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Friday, July 1, 2016

What the Provincial Snakes of Canada Should Be

This post will soon be available in Spanish!

In case, like many Americans, you need a map
Happy Canada Day! And indeed there is a lot to celebrate, in particular Canada's new liberal government and the positive effects it has had on science and the environment. Three summers ago, I wrote in two parts (I and II) about what the symbolic snakes of each of the US states should be, inspired by the witty and spot-on post 'The State Birds: What They SHOULD Be' from thebirdist.com. In response to a tweet from Canadian Field Naturalist, a journal that publishes ecology, behaviour, taxonomy, conservation, and other topics relevant to Canadian natural history, and because Canadian provinces also have various representative symbols (none reptilian, except for the feathered kind, which I might add are somewhat better chosen than those of the US states), this summer I decided to cover the US's northern neighbor as well. Does Canada even have any snakes, you might ask? In fact, Canada is home to 27 species of snake, which might surprise those of us who have grown up in regions farther south. That's enough for every province and territory to have two provincial snakes, with one left over, although the uneven geographic distribution of species precludes that, as we'll see. I followed the same "no duplication" rule as I did for the State Snakes, but I allowed snakes that had been used as U.S. State Snakes to be used again, because almost all of the species found in Canada had also been used for a U.S. state. Feel free to chime in with your opinion about what your favorite province's snake should be, if it differs from my choice.

1. Alberta. Prairie Rattlesnake (Crotalus viridis)

Prairie Rattlesnake (Crotalus viridis)
Alberta, well-known for its dinosaurs, also harbors a fairly substantial diversity of modern reptiles for a place with such long winters. Seven species of snake can be found in the province, but perhaps the most quintessential are Prairie Rattlesnakes. Prairie Rattlesnakes in Alberta occur in shortgrass prairies, dry grasslands, and sagebrush in the southeastern part of the province. At the northwestern edge of their range, Prairie Rattlesnakes in Alberta take 5-8 years to reach sexual maturity, and give birth to 4-12 live young, which are quite large (~11" long; compared to ~9" in the more southerly parts of their range). Females may remain with their young for up to 10 days after giving birth. Historically, Prairie Rattlesnakes were found as far west as Calgary and almost as far north as Red Deer, but the species has declined in many areas due to persecution and habitat loss. Venomous snakes are rarely very popular, but provincial symbol-hood might help establish rattlesnakes as wildlife to be valued rather than pests to be exterminated (and Alberta is already quite progressive about protecting its snakes).

2. British Columbia. Sharp-tailed Snake (Contia tenuis)

Sharp-tailed Snake (Contia tenuis)
BC might be my favorite province, principally because of the Nanaimo Bar, a three-layer no-bake dessert created in the eponymous coastal city of Nanaimo. I chose the Sharp-tailed Snake to represent BC because in some ways it resembles a reversed Nanaimo Bar—the dorsal coloration is similar to the graham-cracker-and-almond base, the color of the sides to the vanilla custard center (sort of), and the belly to the delectable chocolate-and-coconut topping. These snakes are found on Vancouver Island, the nearby Gulf Islands, and possibly on the adjacent mainland. These cute little snakes eat slugs, including the infamous banana slugs, which I bet don't taste anywhere near as good as Nanaimo Bars. Descriptions of Sharp-tailed Snakes were first published in 1852 (by herpetologists Spencer Fullerton Baird & Charles Frédéric Girard, who received collections made the decade before in the Puget Sound area), exactly 100 years before the first printed recipes featuring Nanaimo bar ingredients were published in the Women's Auxiliary to the Nanaimo Hospital Cookbook (although I'll admit that's a pretty tenuis connection).

3. Manitoba. Western Hog-nosed Snake (Heterodon nasicus)

Western Hog-nosed Snake (Heterodon nasicus)
Even though Manitoba is very well-known for its Narcisse Gartersnake Dens, it has greater snake diversity than several of the other provinces, for which the gartersnake must be reserved. Some of Manitoba's most interesting snakes are Western Hog-nosed Snakes, which are found in sandy areas in the southwestern part of the province. As with other snakes at the northern limits of their range, they have a short activity season—they mate in May and lay 5-12 eggs in late June or early July, which then hatch by August. A study of Western Hog-nosed Snakes in Spruce Woods Provincial Heritage Park, Manitoba, found that they emerge from their burrows on any day when they could achieve a body temperature of at least 29°C (84°F). Like gartersnakes (though not quite to the same extent), these snakes can achieve fairly high densities in certain areas, so I think they could be good candidates for expanding our knowledge of snake ecology and behavior in the wild into phylogenetically-uncharted territory, challenging the statement made by Rick Shine in 1987 that "It's a good thing you Yanks have garter snakes, or you wouldn't have anything to study."

4. Newfoundland & Labrador. Maritime Gartersnake (Thamnophis sirtalis pallidulus)

Maritime Gartersnake (Thamnophis sirtalis pallidulus)
Newfoundland and Labrador is the only Canadian province without any native snakes. However, in recent years southwestern Newfoundland in the vicinity of St. David's has apparently been colonized by Maritime Gartersnakes, a beautiful subspecies of Common Gartersnake. Although no genetic analyses have been performed, it's likely that this population was founded by individuals shipped across the Gulf of St. Lawrence in hay bales or other cargo from Québec, New Brunswick, Nova Scotia, or Prince Edward Island. A poll by the CBC revealed that 12% of respondents thought that the recent colonization was "actually kind of cool", whereas a discouraging 49% of respondents were "not happy about it at all". It's rumored that gartersnakes were purposefully but unsuccessfully released in the St. John's area in eastern Newfoundland decades ago, either by farmers hoping to control rat populations or by someone who brought them back from the mainland hoping to sell them as pets (though both scenarios are likely more urban legend than fact). A string of recent mild winters may have allowed the gartersnakes in western Newfoundland to persist, but the extent to which climate change will enable a Florida-pythons scenario writ-small in Newfoundland remains to be seen. At the very least, this could be a golden opportunity for snake biologists to study what happens when snakes enter an ecosystem from which they have been absent for thousands of years, a rare event even in an age of snake invasions.

