Tuesday, May 28, 2013

Readers Write In: What is this Snake I Came Across While California Biking?

      This week someone posted a link on Reddit to my giant dead rattlesnake post and a flood of about 4,000 people linked through. Fortunately, at least some stayed to take a look around.

"Hey David,

I stumbled across your site from reddit! About a week ago I was mountain biking with my father in Southern California specifically in the city of mission Viejo. Which is almost dead center between Los Angeles and San Diego, and we are also about 20 miles in from the ocean. The snake had a red color on top with very small tan diamonds about the size of a half dollar running down his back, he had tan on bottom and had black eyes it seemed (didn't want to get too close to look for a slit). Could you help identify this snake for me? I'm sorry for the distance from the snake, I had just biked past his head by about 5 inches with my bike and I didn't want to alert him anymore by getting closer.



      I told Nick that it's a good thing that he decided not to get too close to examine this animal's eyes. If he had, he would have noticed that it did indeed have pupils that looked like those of cat because this animal is a rattlesnake. I made that determination based on the animal's body shape, particularly the head, and the color patterning (of course, the characteristic rattle would have made this identification very easy but it is hidden in the bush). 

     One of the incredible things about living in the southwestern United States is that there are lots and lots of rattlesnakes. It's not that they are just abundant, there are actually lots of different kinds of rattlesnakes. Here in the southeastern United States, we've got the Timber, Eastern Diamondback, and the Pygmy Rattlesnake. In the southwest, on the other hand, there are about a dozen different rattlesnake species. Sometimes this can make it more difficult to identify a rattlesnake from Arizona or California than one from Alabama or Georgia.

    I'm fairly certain I know which species of rattlesnake this is (an exciting find because they can only be found in a very small portion of this country) but I'm going to call on some western rattlesnake experts to chime in and lend their expertise (attention SocialSnakes and Bryan Hughes). Of course, I encourage everyone to chime and help identify this animal, please add some natural history information for this species, which is making its first appearance on this blog.

Friday, May 24, 2013

Friday Roundup: This Week's Wildlife Links (May 24th 2013)

Snakes aren't the only group of animals surrounded by a lot of misinformation. Bug Girl takes on a grossly inaccurate poster about U.S.A. spiders. While you're there, check out this great natural history summary of the cicadas that are emerging along the east coast. And, on that note, lobsters are not immortal.

Another great take-down of the ridiculous television shows about wildlife that are masquerading as educational.

Texas cop has a ratsnake freakout.

When did bears go extinct in Ireland?

A readable summary of recent studies examining the effects of climate change on amphibians.

Rare pics of rare Javan Leopard and how their presence may influence land use and conservation policies in the region.

Why de-extinction misses the point.

How to tackle the massive problem of wildlife road mortality.

The ongoing efforts to eradicate invasive species from the Galapagos Islands: next up, rats. Includes the innovative strategy of holding rat-eating hawks in captivity until all the poisoned rat carcasses were gone (hold them longer next time).

Hey Rhode Island: learn about your rattlesnakes.

Scottish Wildcats are on their way out...

South Sudan, the world's newest country, is trying to find out if they have any rhinos to help support a nature tourism program.

Why are crocs dying in the Florida Keys?

Thanks but no thanks: how missionaries caused blindness in western Africa (hint: parasites were involved).

Malayan Sun Bears, the world's smallest bear species, are declining.

Amphibians are in a lot of trouble, those that are left, that is.

Newly-described Honduran viper named after environmental hero.

Intimidating clean up crew: White Sharks scavenge too.

It's nesting season: look out for turtles on the road.

Big invasive species: the new world record Brown Trout may have just been caught in New Zealand and the biggest Florida Burmese Python has just been captured.

How the abandonment of traditional-land uses is bad for a European toad.

A great summary of Grand Cayman Blue Iguana conservation efforts.

In the wake of a recent elephant-poaching event, Gabon and the Central African Republic crack down.

It's that time of year: camera traps record baby Red Fox and reveal a large camera vandal with two small accomplices.

Don't miss this Yellowstone landscape.

Finally, did you miss this week's guest posts from Jim Godwin and Erin Abernethy?

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Wednesday, May 22, 2013

Cinco de Snake-O Plus One (Guest Post by Jim Godwin)

Note: This is a Guest Post by Jim Godwin. Jim has spent decades working outside and conducting studies on the natural history and conservation of amphibians and reptiles. He has countless stories. I'm trying to convince him to contribute to this blog regularly; please help me encourage him in the Comments.

