Posts Tagged ‘cottonmouth water moccasin’

100 Species of Reptiles and Amphibians along the Altamaha River, Georgia

July 17, 2017

The corridor along the Altamaha River drainage is the best remaining wilderness in Georgia.  The land here is protected by 11 state wildlife management areas and 2 private landowners.  The Nature Conservancy owns Moody Forest, and the Orianne Indigo Snake Society owns land that hosts the greatest variety of reptiles and amphibians in the state.  Scientists have recently begun studying this largely undeveloped corridor.  From 2008-2016 scientists conducted the first comprehensive survey of reptiles and amphibians along this river system.  They used intensive group searches, turtle traps, and drift fences to find species; and they listened for frog calls.  Drift fences are barriers interspersed with pitfall traps.  Smaller reptiles and amphibians attempt to go around the barriers and fall into the traps.  Surveyors collected an astonishing 100 species, indicating the region has the richest diversity of reptile and amphibian species in the state.  Fort Stewart army base ranks 2nd with 97 species, and the Okefenokee Swamp hosts 88 species.

Image result for map of Altamaha River

Map of the Altamaha River Drainage.  The Altamaha is fed by 3 major tributaries–the Oconee, Ocmulgee, and Ohoopee.

Scientists catalogued 59 species of reptiles and 41 species of amphibians along the Altamaha River.  This number includes 17 species that are considered endangered by the federal and/or state governments, including indigo snake, diamondback rattlesnake, southern hog-nosed snake, rainbow snake, harlequin coral snake, pine snake, pine woods litter snake, slender glass lizard, mole skink, gopher tortoise, spotted turtle, southern dusky salamander, and gopher frog.

Surprisingly, cottonmouth water moccasins were found at less than half the sites surveyed, and they were absent from the main branch of the river.  The authors of this study suggest regular flooding “scours” riverside vegetation, eliminating the cover favored by the venomous snakes.  On the other hand river cooters (Pseudemys concinna) were found to be abundant in the river, though according to the preceding scientific literature they were not known to be present here.

Image result for river cooters scientific name

River cooters are common in the main branch of the Altamaha River.  Before the below referenced survey was conducted, reptiles and amphibians along this river were so little studied, this species was unrecorded in the scientific literature as living in the river.

Image result for red salamander scientific name

Red salamanders (Pseudotriton ruber) reach the southeasternmost limit of their range at the Altamaha River.  This waterway is a geographical barrier for 14 species of reptiles and amphibians.

species photo

The pine woods litter snake (Rhadinia flavilata) reaches the northern limit of its range at the Altamaha River.  This species grows to about 1 foot in length and mostly lives underground.  They are venomous but have rear fangs that are probably unable to break human skin.  They feed on small reptiles and amphibians and are no danger to people.

The reason such a high diversity of species occurs along the Altamaha River is the great variety of habitats.  The corridor hosts open water, bottomland hardwoods, cypress/tupelo swamps, longleaf pine savannahs, sandhills, Carolina Bays, and muddy seepage areas at the bottom of north-facing slopes.  However, the river itself serves as a barrier blocking movement of some species’ populations.  The Altamaha River is the southeasternmost range limit for 13 species, and the northernmost range limit for 1 species.

The high number of reptile and amphibian species is evidence the region of the Altamaha River has been climatically stable for millions of years.  The vicissitudes of Pleistocene climate fluctuations were muted here.  During cold arid stadials swampy wetlands shrunk in size but persisted as relics, while savannahs and scrubby sandhill habitat expanded.  Currently, wetland habitat has expanded but before European settlement grassland and scrub habitat were still extensive.  Western Georgia and Alabama have also experience long term climatic stability.  (See:

https://markgelbart.wordpress.com/2015/04/28/the-pleistocene-ridge-and-valley-reptile-corridor/

https://markgelbart.wordpress.com/2015/08/21/extralimital-species-of-pleistocene-aged-turtle-remains-found-in-the-upper-coastal-plain-of-alabama/

)  Like the black prairie region of Alabama, the Altamaha river also undoubtedly served as a refuge for species of reptiles whose current range was obliterated by an ice sheet during Ice Ages.  Blanding’s and wood turtles may have extended their range this far south then.  Extinct giant tortoises (Hesperotestudo crassicutata and H. incisa) likely lived alongside their smaller cousin, the gopher tortoise.  But otherwise the modern species list of reptiles and amphibians in the region is mostly unchanged from the Pleistocene.