5. New Brunswick. Smooth Greensnake (Opheodrys vernalis)

Smooth Greensnake (Opheodrys vernalis)
Soctsman Andrew Leith Adams was an army physician who served in India, Egypt, and Canada during the 1800s. He spent his spare time studying the natural history of these countries, about which he later wrote several books, including his 1873 Field and forest rambles, with notes and observations on the natural history of eastern Canada. In it, he wrote "The Reptiles of New Brunswick are neither numerous nor formidable.", which, compared with the snake fauna he doubtless experienced in Egypt and India, was certainly true. He mentioned several snake species, in particular noting that "One of our most common fangless snakes is the active little green species (C. vernalis)", using the C. to abbreviate the genus Coluber, which Linnaeus had used for practically all snakes except boas and rattlesnakes. This handsome species has also frequently gone by the binomial Liochlorophis vernalis, among a half-dozen other genera into which it has been placed over the years.

6. Northwest Territories. Red-sided Gartersnake (Thamnophis sirtalis parietalis)

Mating ball of Thamnophis sirtalis parietalis
Red-sided Gartersnakes are the only snakes found in the Northwest Territories, where they achieve high densities near Fort Smith between the southern shore of the Great Slave Lake and Wood Buffalo National Park. Because there are few suitable hibernacula, thousands of individuals share the same den. Long winters and short, cool summers have resulted in a mating system that is unusual among snakes, although it is also possibly the most well-known because it is easily studied. Upon emergence from the in mid-April, snakes spend 2-3 weeks hanging around the entrance, during which time males compete fiercely to mate with females, forming colossal "mating balls". They then migrate over 2.3 miles (3.75 km) to their summer marshland habitat, where they remain until late August, giving birth to litters of young that are relatively small in number (~12 vs. ~19 in Manitboa) and large in body size (191 mm SVL vs. 154 mm in Manitoba). Females in the NWT rarely give birth in two successive years, instead saving up energy from one year in order to reproduce the next. They also mature at larger body sizes (570 mm SVL vs. 527 mm in Manitboa) than snakes further south. I bent the rules a little here since both Newfoundland and the NWT have only T. sirtalis (they have different subspecies, and this species might be split up fairly soon). 

7. Nova Scotia. Ring-necked Snake (Diadophis punctatus)

Brown-morph and normal Diadophis punctatus from Nova Scotia
From Gilhen 2011
Ring-necked Snakes are cute little snakes that mostly eat invertebrates, although they have been known to snack on the occasional salamander. In Nova Scotia, they can be found almost throughout the province, and an unusual brown morph occurs, particularly on Big Tancook Island in Mahone Bay along the east coast. According to the notebooks of Harry Piers, an early 20th century naturalist, museum curator, and historian, ringnecks were known to the native Mi'kmaq People as “the worst snake, Um-taa-kum (k)”, although it's not clear why. One communal nest found under a boulder near McCabe Lake in Halifax County contained 117 eggs, which must have been laid by at last 15, and probably many more, females (clutch size ranges from one to eight).

8. Nunavut. Ellesmere Island erycine (Eocene boa)

Drawing of Ellesmere Island erycine vertebra
Dotted lines show best-guesses at broken-off parts
A. Dorsal and B. right lateral view
From Estes & Hutchison 1980
Unfortunately, there are no living wild snakes in Nunavut. Initially I was going to get around this by writing only about the true provinces, but then I found evidence that a 50-million-year-old fossil snake vertebrae was found on Ellesmere Island, above the Arctic Circle at about 78.5° north (find it here at the awesome new Paleobiology Database Navigator). This vertebra belonged to an undescribed species of boid snake probably related to rubber boas, and it was found in an Eocene fossil deposit that used to be a lush river delta and floodplain, with abundant swamps, alongside pike, bowfin, and gar, mud & softshell turtles, alligators, monitor lizards, giant salamanders, and even primates. The single bone is part of the collection of the Canadian Museum of Nature (specimen number 32403) and hasn't been assigned to a species or even a genus because it's broken. Paleontologists are fairly confident that it is an erycine boid based on comparisons made with a half-dozen other extinct genera that probably belong in this group. Recent phylogenies of booids elevate Erycinae to a family, but do not include extinct taxa, so it's difficult to say for sure how these snakes were related to each other and to living species.

9. Ontario. Eastern Foxsnake (Pantherophis vulpinus)

Eastern Foxsnake (Pantherophis vulpinus)
Ontario has more snake species to choose from than any other province, including seven that are found nowhere else in Canada. At the JMIH meeting in Reno last summer, I posed the question of which one best represented Ontario to herpetologist Jacqueline Litzgus, a native of Ontario and a professor at Laurentian University. She was unhesitant in recommending the Eastern Foxsnake, the only species of snake whose range is mostly in Canada (which perhaps makes it sort of a national snake as well, although the common gartersnake is found in more provinces). Foxsnakes are large constrictors that are closely related to cornsnakes and (slightly less closely) to ratsnakes. They probably recolonized northern North America more quickly after the retreat of the glaciers than most snakes because of their mobility and the flat terrain left behind in the midwest. We once thought that the two species had a disjunct range, with the western foxsnake (formerly P. vulpinus) being found in the USA between the Missouri River and Lake Michigan, separated by a foxsnake-less area in northeastern Indiana and the lower peninsula of Michigan from the eastern foxsnake (formerly P. gloydi), which was found south and east of Lake Huron in Ontario, Michigan, and Ohio. However, a 2011 study used evidence from a single mitochondrial gene to suggest that the Mississippi River seemed to be a more significant genetic barrier and that western foxsnakes east of the Big Muddy in Wisconsin and Illinois were more closely related to eastern foxsnakes than they were to western foxsnakes in Iowa and Minnesota. Because the type specimens for both former foxsnake species were within the eastern lineage, this species became P. vulpinus (the older name), P. gloydi disappeared, and the "new" western foxsnake was named P. ramspotti. Runner up: Massasauga (Sistrurus catenatus), because of the town of Missisauga, Ontario.