I have had a life-long interest in amphibians and reptiles from my early years in northeastern Arkansas where I had access to a great richness of snakes and turtles literally in my backyard.  I later found my way to Alabama, left for a few years, but returned when hired as zoologist with the Alabama Natural Heritage Program.  During my time with ALNHP we have had several homes before permanently settling down at Auburn University.  Here I have been able to focus on survey, inventory, and research projects on a range of herps, including the Indigo Snake, Red Hills Salamander, Black Warrior Waterdog, Flattened Musk Turtle, Gopher Tortoise, Alligator Snapping Turtle, Map Turtles, and Alabama Red-bellied Turtle.

5 May 2012 and snakes are hitting the ground, but not literally.  Tongue flick, tongue flick, tentative forward crawl, tongue flick, slight turn of the neck, tongue flick, tongue flick, twist of the body, rapid slither down a gopher tortoise burrow and one more Eastern Indigo Snake (Drymarchon couperi) has been set free on this warm spring morning.  I, and a small crowd of other indigo enthusiasts, stand nearby to see yet another snake entering the wilds of south Alabama.

      The day began with a gathering in Andalusia, Alabama for the third release of Eastern Indigo Snakes onto Conecuh National Forest.  A short caravan of vehicles that I was heading proceeded south through the early morning fog along US 29 then AL 137 before making the turn leading to the focal point for the morning’s activities.  Represented on this day were indigo snake researchers from Auburn University, The Orianne Society, US Forest Service, the Auburn University student chapter of the Society of Conservation Biology, Georgia Public Broadcasting, The Jones Ecological Center, and other interested individuals.   

     As with the two previous releases in 2010 and 2011, most of these snakes have been implanted with a radio transmitter which allows Jimmy and Sierra Stiles to follow their movements.  Jimmy and Sierra have each taken on studies of these Eastern Indigo Snakes for their research theses.  Without the technological aid of the transmission of a unique radio signal we would not be able to learn of the movements and survival of the snakes.  An adult Eastern Indigo Snake in hand is a large, impressive, deep blue-black, conspicuous serpent, but in the wild the snakes blend with their environment.  The sheen and coloration of their black bodies intermingle with the mottled shade found under vegetation, thus cryptically concealing even the largest of snakes.

      The overall goal of our conservation effort is to establish a population of the Eastern Indigo Snake in south Alabama, and Conecuh National Forest is the chosen location. In concert with the conservation effort is research to test release methodologies, compare movements, home range size, and habitat usage to wild populations in Georgia, determine how many snakes live from year to year, and identify causes of death.

      One year later and my morning begins with the loading of 20 boxes, each containing a snake, into the back of my Land Cruiser, filling the rear seat area floor to ceiling.  The snakes were guests of mine in the motel where I had stayed the previous night, and I was very careful to make a thorough head count before leaving

Today, 9 May 2013, we have no crowds to commemorate the freedom of additional Eastern Indigo Snakes.  Today I am one of only nine on hand to experience the event of the release. Folks from Auburn University, Alabama Department of Conservation and Natural Resources, and the U.S. Forest Service are all that are present.  But with fewer snakes this year small is good. 

     Standing over a gopher tortoise burrow, GPS in one hand and notebook in the other, Jimmy Stiles records the release location of the eastern indigo snake his wife Sierra is setting free.  Today marks the fourth release event for the Eastern Indigo Snake reintroduction project that Auburn University is leading at Conecuh National Forest.  By the end of the morning an additional 20 snakes will be roaming the forest.  Along with those released the three previous years this will bring the total number of juvenile indigo snakes to 98.

     After four releases and three years of radio-tracking snakes what have we learned?  One is that snakes cannot be contained.  The release techniques we tested included keeping a snake temporarily within pens (soft-release) versus just letting it go into the wild (hard-release).  The main question to be answered was whether soft-released snakes had a better chance of surviving. The answer is probably but I have to be vague because most snakes discovered points of exit earlier than planned.  And quite surprisingly, some snakes returned to pens after making an early exit.

