Saturday, January 15, 2011

Cottonmouth Myths I: Snakes Dropping Into Boats

            Some animals just can’t get a break.  Cottonmouths, Agkistrodon piscivorus, (aka water moccasins) would like nothing more than spend their lives within their local swamp or river, either coiled up under a bunch of vegetation waiting for a hapless frog to paddle by, or perhaps patrolling the water’s edge at night looking for some other tasty morsel.  But, we all know that aquatic habitats, although preferred by many a swamp creature, are also popular areas for human recreation.  Every day, thousands of people fish, boat, swim or tube in wetlands that are prime snake habitat.

             Despite this shared affinity, there’s not much else that people and snakes have in common, with the possible exception that neither are often very happy to run into the other.  For many people, fear of getting bit by a snake is of tremendous concern.   Cottonmouths are potentially dangerous animals, but after working alongside (and with) these animals for the past few years, I’ve concluded that to get bitten by one you would either have to be very unlucky or…well, tend to make poor decisions.

            When I’m near a swampy area, I never wear open-toed shoes or sandals and I’m always cautious to watch my step.  But, the number one piece of advice I can offer to those who don’t want to get bitten by a Cottonmouth (or any other venomous snake, for that matter) is to never try to catch, kill, or otherwise bother these animals.   There’s a reason why the number one place for a person to get bit by a venomous snake is on their hands, and it is not because they have Cottonmouths in their pockets.

If you keep your distance from Cottonmouths, they have nothing to gain by attracting your attention.  They’d rather you don’t even notice them.  Even if you were to harass one of these animals, their first instinct is not to bite, but to flash their namesake white mouths to warn you.  Yet, some of the most pervasive myths about Cottonmouths concern their alleged aggression and tendency to approach, attack, or even chase people!

One of these legends states that one must beware of Cottonmouths in tree branches overhanging rivers, as these animals are likely to drop into your boat as you pass beneath them.  I’ve never quite understood why a Cottonmouth would do this or what Phase II of the attack might be, but some might have you believe that after a Cottonmouth drops into your boat, it would then proceed to kill everyone within reach.  That is, of course, unless the snake is killed first.

Here’s the lowdown.  There are snakes that hang out in the branches overhanging rivers and they do sometimes drop out of them.  But they’re not Cottonmouths and the last thing they want to do is land in your boat.

Although Cottonmouths can climb trees, they seldom do.  On the other hand, Brown Watersnakes, Nerodia taxispilota, frequently crawl out onto sunny tree branches to bask and raise their body temperature.  On the East Coast of the United States, both snakes have very similar and overlapping distributions (the Cottonmouth can be found farther west than the Brown Watersnake).  At first glance, these harmless water snakes might look a lot like a venomous Cottonmouth, but there are some considerable differences.  The Cottonmouth has pupils like a cat, a much chunkier body and a boxy head, but you may not remember these differences when your day of river relaxation is interrupted by a snake falling in your lap.

Why would a snake do that?

Watersnakes, as their name suggests, are most comfortable in the water and that’s where they frequently head when they’re scared.  A Brown Watersnake would be a fitting meal for most passing hawks, so when these serpents are alarmed, their first instinct is to drop into the water where these birds (or other predators) can’t nab them.  Now, a scared snake is a scared snake, and they’re probably not paying close attention to just who is doing the scaring; so, if you’re casually floating down the river and you startle a Brown Watersnake, it’s going to try to escape into the water.  And, if you got close enough to this snake before it noticed you, your boat may be between the snake and the safety of the water. Believe me, this snake does not want to fall in your boat; it wants to fall into the water so it can swim away.

This is a young Brown Watersnake

I’ve heard a few stories about “Cottonmouths” falling into boats and canoes, and these stories usually result in the panicked sailors capsizing or using a shotgun to kill the offending (and likely also panicking) snake.  Unfortunately, the latter option invariably leads to a big shotgun blast in the bottom of the boat.  Incidentally, if the snake were still alive, they could likely escape through this new renovation.  As I alluded earlier, this isn’t the only Cottonmouth legend (can I say myth?) floating around out there; we’ll tackle the rest later…

I plan to write future columns about Cottonmouth "breeding balls" and their alleged tendency to chase people.  I've already tackled the longstanding myth that baby snakes are more dangerous than adults.  Am I forgetting any Cottonmouth myths?  Have you witnessed something along these lines?


This isn't the first time I've written about Cottonmouths.  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.

M. S. Mills, C. J. Hudson, & H. J. Berna (1995). Spatial ecology and movements of the brown water snake (Nerodia taxispilota).   Herpetologica , 51, 412-423

Glaudas, X., & Winne, C. (2007). Do warning displays predict striking behavior in a viperid snake, the cottonmouth (Agkistrodon piscivorus)? Canadian Journal of Zoology, 85 (4), 574-578 DOI: 10.1139/Z07-025


Dale Hoyt said...

This story illustrates how tenacious the beliefs of many people are about most snakes.
A herpetologist, call him "Les", from West Virginia often when home to visit his family. On one trip back home he went fishing with some of his old buddies. They were floating along in their boat and having a good time when one of Les's buddies shouted out, "Watch out Les! There's a cottonmouth coming toward you."
Les looked and saw a common water snake swimming toward the boat. He decided that this would be an excellent opportunity to enlighten his friend about the fact that there were no cottonmouths in West Virginia. He reached over the side of the boat and grabbed the snake which immediately, as water snakes are inclined to do, bit him repeatedly. Les says to his friend,"This is no cottonmouth. See, its harmless. Cottonmouths don't occur here." With that he let the snake drop back into the water and it swam away. His friend was speechless and they continued to fish, with his friend giving him furtive looks every few minutes, but still saying nothing. Finally, after 15 or 20 minutes his friend broke the silence. "Les, if that cottonmouth had been sunning itself you'd be dead by now."

David Steen said...

Dale, you are right. People seem to cling firmly to many falsehoods about snakes. You bring up a good point about misconceptions about cottonmouth ranges. In northeastern U.S. I would often hear about water moccasins. I'll put that on the list for future myths to tackle.

Was the friend in the story of the impression that venom production is somehow related to basking behavior?!


Dale Hoyt said...

I think he was searching for a explanation as to why "Les" wasn't showing any signs of having been bit by a venomous snake. Ergo, the cottonmouth must not have been "sunning" itself. I know it's irrational, but that's how I heard the story.

swamp4me said...

We are blessed with an abundance of cottonmouths in our area. I spend a great deal of my time during the warmer months debunking the many myths about these snakes. Some people are receptive to the truth, thank goodness. Unfortunately, many others prefer to hold on to their misconceptions and refuse to even try to appreciate these reptiles.

David Steen said...

What myths do you hear? As I mention I'll be continuing on the same theme and I want to make sure I don't miss anything.


Joy K. said...

As a fifth-grade teacher, I'm constantly having to swat mistaken notions about wildlife, especially concerning snakes and insects. It's a frustrating battle, isn't it?

Your post is part of the House of Herps festival for January. You can drop by the carnival at The Little House in the Not-So-Big Woods.

David Steen said...

Joy, what other wildlife myths do you hear? I'd like to include them in future blogs. Thanks for including my posts in this month's House of Herps carnival (for all readers, link to HOH appear on the right).


Carol said...

The snake in the top photo is beautiful. There were several of these sunning themselves on my brother-in-laws dock pilings. I never had one bother me as I walked the dock. But I didn't bother them either.