10. Prince Edward Island. Red-bellied Snake (Storeria occipitomaculata)

Red-bellied Snake (Storeria occipitomaculata)
Located in the Gulf of St. Lawrence, Prince Edward Island was formed as a sandstone peninsula 250-300 million years ago. The end of the ice age 15,000 years ago and the retreat of the glaciers laid down glacial till and increased the sea level, disconnecting PEI from the mainland. PEI only has three species of snakes, all of which colonized the island within the last 15,000 years. Despite the fact that no lizards or turtles have been able to make the same crossing, PEI is still way ahead of Québec's similarly-sized Île d'Anticosti, which lies ~190 miles (~300 km) to the north and has no native species of amphibians or reptiles. Of the tiny red-bellied snake, PEI naturalist John Mellish wrote in the 1870s "This variety is numerous, is smaller in size, and seems to be less courageous than some of the other species". Although Mellish got this much right, he was as prone to exaggeration as many modern observers, interspersing his species accounts with tales of snakes charming their prey, swallowing their young, and attacking people. In reality, red-bellied snakes mostly attack slugs, and their peculiar lip-curling display is hardly threatening to a human.

11. Québec. Milksnake (Lampropeltis triangulum)

Milksnake (Lampropeltis triangulum)
Québec is best emblematized by the Milksnake, which was first described by a French herpetologist, Bernard Germain de Lacépède, in 1789. Lacépède's two-volume masterpiece, Histoire Naturelle, is a classic work in herpetology. Although Lacépède mostly used French vernacular names,  ("le triangle" for the milksnake, after the double triangles on top of its head), he used Linnaeus's Latin binomial system about 65% of the time in a 59-page table in the third section of the second volume, which covered legless amphibians and reptiles. However, because he was not consistent in his use of Latin binomials, the taxonomic community decided in 1987 that the names in volume two were not valid (volume one, which covers turtles, lizards, and amphibians, contains a 3.5' x 1.75' fold-out table that was consistently binomial, so these names remain valid). Four snake names, including Lampropeltis triangulum, were rescued because of their long history of use. The other three (Agkistrodon piscivorus, Langaha madagascarensis, and Python reticulatus) were much longer-used than L. triangulum, which probably wouldn't have made the cut if not for an earlier decision by the ICZN as part of a case involving the mistaken identity of Linnaeus's scarletsnake (Cemophora coccinea) specimen and the name he gave it, Coluber doliatus, which was mistakenly used for the milksnake for over 150 years. The 1967 case invalidated doliatus and fixed triangulum as the specific epithet of the milksnake, which prevented it from later being invalidated with the rest of Lacépède's snake names. In this way the species is somewhat rebellious (in a nomenclatural sense), which I think would please many Québécois.

12. Saskatchewan. Gophersnake (Pituophis catenifer)

Gophersnake (Pituophis catenifer)
On the first page of one of my favorite novels, Farley Mowat's Owls in the Family, the author describes growing up in Saskatoon, Saskatchewan: "When you stepped off the end of the Railroad Bridge you stepped right onto the prairie and there you were—free as the gophers. Gophers were the commonest thing on the prairie. The little mounds of yellow dirt around their burrows were so thick, sometimes, it looked as if the fields had yellow measles." Although I like owls, these days I more often have another gopher predator in mind—the eponymous gophersnake (Pituophis catenifer), also less-aptly known as the bullsnake. These harmless creatures are often mistaken for rattlesnakes, because they have a superficially similar pattern (and they do rattle their tails, although they have no specialized noise-making structure). Confusion over the common name led Edward Abbey or one of his editors to include the scientific name of the eastern indigo snake (aka the blue gophersnake), Drymarchon corais couperi, for the bullsnake in the essay 'The Serpents of Paradise' in the 1968 edition of Desert Solitaire (although it is correct in 1988 edition).

13. Yukon. ?

I hope they find a snake
The Yukon Territory has no living snakes and no snake fossils (yet). This is actually quite ironic, because most living North American snakes crossed into our continent from Asia over the Bering Land Bridge, and some of them almost certainly slithered through what is today the Yukon. It is possible that somewhere in the southern Yukon exists a population of gartersnakes, which are found in the southern NWT and also possibly in the Alaskan panhandle. Three reliable sight records and one specimen (now lost) from remote areas along Taku & Stikine Rivers in Alaska give us hope, although unfortunately neither basin enters the Yukon. Other snake sightings of snakes from Alaska include odd T. sirtalis and T. ordinoides specimens from more urban areas, which almost certainly represent translocations (genetic evidence supports this in at least one case). T. sirtalis are found just 200 miles (320 km) south of the Yukon border in BC. It isn't completely crazy to imagine snakes living at such northerly latitudes; European Adders (Vipera berus) are found above the Arctic Circle in Scandinavia. If nothing else, gartersnakes from British Columbia will probably disperse there eventually if climate change keeps up with predictions.


Thanks to David O'Connor, JD Willson, Todd Pierson, Andy Teucher, Michael, Gary Nafis, and Nick Scobel for the use of their photos, to Jackie Litzgus for helping me make the decision about Ontario, and to Gareth Hopkins for introducing me to Nanaimo bars.


