Over the past few years the prairies, forests, marshes and deserts of my beloved Texas have provided me with countless natural treasures and memories in the field in pursuit of material for the upcoming book, Herping Texas. I have enjoyed sharing some of these and other adventures with readers, but the time has come to move on, and I am hereby ceasing all connection, contributions and affiliations with the Great Rattlesnake Highway blog and Texas Field Notes. I will also cease publication on my accompanying blog, Coleopteraholic. I have several reasons for this decision, one being the pursuit of an education in Biology. I have enjoyed a good cruise down the Great Rattlesnake Highway, writing about my adventures afield and sharing them with an unparalleled audience of naturalists. Thank you all for your time, advice, comments, readership, and loyalty.
I would not feel justified in the aforementioned changes without contributing one final article, so I have written on Crotalus viridis, the prairie rattlesnake, which has always been one of my favorite snake species, and was the reason I first headed down the actual Great Rattlesnake Highway all those years ago. That transmogrified into a symbol for herping Texas, and I felt there would be none better to conclude with. I hope you enjoy it.
This being said, I won’t draw out these goodbyes any longer than necessary. Thank you all again. Enjoy and appreciate your own great highways, wherever they may take you. Happy herping.
Prairie on the Plains
A full, late moon hung low in the sky like a glowing orb, governing the mesquite-dense hills of Haskell County. Darkness engulfed the land, but my headlights cut through it with twin cones of illumination that fell upon the tubular form of a serpent on the highway. It was unexpected to see anything out and about in the grip of this relentless high pressure-laden drought that plagued these dog days of late July. The air was hot and arid, the ponds and stock tanks reduced to concave depressions of red clay, cracked and peeling in irregular squares. The yellowed mesquite tops and dried stalks of Indiangrass, their withered heads bent in submission to the heat en masse, like a congregation of tormented mourners, provided a testament to the area’s dire need of some serious rainfall. The mercury had soared to 104 degrees Fahrenheit earlier, another day of baking, indifferent sunshine. I had been cruising down the Great Rattlesnake Highway at a low rate of speed, hoping to attract Palo Verde root borers (Genus Derobrachus) to the headlights, which is an easy method for collecting this largest of North American longhorned beetles. I had not seen a snake in several weeks, and had assumed everything had gone underground to estivate until the cooler weather of fall was in the air.
I spun the truck around and doubled back, and when the snake came into view I noticed it was not a western diamondback (Crotalus atrox) as I had suspected due to the species’ incredible abundance in this region, but something else. Western diamondbacks are instantly recognizable in the beam of the headlights by their brightly banded black and white tails, which, like most species of rattlesnakes, they typically hold aloft while crawling. I couldn’t see any rings on this one, which narrowed the possibilities down to either of the two other species native to the rolling plains, the western massasauga (Sistrurus catenatus tergeminus) or the prairie rattlesnake (Crotalus viridis). The massasauga, while not as common as the diamondback, is nevertheless quite prolific here, although it is a comparatively diminutive serpent, rarely exceeding twenty-four inches in length. The snake in question was around three feet long, and while I occasionally come across massasaugas of this size, it is rare enough to make it highly unlikely, especially on this hot, dry night under a full moon when nothing else seemed to be moving.
As I put the truck in park and exited the vehicle with flashlight in hand I noticed the distinct dark-hued basal segment of the rattle, which is yellowish in western diamondbacks and the same color as the other segments in massasaugas. I could also see the raised supraocular scales above the eyes that seem to somehow give this species a permanently angry scowl. I didn’t need to get close enough to locate the three or more internasal scales which meet against the rostral plate that distinguishes the prairie rattler from all other Texas rattlesnake species. The aforementioned characteristics, coupled with the oblong, slightly irregular chestnut-brown blotches edged in cream and fading to a series of pallid bands toward the tail was enough for me to know exactly what I was looking at.