     Our snakes were reared in captivity for nearly two years, from the egg to about a meter in length, or the minimum size to comfortably hold a transmitter. While many were held in large outdoor tubs for a couple of weeks prior to release we actually did not know if the snakes would transition successfully from lab to wild.  The short answer is they did and very well.  As soon as being released snakes began to act like wild snakes.  Some exhibited defensive behavior, all took immediate refuge in burrows, stump holes, or under cover, and one was found consuming a Copperhead (Agkistrodon contortrix) within 18 hours after its release.

     Overall the project is being met with cautious optimism.  Signs of success are evident.  Snakes are surviving from year to year, juveniles are maturing, and reproduction is underway although hatching in the wild is yet to be documented.   But, unfortunately the occasional death of snakes occurs within this experimental population, and the fate of these snakes is usually to be crushed under the tires of a vehicle or captured within the talons of a raptor or jaws of a mammalian predator.

     Success may also be measured in the formation of the partnership that has developed around the Eastern Indigo Snake.  Federal and state agencies, conservation organizations, and an academic animal to Alabama.  Too often - due to our human limitations in understanding the natural world - we think we have the answers.  In this instance we have some of the answers and as each year passes we have more. Many of the answers have come from something unexpected because the snakes are living and behaving as the wild snakes that they should become.

Sunday, May 19, 2013

Shrinking Alligator Penises: Using Wildlife Models to Study How Chemical Contaminants May Affect Human Reproductive Systems (Guest Post)

Erin on the side of a river somewhere
 in western NC, hard at work study obviously.
Erin Abernethy is a Master’s student in the Odum School of Ecology at the University of Georgia, where she is studying scavenging ecology in Hawaii. Before coming to Athens, Erin lived in North Carolina earning her BS in Biology at Appalachian State. For that degree, she was investigating potential fragmentation in freshwater mussel populations around small mill dams. She then worked in eastern NC chasing down Spotted Turtles, Clemmys guttata, for Clemson University, while also learning to garden and bake delicious grape hull pies from her Great Aunt Marie.

Penises are shrinking. In the male American Alligators, Alligator mississipiensis, of Florida’s Lake Apopka, that is. The culprit? Endocrine disruptors. Endocrine disruptors are chemicals that interfere with the endocrine system (the system of glands that secretes hormones directly into the bloodstream) and cause adverse developmental, reproductive, neurological, and immune effects. Well-known endocrine disruptors include birth control pills, BPA (ever heard of BPA-free plastic water bottles?) and DDT (dichlorodiphenyltrichloroethane), a pesticide that is now banned in the USA. I first heard about endocrine disruptors while watching Fooling with Nature, a PBS documentary that introduced me to Lake Apopka and the leading scientist on the project, Dr. Lou Guillette.

Dr. Guillette with an American Alligator.
Hope that duct tape holds!
Dr. Guillette is intrigued by reproduction. He completed his Master’s and Ph.D. work on the reproductive evolution of Yarrow’s Spiny Lizard, Sceloporus jarrovi, and the Mexican Lizard, S. aeneus, respectively. In 1985, he was employed by the University of Florida as an assistant professor in the Zoology Department and began to study American Alligators in Lake Apopka, which is the third largest lake in Florida and is located in central Florida. He says that he began working on Lake Apopka to study the general health and reproductive biology of the alligators. At the time, Florida Fish and Game Commission scientists were concerned that the population of alligators at this lake was not rebounding from previous population declines despite restrictions on hunting them. Dr. Guillette began to notice abnormalities in the alligator eggs and juveniles and started looking for the cause. He discovered abnormal hormonal levels in both male and female alligators and wondered if environmental contaminants could be causing these abnormalities. He hypothesized that Lake Apopka was contaminated with endocrine disrupting chemicals that were adversely affecting the reproductive physiology of these alligators. 

Since developing that initial hypothesis, Dr. Guillette completed many studies on the alligators in Lake Apopka, such as the one published in 1996 entitled “Reduction in Penis Size and Plasma Testosterone Concentrations in Juvenile Alligators Living in a Contaminated Environment.” In this study the penis sizes of two populations of alligators were compared. One population was from Lake Apopka, which had been shown to be contaminated with agricultural and municipal chemicals such as DDT, dicofol (a pesticide), and sulfuric acid. The other population was living in the relatively secluded Lake Woodruff located 65 km (40 miles) away on a National Wildlife Refuge.

