Rattlesnakes on the “Great Rattlesnake Highway” I: The Massasauga

In the early 1960’s, soon after my family moved to north Texas, I was introduced to one of my favorite rattlesnakes. Hanging out with museum biologists, I learned how to drive out west of town around sunset and see little western massasaugas as they started moving and crossed FM 1024, the legendary Benbrook-Aledo Road. Well, at that age, my parents did the driving, which made it that much easier to jump out of the car and see these snakes up close. This was around the same time that Harry Greene and George Oliver were studying these snakes along the Benbrook-Aledo Road and elsewhere. Their observations (Greene & Oliver, 1965) were very consistent with my recollections: the rattlesnake would be stretched out on the pavement, usually motionless, but when approached they would either frantically try to escape into roadside vegetation or coil and snap nervously at the intruder. I was never bitten. My goal was to carefully observe these snakes and pick up road-killed specimens for the museum’s collection. I wanted to be a scientist, not a daredevil.

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Western massasauga

The western massasauga is small in comparison to most rattlesnakes, ordinarily reaching about two feet in length, but it is among the largest snakes within the genus that includes the pygmy rattlesnakes. It is handsomely marked with chocolate brown and white markings around the face and a symmetrical pair of squiggly marks at the top of the head, extending to the neck. Beyond that, there are a series of rounded dark saddles that often are indented at the top, making them somewhat heart-shaped. While most of the larger rattlesnakes (like the western diamond-back) have small, granular scales on the tops of their heads, the massasauga has larger scales above the snout and between the eyes. The belly scales are mottled with charcoal and light color. It has the recessed pit organs that are the trademark of the pit-vipers, capable of sensing infrared heat radiation to assist in locating prey in the dark.

While pit-viper venom is primarily hemotoxic, a collection of proteins designed to break down tissue and kill the prey animal, western massasaugas have neurotoxic components to their venom that could interfere with nerve transmission. That extra bit of toxicity makes it a good thing that these little rattlesnakes have short fangs and can inject only small quantities. Andy Price reported that there have been no human fatalities from massasaugas in Texas (Price, 2009). Nevertheless, a bite from this species should be considered a medical emergency.

The name “massasauga” comes from the name of a subtribe of First Nations people, roughly meaning “the great river mouth.” Manny Rubio suggests that this may derive from the swampy or wetland habitats preferred by the eastern massasauga, found in some Midwestern states and around the Great Lakes (Rubio & Keyler, 2013). The western and desert massasaugas, found in the lower Great Plains, parts of Texas, and westward to Arizona and Colorado, make use of drier habitats but still are often found near some source of water. My own experience with massasaugas, in the Cross Timbers and Rolling Plains, is that they live on rolling grasslands that may collect water here and there in streams. Often there are cattle tanks scattered across their habitat, and sometimes there are belts of trees or rocky outcrops.

When born, the babies are 7 to 10 inches in length, and they must eat animals small enough to be swallowed. This may include small snakes and lizards (such as the little brown skink or newly-born ribbon or gartersnakes) as well as insects and small frogs. There are descriptions of baby massasaugas using tail-luring to attract prey. The baby’s tail tip is yellowish, and may be waved while the rest of the snake’s body is motionless. Small frogs were reported to actually grab at the tail tip, triggering a feeding response from the massasauga (Werler & Dixon, 2000). As they grow, they take bigger prey, largely lizards and small snakes, but also including mice.

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A western massasauga, with heart-shaped dorsal blotches, a dark band edged in white running from the eye to the back of the jaw, and two white lines radiating down from the heat pit to the mouth line.

In north Texas, the western massasauga is not as common as it used to be (Greene & Oliver reported finding 30 of these snakes in May and 27 in June in Parker and Tarrant Counties, back in the 1960’s). People who still drive the back roads in Parker County may turn one up here and there, but no one talks about seeing the numbers we used to see fifty years ago. It is thought that habitat loss and alteration are major factors in the decline of this snake. Werler & Dixon (2000) talked about everything from housing development to prescribed burns and mowing at times of year when the snake would be vulnerable as threats to these snakes. They also mentioned that large numbers of cattle can degrade prairie habitat and adversely affect the snakes.

An odd behavior seen in pygmy and massasauga rattlesnakes is side-to-side head-twitching. While observing a snake that may be mostly still, tongue-flicking and assessing the situation, the little rattlesnake periodically jerks its head a little to the side, as if suffering from some sort of tic. One possible explanation cited by Werler & Dixon is that it might help dislodge tiny scent particles in the snake’s nostril, resulting in its contact with the Jacobson’s organ where its significance may be detected.

