Tuesday, April 26, 2011

Herpin' In The Sandhills Part I: Cottonmouths!

I've been fortunate since moving to this part of the country.  Mostly because I have had the good luck to become acquainted with some incredible herpetologists and naturalists.  Most of these individuals are also nice as hell!  Two stellar examples of what I'm talking about are Jeff Beane (NC Musuem of Natural Sciences) and Ed Corey (NC Division of Parks and Recreation).

I emailed Jeff almost out of the blue when I moved here.  I was told by a good friend of mine from Wisconsin (who is also a herpetologist) that THE guy to talk with about herps down here was Jeff.  Jeff was incredibly nice and immediately agreed to show me around in the Sandhills region.  He has an ongoing telemetry project focused on a few rare snake species down there, and invited me to come out when he tracked snakes.  Although we didn't see any snakes that day, I got to know Jeff as an incredible naturalist.  He not only knows the herps of this region...but also the mammals, fish, birds (by call!) and even many plants.  It was through Jeff that I met Ed, who is also incredible at identifying native flora and fauna.  I'm not sure how they do it!  I can barely stay on top of the species I find in a 20 mile radius of the campus I work on!  It will take years and years to come close to their combined field ID knowledge.

Luckily, however, both of these fine gentlemen were more than willing to take us out to do snake surveys this spring!  So, last weekend...myself a a current undergraduate research student working with me made an excursion down to the Sandhills.  For reference, our wonderful state is divided into three major regions: The Mountains to the west....the Coastal Plain to the far east....and the Piedmont in between.  I live in the Piedmont.  The Sandhills are to the east, associated with the coastal plain region 

The two regions (the Piedmont and the Sandhills) could not be more different.  Whereas the Piedmont is primarily eastern deciduous hardwood forest habitat (where not disturbed), dominated by clay soils.... the sandhills have alot of open pine savannah habitat with sandy soil.  The Sandhills are generally a flat, gently rolling landscape.  In the areas we were visiting (i.e., the state gamelands), the habitats are heavily managed with fire.  In other words, the state purposefully starts fires (that they control) to reduce the amount of shrubby/brushy woody vegetation.  These fires do not burn hot enough to damage healthy adult trees, and removal of the shrubs allows for the proliferation of grasses (for example).  So the undergrowth is not particularly thick or difficult to navigate...there's lot's of open sand and clumps of grasses.  The adult trees that remain are primarily long-leaf pine (Pinus palustris), as you can see in the picture below.

Even based on this very cursory overview of the differences between the sandhills and the Piedmont, you can still probably guess that (like the vegetation) the critters that inhabit these regions differ substantially.  No where this is more evident than when one compares the amphibian and reptile species in each region.  The Sandhills have a very different assemblage of snakes, in particular, than where I live in the Piedmont.  I was really itching to see some of these species!

We were there for two days and boy did we see the critters.  I can't fit them all into one post, so I'll have a series....each highlighting something different.  Ultimately, from reading these posts it will become clear that I was almost a tourist during our trip, but....hey....these were all new and much sought-after species for me :) 

I've got to start with one of my favorite encounters of the trip, which was an encounter with an often maligned critter here in the south: the Cottonmouth (Agkistrodon piscivorus).

I've seen Cottonmouths twice before: once in Louisianna and once in southern Illinois.  Both of these times, I saw juveniles and I really wanted to see a big adult.  Luckily, Jeff and Ed knew a good spot, which happened to be at a fish hatchery.  The large ponds for rearing fish provided habitat for many snakes, turtles and frogs....all of which may be eaten by Cottonmouths.  The ponds and over-flow streams nearby also created ample habitat for Cottonmouths.  Interestingly, this is about as far north in the state as Cottonmouths exist in high densities.  The hatchery really looks nothing like the Sandhills that I described above.  All of the water and thick vegetation reminded me of a southern swamp....not of sandhills.

Anyways, our trip happened to coincide with the day that a nearby univeristy's Herpetology Class was having their annual spring field trip.  More eyes searching meant more critters found.

When we arrived, the class was already there and had uncovered a beautiful adult Cottonmouth.

And boy was it a prickly individual!

But check out that beautiful color!  In pictures, I've always thought adult Cottonmouths were a tad drab, but this one was stunning!  You can just see the white flesh on the inside of the mouth, which gives the "cottonmouth" its name.  When really threatened, this snake will fling its head back and hold its mouth open wide to show off the white innerds as a threat display.

Above: "He's got tha devil in 'im!"
The flash hit the snake's tapedum lucidium just right and caused that
neat eyeshine in this picture.  Also note the enlarged supraocular scale above the eye.

So...we saw a Cottonmouth.  That's cool.  But, we didn't actually find a Cottonmouth.  Not quite as cool.