Hand grabbing gators at night.
Sounds like fun!
So how do you conduct a survey on penis size of alligators? First you have to catch them! To catch juvenile alligators, which are generally less than 1.2 m (4 feet) long, researchers pile into a small boat that is relatively low on the water and motor out to their study sites while the sun is setting. Once the sun sets, they can use a spotlight to find the “eye shines” of the alligators. Alligator eyes reflect light much like the eyes of a deer in your headlights. Once they have their sights set on an alligator, they motor over to it with one brave soul at the front of the boat ready to HAND-grab that little gator. Can you imagine yourself belly down, hanging halfway off the front of a tiny boat, in the middle of the night, getting ready to stick your arm into dark black water in order to grab a baby alligator? One might wonder, “Where’s Mama?” 

By applying gentle pressure, the penis, technically referred to as the cliterophallic structure, on juvenile male alligators can be pushed out of the cloaca. The cloaca is the opening on an animal’s underside through which all products of the intestinal, reproductive, and urinary tracts exit the body. It’s also the place you want to look to see if you’ve got a male or female alligator. Once the penis is fully extended, its length and width are measured. 
Alligator penis diagram with
relevant measurements displayed.

        When the sizes of penises were compared between lakes, alligators in Lake Apopka had on average 24% smaller penises than alligators in Lake Woodruff. When the time came for these juveniles to reproduce, this significant reduction in penis size made it difficult to mate and certainly didn’t impress the lady alligators.

This study showed that male alligators in Lake Apopka, which is contaminated with endocrine disruptors, were significantly different than alligators from a lake that had relatively little pollution. In order to help determine the physiological drivers, in other words the chemical pathways in the body that shape these physical differences, behind this reduction in penis size, Dr. Guillette also looked at plasma testosterone concentrations. Plasma testosterone is responsible for the formation and development of male external genitalia. He discovered that juvenile alligators in Lake Apopka had 70% lower concentrations of plasma testosterone than those at Lake Woodruff. Abnormal hormone levels like these are associated with decreased sperm counts and reduced fertility. This can be disastrous for maintaining healthy wildlife populations. The results of this study inspired Dr. Guillette to continue to look at the physiological effects of endocrine disruptors on reproductive systems.

Over the past couple of decades, Dr. Guillette and many other scientists have described the physiological effects of endocrine disruptors on many groups of wildlife. In male fish and amphibians, these effects include not only a reduction in testosterone but an increase in estrogen (female sex hormone) production and even the production of eggs, egg yolk, and ovaries (yes, in males!). In both sexes of rats, an increase in reproductive system cancers (prostate and breast) and immune system failure was seen when animals were exposed to endocrine disrupting chemicals. Rats, fish, tadpoles, and salamanders exposed to atrazine (an endocrine disrupting pesticide) experienced neurological effects such as damaged brain cells that resulted in decreased cognition, hyperactivity, and erratic behavior. So what do these harmful effects of endocrine disrupters on animals mean for humans?

Dr. Guillette says that he is currently focused on answering that question. He has moved away from simply studying the reproductive physiology of the alligator, and now uses the alligator as a wildlife model for understanding the potential effects of endocrine disruptors on human reproductive systems and embryos. He is now working at the Medical University of South Carolina as a Professor of Obstetrics and Gynecology! He appreciates this unique opportunity to meld his wildlife research with that of medical researchers. Some of his current research is delving into the different routes of exposure to endocrine disruptors and how these influence embryonic development. There are over 1,000 chemicals out there that are endocrine disruptors, and we are all coming into contact with them every day through our drinking water and many consumer products, plastic toys, cosmetics, cleaning products. How are they affecting our bodies and our children? We don’t know, but that is what Dr. Guillette is looking into.

Dr. Guillette believes that if baby alligators are not healthy, our human babies won’t be healthy either. As the evidence for this hypothesis grows (see also Dr. Tyrone Hayes’ website for more information on the effects of endocrine disruptors on humans), scientists must inform the public so that actions can be taken. Public opinion is the most powerful driver for policy change in this country and only a loud public outcry will alter how chemicals are produced, studied, and regulated. USA companies are putting over 500 new chemicals a year on the market without thoroughly examining their potential side effects, which should take years to do.

What actions can you take? Be aware of what you are consuming and coming into contact with. Could it be an endocrine disruptor? Do some research and don’t be intimidated by scientific articles. Many scientists are making an effort to write their conclusions so that they are comprehensible to a wider audience. Write to your representatives and legislators and become involved in local action groups to increase studies and restrictions on new and old chemicals that are being used in consumer products and agriculture without being fully investigated for potentially harmful side effects. Just as in alligators, these pollutants may affect our young. It is critical for the health of our children that we become aware of and regulate what we are putting into the environment and our bodies.