Manitoba Thamnophis on the side of a U-Haul truck
Anonymous. 1987. Opinion 1463. De Lacépède, 1788-1789, Histoire Naturelle des Serpens and later editions: rejected as a non-binominal work. Bulletin of Zoological Nomenclature 44:265-267 <link>

Baird, S.F. and C. Girard. 1852. Descriptions of new species of reptiles, collected by the U.S. exploring expedition under the command of Capt. Charles Wilkes, U.S.N. First part. - Including the species from the Western coast of America. Proceedings of the Academy of Natural Sciences of Philadelphia 6:174-177 <link>

Brongersma, L.D. 1972. On the “Histoire naturelle des Serpens” by de la Cépède, 1789 and 1790, with a request to reject this work as a whole, and with proposals to place seven names of snakes, being nomina oblita, on the Official index of rejected and invalid names in zoology, and to place three names of snakes on the Official list of specific names in zoology (Class Reptilia). Bulletin of Zoological Nomenclature 29:44-61 <link>

Crother, B.I., M.E. White, J.M. Savage, M.E. Eckstut, M.R. Graham, and D.W. Gardner. 2011. A reevaluation of the status of the Foxsnakes Pantherophis gloydi Conant and P. vulpinus Baird and Girard (Lepidosauria). ISRN Zoology 2011 <link>

Estes R, Howard Hutchison J, 1980. Eocene lower vertebrates from Ellesmere Island, Canadian Arctic Archipelago. Palaeogeography, Palaeoclimatology, Palaeoecology 30:325-347 <link>

Gilhen, J. 2011. The Brown Morph of the Northern Ringneck Snake, Diadophis punctatus edwardsii, on Big Tancook Island, Mahone Bay, Nova Scotia. The Canadian Field-Naturalist 125:69-71  <link>

Hodge, R.P. 1976. Amphibians and Reptiles in Alaska, the Yukon, and Northwest Territories. Alaska Northwest Pub. Co.

Larsen KW, Gregory PT, Antoniak R, 1993. Reproductive ecology of the Common Garter Snake Thamnophis sirtalis at the northern limit of its range. American Midland Naturalist 129:336-345 <link>

Leavesley, L.K. 1987. Natural history and thermal relations of the Western Hognose Snake (Heterodon nasicus nasicus) in southwestern Manitoba. MS thesis. University of Manitoba, Winnipeg, Manitoba.

Rossman, D.A., N.B. Ford, and R.A. Seigel. 1996. The Garter Snakes: Evolution and Ecology. University of Oklahoma Press, Norman, Oklahoma. (Shine quote opens chapter 4, page 55)

West, R.M., M.R. Dawson, and J.H. Hutchison. 1977. Fossils from the Paleogene Eureka Sound Formation, N.W.T., Canada; occurrence, climatic and paleogeographic implications. Milwaukee Public Museum Contributions in Biology and Geology 2:77-93.

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

Wednesday, June 8, 2016

Virgin Birth, the Color of Fossil Snakes, and More Recent Updates

This post will soon be available in Spanish

As I did in March, I wanted to highlight some recent and exciting updates to some of my older articles.

Snakes That Give Virgin Birth

Phylogenetic pattern of parthenogenesis in snakes
Molecular tree on left, morphological tree on right
From Booth & Schuett 2016
When I wrote about asexual reproduction in snakes in February 2014, new records of this phenomenon were rapidly accumulating, from snakes as distantly related as cottonmouths and boa constrictors. In a new paperWarren Booth and Gordon Schuett review the knowns and unknowns of "virgin birth" in snakes, a subject which has become their specialty (it even has its own Facebook group). Although obligate parthenogenesis is still known only from Brahminy Blindsnakes (Indotyphlops braminus), the new summary reports that facultative parthenogenesis has now been documented in 20 species of alethinophidian1 snakes, and this list is anticipated to grow, although so far confirmed cases are limited to five lineages: boids, pythonids, Acrochordus, Crotalinae, and Natricinae. This new synthesis formalizes one of the trends that I wrote about in 2014, namely distinguishing between "Type A" facultative parthenogenesis, in which the offspring produced are large clutches of viable females that seem to have a strange "WW" sex chromosome arrangement (apparently typical of boas and pythons), and "Type B" facultative parthenogenesis, which is where all the offspring are male and few are born alive, many with extreme developmental abnormalities (apparently typical of colubroids).

Most intriguing is the hypothesis laid out for explaining this dichotomy: that boas and pythons (and possibly other basal alethinophidian snakes) might have an XY sex determination system rather than a ZW one like most snakes. Changes from ZW to XY or vice versa (and between genetic and temperature-dependent sex determination) have been documented in geckos and turtles, and could have been overlooked in boas and pythons due to their similar-looking sex chromosomes (tests are currently underway to falsify or verify this hypothesis). If true, this would explain the production of all-female offspring by facultative parthenogenesis; instead of WW, those females would be XX, just like humans!

Identifying Snake Sheds

True-color representation of the fossil snake
(MNCN 66503) in McNamara et al. 2016.
The dentition looks too solenoglyphous for a
colubrid, although the 10-million year old specimen,
which is missing its head, has not and
probably can not be identified to species.
Ever since the first reports of color from the skin and feathers of dinosaur fossils were published in Science in 2010, I've been fascinated by the ability of paleontologists to see in color when they look into the past. A new paper in the journal Current Biology reveals the color of a fossil snake, determined from using scanning electron microscopy (SEM) to examine microfossils of certain types of skin cells, called chromatophores. So far, only melanin-based chromatophores (melanosomes, which are responsible for brown and black color) have been detected in fossilized skin and feathers, probably because they are the most resistant to the decomposition process. But, this study was also able to detect and measure other types of chromatophores from fossilized skin, including xanthophores (responsible for yellow, orange, or red color, derived from carotenoids or pteridines) and iridophores (responsible for iridescence). By comparing the fossil's chromatophore abundance and position to that of living reptiles, they were able to reconstruct the original color and pattern of the fossil snake's skin. For example, in the skin of living snakes, xanthophores with many more pteridine granules than carotenoid granules produce a red hue, whereas xanthophores with equal amounts of carotenoid granules and pteridine granules—as in the fossil—produce yellowish hues. Skin regions with abundant iridophores and xanthophores, but relatively few melanophores, are associated with green hues in some living skinks, whereas skin regions with many melanophores, a few xanthophores, and no iridophores suggest correspond to dark brown or black tones. As you can see in the depiction, this snake seems to have had a pale, creamy venter and a green back and sides, with areas of brown/black and yellow/green, perhaps not unlike modern Green Watersnakes (Nerodia floridana) or Boomslangs (Dispholidus typus).

