Why snakes are long (and other recent updates)

This post will soon be available in Spanish 

A Western Hog-nosed Snake (Heterodon nasicus)
depredating a turtle nest in Nebraska

As I did in March and June, I wanted to highlight some recent and exciting updates to some of my earlier articles. There is so much recent snake news this month, which is lucky for me because I've been writing my dissertation, which I'll be defending next month, so I haven't had much time to write. anything else! I hope to return to longer-form content in October.

Also, although I rarely promote my own research on this blog, I'm very excited to have just published the second chapter of my masters thesis, documenting the diet of Western Hog-nosed Snakes (Heterodon nasicus) in Illinois using stable isotopes to quadruple our sample size. We showed that the diet of juveniles was composed mostly of Six-lined Racerunners (Aspidoscelis sexlineata) and their eggs, whereas adults mostly feed on aquatic turtle eggs! Surprisingly, we found very little evidence that these snakes were eating amphibians, which are considered to be staples of their diet elsewhere.

Snake Genomes, Lizards of Glass, and Why Snakes are Long

Variation in the length of different vertebrate bodies,
including a Rosy Boa (Lichanura)
From Head & Polly 2015

Researchers from the Gulbenkian Institute of Science in Portugal used data from the king cobra and Burmese python genomes as part of new research that's too meta for me not to write about. The developmental biology of snakes deserves a whole article (and, indeed, is the subject of an entire book chapter), but snake development is uniquely interesting from the perspective of understanding the evolution of both limblessness and body elongation. A very recent article in the journal Developmental Cell shed light on the genetic regulation of body length in vertebrates, which varies from a dozen or fewer in humans and most vertebrates to over 200 in many snakes and caecilians and exceeds 400 in some snake species.

For a long time, scientists thought that Hox genes, which control many aspects of body layout and development, probably controlled body length too. But, so far experiments modifying Hox genes have failed to produce differences in body length, and most snake Hox genes are not substantially different from those of other vertebrates. Instead, the new study showed that the "junk DNA" surrounding a different gene, called Oct4, apparently influences body length in developing vertebrate embryos. Although the Oct4 gene itself was already known to play a role in regulating stem cell flexibility, the surrounding DNA was formerly considered to be "junk DNA" because it was not translated into RNA and seemed to have no purpose. Measurements showed that Oct4 is active for longer in developing snake embryos than in mouse embryos, which is probably what causes their bodies to grow so long. And, just by copying snake "junk DNA" into mouse embryos, the researchers were able to artificially increase both the level of expression of Oct4 in mouse embryos as well as the length of their bodies. Comparing the genomes of snakes, lizards, and mammals showed that the Oct4 "junk DNA" of snakes differed from that of lizards and mammals. Interestingly, glass lizard (Ophisaurus) Oct4 "junk DNA" was similar to that of geckos and anoles, even though these limbless lizards share an elongated snake-like body form with snakes.

Conservation Successes with Indigo Snakes

Seasonal variation in the probability of moving of female (top)
& male (bottom) Eastern Indigo Snakes (Drymarchon couperi)
in Florida. From Bauder et al. 2016

Many snakes make seasonal movements to and from hibernacula, in search of food or mates, or for other reasons. Often, we think of these movements as driven by the changing of seasons, either the wet and dry seasons in the tropics or the four well-defined temperate seasons. But, we don't know much about the seasonal movements of snakes that live in tropical and sub-tropical zones. For a species with such a small range, Eastern Indigo Snakes have fairly different requirements in the northern part of their range, where frosty Georgia winter nights force them to rely on deep, warm Gopher Tortoise (Gopherus polyphemus) burrows, and in sub-tropical peninsular Florida, where they are less reliant on such particular shelters. A recent study by a group of Florida scientists, including Orianne Society staff, used radio-telemetry to document a seasonal pattern of movement in Florida Indigo Snakes that differs from their pattern in Georgia. In particular, male Florida Indigos are most likely to move in the late fall and early winter, when they are searching for mates, whereas both males and females stay put during the spring, for reasons yet unknown. In contrast, Indigos in the rest of their range maintain small winter home ranges on xeric sandhills but use much larger home ranges and a greater diversity of habitats during the rest of the year.

Malagasy Leaf-nosed Snakes

A female Langaha pseudoalluaudi
Photo from iNaturalist

Global all-taxa citizen science portal iNaturalist's observation of the week this week was a very rare snake indeed, a photograph of Langaha pseudoalluaudi. Less than two dozen other individuals of this species have ever been found by scientists. The first was collected in 1966 and described in 1988, and the second individual was photographed in 2003 by a Durrell Wildlife Conservation Trust biologist. Since that time, a handful of other records have trickled in from the field in Madagascar, including a few photos on Flickr and the only known photo of a male, published in a field guide in 2007. This individual was found by group of Operation Wallacea volunteers on a conservation research expedition, one of whom, Victoria Jackson, a student of Biological Sciences at the University of Exeter, posted it on iNaturalist. Of the three species of Langaha, none of which are particularly well-known, L. pseudoalluaudi is by far the rarest and most poorly-known. Perhaps the most fascinating aspect of Langaha biology is their obvious anatomical sexual dimorphism, a feature that is very rare among snakes. Females of all three Langaha species have a serrated snout that resembles a small flower that has not fully bloomed. Female L. pseudoalluaudi also have protruding horn-like scales above their eyes. Males have smooth, pointed snouts instead that resemble the seed pods of a Madagascan legume. We have very little idea why these snakes might be sexually dimorphic—the nose ornaments could be shaped by sexual selection, or they might function to make the snakes more cryptic to predators or prey, if the sexes forage or hide in different environments or on different foods.

Do Snakes Sleep?