For further information about endocrine disruptors, please refer to these websites and/or scientific articles:

Guillette Jr., L., Pickford, D., Crain, D., Rooney, A., & Percival, H. (1996). Reduction in Penis Size and Plasma Testosterone Concentrations in Juvenile Alligators Living in a Contaminated Environment General and Comparative Endocrinology, 101 (1), 32-42 DOI: 10.1006/gcen.1996.0005

Friday, May 17, 2013

Friday Roundup: This Week's Wildlife Links (May 17th, 2013)

This article could use a little more reflection about working alongside potentially dangerous animals and a little less sensationalism. But, it's still an incredible story: I was swallowed by a hippo.

Who knew? Snakes like hot springs too.

The Roundup from a couple weeks ago featured amazing pictures of a pod of Orcas attacking a group of Sperm Whales. This week's unlucky victim is a dolphin.

Anglers take note: climate change is projected to drastically reduce the amount of trout habitat (see citation below).

An interesting summary about how much of what you think you know about wolves is based on early and outdated research and incorrect inferences by the researchers.

Restoring wetlands: a few days ago I wrote about an unusual wetland in Alabama that harbors rare reptiles. When a similar wetland in Mississippi was restored to its former glory, endangered amphibians (Gopher Frogs) took note and moved in.

An article about the work The Orianne Society is doing to conserve the Midget-faded Rattlesnake in Colorado (paywall).

Sea turtle nesting season has started in Georgia.

The largest crocodile in captivity recently died. Here's why. On that note, Frank Indiviglio remembers meeting Gomek, the 17-foot crocodile that lived at the St. Augustine Alligator Farm. When I visited St. Augustine, Gomek had just died and there was just a big empty tank where he once reigned.

Eat (more) bugs.

Otters are making a comeback on the California coast. No, not Sea Otters, River Otters.

Attention fish hobbyists: do you have a female cichlid? Female desperately needed to pair with the last three males of this species.

A Bald Eagle battle goes awry.

Wenger SJ, Isaak DJ, Luce CH, Neville HM, Fausch KD, Dunham JB, Dauwalter DC, Young MK, Elsner MM, Rieman BE, Hamlet AF, & Williams JE (2011). Flow regime, temperature, and biotic interactions drive differential declines of trout species under climate change. Proceedings of the National Academy of Sciences of the United States of America, 108 (34), 14175-80 PMID: 21844354

Saturday, May 11, 2013

Undercover For Forty Years: Does the Black Swamp Snake Still Exist in Alabama?

One of the most valuable ponds in Alabama, if you ask me
            It was a drive from Auburn University to a conference in the Florida panhandle that allowed us a short detour to visit one of the most storied wetlands in Alabama herpetological history. But, I didn’t realize that at the time.

            You wouldn’t know it by looking at them now, but there are a few wetlands in Conecuh National Forest that harbor some of the most extraordinary reptiles in the state, if not the southeastern United States. Today, the handful of adjacent ponds within Open Pond Recreation Area don’t look so welcoming to rare animals; closely-mowed grass reaches right to their borders and the entire area is more reminiscent of a golf course (albeit with picnic tables and camping spots) than the backwoods. But the tame lawn immediately surrounding these few small ponds belie their wild past, a past hinted at by the landscape of longleaf pine forest in the distance.

            Rainbow Snakes are one of the most infrequently observed and perhaps rarest animals in Alabama. Glossy with striking red stripes, the animal is beautiful and unmistakable. That is, if you ever see one. Despite being closely-linked to specific haunts—clear streams with lots of their preferred prey, eels—there are no places one can go to reliably find a Rainbow Snake. If you spend enough time outdoors, and together with a combination of timing and luck, a Rainbow Snake just might present itself someday. But don’t hold your breath.