Reference:

Stevenson, Dirk, and Houston Chandler

“The Herpetofauna of Conservation Lands along the Altamaha River, Georgia”

Southeastern Naturalist 16 (2) 2017

The Savannah Wildlife Refuge

August 10, 2012

Until the late 18th century a vast cypress swamp covered the area just north of Savannah, Georgia, a city founded in 1704 by General Oglethorpe. Plantation owners had cultivated rice in the South Carolina low country for a century before they cleared the cypress swamp north of the then young metropolis of Savannah.  In the process they completely converted the landscape from deeply wooded swamp to a virtually treeless marsh.  The end of the Civil War also brought an end to rice cultivation in this region because the freed slaves left, and the white plantation owners didn’t know how to farm rice.   The rice fields gave way to freshwater marshes that became a haven for wintering waterfowl.  In 1927 the federal government bought the land and declared it a National Wildlife Refuge.  Federal maintenance workers still operate the rice field trunks that control the flow and level of water for the benefit of wild plants.  The aquatic vegetation provides a bounty of food for wintering ducks.

Recess Plantation Trail.  It’s over 3 miles long and is simply an old rice dike.  Birdlife abounds.

Vegetation is lush and includes giant cutgrass, giant plume grass, wild rice, cattails, bamboo cane, lilly pads, and arrowleaf, among many other species of plants.

A thick stand of arrowleaf (Sagitteria).  Also known as duck potato, in the fall and winter it produces an underground tuber that allegedly tastes similar to new potatoes.  It was an important food of Native Americans.

The SWR also protects a still extant cypress swamp on the Georgia side of the Savannah River, but this part is accessible only via boat.  Last Monday, I visited the readily accessible South Carolina side.  The 4 mile long Laurel Hill Wildlife Drive is a road that crosses the top of an old rice dike.  Lush, year round vegetation grows in the wet fields.  The flora is dominated by giant cutgrass, giant plume grass, cattails, wild rice (yes, the edible gourmet grain), and arrowleaf.  I was going to harvest some wild rice, but it grows in deep water surrounded by alligators.  (It wasn’t until after I read the visitor center’s brochure that I realized harvesting plants was against refuge rules.)  Many of the aquatic plants are edible for humans as well as birds. 

Even though I visited the refuge at a bad time of day and year, I saw lots of birdlife.  The first bird I saw was an especially exciting find–an immature roseate spoonbill (Ajaia ajaja).  The bill on this species is unmistakable, but according to bird guides it lives no farther north than south Florida.  I couldn’t get close enough for a photo, but other birders have seen and photographed this species in South Carolina and Georgia, so it must be expanding its range.  Below is a photo of a roseate spoonbill taken in South Carolina by another birder.

Roseate Spoonbill

Roseate spoonbills develop pink feathers from eating shrimp.  The immature ones are pure white. It feeds on small animals by using its spoonbill to sift through shallow water.

Swallows (I think tree swallows, but they never stay still enough for positive ID), red-winged blackbirds, and cattle egrets were the most common birds.  I saw several purple gallinules–along with the roseate spoonbill another species I’d never seen before.  Though this chicken-sized rail can fly, they more frequently escape danger by running across lilly pads, diving into water, or climbing into ditch-side bushes.

A purple gallinule (Ionornis martinica).  Click to enlarge and examine the bottom center of the photo.  I saw or heard about 16 species of birds in little over an hour about noon on a hot August day.  The best time for bird-watching in the SWR is during the winter when over 20 species of ducks migrate here.  The flocks attract hunting bald eagles.

Other birds on my checklist for the 90 minutes I was inside the refuge include eastern kingbirds, mourning doves, great egrets, little blue herons, a small unidentified heron or bittern, double crested cormorants, a clapper rail (I think), an unidentified duck, and turkey vultures.

Spanish moss clinging from a live oak.  An island in the middle of the marsh supports a maritime forest of live oaks, palms, and loblolly pines.  This is the only place in the refuge where mosquitoes bothered us.

A live oak  growing on the island.  Grass is growing out of the ancient cistern that rests in front of this tree.  The cistern is the sole surviving relic from the days of rice cultivation.  Archaeologists think gutters from the roofs of 4 slave houses led to the cistern.  The slaves who cultivated the rice lived on the island which is the only dry land in the marsh.  After the Civil War and the collapse of slavery, rice farming in South Carolina died.  No white southerners knew how to cultivate rice.

The only reptiles I saw were 2 alligators, and I could hear bullfrogs.  Reportedly, cottonmouth water moccasins and banded water snakes are common here.