Sleep in Bearded Dragons
From Shine-Idelson et al. 2016

There has only ever been one study of sleep in snakes. It was conducted in France in 1969 on an African Rock Python (Python sebae), which produced sleep-like brain waves almost 16 hours a day, increasing to over 20 hours following feeding. The data suggest that these brainwaves corresponded with slower breathing and heart rate, some muscle relaxation, and perhaps a lowered behavioral response threshold. There was no evidence for REM sleep in this snake. Evidence for REM sleep in other reptiles is mixed. The April 29th issue of Science contained new data from the Max Planck Institute for Brain Research documenting slow-wave and rapid eye movement (REM) sleep in Bearded Dragons (Pogona vitticeps). [Edit 4/19/2017: This research has since been criticized for failing to exclude the possibility that putative REM sleep was actually partial or full awakenings from sleep, which looks very similar.] This is pretty cool because Bearded Dragons and snakes might be pretty close relatives (if phylogenetic trees using molecular data are to be believed) and it suggests that not only do reptiles definitely sleep, they may also dream. Previously, scientists had hypothesized that slow-wave and REM sleep evolved independently in birds and mammals and, like parental care, could be linked to endothermy. The unequivocal [see above edit] evidence for these sleep phases in reptiles suggest that REM sleep evolved much earlier and probably only once. The senior author on the study, neuroscientist Gilles Laurent was quoted as saying "If you forced me to speculate and to use a loose definition of dreaming, I'd speculate that [Bearded Dragon] dreams are about recent notable events: insects, maybe a place where there are good insects, an aggressive male in the next terrarium, et cetera. If I were an Australian dragon living in Frankfurt, I'd be dreaming of a warm day in the sun."

The 9,999th Reptile

Geophis lorcana
From Canseco-Márquez et al. 2016

Snake species number over 3,600 this month, in part because of the description of a new species of Geophis from Mexico. The beautiful Geophis lorcana is the 50th species in the genus Geophis and the 8th new species in that genus since the turn of the century. It was discovered in the cloud forests of the Sierra Zongolica and Sierra de Quimixtlán mountains by biologist Miguel Ángel de la Torre Loranca, in whose honor the new species is named. Like other Geophis, this snake is fossorial and secretive, and has a small geographic range. Further exploration of this region combined with molecular and anatomical data is likely to yield additional new species, although the habitats in which they are likely to be found are vulnerable to a variety of threats. Other new snake species from the past year include 10 new blindsnakes in the genus Epictia from Central and South America, a new boa from the Bahamas that sheds light on the island biogeography of the Caribbean, and a new species of Neotropical watersnake (genus Helicops) whose specific epithet is taken from one of Tolkien's Elvish languages.

Identifying Snake Sheds

Antaresia stimsoni inside its shed skin
Video still from Alice Springs Reptile Centre

It's not peer-reviewed research, but a recent video from the Alice Springs Reptile Centre in Alice Springs, Australia showed an unusual occurrence—a shedding Stimson's Python (Antaresia stimsoni) that seemed to have gotten stuck inside of an endless loop of its own shed skin. The snake must have crawled into the mouth orifice of the shed skin before it finished shedding the skin from the posterior part of its body. According to a Facebook post, the Alice Springs Reptile Centre staff reported that they had not observed this phenomenon before and that the python was able to free itself after about three hours of crawling in a circle by making a small, tidy exit hole in the shed. The video was featured on the popular IFLS science fan site.

ACKNOWLEDGMENTS

Thanks to John Iverson for the use of his photo.

REFERENCES

Female Langaha pseudoalluaudi
From its original description
in Domergue 1988

Aires, R., Jurberg, Arnon D., Leal, F., Nóvoa, A., Cohn, Martin J. & Mallo, M. (2016) Oct4 is a key regulator of vertebrate trunk length diversity. Developmental Cell, 38, 262-274 <link>

Aulsebrook, A. E., T. M. Jones, N. C. Rattenborg, T. C. Roth, II, and J. A. Lesku. Sleep Ecophysiology: Integrating Neuroscience and Ecology. Trends in Ecology & Evolution 31:590-599 <link>

Bauder, J.M., Breininger, D.R., Bolt, M.R., Legare, M.L., Jenkins, C.L., Rothermel, B.B. & McGarigal, K. (2016) Seasonal variation in Eastern Indigo Snake (Drymarchon couperi) movement patterns and space use in peninsular Florida at multiple temporal scales. Herpetologica, 72, 214-226 <link>

Canseco-Márquez, L., C. J. Pavón-Vázquez, M. A. Lòpez-Luna, and A. Nieto-Montes de Oca. 2016. A new species of earth snake (Dipsadidae, Geophis) from Mexico. ZooKeys 610:131-145 <link>

Costa, H. C., D. J. Santana, F. Leal, R. Koroiva, and P. C. A. Garcia. 2016. A New Species of Helicops (Serpentes: Dipsadidae: Hydropsini) from Southeastern Brazil. Herpetologica 72:157-166 <link>

Domergue, C. A. 1988. Notes sur les serpents de la région malgache. VIII: Colubridae nouveaux. Bulletin du Muséum national d'histoire naturelle. Section A, Zoologie, biologie et écologie animales 10:135-146 <link>

Durso, A. M. and S. J. Mullin. 2016. Ontogenetic shifts in the diets of Plains Hog-nosed Snakes (Colubridae: Heterodon) revealed by stable isotope analysis. Zoology DOI:10.1016/j.zool.2016.07.004 <link>

Head, J. J. and P. D. Polly. 2015. Evolution of the snake body form reveals homoplasy in amniote Hox gene function. Nature 520:86-89 <link>

Held Jr., L. I. 2014. The snake. Pages 75-94 in L. I. Held Jr., editor. How the Snake Lost its Legs. Cambridge University Press, Cambridge <link>

Kuchling, G. (2003) New record, range extension, and colouration in life of Langaha pseudoalluaudi (Reptilia: Colubridae) in north-western Madagascar. Salamandra, 39, 235-240 <link>

