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.
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.
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.