Sunday, April 3, 2011

Cottonmouth Myths IV: I Got Chased by a Cottonmouth

        Let’s get back to some common Cottonmouth myths…

            When I am introduced to new people, and the conversation inevitably turns to my presumably bizarre career choices, often I am asked whether a particular species of snake is aggressive. Occasionally, I am also asked to comment on what type of snake is the most aggressive. I don’t imagine my typical answers are very satisfying.

            I have never come across any species of snake, or any individual snake for that matter, that I would consider “aggressive.” I have, however, experienced a wide variety of defensive behaviors. Some snakes are prone to bite when handled, some play dead, some crawl away as quickly as possible, and some may even puke up their last meal in the hopes of convincing you they’re not worth eating (I’m convinced, I’m convinced).  None have initiated any contact with me, let alone in a manner that I would consider aggressive.

            Perhaps the snake with the reputation for being the most aggressive is, of course, the Cottonmouth. Legend has it that when they’re not falling into your boat, they are chasing you around the beach, eager to teach you a lesson for wandering into their territory.

            I have heard this tale enough to give it some credibility. However, the idea that Cottonmouths chase people can be chalked up to a misperception of snake behavior. First, let’s list the reasons why it might benefit a snake to initiate or prolong contact with a threatening figure perhaps one hundred times their size….Still thinking of one? Me too.

            Cottonmouth venom is potent, and a bite from any venomous snake warrants medical attention. But, a snakebite doesn’t typically result in immediate death, there is still plenty of time after a bite for an angry and envenomated person (or animal) to take out their wrath on the offending snake. And no snake is going to give up their life just to make a point. It’s a lose/lose situation.

            When confronted by a potential predator, an animal’s best bet is to head in the other direction as fast as possible. It doesn’t make sense to start fighting until it’s a last resort, there’s just too much at stake.

            Let’s break it down: in a fight with a predator, if the potential prey wins then it is still alive, just like it was before the encounter happened. If it loses, it’s dead meat. So, why engage in a risky behavior when the best-case scenario is you end up where you were when you started?

            In some cases, it does make sense for an animal to risk it all. Namely, when they’re protecting their offspring. A protective parent is not likely to take off running at the first sign of danger. Cottonmouths however, do not exhibit parental care. Once a female gives birth, her young are on their own. Perhaps Cottonmouths haven’t developed parental care since the venomous babies can do a good job of defending themselves without her help.

            But in any case, I mentioned earlier that I have heard multiple stories about Cottonmouths chasing people. Why would people think they’re being chased by these snakes?

            The answer is because if a snake feels threatened, it is going to try to get from point A to point B as quickly as possible. And if a person is in the way, it’s going to look like the snake is coming right for them. Cottonmouths feel safest in the water and if they are disturbed while they are traveling on land they are going to head straight into the lake. They will do this even if they have to go right through what disturbed them in the first place. Their behavior, it seems, is just hardwired this way.
            Keep them from getting into the water, and Cottonmouths are likely to exhibit some other defensive behaviors, such as coiling up and rapidly vibrating their tail (which may sound like a rattlesnake in dry leaves), or, by flashing their white mouths. Both behaviors are designed to scare off predators. Cottonmouths will sometimes do a lot, it seems, to avoid biting someone.
            One reader once asked me to comment on a story related to him by his friend. This man, fishing on the water’s edge one day, had had his afternoon interrupted by not one, but two angry Cottonmouths. These two snakes had been chasing each other through the water, interspersed with occasional wrestling bouts. After one of these wrestling matches, a snake had made a beeline for the wary fisherman, who promptly executed the animal. To his surprise, then the other snake headed right for him. This snake also met a similar fate.

            We can only guess what was motivating these animals. But here’s my take: Male Cottonmouths, like some other pit vipers, are known to engage in combat over females. To the untrained eye, they may appear as wrestling bouts. When a winner is decided, and we don’t exactly know how they figure this out, the victor is likely to head right to the female, in the hopes of breeding. Perhaps the female was hiding out somewhere on the other side of the fisherman. When the winning snake was dispatched, perhaps the other Cottonmouth saw an opportunity to mate after all.  Little did he know she was not worth it.