The next day, Jeff, Dave and I returned to the fish hatchery.  We hoped to see a Cottonmouth in a more natural setting, as opposed to dumped out of a pillow case onto a mowed lawn.  After arriving, Jeff (who always knows the best spots) had us focus on a stream that runs adjacent to some of the hatchery ponds.  The riparian area, or area of land closest to the stream bank, had alot of dense shrubs and trees.  Not great for seeing snakes, and alittle unnerving to walk along knowing there are Cottonmouths about.  Unfortunately we didn't have hip waders, so we couldn't really get into the water and search the stream that way. 

So, we walked to the stream on a trail and stood at an open spot and visually scoured the banks.  Jeff had binoculars, which helped...and he saw a big adult on the opposite bank.  It was wary though, and slipped into the water soon after we saw it.

No more Cottonmouths to be seen at that spot. 

We decided to walk along the artificial hatchery ponds...hoping to get snakes sitting in the sunny grass or hunting for frogs along the pond edge.  I hugged the pond edge, Jeff watched the brushy woodland edge to my left and Dave walked in between us on the hatchery maintenance road.  The stream we had hit early on also meandered along to Jeff's left, in the woods.  Occassionally it would run its course close to Jeff and he could give the banks a glance with his binoculars.  We were feeling confident.

After a few minutes, I saw a watersnake of some sort, but it pulled into a hole before I could grab it (...and I ain't sticking my hand in a hole at a Cottonmouth site!). 

Not long afterwards, Jeff noticed a pipe discharging water into the woods.  I think it was an overflow pipe from the hatchery ponds...but can't remember.  The water rushed out of the pipe into a scoured-out channel that eventually connected to the stream we had started at (see below).  It wasn't long before he saw some Cottonmouths near the pipe!

Two adults were sitting in the sun among a tree root mass.  Nice ones too.  Then Jeff got a glimpse of a coil in the water below the root mass....a third snake.  Next, he saw another Cottonmouth (a smaller one) resting on the steep bank across from us....a fourth snake.  Finally, he looked down into the channel two foot below where we stood and saw a juvenile Cottonmouth resting near the water's edge....a fifth snake!  If I remember correctly, a few minutes later we actually turned up a sixth Cottonmouth slightly upstream of the root mass.


Unfotunately, the rather dense vegetation meant it would be difficult to get in at the snakes with a hook or tongs and safely maneuver them into an open area for photos.  Plus, I didn't have any experience with Cottonmouths...and after seeing that big ornery adult the day before, wasn't feeling very confident about my chances in such a tight place.

Jeff, however, didn't have any problems kneeling on the bank and hooking the little juvenile at our feet.  He brought it up so we could get some photos. 

And what a handsome little devil he was!

I didn't have the flash on in the top picture and it's not a terribly complimentary shot.  The lower one, I quite like however!

Easy to see how those little juveniles blend into the ground debris so well.  A great hunting advantage!

Notes On Cottonmouth Aggression and Ecology:
As already mentioned, Cottonmouths are often treated with scorn by folks.  This is largely out of fear and due to misinformation/myth.  In fact, David Steen has written some great blog entries dispelling common Cottonmouth myths on his blog.  Check 'em out (Cottonmouths Dropping Into My Boat, Cottonmouth Breeding Balls, Cottonmouths North of Virginia,  and I Got Chased by a Cottonmouth).  Anyways, they get sort of a bad reputation as being unusually aggressive, and scary.  Obviously, they are a venomous snake and must be treated with a hefty dose of respect, but they are not really a "scary" animal.  They look initimidating because of their tendencey to open their mouth and display the white flesh when threatened.....their supraocular scales (scales just above each eye) also jutt out slightly.  This almost gives the snake the appearance of being angry or annoyed, which may seem scary to some. 

As for the notion that they are particularly aggressive snakes.....  an interesting study by Gibbons and Dorcas (2002) sheds some light on the reality of these claims.  They confronted 45 wild Cottonmouths with a variety of artificial "threats".  These included (1) standing beside the snake with snakeproof boots and touching the snake with the boot, (2) stepping on the snake lightly, or (3) picking up the snake with an artificial hand.  Of the 45 snakes approached 23 (51%) tried to simply escape (NOT bite).  28 individuals (78%) used threat displays or defense behaviors.  Others simply sat there.  Only 13 of the 36 cottonmouths grasped with the artificial hand bit.

Cottonmouths are very general in their dietary preferences.  They opportunistically consume many prey items, and even known to eat carrion.  However, fish and amphibians are likely to most commonly consumed prey animals (Ernst and Ernst 2003).  They occupy nearly any type of aquatic habitat, including brackish coastal marshes....but also rivers, streams, wetlands, ponds, lakes, impoundments, ditches and etc..  Usually these habitats have many downed logs, brushy edges, etc. for cover (Ernst and Ernst 2003).

Literature Cited:

Ernst, C.H, and E.M. Ernst. 2003.  Snakes of the United States and Canada. Smithsonian Press. Washington, DC.

Gibbons, J.W., and M.E. Dorcas. 2002. Defensive behavior of Cottonmouths (Agkistrodon piscivorus) towards humans. Copeia 2002: 195-198.

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