can), Pauly explains that “bigger snakes have much bigger venom sacs, and adults can deliver far greater volumes of venom than babies even if they only inject a small percentage of the total volume available.” Meaning, of course, that the potential severity of an adult bite is significantly higher than that of a young rattlesnake.

western rattlesnake adult

An adult western rattlesnake. (Photo by Zach Lim)

As to whether adult rattlesnakes give “dry” bites more often than young ones do, Pauly told me, “there isn’t solid data to suggest that the frequency of dry bites varies across age classes.” Either way, a paper by Lynchburg General Hospital doctor Donald Janes and colleagues in California, which examines nine years of snakebite reports in Southern California, concludes that “Rattlesnake size was positively correlated with [Snakebite Severity Score] … [and] we showed that patients bitten by larger snakes and who had more severe envenomations received more vials of antivenom and had longer hospital stays.”

However, note that any rattlesnake bite is a serious medical emergency and the victim should get to a hospital as soon as they can, meaning definitely do not cut or suck the wound. Here’s some excellent advice for how to handle a rattlesnake bite.

What’s best, of course, is to not get bitten in the first place. Rattlesnakes are shy animals and will only strike when left with no other option, such as when handled, accidentally stepped on, or cornered. The express purpose of that famous rattle is to keep the snake from being in a situation where it has to bite, which I think is pretty considerate. The majority of rattlesnake bites in the United States occur when someone purposely handles a rattlesnake, either by mistake or when trying to harass or kill it (yes, attempting to kill a rattlesnake is much more dangerous than leaving it alone).

Most of the latter bitees are young, male, and often intoxicated. So unless you are experienced enough to consider multiple features when identifying a snake, don’t handle it (and it is against the rules of most parks to handle or harass wildlife). In the Bay Area, rattlesnakes look quite similar to gopher snakes, night snakes, and juvenile yellow-bellied racers; young rattlesnakes, which are more prevalent in the spring, often lack a rattle on their tails, which further confuses the issue. When in doubt, give the snake a wide berth — it won’t chase after you.

It’s also prudent to be vigilant when you’re in rattlesnake habitat, especially around rock formations and outcrops. Rattlers use these areas as both shelters and basking surfaces, so always watch your step and and your hand placement when climbing about on rocks. You might be enjoying the sun but inadvertently startle a rattlesnake who’s trying to do the same.

While rattlesnake are a concern in the Bay Area, practicing avoidance and vigilance will greatly reduce your chances of getting bitten. And if you should be lucky enough to encounter a rattlesnake in the wild, give the reptile some space and take a moment to admire it. I think it’s a privilege that we get to share this place with one of nature’s most beautiful, elegant, and polite predators.

Tony Iwane portraitA resident of Oakland, Tony Iwane is the Outreach Coordinator for iNaturalist and an interpretive naturalist for the California Center for Natural History. Check out his photos on Flickr and his nature observations.

Ask the Naturalist is a reader-funded bimonthly column with the California Center for Natural History that answers your questions about the natural world of the San Francisco Bay Area. Have a question for the naturalist? Fill out our question form or email us at atn at baynature.org!

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Michael Marchiano on May 8th, 2018 at 10:59 am

Tony…Really great article. I like people who have their facts straight. I may be way off But I have read several article that claim rattlesnakes a few years old will deliver dry bites from 30 to 40 percent of the time…still should never take the chance. I have never read anything about studies on juveniles frequencies of envenomation. (nicely pointed out in your article) Also in the East Bay mother northern pacific rattle snakes give live-birth in late summer, early fall and stay with their young up to 10 days. This is when I have encountered most of the single button baby. In spring those that make it through the winter (first winter has high mortality rate)the now are 5 to 6 month old will be seen with two or three buttons depending on how may times they have shed.

Tony Iwane on May 8th, 2018 at 4:32 pm

Hey Michael,

Thanks for the reply and compliment. I don’t know if there’s great data on how many adult rattlers will give a “dry bite” when defending themselves, but you’re totally correct that it’s definitely not worth the chance! Much better to admire from a safe distance.

Here’s more from Dr. Pauly regarding young snakes that I wasn’t able to include in the article. You’re correct about the life cycle. “At this time of the year (i.e., early spring) many of the young-of-the-year only have a single rattle segment, termed the button…When rattlesnakes are born, which would have been in or around September, they have a prebutton, which comes off with the first shed and is replaced with the button. Hereafter, a new rattle segment is added with each shed. In early spring, most baby rattlesnakes have not yet had another shed so they only have this single button and the rattle doesn’t make a sound. Even after 1-2 more sheds, the segments are so small that the rattle isn’t yet the loud, characteristic sound of an older individual. As a result, people that think rattlesnakes must rattle can more easily misidentify a juvenile.”

Interestingly, I just visited Idaho State University and was hosted by their herpetologist. He told me that the rattlesnakes up there (at elevation, in an overall colder climate) are only active for a few months of the year and therefore don’t have too much time to feed. On average, female rattlers there only become receptive to mating about every 4 years, because that’s how long it takes them to build up enough resources to bear young!

Darrell Correia on May 10th, 2018 at 3:50 pm

very good write up, this Urban Legend was also confirmed by Dr. Sean Bush, Venom ER at Loma Linda Hospital, in Southern Calif. he stated the venom is the same, just depends how much venom is injected, the larger snakes will and do have larger fangs and duct work, so a lot of variables are to be considered.

Linda Harrison on May 11th, 2018 at 4:16 pm

In a lecture on rattlesnakes at Anza Borrego State Park Visitor’s Center recently, an expert said that you should never apply a tourniquet to a bite, and you should move around to help distribute the venom throughout your system. Tourniquets often lead to amputation. It would be helpful to include some instruction as to what to do if you are bitten.

Tony Iwane on May 16th, 2018 at 7:55 pm

Darrell – yes, there are many factors to take into account, like the ones you mentioned. Another variable is how one’s body reacts to the venom. Some people might have an anaphylactic reaction, for example.

Linda – you might have missed it, but I linked to this page (https://www.ucirvinehealth.org/blog/2017/07/snake-bites) in paragraph 6. As I have no medical training, I didn’t feel qualified to write any medical advice in the column.

Thank you for reading the column, and for the thoughtful comments. – Tony

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