I wrote about one episode with massasaugas in Clint’s and my book which is in the publication process (stay tuned for updates!). That episode is helpful for understanding stories of people being “chased” by venomous snakes. Steve Campbell and I had stopped for a massasauga on Bear Creek Road, back when a large part of it was unpaved and little-used. The snake was motionless and Steve and I admired it for a minute or so. Then we decided we would like to see it in a different position, and so I touched it with a snake hook. At that point, the snake (which no doubt had been sitting in frozen apprehension, waiting to see if we would just move on) burst into frenzied motion, straight toward Steve! Neither of us was lithe and graceful, but Steve nearly back-flipped out of the way. As he did so, the snake continued on in the same direction it had been headed, across the gravel and caliche and into the darkness on the opposite side of the road. Snakes are not always great problem-solvers when it comes to choosing an escape path, and they may go toward a familiar refuge, even if a human is in the way.

The taxonomic relationships among the eastern, western, and desert massasaugas has been investigated to better understand how they are related. One investigation, by Steven Hein at University of Texas at Tyler (Hein, 2015), found that the eastern massasauga comprised an eastern clade and the western and desert massasaugas comprised a western clade (a “clade” is a group of organisms with a single common ancestor). His suggestion was that the eastern massasauga should become Sistrurus catenatus, while the western and desert massasaugas should be subspecies of Sistrurus tergeminus. Taxonomy always seems to be a work in progress, so we will see if that is the end of the story.

This is a snake I always look forward to seeing, always on my list of “hopefuls” to be seen when I’m out walking or driving west of the Fort Worth area. Maybe it’s partly nostalgia for those first night drives in the 60’s, and partly the handsome patterns and interesting natural history of this little reptile. Whatever the reasons, it remains one of my favorite snakes.

Greene, H.W., and G.V. Oliver, Jr. 1965. Notes on the natural history of the western massasauga. Herpetologica 21:225-228.

Hein, Steven R. 2015. An Integrative Approach to Species Delimitation in the Massasauga Rattlesnake (Sistrurus catenatus) with an Emphasis on the Western Massasauga, S.c. tergeminus, and Desert Massasauga, S.c. edwardsii in Texas. Biology Theses. Paper 29.

Price, A.H. 2009. Venomous snakes of Texas: A field guide. Austin: University of Texas Press.

Rubio, M., & D.E. Keyler. 2013. Venomous snakebite in the western United States. Rodeo, NM: ECO Herpetological Publishing & Distribution.

Werler, J.E., & J.R. Dixon. 2000. Texas snakes: Identification, distribution, and natural history. Austin: University of Texas Press.

A Fall Visit to Shackelford County

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The Rolling Plains, with a harvester ant mound in the foreground

In Shackelford County, just beyond the reach of the Cross Timbers ecoregion and into the Rolling Plains, the stands of oak trees give way to mesquite and open scrub land, with red dirt and plenty of cacti. In some places, open fields of broom weed cover the landscape in knee-high rounded domes. Here and there, a spot of bare earth is marked with a small circle of gravel indicating a harvester ant colony, with little cleared paths branching out from the center. The ants come and go along these little highways, searching for seeds and other food to bring down into the underground chambers. And of course, where there are harvester ants, there may be horned lizards, waiting in ambush along the ant highways to lap up the unlucky insects.

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A Texas horned lizard seen in 2013

Clint and I have found the Texas horned lizard here, although it may not be very common. We found one on my first trip to the ranch land where Clint has permission to roam around looking for herps, insects, and Native American artifacts. In early spring of 2013 we saw a big male Texas horned lizard, and he waited patiently while we took photos. He probably hoped his pattern of sandy brown and yellowish color, broken up by a thin white stripe running down his back, would conceal him like just some chunk of dirt with dead grasses or pebbles. This camouflage had nearly kept us from spotting him, but once your eyes lock in on the spikey head and flattened body with a fringe of spines, the horned lizard image is unmistakable.

Today we visited the ranchland at the other end of the annual season, in autumn when days were still sunny and quite warm, even on October 30. A year with good rainfall had produced lots of plant growth, and I barely recognized the place. The grasses had grown high, but more striking were the thickets of some shrubby plant growing to seven or eight feet and weaving themselves into impenetrable barriers. And these bushes were blooming, attracting a profusion of bees, wasps, and butterflies.