Snakes Flying Without Planes

Photo and diagram of courtship behavior of Chrysopelea paradisi
Taken at the Sepilok Jungle Resort in Sabah, Malaysia
Female shown in gray, males in blue, green, and orange
From Kaiser et al. 2016
A new report on the mating behavior of Paradise Flying Snakes (Chrysopelea paradisi) showed that their courtship can involve multiple males. Although several experiments have been performed on the gliding behavior of these snakes, almost nothing is known about their natural history in the wild. Males of many species of snakes court females en masse by rubbing their chins along their bodies, a behavior which allows them to sense her sex pheromones and jockey for position. The role played by the female in choosing a male is unclear in most snake species; although conventional biological wisdom suggests that females should be the choosy sex, male-male competition seems to dominate courtship behavior in several species of snakes. Multi-male courtship behavior precedes mating in some well-studied temperate snakes (e.g., gartersnakes emerging from hibernation), as well as in some tropical species (e.g., anacondas, some other southeast Asian colubrids, such as Boiga irregularis and Dryophiops rubescens). Of course, it seems that most female snakes can store sperm for long periods of time, and they may have some control over which male's sperm to use to fertilize their eggs, so the genetic contribution of a female snake's male partners may not follow from their courtship or mating success. Unlike the terrestrial or aquatic mating balls documented for other snakes, the flyingsnakes in this observation were able to move as a unit for almost 50 feet through complex habitat—under a porch, up a tree—an adaptation that seems to fit their active, arboreal lifestyle and might help reduce the likelihood of a predatory attack during what must otherwise be a vulnerable time.

1 In a few places, the authors use "alethinophidian" to refer to boas, pythons, and their relatives but not caenophidians, when instead they should have either used "henophidian" or "basal alethinophidian" (they mostly use the latter term throughout). Many people don't like the term "henophidian" because it is a paraphyletic group, but it is a convenient way to refer to non-scolecophidian, non-caenophidian snakes. In my mind it's essentially synonymous with "basal/stem alethinophidian". Alethinophidians are all snakes except for blindsnakes (scolecophidians), and Caenophidia is a subset of Alethinophidia. There are also at least three references to "Caenophidia + Colubroidea", which is confusing because Colubroidea is a subgroup of Caenophidia, and Caenophidia = Colubroidea + Acrochordus, which is perhaps what they meant.


Thanks to Gordon Schuett for clearing up some of the details of his recent paper.


Booth W, Schuett GW (2016) The emerging phylogenetic pattern of parthenogenesis in snakes. Biological Journal of the Linnaean Society 118:172-186 <link>

Gamble, T., J. Coryell, T. Ezaz, J. Lynch, D. Scantlebury, and D. Zarkower. 2015. Restriction site-associated DNA sequencing (RAD-seq) reveals an extraordinary number of transitions among gecko sex-determining systems. Molecular Biology and Evolution 32:1296-1309 <link>

Kaiser H, Lim J, Worth H, O’Shea M (2016) Tangled skeins: a first report of non-captive mating behavior in the Southeast Asian Paradise Flying Snake (Reptilia: Squamata: Colubridae: Chrysopelea paradisi). Journal of Threatened Taxa 8:8488–8494 <link>

Kuriyama, T., K. Miyaji, M. Sugimoto, and M. Hasegawa. 2006. Ultrastructure of the Dermal Chromatophores in a Lizard (Scincidae: Plestiodon latiscutatus) with Conspicuous Body and Tail Coloration. Zoological Science 23:793-799 <link>

Li, Q., K. Q. Gao, J. Vinther, M. D. Shawkey, J. A. Clarke, L. D’Alba, Q. Meng, D. E. G. Briggs, and R. O. Prum. 2010. Plumage color patterns of an extinct dinosaur. Science 327:1369 <link>

McNamara, Maria E., Patrick J. Orr, Stuart L. Kearns, L. Alcalá, P. Anadón, and E. Peñalver. 2016. Reconstructing Carotenoid-Based and Structural Coloration in Fossil Skin. Current Biology <link>

McNamara, M. E., D. E. G. Briggs, P. J. Orr, D. J. Field, and Z. Wang. 2013. Experimental maturation of feathers: implications for reconstructions of fossil feather colour. Biology Letters 9 <link>