Reynolds, R. G., A. R. Puente-Rolón, A. J. Geneva, K. J. Aviles-Rodriguez, and N. C. Herrmann. 2016. Discovery of a Remarkable New Boa from the Conception Island Bank, Bahamas. Breviora 549:1-19 <link>

Shein-Idelson, M., Ondracek, J.M., Liaw, H.-P., Reiter, S. & Laurent, G. (2016) Slow waves, sharp waves, ripples, and REM in sleeping dragons. Science, 352, 590-595 <link>

Wallach, V. 2016. Morphological review and taxonomic status of the Epictia phenops species group of Mesoamerica, with description of six new species and discussion of South American Epictia albifrons, E. goudotii, and E. tenella (Serpentes: Leptotyphlopidae: Epictinae). Mesoamerican Herpetology 3:216-374 <link>

Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

Blog Carnival: Ecology of Snake Sheds

Clic aquí para la edición española

Today I am participating in my first Blog Carnival (or blogero, click here for the Spanish edition), which is called #SnakesAtYourService and is about the roles snakes play in ecosystems. Check out the links to the other posts below.

I've already written a series of posts about identifying snake sheds, which is definitely the most common question people ask about them (those three posts make up over a third of all the traffic on this site). People ask other questions about snake sheds much more rarely. In fact, I never stopped to ask some basic questions myself. What are snake sheds made of? What are they used for, and by whom? Where are they found? Do they make substantial contributions to ecology? You might think that because snake sheds are so insubstantial that they don't have much of an impact, but several facts about snakes lead us to believe otherwise.

Part I: Contributions to nutrient cycling

Oodles of Black Swampsnakes (Seminatrix pygaea)
from Ellenton Bay, South Carolina

Snakes can occur at high densities, although their population density can be difficult to measure because snakes are so hard to find. Some estimates provided by snake population ecologist JD Willson in his dissertation included 4-14 vipers per hectare in Scandinavia, 275 vipers per hectare on Shedao Island in China, and over 1000 ring-necked snakes per hectare in Kansas. Aquatic snakes in Ellenton Bay, South Carolina, where I did my undergraduate field research, can reach densities of  170 snakes/ha. I did a couple of back-of-the-envelope calculations using these estimates, plus those for snake shed frequency and shed energetic content, and found that all snakes shedding across the entire continental United States probably generate close to 1.6 billion pounds of shed skin each year, which contain about 3.6 trillion calories of energy. That's enough for everyone in Alabama to survive eating nothing but snake sheds every day all year long (ma, not this for dinner again!), if they could somehow collect all the snake sheds from the entire country. So it isn't an unimaginably immense amount of energy, but it's not insubstantial either. Given the results of this rather bizarre thought exercise, I think it's safe to say that shed snake skin contributes substantially to nutrient cycling in areas where snakes frequently shed.

A food web showing snakes as top predators

What exactly do I mean by nutrient cycling? Think of it as nature's ultimate recycling. It's one example of the services that ecosystems provide for free, and it's why you have regular access to clean water to drink, air to breathe, food to eat, and other essentials, without having to manufacture or engineer systems to produce these things. The cycles of carbon, nitrogen, sulfur, and other elements in and out of the water, air, soil, and the bodies of plants, animals, and microbes, are critical to maintaining a healthy ecosystem. Perturbations can lead to serious imbalances, like the changes to the global carbon cycle that result from the burning of fossils fuels. Few people have investigated the roles that amphibians and reptiles play specifically in nutrient cycling, but we are beginning to suspect that they are important components of many ecosystems. They may be small, but there are a lot of them. For instance, redback salamanders in forests in the northeastern US outnumber all other terrestrial vertebrates combined. On some tropical islands, lizards occur at densities of over 67,000 per hectare. Snakes can occur at really high densities as well, partly because they are so efficient at converting food into biomass as a result of being ectothermic (cold-blooded) and partly because feeding as infrequently as they do reduces the effects of competition with other snakes. By one estimate, snakes are 25 times more efficient at turning food into biomass than carnivorous mammals of equal size, and occur at population densities 20 – 1400 times greater, meaning that they probably contribute disproportionately to nutrient cycling. Explicit investigation of this phenomenon is underway in turtles, which have large bony shells that probably contribute to cycling of calcium and phosphorus, but to my knowledge no one has so far studied this in any snake, let alone for shed snakeskin.

A red-tailed green ratsnake (Gonyosoma oxycephalum)
sheds its skin

In the wild, shed snake skins disintegrate in about a week, although if you collect one and put it in a plastic bag, they can last decades. The chemical composition of snake sheds is poorly known, but they contain some keratin and some lipids, among other things. Some fungi feed on keratin, including those that cause athlete's foot and ringworm as well as the chytrid fungus that has caused amphibian declines worldwide (with disastrous consequences for the snakes that specialize on them), but these species mostly grow on living organisms. Although we don't know for sure, it seems likely that numerous fungi and microbes have probably evolved to take advantage of the abundant energy found in snake sheds. Of course, the dead bodies of the snakes themselves also eventually contribute to nutrient cycling, but depending on the source of mortality, many of those are probably eaten by predators, and fewer probably decompose compared with snake sheds.

Part II: Use by other animals

An Eastern Indigo Snake (Drymarchon couperi)
getting ready to shed

Snakes shed their skin in order to grow bigger. You do this too, just not all in one piece. Once a snake sheds its skin, it's typically done with it. However, both snakes and you might be surprised to learn that snake sheds are frequently used by other animals for a variety of purposes. As I mentioned previously in my article on conservation successes with Eastern Indigo Snakes, snake sheds are really smelly, and specially-trained dogs can sniff out even individual scales left over from a decomposing snake shed. This might be one reason that, although snakes usually spend several days inactive at their shedding site prior to shedding, they don't normally hang around for long afterwards - their predators might have an easier time finding their stinky sloughs than they would finding the snakes themselves. This could be especially true when those predators are other snakes. Some evidence suggests that dogs have an easier time sniffing out snake skins than actual snakes - the indigo-snake -sniffing dogs correctly identified a concealed snake 4 out of 5 times, but they got the sheds right every time. Dogs have also been used to help search cargo on Guam for hitchhiking Brown Tree Snakes, an invasive species which has spread around the Pacific. No word on whether the Brown Tree Snakes were shedding or how this affected the dogs' ability to smell them.

