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Observations on Cottonmouths and Leeches

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 Recently I was in the Bankhead National Forest where I have a project to study the movements of Flattened Musk Turtles (Sternotherus depressus).  The gist of the study is following both male and female turtles in two streams within the forest.  The Bankhead National Forest is north and west of Birmingham, and lays on the Appalachian Plateau, an area with numerous exposures of sandstone favored by Green Salamanders (Aneides aeneus).  One site is Brushy Creek a nice clear, shallow, rocky-bottomed tributary of the Sipsey Fork.  Waters of Brushy Creek flow over riffles, along short runs, and through deeper, often sandy-bottomed, pools.  Beds of water willow (Justicia americana) are rooted in gravelly stream-side shallows and the banks are lined with hardwood trees that provide shade along the stream course. 
    Streams of the Bankhead National Forest, at least in my mind, do not conform to typical Cottonmouth (Agkistrodon piscivorous) habitat – slow, sluggish, swampy stream courses and ponds.  Yet, Cottonmouths are one of the most commonly seen snakes along Brushy Creek.  And to add to Brushy’s faunal list are leeches, the best population I know of.  Wading in Brushy Creek the question that may come to mind is not, “will I pick up a leech or two?”, but “how many?”

    On this day in mid-June my son Hugh and I, along with Joe who is on the project this summer as turtle tracker, were looking for turtles along Brushy Creek.  I noticed a snake rapidly swim across the creek and because of its swift movement, smooth action, and bright tannish coloration I identified it as a Midland Water Snake (Nerodia sipedon).  And of course I decided to catch it.  I noted the spot along the bank where it left the water and carefully walked to it, but when close I further noted that my identification was in error.  This was a Cottonmouth.  

    Half of the body was in the water and half in a water willow bed.  The snake threw back its head and opened its mouth as a defensive, not aggressive, warning.  Yep, no doubt a Cottonmouth.  I eased up with a camera and after two or three photos the snake fled into the stream and swam to the bottom to take refuge, although it was still in view.  The water at this spot was perhaps a foot deep and little more.  After a bit the snake surfaced; by this time Hugh and Joe had come over.  Our actions further disturbed the Cottonmouth and it again swam down but into a new location.
    In between the Cottonmouth’s game of hide-and-seek I had been watching a nicely colored leech (Placobdellasp.)  at the edge of the creek.   Not only are the leeches in the stream in abundance but they’re also large, 4-6 inches in length.
Now this is the cool part.

When the Cottonmouth went down the second time leeches picked up on it, swam to it, and attached around its mouth, at least three. The attachment of the leeches along its lips was apparently very irritating to the Cottonmouth as it began to swim around and scrape its jaws against rocks.  After a few moments the Cottonmouth rid itself of the leeches and swam away, but for those few moments the snake was in an apparent state of irritation.