Click to enlarge the photo and look for the 5-8 foot gator swimming in the canal.

Lilly pad covered expanse of water.

I didn’t arrive early enough in the day to see mammals which are more likely to emerge at night, but the refuge is reported to be home for bobcats, mink, otter, raccoons, rice rats, and marsh rabbits.  Habitat such as this artificially maintained marsh would be ideal for some now extinct aquatic species of Pleistocene mammals–giant beavers (Casteroides ohioensis), 2 different species of capybaras (Neochoreus and Hydrochoreus), and mastodons (Mammut americanum).  Fossil specimens from these species have been recovered locally, suggesting that open marsh environments did exist in the region long before men could have felled the cypress swamps.  Dramatic climate fluctuations must have been the primary force creating marshy habitat where cypress swamps later dominated.  I propose that alternating wet and dry climate cycles caused a varying combination of drought, fire, windstorms, and flood, resulting in these pre-historic marshes.  These are not unlike the factors influencing the make-up of the current day Okefenokee Swamp where marshland is interspersed with cypress swamps.

The Laurel Hill Drive Exit.  A park maintenance worker had just mowed here, stirring up insects, and attacting cattle egrets which were one of the most visibly common birds in the refuge.  An extinct species of stork was likely the Pleistocene ecological counterpart to the cattle egret.

Map of the South Carolina part of the Savannah Wildlife Refuge.  Laurel Hill Drive is off 170, not 17 as erroneously reported on other online sites.  Make sure you approach the refuge from Savannah to see the view from on top of the Herman Talmadge memorial bridge.  The refuge from this vantage point looks like an African savannah.

Tybee Island Avifauna

We stayed at the Howard Johnson Hotel on Tybee Island the night before out trip through the SWR.  It gave me a little time to survey the avifauna on this narrow barrier island east of Savannah, Georgia.   Along the beach laughing gulls, herring gulls, and boat-tailed grackles abound.  Mourning doves and dusky seaside sparrows forage in the dunes immediately behind the beach.  This was the first time I’d ever seen the latter species.  The literature states that dusky seaside sparrows (Ammospiza maritima) occupy a narrow niche, living  in salt marshes and beach dunes.  Unlike most species of sparrows which feed mainly on grass seeds, dusky seaside sparrows eat snails, fiddler crabs, and other animal matter.  However, I saw them feeding on sea oat grains.  I surveyed 2 other sea birds–brown pelicans and a least tern (I think).  On the inland part of the island I saw city pigeons, starlings, and a cardinal.

AJ’s Dockside Restaurant 

We ate supper at AJ’s Dockside Restaurant.  It offers a great view of a small dock and a large salt marsh.  Dolphins and schools of mullet are probably often seen in the inlet behind the back patio where we ate, but I didn’t see any.  My fried flounder po’ boy was delicious.  My daughter ordered grilled pork chops.  The chops were good, but I must say they were served with the worst hushpuppies I ever ate in my life.  They were dense and doughy.  Hushpuppies should be light and airy.  AJ’s needs to change the recipe they use for hushpuppies.  Stick to the po’boys.  They’re good and won’t bankrupt you.

View from AJ’s Dockside Restaurant.

Disjunct Populations of the Cottonmouth Water Moccasin (Agkistrodus piscivorus)

March 4, 2012

When I first started reading about disjunct populations of the cottonmouth, I thought they might be interesting examples of populations isolated due to climate-influenced habitat change, but I later learned that most of them have become isolated because man has altered the surrounding environment, rendering it unsuitable for the snakes to survive.  Horizon-to-horizon cotton and corn fields eliminated habitat for intervening populations over 100 years ago in some areas and even more recently in others.

Older adult cottonmouth.  The adults turn so black, it’s difficult to see their markings.

Young cottonmouth killing a northern watersnake.  Note the brown striping which is so colorful compared to the older individual above.

Cottonmouths are a semi-aquatic snake that forages in swamps and lowlands, but in regions where frosts occur during winter, they need adjacent forested uplands where they can den in rocks, fallen logs, and rotted tree trunks.  A disjunct population of cottonmouths exists at Fosters Bend (a notable locality of which I discuss in more detail below).  Fosters Bend is an oxbow lake bordering an intact forest in northwest Georgia.  Dr. Charles Wharton believes the population of cottonmouths became isolated here because the surrounding land was cleared for agriculture.  Other disjunct populations on the periphery of cottonmouth range were Livingston County, Missouri where they were extirpated in 1987, and Montgomery County, Kansas where they were extirpated in 1993.  A genetically isolated population still occurs on Seahorse Key in Florida, but this population is isolated by sea water.