Most shedding sites are protected in some way, because snakes are vulnerable prior to shedding - they cannot see and other functions may be impeded as well. Shed sites used by Black Ratsnakes in Ontario include old barns, old mining machinery, cracks in building foundations, old hay piles, large hollow logs, rock crevices, and standing dead trees. Most of these things sound like something somebody might want to "clean up", but the fact is that they are important habitat features that many amphibians and reptiles use for shedding and also for hibernation. Many burrowing snakes come to the surface to shed, and shedding snakes may remain on the surface even during cold weather, when other snakes have retreated underground.

Sometimes other animals exploit the stink of snake sheds. Ground squirrels in California use them to scent themselves - first they chew up shed rattlesnake skins, then vigorously lick their own fur, which results in  a type of olfactory camouflage that reduces a rattlesnake's ability to correctly identify snake-scented ground squirrels as prey. Rattlesnakes and ground squirrels in California are partners in a coevolutionary relationship that goes back millions of years and has been well-studied by scientists from both the predator's and the prey's point-of-view.

A Great-crested Flycatcher nest with several
snake sheds

Birds use snake sheds in their nests, something people have noticed since at least as far back as the 1800s. Although birds cannot smell, ornithologists (who should study snakes more often) wondered whether the shed skins helped protect eggs or nestling birds by deterring would-be predators. Recently, two experiments have helped determine which predators might be frightened off and whether the strategy really works. Ecologists at Arkansas State University conducted a study to test whether snake skin is an effective deterrent to predators. They found that flying squirrels, a major nest predator, ate the eggs out of 20% of nests without sheds, but didn't depredate any nests with sheds. Because flying squirrels are themselves vulnerable to predation by snakes, this makes intuitive sense. Interestingly, they also noticed that the deterioration rate of the snake skins in their experimental nest boxes (which were not occupied by birds) was much faster than that in real nests, where birds were actively raising chicks. Many of the sheds were eaten by ants, which would probably have been eaten by birds maintaining active nests. Ornithologists in Slovakia found opposing results - nests of great reed warblers festooned with snake sheds were no more or less likely to be depredated by birds and small mammals. However, over a third of reed warblers incorporated grass snake (Natrix natrix) sheds into their nests. When given a choice, two thirds of female reed warblers elected to use sheds left near their nests, whereas only 10% used ribbons of a similar length and color. If they weren't deterring predators, what were they for? The researchers suggested that because snake skins were mainly incorporated by female birds early in the nest-building process, they may have functioned as a signal to male reed warblers that the nest-builder was good at finding rare nest materials, which might lead the male to invest more heavily in helping share the duties of parental care later on in the nesting season.

This holiday season, you can choose from a variety
of snake shed jewelry for that special someone

Humans use snake sheds too. Because of their many similarities with the outermost layer of human skin, shed snake skins are used as model membranes in membrane permeability research, which primarily includes studies of ways to better transport pharmaceuticals into target cells, including some drugs that are inspired by or derived from snake venom (another ecosystem service). Snake sheds are a good alternative to using human, mouse, or synthetic skin, because they are cheap, large, and lack hair. This work is just one of many examples of snakes being used as model organisms to study general concepts in biology. Snake sheds can also be very aesthetically pleasing - many people have taken to creating beautiful snake shed jewelry.

Finally, snakes are themselves very olfactory creatures. Skin lipid pheromones have been shown to play important roles in male combat and in mating behavior, which could mean that sexual selection could act on these chemicals, creating species-specific diversity and dimorphism between males and females, which is mostly lacking in other snakes (except for a few species, including Langaha from Madagascar, where snake play many important cultural and ecological roles). Because most of these pheromones are in the skin, what's the potential for snakes to use their shed skins to mark territories, communicate information about their reproductive stage, select ambush sites, or perform other functions? Really, no one knows. Although territoriality is not the norm in snakes, some species have been suggested to be territorial and others may exhibit other types of social behavior. I hope that by understanding more about the important roles snakes play in ecosystems, people attending this carnival will be more likely to see them as valuable and less likely to fear them. As I hope I've been able to communicate, the old axiom that 'the only good snake is a dead snake' is just not true.

ACKNOWLEDGMENTS

Thanks to JD Willson, Angie Luebben, and Volker Wurst for their photographs and to everyone who helped publicize this blog carnival. A special thanks to the other #SnakesAtYourService blog carnival participants. Be sure to check out their contributions:

Social Snakes: Good Neighbors Make a Greater Impact: How Viper Behavior Increases Their Effect on Prey Populations by Melissa Amarello, @socialsnakes

Living Alongside Wildlife: Kingsnakes Keep Copperheads in Check by David Steen, @AlongsideWild

Nature Afield: Pythons as Model Organisms by Heidi Smith, @HeidiKayDeidi

Ophidiophilia: Converting Ophidiophobes to Ophidiophiles, One Kid at a Time by Emily Taylor, @snakeymama

The Traveling Taxonomist: Snakes of Madagascar: Cultural and Ecological Roles by Mark Scherz, @MarkScherz

Strike, Rattle, & Roll: Snakes and the Ecology of Fear by Bree Putman, @breeput

Australian Museum: When the Frogs Go, the Snakes Follow by Jodi Rowley, @jodirowley

SnakeBytes: The Brown Tree Snake of Guam by Brian Barczyk (@SnakeBytesTV) 