The prairie rattlesnake is one of North America’s most widespread serpents, ranging across most of the central-western United States, from Montana south into Wyoming, eastern Colorado, and most of New Mexico. It is the predominant rattlesnake species on the Great Plains to the east as well, from southwestern North Dakota, Nebraska, western Kansas, and the Oklahoma Panhandle. In Texas it is found in grassland habitats, from the high plains in the panhandle, south to the isolated desert grasslands of northeastern Brewster County in the upper Chihuahauan Desert region (Stebbins, 1966). It is quite cold-tolerant, enough so to occupy such northern latitudes as eastern Alberta and western Saskatchewan, Canada, an area where few other snakes are able to survive. Here, it congregates in winter hibernacula in large numbers, although in Texas it is more prone to gathering in smaller groups in abandoned mammal burrows or in the broken, heat-cracked labyrinths on the eastern slopes of canyons (Savage, 2004). In my earliest days of snake hunting post-high school, the prairie rattlesnake was at the top of my bucket list of hopefuls, especially after learning of its occurrence in the form of a handful of museum records at the eastern end of its Texas range, in the shortgrass mesquite and prickly pear dominant rolling plains of Haskell and Throckmorton Counties (Werler & Dixon, 2000). So I set out for the open road, and spent countless nights cruising the blacktop with red eyes and iron will. Eventually I chanced upon a DOR (dead-on-road) specimen in western Throckmorton County, and this served to goad my fanatical search into overdrive. Over the coming years I would find many prairie rattlesnakes in Texas, my first half-dozen or so around the Lubbock area some two hours to the west, and a few more in the Trans-Pecos east of Alpine, but it would be over a decade before I would finally find my first live Haskell County viridis. After that blessed, long-awaited day, I turned up a DOR in neighboring Stonewall County, which ended up being a county record and is now floating in a jar of formalin somewhere in the bowels of the University of Texas at Arlington’s Amphibian and Reptile Diversity Research Center. The current snake in front of me was my second Haskell County specimen, and one of only four that I have ever found east of the Lubbock area.
In Situ photograph of my first live Crotalus viridis, taken in May of 2003 in Garza County east of Lubbock
All this talk of isolated records and localities is hardly reflective of the species as a whole. In fact, generally speaking, it is one of the most abundant serpents across much of its range, especially in the Great Plains, where it has been reported to outnumber all other large snake species in some areas. Here in Texas, though, prairie rattlesnakes are only locally common at best, and even then only when the habitat is optimal. This particular population clings determinedly to the eastern margins of its shortgrass habitat, encircled by ever-expanding acres of cotton and winter wheat. These areas are comparatively easily occupied by the prairie rattlesnake’s cousin, the western diamondback, which I have found as consistently in cultivated areas as I have unaltered landscapes. It seems that, while able to withstand and survive seemingly inhospitable temperature extremes the western diamondback is incapable of, the prairie rattler is much more susceptible to habitat alteration. It needs its prairie, and when the prairie is gone, it undoubtedly will go as well. Unfortunately this habitat is disappearing at an astonishing rate, and prairie rattlesnakes are not the only species being affected. In the 2016 Plowprint Report by the World Wildlife Fund, the statement is made that temperate grassland ecosystems are offered less protection than any other biome in the world, and that their destruction affects species on a level equivalent with rainforest loss, as well as the unique services they provide, such as carbon sequestration, which stores carbon dioxide and slows atmospheric accumulation of greenhouse gases (WWF, 2016). According to the report original grasslands have been reduced to fifty percent of their former size, with over fifty million acres put beneath the plow for cropland in the last decade. (Gaworecki, 2016).
The eastern edge of the Rolling Plains, taken on one of my first trips to the area in April of 2003
On what remains of the High and Rolling Plains in Texas, prairie rattlesnakes continue to survive in the looming face of “progressive” expansion. They are highly evolved, formidable predators of mammals and birds, from small mice and kangaroo rats to larger species such as prairie dogs and young quail and pheasants (Werler & Dixon, 2000). Lizards are also fair game, especially in the case of younger snakes, whose smaller girth restricts their mammalian diet to only the youngest rodents. In fact, Werler and Dixon refer to several field reports of almost exclusive lacertilian predation by neonate and juvenile prairie rattlesnakes (Hamilton, 1950; Hayes & Duvall, 1991).
The darkness was all around, save for the blue-white glow of my flashlight, which fell upon the prairie rattlesnake some six feet in front of me. It lay motionless, stretched out in the rectilinear fashion typical of rattlesnakes, with the high yellow grama and bunchgrass all around it, the crumbling red clay soil and interloping black asphalt beneath, and the endless plains sky above. I took a moment to observe the intricate aesthetic details that make it unique: the closely-spaced, elongate russet blotches on a mottled beige background, beset laterally by alternating spots of light and dark brown. I caught a glimpse of the nuchal blotch behind the venom-swollen cheeks, ending in a point shaped like a crude arrow; I thought of the potent cocktail of proteins and peptides within, a concoction which is reported to be two and a half times more toxic than that of the western diamondback, although the venom yield is only roughly 1/7th that of the diamondback (Klauber, 1956). I admired the chocolate brown stripe that ran diagonally from behind each eye, their margins traced by the same cream-white that bordered the pattern on the body. It was a truly remarkable and amazing work of creation, admired by some and loathed by many others, but demanding respect regardless.
