And the Cascabel will Fall Quiet…

Crotalus viridis helleri

Rattlesnakes were described by many cultures prior to the English invasion of the New World and were known by some Spanish and Portuguese explorers who likened the sound of the snakes tail when vibrated to that of a bell. According to Klauber this erroneous notion came from the English translation of cascabel which is the word in Spanish meaning small bell. This was somewhere during the 1600’s that these descriptions were being given. Today in America we know this to be far from the truth as anyone who has heard a rattlesnake can attest, it sounds nothing like a bell at all; more likely a baby rattle moved at incredibly high speed would be the more appropriate description of the sound of an agitated rattlesnake.
Fast forward 400 years and now we (herpetoculturists and herpetologists) are hearing reports from those participating in rattlesnake round-ups that the larger adults who are sought after for the prize money are ‘going silent.’ These folks are saying large adult rattlesnakes are no longer rattling as they once did. Apparently, the round-up participants who were able to locate the rattlesnakes by walking through the terrain and listening for the tell tale signal of buzzing by the rattlesnakes tail are finding the rattlesnakes are falling silent to avoid detection.

Snakes Don’t Need Hearing Aids

We all have heard that snakes are in fact essentially ‘deaf’ as they have no external ear with which to channel the vibrations of sound into an inner ear. This being the case it would seem to be a ‘mistake’ for evolution to allow for the development of a noisemaking device on the terminal end of an animal which will never hear it in the first place right? I mean how would it know if it was making sound? Why make the sound in the first place if the animal it was attached to couldn’t tell if was doing them any good?

Well, snakes have an inner ear with a functioning cochlea.

This means, according to the study done by J. Leo van Hemmen and Paul Friedel at the biophysics Department of the Technical University Munich and Bernstein Center for Computational Neuroscience in their work with their colleague Bruce Young of the Biophysics Department of Washburn University at Topeka, that snakes can ‘hear’ and locate prey using the vibrations on a sandy surface. When the snake lays its head on the ground it can pick up these vibrations and then locate the source of the ‘sound’.

As with all of nature there are no ‘mistakes’ only those things which we have yet to comprehend. To understand the rattle of the rattlesnake we can look at many reasons for it, such as a device for communication, but science has shown, at least so far anyway, that the keratin created rattlesnake tail is not used for intraspecies communique. So what reason could there possibly be for what essentially is a maraca on the tail. To our current understanding of the Crotalinae it would appear as though this rattle is used as a warning to other species that a potentially dangerous creature is near by.

For all of our studies of rattlesnakes it would appear their primary defense would be crypsis. This essentially means through evolution certain characteristics have been promoted and others not, so the snakes outline can be broken up and camouflaged in its surrounding area. Avoiding detection by predators. Crypsis doesn’t always work however, so what is a venomous snake supposed to do when faced with a six hundred pound to one ton beast? Well, you make noise right? According to at least one idea this could very well be the case.

Silent rattlesnakes?!

There is a species of rattlesnake the Catalina Island Rattlesnake Crotalus catalinensis which is the only known species of rattlesnake which has no rattle as do its 34 counterparts which make up the Crotalus genre. From what I have heard, there are two ‘theories’ on why this is. One says that because no bovines or large animals are present nor have there been in some time the rattles were not necessary so they evolved to not have rattles.

Another ‘theory’ I have heard is this is an adaptation for hunting birds. I looked for further reference to this theory but found nothing and to be honest I didn’t pursue it that far as this to me is one that doesn’t deserve much credence. I say this because as anyone who has ever worked with rattlesnakes knows the rattle is silent unless it is in action by the snake. When sitting still (as ambush predators do) there would be absolutely no reason for the tail to move and make noise so I am not clear as to why a rattlesnake without a rattle would serve for hunting birds, as the rattle is used as a warning and rarely makes noise when not being used as such and if it does I don’t think it loud enough to be evolved or phased out as hunting mechanism for birds. Who would be presumably skittish at sounds etc.