The famed Alabama Black Swamp Snake
            Black Swamp Snakes, on the other hand, don’t have the same reputation. These small, non-descript snakes (with bright red bellies) are also closely-linked to specific habitats—mostly isolated ponds with lots of aquatic vegetation—but once you find these ponds, a little mucking around will likely produce a small and wriggling Black Swamp Snake. Much of the research on this species has taken place in South Carolina. Spending time wading around certain ponds in these areas will result in buckets of Black Swamp Snakes (literally, in some cases) and that easily can give the impression that they are common. They are not. At the edges of their range, such as in Alabama or western Florida (where they are technically not even the same subspecies as the animal in South Carolina), the handful of ponds that harbor Black Swamp Snakes are few and far between and probably about as rare as the number of people that can point them out.

            In the short section dedicated to Rainbow Snakes in Dr. Robert Mount’s classic book, “The Reptiles & Amphibians of Alabama”, there is a brief passage that is as bewildering as it is understated in describing what was found at a “site” in Covington County in the 1960s:

“Eight specimens (Rainbow Snakes) were found there at night along with 28 Seminatrix pygaea (Black Swamp Snakes)...”

            I remember reading that passage over and over again. Eight Rainbow Snakes in one place at one time?! Twenty-eight Black Swamp Snakes? How was that even possible? Being students at Auburn University, we had access to something most did not: the esteemed professor emeritus Dr. Mount himself. And it was he who revealed some more specifics about this mysterious “site”.

            Dr. Mount had been hit up for this information prior to our trip, but this was unbeknownst to me as I sat in the van along with Craig Guyer, Sharon Hermann, and Sean Graham, and came to a stop on a dirt road in the Conecuh National Forest. Not far from the picnics and Frisbees surrounding Open Pond itself, we had reached a small wetland segregated from the popular recreational areas by thick vegetation. More vegetation surrounded the small pond itself, which was ankle-deep and seemingly small enough that one could lightly toss a rock across the entire expanse of the open water. Not what I would consider promising for rare wildlife.

We also found an ogre eating some snakes
            But the key was in the mats of dried vegetation surrounding the pond. As the water dried over the summer and into the fall, the water level gradually shrank lower and lower, leaving a thick green carpet of the previously submerged and aquatic plants. Rolling back this carpet like a mat of sod revealed a mud that was wet, gray and teeming with Black Swamp Snakes. Perhaps this was how they stayed hydrated, secure, and alive through Alabama droughts.

            Reveling in our find, the first Black Swamp Snakes seen in Alabama for decades (despite being mere kilometers from the homes of three herpetology-minded friends that shall remain nameless), it was some time before I realized that the Rainbow Snakes had eluded us. As did the Black Swamp Snakes when we returned to the pond some months 
A more photogenic herpetologist
later when it was full of rainwater. In their place, a sole Mud Turtle (Kinosternon subrubrum) patrolled the shallows. Maybe we didn’t find any snakes on this return visit because the habitat had changed so much. After all, we no longer had any convenient vegetation mats to roll back and check under; but, I would have expected to see at least see one or two snakes swimming around the pond or hiding within the submerged plants. I couldn’t help but wonder about the fate of this small, isolated population of animals; it wasn’t hard to imagine that they had just blinked out of existence, maybe from some disease, a careless chemical dump, or just because it was a bad year for the small salamanders and invertebrates they feed on.

       If Black Swamp Snakes have a future in Alabama, it is an incredibly precarious one; yet, they are not afforded any particular protections. Perhaps their abundance elsewhere is a disincentive for conserving them even where they are rare. Perhaps this mindset is why more species have vanished from Alabama than any other state in the continental United States. Perhaps we will soon have to add the Black Swamp Snake to the list.

Related Blog Posts:

Willson, J., Winne, C., Dorcas, M., & Gibbons, J. (2006). Post-drought responses of semi-aquatic snakes inhabiting an isolated wetland: Insights on different strategies for persistence in a dynamic habitat Wetlands, 26 (4), 1071-1078 DOI: 10.1672/0277-5212(2006)26[1071:PROSSI]2.0.CO;2

Winne, C., Dorcas, M., & Poppy, S. (2005). Population Structure, Body Size, and Seasonal Activity of Black Swamp Snakes (Seminatrix pygaea) Southeastern Naturalist, 4 (1), 1-14 DOI: 10.1656/1528-7092(2005)004[0001:PSBSAS]2.0.CO;2

Dodd Jr., C.K. (1993). Population structure, body mass, activity, and orientation of an aquatic snake during a drought Canadian Journal of Zoology, 71 (7), 1281-1288 DOI: 10.1139/z93-177

Photos appear courtesy of Sean Graham.