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A bullfrog floats on the pond surface

Our first stop was along a cattle tank, a small, man-made pond that was home to lots of frogs. It was hard to spot them before they spotted us, and in my walk around the pond I saw many of them hop into the water and disappear before I could identify them. However, some of them appeared at the surface shortly afterwards, and these were all bullfrogs. They would float in leisurely fashion, their bulbous eyes and green snouts above the water, watching the strange visitor to their world. Further around the edge of the pond, I spotted a butterfly that I initially thought was a monarch but was really a queen, as I later learned from Clint.

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Queen butterfly

The muddy edges of the pond were hopping – and some of the activity was jumping grasshoppers, while the rest came from cricket frogs. These little relatives of the treefrogs are nearly invisible as they sit still, and populations often come to resemble the substrate they live on. Those that inhabit dark, bottomland soil are usually dark with little splashes of green, while those living on limestone and clay typically a gray color. When something gets too close and disturbs them, they typically hop into deeper vegetation or else dive into the shallow water, only to double back and dig into some place of concealment. Cricket frogs are nimble and quick, but even the quickest often fall prey to shore birds and other predators, including ribbonsnakes.

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A cricket frog on dried mud

Ribbonsnakes specialize in the same water’s edge habitat as the cricket frogs, and the snake has a sharp eye for movement. The slender striped snake cruises along until it flushes the frog, and then the chase is on. When the frog stops and freezes, the snake may stop as well, its body tense and ready for when it detects the slightest movement from the frog. When the frog makes its move, the snake instantly responds. There is hardly anything more graceful and beautiful than a ribbonsnake swimming and threading its way through streamside vegetation. Many of them, especially in central Texas, have a dorsal stripe that starts as a deep orange-red, becoming more pale toward the tail. Along the gulf coast, that dorsal stripe is a rich, butter-yellow. In some localities, this stripe (and the two others along the snake’s sides) have a bluish cast. When they swim, their slender bodies undulate in symmetrical curves, like a ribbon with three stripes propelling itself rapidly across the water.

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Juvenile ribbonsnake

Today, however, I found a muddy little ribbonsnake, motionless on the mud at the water’s edge. Its central stripe was red enough under a little film of sediment, but when I first spotted it, it hardly looked much different from the surrounding mud. After I took a couple of photos and moved in a little too close, it took off into the water in tight little undulations, shooting down into the muddy depths to hide.

After a while, I set off to explore the brushy landscape that led up toward a hillside I remember exploring with Clint on that trip three years ago. I chose my steps carefully, since the treacherous pencil cholla (or Christmas cholla) is one of the cacti growing in almost any spot near a clump of trees on this ranch. While you can accidentally step on a pad of prickly pear and it won’t penetrate your boot, the slender, jointed segments of this cactus grow up to three feet or higher and can send you on your way with barbed spines in your jeans or your arm.

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A pencil cholla in the foreground, framed by mesquite and prickly pear behind it

On my walk toward the hillside, I came upon another, smaller cattle tank bulldozed out of the red soil. Another group of frogs called this oversized puddle home, and each step toward it brought another “plunk” as another frog jumped in. On a couple of sides, this little oasis was at the bottom of a steep three or four-foot embankment. As I walked near the edge, the grasses and broom weed moved as one frog after another hopped from several feet away, plunged off the edge and dropped to the water. I was a little surprised, as it was mid-afternoon and quite warm, but I suppose these frogs were foraging for insects under the sparse shade of the low vegetation, some distance from the water. Most of these frogs were plains leopard frogs, with big spots and two light dorsolateral folds running down their backs. On spring nights, the calls of the males are a mixture of chuckles and grunts, calling out to females who may be ready to lay eggs in the water, needing only to find a suitable male to fertilize the eggs.

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A plains leopard frog

At the end of the afternoon, turning from a dirt road onto a paved farm road, we found the only other snake we saw on this day, a juvenile Texas patch-nosed snake. They are fast like racers, and the only reason Clint was able to capture it for a few moments was that it was surprised on the pavement, where the serpentine curves of its body could find only very small irregularities to push against. On rocky ground, in grass, or among the other objects in its typical habitat, its strong and lithe body finds plenty of places where it can push forward, and it disappears quickly. Once captured, this pugnacious little snake gaped and bit with its tiny, recurved teeth, to no avail. We took a couple of photos and then released it to go on its way.

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Juvenile Texas patch-nosed snake, unwilling to sit still for a more naturalistic photo

It had been very nice little October 30th road trip, trick or treat a day early, and the Rolling Plains had bestowed plenty of treats on this day. Maybe no Texas horned lizard this time, but there’s always next time!