Cottonmouth Myths I: Snakes dropping into boats

January 28, 2011

Cottonmouth photo courtesy Matt Greene.

Living alongside wildlife

By David Steen

Editors note: David Steen is an Auburn University Ph.D. candidate working in the longleaf pine forests of northwestern Florida. He conducts research primarily pertaining to the ecology and conservation biology of reptiles. Most of the time, you can find him checking his snake traps in the piney woods but once the sun sets he is often wading through wetlands spotlighting water snakes.

Cottonmouth photo courtesy Matt Greene.

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.

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?

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

To learn more about David Steen and his work, go to: http://davidasteen.blogspot.com

3 Comments
    1. I paddle a lot, and know of four bonafide cases of snakes falling into canoes/kayaks I have never heard anyone say they are cottonmouth snakes and the people in the boat want the snake in the water just as badly as the snake wanted to be in the water. Sometimes snakes can mistake a boat for a dry spot. I saw a video of a snake swimming in the water and popping right up onto a kayak. The paddler managed to gently guide the snake back in the water before it got into her seating and leg area.

      Life happens so when you are out in the wild you have to tolerate wildlife.

    1. dear sir

      YOU SPOKE OF COTTONMOUTHS FALLING IN A BOAT FROM A LIMB
      IN 1960 MY BROTHER AND I HAD WATCHED A JUNGLE MOVIE AT THE THEATRE AND IT HAD A RATHER LARGE PYTHON FALL IN THE BOAT OF A TRAVELER
      WE ARE FROM CEDAR KEY FL. AND IT WAS ONLY A SHORT RIDE TO THE SWANNEE RIVER WE WERE IN A WOODEN SKIFF BOAT AND IT WAS JUST GETTING DARK.MY BROTHER WENT UP UNDER A MOSSEY OAK TREE AND WE HAD BEEN DISCUSSING THE PYTHON FALLING IN THAT BOAT AND WHAT WE WOULD DO IF IT HAPPENED TO US.
      WELL, A PIECE OF MOSS LAID ACROSS MY BROTHERS NECK AND WHEN HE SCREAMED AND SLAPPED IT AWAY THE ROTTEN LIMB IT WAS HOOKED TO FELL IN THE BOTTOM OF THE BOAT MY BROTHER YELLED SNAKE IN THE BOAT AND I PROMPTLY SHOT AND KILLED THAT MOSSY LIMB/COTTONMOUTH AND AT THE SAME TIME BLEW A RIGHT SIZE GOOD HOLE IN THE BOTTOM OF THE BOAT.WE SPENT THE REST OF THE NIGHT ON THAT INSECT INFESTED RIVER BANK UNTIL OUR DAD CAME THE NEXT DAY TO GET US. THAT WAS WHEN HE CHOSE TO TELL US THAT SNAKES WOULD MOST LIKELY NOT FALL IN A BOAT.HE WAS JUST A LITTLE TO LATE WITH THAT ONE.

    1. Great story Rick! I guess you learned two lessons that night! Cottonmouths don’t often fall from trees and it’s a smart move not to shoot into the boat!

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