As if to remind me of this, the snake sprang into sudden action, as most prairie rattlers are eventually prone to do if not promptly left alone. With rattles whirring it threw itself into a twisted coil, full of electricity, its tongue curled up over its nose in a smooth, menacing gesture that left little doubt as to its intentions should I advance any closer. Prairie rattlesnakes are like badgers. They put up with little provocation and display an almost characteristic pugnacious form of self-defense, showing no quarter. While western diamondbacks, massasaugas, and all other species of rattlesnakes I have encountered over the years tend to display a variable range of personality, from placid to aggressive, every prairie rattler I have crossed paths with has exhibited this same line of behavior. They sit still for a minute or two, then suddenly spring into hyperdrive, exploding into restless, sinuous coils, with rattles buzzing, always facing me, daring me to come closer and reap the dire consequences of my foolishness.
According to a statistical study conducted at the University of Florida based on hospital records of snakebite cases, pit vipers were shown to give “dry” bites (bites where one or more fangs punctured the skin but did not deliver any venom) 20-25 % of the time (Johnson, 2012). It would be interesting to break this down even further to species level, as nothing about the demeanor or suggestive body language of a prairie rattlesnake has ever given me the insinuation that they were considering the possibility of dry-biting. In fact, several years ago an acquaintance of mine who regularly handles prairie rattlesnakes in the Lubbock area was accidentally bitten on the pad of the thumb with both fangs by an adult specimen and described trying unsuccessfully to shake the snake loose while watching both venom glands expand and contract, pumping the full load of venom into his system. As reported in Werler & Dixon, he experienced many of the typical symptoms of envenomation by this pit viper, including the metallic taste in the mouth and tingling sensation in the digits, face and tongue. The venom contains a complex blend of both hemotoxic and neurotoxic properties, which can vary between populations, with certain localities being “hotter” than others. Cardiotoxins have been identified in prairie rattlesnake venom as well, and in some populations these combined with significant neurotoxins can lead to paralysis and heart failure. While fortunate in this regard, my acquaintance did lose his entire thumb after a week-long hospital stay and acquired several hundred thousand dollars in medical bills.
While definitely not seeming to entertain the idea of either fleeing or putting up with any guff, the irascible prairie rattlesnake posed defiantly as I took pictures, a subject worthy of a Gadsden flag emblem and a doubtless testament to its ability to survive for thousands of years in an ecosystem dominated by large herding ungulates, be they native bison or today’s cattle. If it was having any thoughts of turning tail and fleeing it was doing a good job of disguising them. With no hook available in which to move the rattlesnake to the safety of the roadside grass (remember, I had been looking for beetles, assuming snakes were out of the question) I simply backed away slowly and left it to the deserted highway to resume its nocturnal business. I wished it well as I flicked off the flashlight and its form was swallowed up in darkness, the rattle still singing that melancholy death song that has struck fear in the hearts of man and beast for so many centuries. In the dark of the night it sounded even more sinister and foreboding.
“Good luck you little devil”, I told him. “Try to find you a nice place to hide before the sunrise. It’s supposed to be another hot one.”
I closed the door of the truck and put it in drive, leaving the prairie rattlesnake to the rolling plains, and headed back down the Great Rattlesnake Highway, eager for the next adventure.
Stebbins, Robert C.; A Field Guide to Western Reptiles & Amphibians; Houghton Mifflin Co. Boston, 1966
Savage, Candace; Prairie: A Natural History; Greystone Books D& M Publishing; 2nd Ed; 2011 (orig 2004)
Werler, John E. & Dixon, James R.; Texas Snakes; University of Texas at Austin Press: 2000
Klauber, Laurence M.; Rattlesnakes: Their Habits, Life Histories, & Influence on Mankind; Vol. II, 3rd Edition; University of California Press; 1997 (orig. 1956)
Rubio, Manny; Rattlesnake: Portrait of a Predator; Smithsonian Institution Press, 1998
Hayes, William K. & Duvall, David; A field study of prairie rattlesnake predatory strikes; Herpetologica Vol. 47, No. 1 (Mar, 1991) pp. 78-81; Allen Press
Murphy, B.P., Andersen, A.N., & Parr, C.L. The underestimated biodiversity of tropical grassy biomes; Phil. Trans. R.Soc.B; 2016
Gaworecki, Mike; Grasslands in U.S. Great Plains are being destroyed at an “alarming rate”; 2016; http://news.mongabay.com
Plow print Report (World Wildlife Fund); http://www.worldwildlife.org
Johnson, Steve A.; Venomous snake FAQs; Department of Wildlife Ecology & Conservation; University of Florida; 2012; http://ufwildlife.ifas.ufl.edu