The Agkistrodus genus is part of the pit viper family of snakes.  DNA analysis suggests copperheads (Agkistrodus contortrix) evolved first, probably before the Pleistocene began. Cottonmouths evolved from copperheads that began foraging in swamps rather than dry upland forests. The speciation was likely a result of a differentiation of habitat preference.  The cantil (Agkistrodus bislineatus) then evolved from cottonmouths that expanded their range into Mexico.  Pleistocene cottonmouth fossils (just 4 vertebrae) were excavated from the Isle of Hope site in Chatham County, Georgia. Fossil skeletel remains of copperheads were found in Kingston Saltpeter Cave, Bartow County, Georgia.  Both species have a long history in Georgia, probably dating back at least 2 million years.  Reptile evolution is particularly slow.

Cottonmouth range map color-coded to depict subspecies.  The blue region is populated by the eastern cottonmouth, A. p. piscivorus.  The Florida cottonmouth A.p. conanti inhabits the red region.  The green region is inhabited by the western cottonmouth, A.p. leucostoma.  The gray area has intermediates between all 3 subspecies.

A copperhead.  Copperheads inhabit dry upland forests, while cottonmouths live in the lowlands.  Cottonmouths probably evolved from copperheads that began foraging in lowland swamps.

Pit vipers sense their prey with the pits located near their nostrils.  The pits detect changes in temperature–both warm-blooded and cold blooded prey have body temperatures that differ from the surrounding environment.  Cottonmouth poison is of the tissue destroying kind.  After they strike cottonmouths hang on to small prey such as mice and frogs which might escape before croaking (forgive the pun), but will release larger animals to avoid injury while the animal struggles.

Cottonmouths feed on small mammals, birds, birds’ eggs, baby alligators, fish, other snakes including other cottonmouths, snails, insects, and carrion.  Algae is often accidentally injested.  They are known for congregating around shrinking water holes where they can easily catch concentrated and trapped fish.  On Seahorse Key cottonmouths specialize in feeding upon dead fish dropped or vomited by wading birds.

Cottonmouths sometimes eat king snakes, and vice-versa–it depends on the size of the snake.  Smaller cottonmouths can occasionally repel larger king snakes with body blows, using their head to punch the bigger snake and knock it away repeatedly.  They also exude a musky odor when threatened.  Other natural enemies include alligators, great blue herons, indigo snakes, and largemouth bass.  Cottonmouths return the favor and prey on fledgling herons and trapped bass.  There’s a cycle of unwitting revenge in the swamp theater, depending on the age and size of the players.  Mites can infest and kill cottonmouths, and almost all are plagued with tapeworms from living on a diet of raw fish. 

During winter animosity between cottonmouths and other snakes disappear, and they will nest communally.

I’ve only seen a wild cottonmouth on one occasion.  The snake was a large fat adult, resting on a bank next to Woodbridge Lake in Evans, Georgia.  Young cottonmouths have brown stripes but older ones turn so black that the markings become less visible.  The individual I saw was completely black.  Studies show cottonmouths are not aggressive snakes.  About the only way a person can get bitten is if they step on or handle the snake.  Doctors treat the tissue-destroying venom with Crofab antivenom.  Marlin Perkins, the late zookeeper of Wild Kingdom fame, wrote that the only good thing about getting bitten by a poisonous snake was enjoying a complete recovery, once the antivenom treatment worked.

I don’t understand why people keep reptiles as pets.  Reptiles form no bonds with people.  The part of the brain involved with emotion does not exist in reptiles or any vertebrate less advanced than a bird.

Fosters Bend

Here’s a spot that may be worth exploring, if it hasn’t been developed since Dr. Wharton described it 30 years ago.

Photo of Fosters Bend in Floyd County near the border between Alabama and Georgia.  It’s from The Natural Environments of Georgia by Dr. Charles Wharton.

Fosters Bend is a Coosa River oxbow lake located in Floyd County in northwestern Georgia.  He found a floodplain hardwood forest with species more characteristic of the coastal plain than of the surrounding mountains of north Georgia.  One end of the lake has a forest of tupelo.  A forest of willow oak, water oak, overcup oak, hickory, and persimmon grows in a dried out oxbow.  The natural levee between the oxbow and the Coosa River has a diverse forest of sycamore, silver maple, willow, mulberry, basswood, and several species of oaks.  Archaic and woodland Indians sites occur here as well.