 Have you been 'chased' by a Cottonmouth? 


This isn't the first time I've written about Cottonmouths.  For a discussion of Cottonmouths allegedly dropping into boats, click here. Or, to read about breeding balls, click here. To learn about where in the world you can find Cottonmouths, and where you can't, click here.

I wrote about how these snakes are quick to show up when a lot of toads (= food) appear here.  I've also written about accompanying Cottonmouth researchers as they wade through swamps to catch snakes in the spring as the reptiles try to take advantage of the new warmth and at night in the summer as the venomous snakes swam around me.  Finally, I provide some tips on recognizing Cottonmouths from non-venomous watersnakes here.

Cottonmouth pictures provided courtesy of Fingerprince Prints.

Much of what I write is based on my experience in the field, however I also rely on the research of others, citations of some relevant scientific articles are below.

Gibbons, J., & Dorcas, M. (2002). Defensive Behavior of Cottonmouths (Agkistrodon piscivorus) toward Humans Copeia, 2002 (1), 195-198 DOI: 10.1643/0045-8511(2002)002[0195:DBOCAP]2.0.CO;2

D. B. Means (2010). Blocked-flight aggressive behavior in snakes. IRCF Reptiles & Amphibians, 17 (2), 76-78


Bob said...

Great post David. I have been between cottonmouths on a levee and the water they wanted to get to to escape. I knew they were jut trying to get to the water but someone else could have thought that they were attacking them. When harrassed they also can strike vigorously enough to actually carry their body toward the intruder. Keep up the good work!
Bob Herrington

Kory said...

I enjoy your blog, David. Nitpicking a little... I was a bit disappointed to see you throw the *vibrate tail in dry leaves to imitate a rattlesnake* part into the post. I think it could easily be argued that this, in itself, is also a myth...or at the least a misconception/half-truth. We had an interesting discussion about this recently on the Herps of Arkansas website, but I'm not sure we fully fleshed out the ideas or pulled up pertinent research to it.

In any case, I'd be very interested to hear your take...possibly in a future blog post?

David Steen said...

Hi Kory,

Thanks for your comment and glad to hear you enjoy the blog. I believe you misquoted me, as I did not say Cottonmouths vibrate their tails to "imitate" a rattlesnake. They do however, "sound" like a rattlesnake in dry leaves. I checked out your link; I do think it can be controversial to suggest snakes are exhibiting some mimicry when they are shaking their tails; it's perhaps more likely that this was the ancestral behavior that eventually lead to rattles. You're right, this could be a good future blog.


David Steen said...

Thanks Bob,

I believe that is exactly the type of circumstance that begat this myth!


Kory said...

Hey Dave,
Not trying to push an argument here, but I didn't intend to quote you word for word in the first place. (If I had I would have used " rather than *.) I was simply expressing a general idea that you touch on in your blog post...and that I personally think could be misinterpreted/over-read by your intended audience (the non-herper types). I dunno, I was kind of thinking to myself that Cottonmouths vibrating their tails in dry leaves sounds a lot like...Ratsnakes vibrating their tails in dry grass. ;-)

David Steen said...

Hi Kory,

You'll get no argument from me. Your point is well-taken. I think I was channeling the people who tell me they are sure they saw (and killed) a rattlesnake because they heard something that sounded like a rattle. I'll be more careful with my wording next time.


Nolan Tomlinson said...

I wouldn't say I have ever been chased by a moccasin, however I have observed that while fishing, the splashing and activity has at times seemed to attract one. I figure they are investigating a possible food source in those circumstances is all.

David Steen said...

I agree. I imagine that when you have a diet as varied as a Cottonmouth does, any sound in the swamp is likely to come from something they would want to eat.

Trailblazer said...

Glad to see your new post! Well-done!

Now finish that dissertation!


David Steen said...

Thanks for the words of encouragement, but I imagine more people will read the blog.

Trailblazer said...

True...but the blog wont get you a job some day! :)

I look forward to seeing some pubs from your dissertation...make sure and send them my way once they come out!