REFERENCES

Blem, C. R. and M. P. Zimmerman. 1986. The energetics of shedding: energy content of snake skin. Comparative Biochemistry and Physiology Part A: Physiology 83:661-665 <link>

Blouin-Demers, G. and P. Weatherhead. 2001. Habitat use by black rat snakes (Elaphe obsoleta obsoleta) in fragmented forests. Ecology 82:2882-2896 <link>

Clark, R. W. 2007. Public information for solitary foragers: timber rattlesnakes use conspecific chemical cues to select ambush sites. Behavioral Ecology 18:487-490 <link>

Clucas, B., D. H. Owings, and M. P. Rowe. 2008. Donning your enemy's cloak: ground squirrels exploit rattlesnake scent to reduce predation risk. Proceedings of the Royal Society B: Biological Sciences 275:847-852 <link>

Engeman, R. M., D. V. Rodriquez, M. A. Linnell, and M. E. Pitzler. 1998. A review of the case histories of the brown tree snakes (Boiga irregularis) located by detector dogs on Guam. International Biodeterioration & Biodegradation 42:161-165 <link>

Itoh, T., J. Xia, R. Magavi, T. Nishihata, and J. H. Rytting. 1990. Use of shed snake skin as a model membrane for in vitro percutaneous penetration studies: comparison with human skin. Pharmaceutical Research 7:1042-1047 <link>

Medlin, E. C. and T. S. Risch. 2006. An experimental test of snake skin use to deter nest predation. The Condor 108:963-965 <link>

Stevenson, D. J., K. R. Ravenscroft, R. T. Zappalorti, M. D. Ravenscroft, S. W. Weigley, and C. L. Jenkins. 2010. Using a wildlife detector dog for locating Eastern Indigo Snakes (Drymarchon couperi). Herpetological Review 41:437-442.

Trnka, A. and P. Prokop. 2011. The use and function of snake skins in the nests of Great Reed Warblers Acrocephalus arundinaceus. Ibis 153:627-630 <link>

Willson, J. D. 2009. Integrative approaches to exploring functional roles of clandestine species: a case study of aquatic snakes within isolated wetland ecosystems. PhD dissertation, University of Georgia, Athens, GA <link>

Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.

What the State Snakes Should Be: Part I

Click here to read this post in Spanish!
Haga clic aquí para leer este blog en español!

The 50 United States have various state symbols, including state trees, flowers, songs, drinks, and even fossils. Just over half the states have a state reptile, and none have a state snake (although a few of the state reptiles are snakes). This post was inspired by the witty and spot-on post 'The State Birds: What They SHOULD Be' from thebirdist.com, which struck a chord with me because I've always been underwhelmed by the state birds, many of which are uncreative and absurd. The selection of state reptiles has been characterized by the same lack-of-creativity, bordering on willful ignorance of a state’s unique and endemic biodiversity, as the selection of state birds. In fact, it's probably worse, since most people can at least name several different kinds of birds whereas even distinguishing reptiles from amphibians or fishes (or worms) is apparently beyond many. Perhaps having a state snake would help remedy this problem as well as improve upon the massive and undeserved PR problem faced by snakes in general.

At the risk of catalyzing a scandal on par with my home state of North Carolina's State Fruit Fiasco of 2001, which in an effort not to alienate any of several fruit growing lobbies resulted in an official state red berry (the strawberry), state blue berry (wait for it…the blueberry), and state fruit (the scuppernong grape), I've taken the liberty of choosing a state snake for each of the 50 U. S. states, 44 of which I've been to and almost half of which I've caught snakes in. This was surprisingly hard to do, because some snakes have too many good choices and others have too few. I used the same rules as thebirdist: I didn't repeat any species. Feel free to chime in with your opinion about what your state's snake should be, if it differs from my choice.

1. Alabama. Eastern Diamond-backed Rattlesnake (Crotalus adamanteus)

Crotalus adamanteus

The Eastern Diamondback is iconic in the southeast, appearing on America's first flag, the Gadsden flag (better known as the 'Don't Tread on Me' flag) and in the first political cartoon appearing in an American newspaper (Ben Franklin's 'Join, or Die'). State symbolism of the world's largest rattlesnake might help abate pressure from rattlesnake roundups in Alabama and other states, which have caused declines so serious that this species has been considered for listing under the Endangered Species Act.

2. Alaska. Northwestern Gartersnake (Thamnophis ordinoides)

Thamnophis ordinoides

Alaska's only got one snake, and I do mean one: a road-killed juvenile gartersnake was found outside of Haines, Alaska, in August of 2005. The poor condition of the specimen prevented a positive identification based on morphology alone, so some of my colleagues including my fellow USU graduate student Lori Neuman-Lee sequenced genes from the snake and identified it as a T. ordinoides. This highly variable species eats mostly slugs. Because the closest known population of Northwestern Gartersnakes is over 600 miles south of Haines, the snake might have been transported there accidentally. However, reports of gartersnakes on the banks of the Taku and Stikine rivers in Alaska, including one ostensibly vouchered (now lost) specimen, keep the door open for future discovery of a naturally occurring population of snakes in The Last Frontier. Don't lose hope, Alaska! If nothing else, gartersnakes from British Columbia will probably disperse there eventually if climate change keeps up the way it's been going.

3. Arizona. Arizona Ridge-nosed Rattlesnake (Crotalus willardi)

Crotalus willardi

This actually is the state reptile of Arizona! Way to go, Arizona! This snake is a phenomenal choice for its beauty and uniqueness. Principally a Mexican species, it is found in scattered, isolated "Sky Island" mountain ranges separated by uncrossable desert. Former Staten Island Zoo reptile curator and herping godfather Carl Kauffeld, in his classic 1957 memoir Snakes and Snake Hunting, called this species "sublime" and said of finding one that "no greater triumph is possible". It was the last rattlesnake species discovered in the United States, in  1905 (just as the "Baby State," as it was once known, was one of the last states to enter the union, seven years after C. willardi was discovered). These small rattlesnakes grow to be only one to two feet long and as a result are relatively unthreatening. Few bites have been recorded, none serious, although I wouldn't go picking one up. Runner up: Glossy Snake (Arizona elegans), which shares its genus name with the state.