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

Saturday, May 28, 2016

Rattlesnake Roundups Revisited

This article will soon be available in Spanish

A chalkboard at the 2016 Sweetwater Rattlesnake Roundup,
showing that a record number of pounds of snake had
already been bought and sold by the second day, and that
commerce was suspended on the third and fourth days of the
event due to the massive surplus.
Photo source unknown.
At the 58th annual Sweetwater Rattlesnake Roundup this March, a record 24,481 pounds of rattlesnakes (about 21,000 individuals), primarily Western Diamond-backed Rattlesnakes (Crotalus atrox), were slaughtered. That's over four times the all-time average and about five times the recent average, breaking from a trajectory of slow decline at the few remaining rattlesnake roundups. The Sweetwater Jaycees attribute this year’s record catch to heavy rains, an explanation which might hold some water, but another probable contributing factor is the possibility of an impending Texas Parks & Wildlife ban on using gasoline fumes to collect rattlesnakes, which was discussed this week at a meeting in Austin on May 25th, 2016. The Texas Parks and Wildlife Commission decided to begin developing language for a new rule either prohibiting or further regulating this practice in the state. The rule is still far from going into effect, and would include a two-year delay on the effective date. It won't be reviewed again until November 2016 (at which time, watch this space for a link to an opportunity for a public comment, if available). TPWD's Snake Harvest Working Group recommended earlier this year that Texas join 29 other states in banning this environmentally-harmful practice, which has been shown to kill numerous non-target species and has been compared with other unsportsmanlike methods of hunting, such as shooting at an out-of-range bird or fishing with dynamite. The state wildlife agency has been moving slowly but steadily to regulate rattlesnake collection in Texas because of the economic importance of rattlesnake roundups to towns like Sweetwater (e.g., over 25,000 people contributed over $8 million to the local economy in 2015, although the TPWD report found that the weather and the diversity of other events had stronger associations with profits than the number of rattlesnakes at an event).

Locations of the remaining rattlesnake roundups,
including non-lethal festivals.
From TPWD Report Reference Document (p. 22)
Ironically, this year's surplus of snakes drove the price of rattlesnake down so much (historically as high as $10.00 per pound, this year the price fell below $0.50/lb. despite efforts to maintain higher prices) that only about a quarter of the rattlesnakes collected were purchased for their meat, rattles, and skins before all demand had been exhausted. Rattlesnakes collected using gassing are no longer purchased by the antivenom industry, because of their short lifespan and poor health (as well as a more nuanced understanding of the importance of geographic variation in venom composition, emphasizing the necessity of knowing the geographic origin of each snake used in venom research). The fate of the rattlesnakes left unsold after Sweetwater (which some have speculated as being up to 75,000) has not been made public, although reports suggest that prices are also down at other roundups in Texas and Oklahoma, possibly as a result of vendors trying to sell their snakes there. Anyone who has gone to great expense to collect snakes in this manner and now cannot find a buyer is at risk of losing their investment. Claims about the impacts on snakebites to humans and livestock if these snakes were to be released are unsubstantiatable and untrue, considering that the survival of wild snakes captured and released elsewhere is greatly reduced (not to mention the dubiousness of the link between rattlesnake abundance and snakebite frequency in the first place).

Trajectory of profit (red, blue), number of snakes (purple), and
weather conditions (green) at the Sweetwater Roundup over the last decade.
Chart prepared by Rob Denkhaus, TPWD Wildlife Diversity Advisory Committee
and presented in TPWD Report Reference Document (p. 64)
I am hopeful that eventually all stakeholders can overcome the cognitive dissonance between the flawed concept of predator population control (which was the original impetus behind rattlesnake roundups) and the implicit economic reasons behind their persistence. Although rattlesnake roundups are inarguably sensational and exploitative, claims about the sustainability of the wild rattlesnake harvest cannot currently be independently evaluated (I encourage anyone interested in the subject to read my previous article and check out this well-researched book). But, increasing oversight by Texas wildlife agencies could allow them or others to monitor the effect of the harvest on rattlesnakes, which could lead to valuable insights into snake biology and help prevent economic and environmental disasters like this year's Sweetwater roundup. This week's decision inches us towards the hopeful possibility of a sustainable snake harvest that could, over time, change the relationship between humans and western diamondbacks into a positive one, similar to our view of white-tailed deer, bobwhite quail, or largemouth bass. It's a non-traditional model for snake conservation, to be sure, but the efforts of the TPWD Snake Harvest Working Group combined with actions being taken by some unlikely allies, such as roundup organizer Jackie Bibby, will hopefully continue to move us towards a common goal of respectfully managing rattlesnakes as either game or non-game wildlife and not as pests. [Edit: An analysis from 2000 showed that imposing size restrictions on rattlesnake harvests to individuals >90 cm in SVL (the size at maturity for most females) would earn hunters 19% more money.] The best part: we can help people in the process (e.g., by providing healthier products with stable prices, such as rattlesnake meat untainted with gasoline).

Percentage of time radio-tracked Burmese Pythons spent
fully concealed (black), partly visible (gray), and mostly visible (white).
In nineteen 30-minute searches of a 30 x 25 m enclosure containing
ten pythons, only two pythons were detected out of
190 possible detection opportunities.
From Dorcas & Willson 2013
And—as if the irony weren't already thick enough—compare the above totals with the ~2000 lbs. of Burmese Python (106 snakes) collected in Florida this year as part of an Florida Fish and Wildlife Conservation Commission-sponsored contest to control a snake whose populations actually do need to be "controlled" (despite the near-total impossibility of doing so). Among the several reasons for the difference include the lack of cultural inertia promoting snake hunting in Florida, the challenging habitat of the Everglades, and the snakes' biology—pythons don't aggregate the way rattlesnakes do. If gassing is banned in Texas, flushing rattlesnakes out of their hibernacula en masse will no longer be a legal hunting strategy. Does this mean that rattlesnake roundup totals will become more like those of the Python Challenge? Not necessarily—the TPWD report references alternative strategies already in use in other parts of the country that can still yield hundreds of pounds of rattlesnakes. Would a change in the hunting methods allowed have positive effects on snakes and other wildlife? Almost certainly. What would be the impacts on the roundup? I think it's worth pointing out that many former roundups, such as the Claxton Rattlesnake Festival in Claxton, Georgia, hosted by the Evans County Wildlife Club, and the Fitzgerald Wild Chicken Festival in Fitzgerald, Georgia, still generate economic opportunity for their towns without collecting and killing wild snakes. I think it's quite likely that events like the Sweetwater Rattlesnake Roundup could continue to bring benefits to their communities without using gas to extract rattlesnakes from their dens.