Here we come again to the original question

‘Are rattlesnakes adapting or ‘learning’ to go silent instead of buzzing at the feel of impending doom echoed through the booted heels striking upon the ground nearby?’

The Learning Reptile

Reptiles are too stupid to learn, or are they? What is intelligence after all? Intelligence as measured by human primates usually starts with the human primate at the apex and then delineates from there. The humans are writing the text; we are naturally inclined to put ourselves at the top. Obviously, we are the most intelligent when we are writing the literature.

Can reptiles ‘learn’ novel behaviors? Yes, many species have shown the ability to acquire novel behaviors. Some monitor lizards have learned to access food that has been placed in a sort of puzzle. Most studies to my knowledge have been focused on monitor lizards or tortoises.

This doesn’t mean snakes are not cognizant as many would believe. In my own piece on The Cognitive Reptile I referred to Laurence M. Klauber who spoke of his rattlesnake collection possibly being able to distinguish between himself and colleagues who entered his snake collection room. He claimed this because when he entered alone, the rattlesnakes did not sound off. When his colleagues entered the rattlesnakes would sound off. This has also been my personal experience with rattlesnakes that I have owned over the years. It has also been reported by numerous keepers of rattlesnakes that the rattlesnakes will not sound off at the approach of their caretaker but will sound off at strangers. This reported behavior alone would cause me to infer that snakes can and do learn on some level.

The Communicating Reptile

Dr. Rulon Clark of San Diego State University published a paper in 2007 Public information for solitary foragers: timber rattlesnakes use conspecific chemical cues to select ambush sites. This study states essentially that the timber rattlesnake Crotalus horridus uses chemical cues left behind not only by their own species but also by conspecifics as well and from this are able to ascertain which ambush sites would lead to better prey. In another paper Pursuit-deterrent communication between prey animals and timber rattlesnakes (Crotalus horridus): the response of snakes to harassment displays Dr. Clark discusses the predator prey communication system where when rattlesnakes are discovered by potential prey items they are harassed until the point of being driven away to another ambush site but this harassment is not always physical it can also be vibrational. Therefore there is actual communication happening between two conspecific animals wherein there is an actual informational exchange and understanding.

With the above information it is completely plausible that the rattlesnakes who are being hunted for roundups have learned, at the approach of footsteps not to sound off. Sounding off as it were, exposing them to predation. If the hunters are indeed only taking the noise making rattlesnakes then that leaves a population of those that remain silent at the approach of footsteps. This creates an issue of safety not only for the unaware hunter of rattlesnakes but also the casual hiker or passerby whom may travel the same paths as the hunters. Potentially once again, humankind is creating their own perfect storm wherein more people can be injured due to ignorance and unwillingness to actually educate themselves regarding the natural world.


Round-up is the term to which persons who participate in the event call it when you go in search of wild rattlesnakes, capture them, and then bring them back to a predetermined locale. Once here they are usually thrown into the attention grabbing named “Pit of Death”. This is where there is a single individual walking about the hundred plus rattlesnakes that are being emptied into the arena and they are speaking into a microphone exhorting the educational ramblings of uneducated rumors and hearsay, rarely does any scientific matter get recited.

The typical behavior is to harass a rattlesnake or two into rattling to show off for the crowd so their is a real sense of impending danger to the person talking. The fun doesn’t stop there, oh no, there’s even more fun to be had. Some round-ups allow you to have your picture taken with a live rattlesnake! Have no fear, you’re completely safe.

You see the rattlesnake, prior to being slung around your neck has had its fangs removed with pliers and then just to be extra careful, the ever cautious round-up participant then places the rattlesnake into a chest of ice to calm it down. After it has calmed down enough, they then sew the mouth of the snake shut so when it is around your neck it cannot bite you. How kind is that, that the round-up participants are so concerned with your safety that they are willingly torturing and mutilating a live animal for your entertainment.