4. Arkansas. Cottonmouth (Agkistrodon piscivorus)

Agkistrodon piscivorus

When I asked my colleague Geoff Smith, a native Arkansan, about snakes iconic to Arkansas, he first informed me that, as someone born above the Arkansas River, he was an Arkansawyer rather than an Arkansan. He went on to suggest that the Cottonmouth was a good choice because every snake someone sees in Arkansas is identified as a Cottonmouth (a joke that is all too true, poor Nerodia). He also suggested some similarities between Arkansans and Cottonmouths: they stink¹, they're fat, they like to eat fish. I decided not to contradict him because 1. I haven't been to Arkansas, and 2. he's from there so he can say that. In the end, we decided that a generalist state needed a generalist snake. Because Arkansas' diverse landscapes encompass the range edges of many species that are more characteristic of other places (for example, Queensnakes, Coralsnakes, and Western Diamond-backed Rattlesnakes can all be found in the state), choosing a widespread generalist is appropriate. I know of few better examples than the Cottonmouth, a denizen of river swamps that eats a variety of other vertebrates. Furthermore, Cottonmouths might have the worst PR problem of any snake: in addition to being misidentified, they suffer from exaggerated accounts of their aggression, size, breeding habits and even basking behavior ("A Water Moccasin tried to get in my boat!"). State snakehood might help with that.

5. California. Giant Gartersnake (Thamnophis gigas)

Thamnophis gigas

This largest of gartersnakes is endemic to California's Central Valley, where it historically occupied tule marshes but today persists mostly in rice fields and their associated canals and drains, where it mostly eats introduced fishes and Bullfrogs. Because of the massive agricultural use of this area, this species has lostmuch of its habitat and is on the edge of extinction, so it could use some positive PR. It is highly aquatic, with habits more similar to eastern Nerodia watersnakes than to its  western congeners - the same could be said of many Golden State residents in terms of their political opinions and attitudes.

6. Colorado. Great Plains Ratsnake (Pantherophis emoryi)

Pantherophis emoryi

Once considered a western subspecies of the Cornsnake, Great Plains Ratsnakes were re-elevated to full species status in 2002 by College of Staten Island snake taxonomist Frank Burbrink. Although Colorado's majestic landscapes are home to many beautiful snakes, not one but two geographically-separated forms of Great Plains Ratsnakes are found in the state: the larger, more brightly colored nominate subspecies in the high plains and tablelands of southeastern Colorado, and the smaller, drabber Intermountain Ratsnake (P. e. intermontanus) on the Colorado Plateau in the west-central part of the state. Originally named by Baird & Girard for surveyor and U.S. Army officer William H. Emory, these large constrictors are more subtly colored than other ratsnakes but just as harmless and beautiful.

7. Connecticut. Northern Watersnake (Nerodia sipedon)

Nerodia sipedon

Northern Watersnakes are some of the most common snakes in eastern North America. Found in almost every aquatic habitat, they are frequently seen basking on fallen logs, from which they will drop into the water at the slightest provocation. Leo Finneran reported this species from the Branford area in the 1940s, saying that it was "a very common snake occurring along water bodies in all parts of the town" and noting that some carried heavy loads of parasites, which is common in watersnakes. You can remember how to tell this species from its southern counterpart because the bands across its back fail to connect near the tail. OK, I'm stretching a bit for this one. Keep reading, it gets better.

8. Delaware. Copperhead (Agkistrodon contortrix)

Agkistrodon contortrix

Delaware was the first state, and the Copperhead is the first snake you should learn to identify if you live within its range. Delaware's Brandywine Valley is reminiscent of New England, whereas its middle and lower parts resemble the tidewater South. Both regions are inhabited by Copperheads, which are found from New York to Texas, where they are the most common venomous snakes in many suburban areas. Due to the high encounter rate, more than a third of U. S. venomous snakebites are from Copperheads. Fortunately, they seldom require antivenin, because they have the least potent venom of any North American viper, and the fatality rate is negligible. Furthermore, the vast majority occur when someone deliberately attempts to handle or kill the snake. In this way, Copperheads and their relatives are distinctly "antiwar," eponymous as they are of the vocal antebellum Democrats that once represented Delaware and other Union states in Congress.

9. Florida. Eastern Coralsnake (Micrurus fulvius)

Micrurus fulvius

Florida as a state is unlike any other U. S. state. Coralsnakes are unlike any other North American snakes - they are more closely related to cobras and sea snakes, which live on other continents or in the oceans. They're also brightly colored, like the iconic pink flamingos often seen on Sunshine State lawns. Coralsnakes spend most of their time underground and are difficult to find. When asked how to see one in the wild, most herpers reply: "Go to Florida." Although Coralsnakes are quite venomous, they are secretive and non-aggressive, so very few Coralsnake bites ever occur. Runners up: Short-tailed Snake (Lampropeltis [Stilosoma] extenuatum) or Rim Rock Crowned Snake (Tantilla oolitica), both endemic to the state.

10. Georgia. Eastern Indigo Snake (Drymarchon couperi)

Drymarchon couperi

The largest snakes in North America and literal "lords of the forest" (from the Greek drymos: forest and archos: commander), Eastern Indigo Snakes are in decline due to habitat loss and fragmentation. Georgia boasts some of the best remaining indigo habitat (both Fort Stewart and Fort Benning harbor large, unfragmented tracts of longleaf pine savanna with healthy populations of Gopher Tortoises, the actual Peach State reptile and the burrows of which these snakes depend upon) and the headquarters of the Orianne Society, a non-profit formed to help conserve indigo snakes and other rare reptiles.