Thanks to Ray Autry and Dale Burton from the Rise Against Rattlesnake Roundups Facebook group for pointing me to some resources about the 2016 Sweetwater Roundup.


Adams, C.E. and J.K. Thomas. 2008. Texas Rattlesnake Roundups. Texas A&M University Press, College Station, Texas <link>

Arena, P. C., C. Warwick, and D. Duvall. 1995. Rattlesnake Round-ups. Pages 313-324 in R. L. Knight and K. Gutzwiller, editors. Wildlife and Recreationists. Island Press, Washington, DC <link>

Campbell, J. A., D. R. Formanowicz Jr, and E. D. Brodie Jr. 1989. Potential impact of rattlesnake roundups on natural populations. Texas Journal of Science 41:301-317.

Dorcas, M. E., and J. D. Willson. 2013. Hidden giants: problems associated with studying secretive invasive pythons. Pages 367-385 in W. I. Lutterschmidt, editor. Reptiles in Research. Nova Biomedical, New York, New York <link>

Elliott, W. R. 2000. Conservation of the North American cave and karst biota. Pages 665-689 in H. Wilkens, D. Culver, and W. Humphreys, editors. Subterranean Ecosystems. Elsevier, Amsterdam.

Fitzgerald, L.A. and C.W. Painter. 2000. Rattlesnake commercialization: Long-term trends, issues, and implications for conservation. Wildlife Society Bulletin 28:235-253 <link

Jackley, A. M. 1939. Rattlesnake Control and Conservation. South Dakota Conservation Digest 6:11.

Margres, M. J., J. J. McGivern, M. Seavy, K. P. Wray, J. Facente, and D. R. Rokyta. 2015. Contrasting modes and tempos of venom expression evolution in two snake species. Genetics 199:165-176 <link>

Reinert, H., and R. Rupert. 1999. Impacts of translocation on behavior and survival of Timber Rattlesnakes, Crotalus horridus. Journal of Herpetology 33:45-61 <link>

Texas Parks and Wildlife Department. 2016. Snake Harvest Working Group Final Report <link> <references> <summary>

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

Tuesday, April 26, 2016

Even snakes have their charismatic megafauna

This post will soon become available in Spanish.

Bitis harenna
From Gower et al. 2016
Last year, I wrote about the 10,000th reptile and the 3,500th snake species to be described by scientists. The pace has not slowed down—as of its most recent update last week, The Reptile Database currently lists 3,596 species of snakes out of a total of 10,391 species of (non-avian) reptiles. A few weeks ago, the March 21st issue of the frequently-published journal Zootaxa (volume 4093, issue 1) included descriptions of three of these new snake species. What's interesting is that I initially looked this issue up because I saw one of them being shared a lot on social media—a new large species of viper. The other two, a pipesnake and a blindsnake, hadn't received as much attention. Zootaxa tweets all of their new species, and an examination of their feed shows that the viper tweet received 4 retweets and 2 likes, whereas the pipesnake and the blindsnake received 2 retweets and one like each (even though the pipesnake had a photo1 and was on the cover). Even though that's a small sample size, I think it's telling that even snakes have their charismatic megafauna.

A bongo (Tragelaphus eurycerus, top)
and a tiger (Panthera tigris, bottom).
You only needed a caption for one
It seems backwards, in a way, that the dangerously venomous viper should be more popular than the innocuous pipesnake. One conservation blogger, Corey Bradshaw, put it nicely by saying that "the only thing worse than being labelled deadly is not being called anything at all". Bradshaw pointed out that drawing attention to the potential for a species to cause harm to humans is not necessarily bad for the species in question. Even though snake biologists often decry these claims as exaggerated (usually because they are), Bradshaw wondered whether they are really very harmful. He suggested that people are generally more fascinated with animals that could kill us (even if they rarely do) than they are with entire groups of benign species, such as skinks or plethodontid salamanders, which are often considered boring (if a person is even aware of their existence). Compare tigers with, say, bongos. Both are critically endangered, inarguably gorgeous animals from exotic places. Tigers sometimes kill and eat people. Everyone knows a tiger. Most people think a bongo is a drum. Or, if you want a snake example, take rattlesnakes. Rattlesnakes are the Bald Eagles of snakes. They are distinctly North American. Everybody in North America knows them. One was on our flag. In contrast, the USA has never had a Smooth Greensnake (Opheodrys vernalis) on its flag, even though they are beautiful and North American and eat spiders. Perhaps the idea that any publicity is good publicity applies to conservation as well. Then again, perhaps not—many residents of Massachusetts are needlessly worried about a Timber Rattlesnake reintroduction plan on an island in the Quabbin Reservoir, probably in part because of the bad PR that rattlesnakes get on a regular basis. If the Massachusetts Division of Fisheries & Wildlife were reintroducing Smooth Greensnakes, I doubt that most people would care (and it certainly wouldn't have been the subject of such venomous debate in the media). Indeed, Illinois's Lincoln Park Zoo is reintroducing Smooth Greensnakes in Chicago, and nobody is writing letters to the editor about it (and, in a way, that's a shame, because it's an interesting and worthwhile effort).

Letheobia mbeerensis
From Malonza et al. 2016
Anyway, I wanted to give some well-deserved press to the two less-publicized new snakes. The blindsnake, Letheobia mbeerensis, is pink with tiny, barely visible eyes. It was described from a single specimen collected southeast of Mt. Kenya in April of 2014 by a local farmer, who found it while tilling his fields. This person, whose name was not known to the scientists who wrote the article, made a considerable effort to get the snake identified—he traveled 125 miles from Siakago to Nairobi, where he gave the specimen to the Nairobi Snake Park, who forwarded it to herpetologists at the National Museums of Kenya. It is unique in having a relatively long tail (for a blindsnake), and in being found in a moist inland savanna. The other two Kenyan species of Letheobia, one of which was just described in 2007, are found in coastal lowlands with sandy soils. It is the 24th species of blindsnake known from Kenya, but I can guarantee that it won't be the last.