Round-up participants also claim that venom collected during round-ups is then sold to laboratories and used for research or in the production of antivenin. Numerous people will claim this as false and will raise questions such as wanting to see receipts of the venom sold etc. and from my personal sources which I will not reveal I have been told thusly. Large laboratories will in fact buy venom from round-ups. The reason that the person milking the snakes is not producing receipts is number one they legally don’t have to. Number two, the large laboratories they are selling to don’t want to be associated with what really amounts to the wholesale slaughter of thousands of pounds of rattlesnakes ever year. Not to mention, if the researchers found out, they themselves may think twice of buying the venom from said laboratories.

Slaughter of rattlesnakes you ask? Oh yes, yes indeed. There is a special booth dedicated to the slaughter of rattlesnakes. At some round-ups, the kids can not only chop the head off their very own rattlesnake they can even put their hands in the blood and then put the bloody hand prints on  a wall of death! Sounds like a great day out with the family doesn’t it!

They even have contests to see who can bring in the most rattlesnakes, the heaviest rattlesnake, and the longest. Now then, think about this for a moment. Rattlesnakes or reptiles period generally do not grow very rapidly, for a rattlesnake to get to the large or longest prize winning size they would have to be an older snake.

Taken one step further, rattlesnakes may have a home range from 160 acres for some Timber Rattlesnake Crotalus horridus horridus males to as little as 9 acres for gravid females. Rattlesnakes of all species tend to have low productivity and even lower rate of mortality when it comes to their offspring. So if round-up participants are in fact hunting out the heaviest and longest snakes they are decimating a population even further by not allowing the population to recover. This is especially true when the round-ups are an annual event. The round-up participant is now going outside of the designated round up areas and gathering snakes which are sometimes hundreds of miles away from the round up locations. These rattlesnakes are then kept for days without food or water being provided. Did I mention that in most states the type of treatment that the rattlesnakes receive is actually a felony? This of course goes without mentioning that the local law enforcement is in attendance to keep an eye on the crowd. Now read this again carefully. Local law enforcement is on site and there are felonious activities being witnessed by said law enforcement and no arrests are being made. That just seems odd to me, to say the least.

It’s in the Numbers

Over the span of ten years almost 50,000 rattlesnakes have been tortured and died at the hands of the Sweetwater, Texas Rattlesnake Round-Up where they hold the worlds largest rattlesnake round-up and it has been reported on several occasions that the round-up participants are actually bringing the snakes from hundreds of miles away, as they are unable to find them in the local areas specified for round-up participants. Something which I found personally interesting, the years when there were spikes in numbers of rattlesnakes collected in Sweetwater, TX there were spikes also in rodent borne diseases such as lyme disease. I am no researcher but there does seem to be a correlation there of some type.

One thing is absolute fact. Rattlesnakes are a part of the ‘pest’ control system which evolved without mans intervention. We have seen numerous times how humankind and their interference will or has already upset entire biological systems which were operating under their own natural regulatory systems until humankind entered. When we take away part of the biological system that has been in place for millennia in the end humankind will pay the price in some form or fashion.

What Can I Do? 

For starters you already have completed your first task. You have read this article. Now then, I would immediately go to the Rise Against Rattlesnake Roundups page and donate to get our teams out to the round-ups to document and build a case against these barbaric practices even happening in the first place. The next step would be to join the RARR Group on Facebook and start talking with the folks there on who to contact and how to make contact etc. Finally, make the calls, write the letters, and send the emails to those who need to hear your voice.

Silence is NOT Golden

I have shown that by collecting the amount of snakes that are currently collected there could indeed not only be an ecological impact on the current environment but there could also be an unintended dangerous counteraction which could potentially harm many humans as the rattlesnakes are potentially falling silent at the approach of humankind. Silence is not golden, these animals need the same amount of respect as do any other species on the planet. Do your part now and get involved.  


Manrod JD, Hartdegen R, Burghardt GM. (2008) Rapid solving of a problem apparatus by juvenile black-throated monitor lizards (Varanus albigularius albigularius) Anim Cogn 11:267-273