11. Hawaii. Yellow-bellied Sea Snake (Pelamis platura)

Pelamis platura

This is the Aloha State's only native snake, making it a pretty easy choice. It's also awesome! Yellow-bellied Sea Snakes are the only pelagic snakes, and the most widely distributed and specialized of the sea snakes. They are most commonly seen in Hawaiian waters in El Niño years, when average water temperatures are in the upper 70s. Pelamis have fast-acting venom that they use to kill fishes. They shed their skin often to remove barnacles, using a knotting behavior to compensate for the absence of objects to brush against in the open ocean. Paying homage, a Scottish tidal energy company adopted the genus name of this snake for both their company and the offshore wave energy converter itself, although the company closed its doors in 2014.

12. Idaho. Rubber Boa (Charina bottae)

Charina bottae

I've written about Rubber Boas before, but man are they cool. Some of the best research on Rubber Boa thermal biology and behavior was conducted in southeastern Idaho, and Craters of the Moon National Monument is a great place to see them. Incredibly, these snakes are active at temperatures as low as 40°F, which is good news for them given that they live in Idaho's mountains. Roughly the same color as a potato, Rubber Boas mostly eat small mammals, which they kill by constriction similar to their larger relatives, which include Anacondas and Boa Constrictors. As is fitting for the Gem State, their small, smooth scales have a rubbery shine.

13. Illinois. Prairie Kingsnake (Lampropeltis calligaster)

Lampropeltis calligaster

Illinois, like Arkansas, contains many ecoregions but is not dominated by any one that isn't more iconic of elsewhere. There are actually more species of snakes in Illinois than in many southern and eastern states, due to its mixture of northern, southern, eastern, and western ecosystems. I lived here for a while, but it was hard to pick a snake for Illinois because its habitats are so varied. Prairie Kingsnakes are common along Illinois roads and lake shores in spring. Unfortunately, many are run over by vehicles during this time, and still more are mistaken for venomous snakes are maliciously killed. In fact, these large and harmless constrictors are highly beneficial, consuming mice and voles that would otherwise overrun farms, gardens, and homes. In the agricultural desert of the Prairie State, Prairie Kingsnakes are one species that seems to do reasonably well.

14. Indiana. Eastern Ribbonsnake (Thamnophis sauritus)

Thamnophis sauritus

The slender, long-tailed ribbonsnakes share a genus with gartersnakes, from which they are not terribly different. Ribbonsnakes show a preference for wetter habitats and eat predominantly fishes and amphibians. Indiana harbors two subspecies of Eastern Ribbonsnakes, which together are found essentially throughout the state where suitable habitat still exists. Because of the Hoosier State's intensive agricultural land use, a state snake that requires intact wetlands with healthy prey populations could encourage a shift towards sustainable agricultural practices that use minimal pesticide and fertilizer and promote healthy waterways.

15. Iowa. Western Foxsnake (Pantherophis ramspotti)

Pantherophis ramspotti

These large constrictors used to be considered the same species as Eastern Foxsnakes, Pantherophis vulpinus, but were elevated to full species status by Brian Crother and colleagues in 2011. Rapid northward expansion by Foxsnakes from refugia in various southern states following the last glacial maximum has resulted in their odd modern distribution: two species apparently separated not by the gap in the range of the eastern in Michigan but by the Mississippi River. Because they no longer occupy any of the habitat where their fossils are found, it seems that Foxsnakes simply filled in the new habitat made available by the retreat of the glaciers. They had few barriers since the glaciers flattened the topography, and few states beat the Hawkeye State for flat.

16. Kansas. Milksnake (Lampropeltis triangulum)

Lampropeltis triangulum

The Red Milksnakes of Kansas are like jewels. Essentially fancy kingsnakes, these beauties are easy to find underneath large, flat rocks in prairies and fields almost throughout the state. They eat lizards as well as small mammals and other snakes, which should be easy for them to find since they all live under the same rocks. The late herpetologist extraordinaire Henry Fitch undertook detailed natural history studies of nearly every Kansas snake during his long and productive career, publishing hundreds of articles of the highest caliber, and his 1970 paper on milksnake ecology and natural history is no exception. About as popular as a snake can get, the Red Milksnake (L. t. syspila) is an easy choice for the state snake of the Sunflower State. All those states within the range of the Scarlet Kingsnake (L. t. elapsoides) only wish they weren't also home to so many other strong contenders.

17. Kentucky. Plain-bellied Watersnake (Nerodia erythrogaster)

Nerodia erythrogaster

Common elsewhere, a threatened subspecies of Plain-bellied Watersnake, the Copper-bellied (N. e. neglecta), is found in isolated spots in the western part of the Bluegrass State, as well as in adjacent areas in Illinois and Indiana. It is the most terrestrial of the ten species of watersnakes in the US, in part because it prefers frogs and toads to the other, more aquatic prey of its congeners. Uniquely among watersnakes, this species may possess resistance to toad toxin. It has been found that, atypically for a watersnake, these snakes tend to choose hibernacula close to wetlands, such as crayfish burrows and muskrat lodges. During spring floods, they are often submerged, but somehow are not drowned or swept away. The presence of these amazing snakes helps justify wetland buffers and adjacent upland conservation as part of the innovative Copperbelly Watersnake Conservation Agreement made between coal mining companies and state environmental groups within the range of the snake, particularly in Kentucky.

18. Louisiana. Louisiana Pinesnake (Pituophis ruthveni)

Pituophis ruthveni

Notable for its large eggs and small clutch sizes, the Louisiana Pinesnake is indigenous to west-central Louisiana and eastern Texas, where it relies strongly on Baird's pocket gophers for burrows and food. The Louisiana Pinesnake is rarely seen in the wild and is considered to be one of the rarest snakes in North America. The demise of the species is due to its low fecundity coupled with the extensive loss and degradation of suitable habitat, the longleaf pine savannas of the Gulf coastal plain. Now nearly a lost cause, some positive PR could help ensure that the last fragments of longleaf pine are preserved in perpetuity, for Louisiana Pinesnakes as well as their other unique flora and fauna.