Historical drawings of Cylindrophis ruffus
Illustrations A-C from Scheuchzer 1735
D-E from 
Seba 1735
From Kieckbusch et al. 2016
The story of the new pipesnake is even more interesting, and I suspect the paper in which it is described will ultimately be the most read and most cited of the three snake papers in this issue. This is because, in addition to describing the new species, it contains "an overview of the tangled taxonomic history of C[ylindrophis] ruffus", a widespread species commonly known as the Red-tailed or Common Pipe or Cylinder Snake. The fourteen species of Asian Pipesnakes (family Cylindrophiidae) are secretive and semifossorial snakes with small eyes, bodies that barely taper at all, and ventral scales only slightly larger than or equal in size to their dorsal scales. Many have contrasting light and dark ventral blotching with conspicuous bright coloration on the underside of their short tail, which they expose when threatened. Scientific knowledge of these snakes predates modern biological nomenclature. One is pictured in Albertus Seba's Thesaurus, which was one of Linnaeus's main sources, although Linnaeus didn't include C. ruffus in either the 1758 or the 1766 edition of his Systema Naturae—instead, its first post-Linnaean description was written by Laurenti in 1768. Compared with other CylindrophisC. ruffus has a much larger distribution than any other species of Asian pipesnake. It's one of those species that is really a species complex—a group of closely related species that are very similar in appearance, to the point that the boundaries between them are often unclear. Other well-known examples include African House Snakes (Boaedon fuliginosus, formerly Lamprophis fuliginosus) and American Milksnakes (Lampropeltis triangulum). Often unusual populations of these species are described as separate species, but without extensive rangewide sampling it's easy to miss more subtle, clinal variation, especially when that variation is genetic rather than morphological. A recent revision of milksnakes split this wide-ranging species into several, and researchers have been working on African House Snakes as well. But no one has really examined Red-tailed Pipesnakes. Last year, a group of European and Indonesian researchers examined a large number of Cylindrophis museum specimens and discovered several specimens which did not fit any recognized species. But many of these specimens are old and some of their locations are uncertain. We don't have a lot of molecular data, and we have no specimens at all from many areas. And, no one has yet carried out a totally comprehensive review of the species complex (which really should encompass the entire genus, since the milksnake researchers found that some "milksnakes" were actually more closely related to mountain kingsnakes than they were to other milksnakes).

Cylindrophis ruffus raising its tail "flag"
Despite its re-description in 2015, Cylindrophis ruffus is still a species complex that suffers from a lot of complexity. Its morphology is highly variable. Its geographic range limits are unsettled. There is no type specimen. The original type locality (“Surinami”) is a hemisphere away, obviously an error, which complicates decisions about which populations of C. ruffus should get to keep that name and which should change. The 2015 paper, as the authors of this month's paper delicately put it, "contain[s] some inaccuracies, including descriptive errors, which unfortunately increase the complexity of an already intricate taxonomic situation". The researchers state that they are currently undertaking the kind of comprehensive review that I called for above, but that in the process they discovered a morphologically distinct population from central Java, which they describe as Cylindrophis subocularis in this paper. But the real value of this paper, in my mind, is the step-by-step description of the history of this snake, starting with its first depiction in 1735 and continuing to present day. I'll leave the gory details for those who are really interested (the full-text is available here), but suffice it to say that the story of Cylindrophis ruffus is much more interesting than I ever knew (it took almost 100 years to get the geography right), and far from over.

1 Granted, it was a photo of a preserved specimen.


Thanks to M. A. MuinNigel Swales and Marcus Meissner for the use of their photos.


Amarasinghe, A. A. T., P. D. Campbell, J. Hallermann, I. Sidik, J. Supriatna, and I. Ineich. 2015. Two new species of the genus Cylindrophis Wagler, 1828 (Squamata: Cylindrophiidae) from Southeast Asia. Amphibian and Reptile Conservation 9:34-51 <link>

Gower, D. J., E. O. Z. Wade, S. Spawls, W. Böhme, E. R. Buechley, D. Sykes, and T. J. Colston. 2016. A new large species of Bitis Gray, 1842 (Serpentes: Viperidae) from the Bale Mountains of Ethiopia. Zootaxa 4093:41-63 <link>

Kieckbusch, M., S. Mecke, L. Hartmann, L. Ehrmantraut, M. O’Shea, and H. Kaiser. 2016. An inconspicuous, conspicuous new species of Asian pipesnake, genus Cylindrophis (Reptilia: Squamata: Cylindrophiidae), from the south coast of Jawa Tengah, Java, Indonesia, and an overview of the tangled taxonomic history of C. ruffus (Laurenti, 1768). Zootaxa 4093:1-25 <link>

Malonza, P. K., A. M. Bauer, and J. M. Ngwava. 2016. A new species of Letheobia (Serpentes: Typhlopidae) from central Kenya. Zootaxa 4093:143-150 <link>

Scheuchzer, J. J. 1735. Physica Sacra Iconibus Anaeis Illustrata, Procurante & Sumtus Suppeditante. Tomus IV. Augustae Vindelicorum et Ulmae, Ulm <link>

Seba, A. 1734-1765. Locupletissimi rerum naturalium thesauri accurata descriptio, et iconibus artificiosissimis expressio, per universam physices historiam :opus, cui, in hoc rerum genere, nullum par exstitit. Apud Janssonio-Waesbergios & J. Wetstenium & Gul. Smith, Amstelaedami <link>

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