19. Maine. Smooth Greensnake (Opheodrys vernalis)

Opheodrys vernalis

Although the Pine Tree State has a reputation for being snowy and cold, it is actually replete with snakes, at least in summer along its rocky coast. In the crumbling foundations of homes in old fields live many Smooth Greensnakes, a species that is a good example of the ecosystem services that snakes provide because it eats so many insects and spiders. Only a few species of snakes eat insects, this one chief among them. Less arboreal than their rough-scaled congeners, Smooth Greensnakes are quite beautiful and most people seem to know that they are harmless. A ranger in Acadia National Park found them "common" from sea level to above 1000 feet in 1938. Smooth Greensnakes are even found on Isle au Haut, a remote island in the outer reaches of Maine's Penobscot Bay first settled by Europeans in 1792, so it is likely that this is one of the first North American snakes ever seen by Europeans. Isle au Haut is home to Microneta bowditchiae, an endemic spider, which is undoubtedly eaten by the local O. vernalis.

20. Maryland. Queensnake (Regina septemvittata)

Regina septemvittata

Named for Queen Henrietta Maria of France and crisscrossed by myriad freshwater habitats, including the cool crayfish-filled streams preferred by Queensnakes, Maryland is a beautiful but densely-populated state. From the Central Appalachians in the west to the tidal marshes and barrier islands of the Delmarva peninsula and Chesapeake Bay, Maryland seems to represent the entire gamut of eastern North American habitats. Queensnakes inhabit most of these, although they are absent from the lowest and highest elevations and from brackish water. Research has shown that Queensnakes are exquisitely sensitive to the crayfish molting hormone ecdysone. Because numerous stream contaminants are known to imitate ecdysone and disrupt the arthropod molting cycle, this finding may have important implications for the conservation of Queensnakes and their conegners.

21. Massachusetts. Red-bellied Snake (Storeria occipitomaculata)

Storeria occipitomaculata

These little slug-eaters are named for a Massachusetts herpetologist, David Humphreys Storer, who wrote Report on the fishes, reptiles and birds of Massachusetts in 1839. Being one of the original 13 colonies, Massachusetts should show a little appreciation for its herpetological history. In my experience, these snakes are more common in New England's forests than they are throughout the rest of their range, particularly in Maine, which was once a part of Massachusetts. The Bay State gets kudos for actually selecting a group of snakes as their state reptile: the genus Thamnophis, the gartersnakes, is not an inapt choice, although it is a little vague.

22. Michigan: Eastern Massasauga (Sistrurus catenatus)

Sistrurus catenatus

The Eastern Massasauga Rattlesnake has declined dramatically over the last century and is critically endangered in nearly every state where it occurs. Due to human persecution and the nearly complete conversion of native wet prairie habitats to agriculture, this formerly widespread and abundant species is seemingly relegated to just a few viable populations within its historic range in Wisconsin and Illinois. Michigan is its stronghold, and state snakehood might help keep it that way.

23. Minnesota. Plains Gartersnake (Thamnophis radix)

Thamnophis radix

These beautiful gartersnakes are common in the plains of southern Minnesota. In northwestern part of the Land of 10,000 Lakes, the prairie-forest ecotone is characterized by the westward extension of the forests, which terminate roughly along the Big Stone Moraine, from which scattered areas of relict prairie form "fingers" that extend eastward into the woodland. Both Plains and Common (T. sirtalis) Gartersnakes co-occur there, but are not usually found together in high densities, perhaps because the diets of both species consist essentially of the same items: earthworms, minnows, and frogs. Unfortunately, Minnesota's many lakes (the combined shorelines of which exceed those of California, Florida, and Hawaii combined) are too cold, young, and oligotrophic to support any endemic snakes.

24. Mississippi. Mudsnake (Farancia abacura)

Farancia abacura

The Mississippi Mudsnakes has a good ring to it. Found in swamps, which abound in the western part of Mississippi, these gorgeous snakes eat mostly giant aquatic salamanders such as sirens and amphiumas. Seldom seen, their name belies their fabulous coloration, which more than compensates for their clandestine nature. Any state in their range would be proud to honor the Mudsnake with a state snakehood. Mudsnakes prefer still, acidic waters with aquatic vegetation and bottom debris. They also occur along small, acidic streams with swampy edges. Runner up: The Mississippi Green Watersnake (Nerodia cyclopion) shares its name with the state.

25. Missouri. Lined Snake (Tropidoclonion lineatum)

Tropidoclonion lineatum

Little is known about the tiny Lined Snake, a small relative of watersnakes and gartersnakes whose scientific name is longer than it is. Little is left of their original habitat, wet prairies, now mostly converted to agriculture. Lined Snakes, often incongruously misheard as "lion snakes," are secretive and semifossorial. The Forest Park neighborhood of St. Louis, south of the zoo and near the wonderful Turtle Park, was built on a hill during the 1920s and harbors a dense population due to the relatively light disturbance to the area's soil, so many urban residents of this city and others in the Show-Me State could show themselves their state snake by turning over paving stones or garden gnomes in their yard or garden.

Stay tuned, faithful reader, for Part II!

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1 Life is Short but Snakes are Long does not officially endorse the views of interviewed persons.^↩

ACKNOWLEDGMENTS

Thanks to photographers Dave Irving, JD Willson, Todd Pierson, James Turek, Lost Springs Ranch, Jason Folt, David Jahn, Jonathan Mays, Atrox, Eric Vanderduys, and Nathanael Herrera.

Life is Short, but Snakes are Long by Andrew M. Durso is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.