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DFW Herpetological Society - Herp of the Month
October 2003


The DFW Herpetological Society is a group with a mission - to promote understanding, appreciation and conservation of reptiles and amphibians, and to encourage respect for their habitats.

If you want to learn about native species and recognize venomous snakes, this is the group for you!  Interested in observing and photographing reptiles and amphibians in the wild?  DFW Herpetological Society members enjoy field trips to local destinations as well as weekend-long expeditions to locations such as the Hill Country and Trans Pecos.

Anyone interested in herps is welcome at their meetings!  Meetings are held the 3rd Saturday of the month at 7:00pm, in the UTA Life Sciences Building, Room 119.  Check out www.dfwherp.org to learn about this great group!


This article is reprinted with permission of the DFW Herpetological Society.
Author Michael Smith, Editor  Cross Timbers Herpetologist


Sistrurus catenatus tergeminus

Western Massasauga

The genus Sistrurus is a small group of rattlesnakes found in the United States and southern Mexico. The genus consists of three species: the Pygmy Rattlesnake (S. miliarius) with three subspecies found in the southeastern United States, the Massasauga (S. catenatus) with three subspecies found in the northeastern and central United States, and the Mexican Ground Rattlesnake (S. ravus) with four subspecies found in southern Mexico (Klauber, 1997). North Texas is unique in that it is one of only two places in the world with sympatric (= occurring in the same geographical area) species of Sistrurus, the Western Massasauga (S. c. tergeminus) and the Western Pygmy Rattlesnake (S. m. streckeri).


Description
Members of the genus Sistrurus are distinguished from all other rattlesnakes (genus Crotalus) by the presence of nine enlarged scales on the crown of the head. This head scalation pattern is similar to that found in most harmless species of snakes and the deadly Coral Snakes (Micrurus and Micuroides).

The Western Massasauga is a stout-bodied snake that can reach lengths of up to 86 cm (34 in) (Conant and Collins, 1991). These animals have a background color that can range from a sandy brown to a grayish green to a dark gray (the most common in our area). There is a row of dark blotches that runs down the back of the snake, ending in small bands around the tail region. These dorsal blotches range from dark brown to black in coloration and are often bordered by a light gray or white edge. The dorsal blotches are square-like in shape, although in some specimens they are a characteristic heart shape. There is a row of irregular shaped spots running down both sides of the body. These spots are usually dark gray in coloration and are offset from the dorsal spots. There is a dark stripe running from the snout through each eye and extending to the back of the jaw. This stripe is bordered by thin white stripes. The underside of the snake is white in coloration with small, irregular shaped smudges of dark pigment scattered throughout. Some juveniles may have lime green or yellow tail tips, which is sometimes retained by adults. Juveniles are also usually lighter in coloration than adults, with the pattern and colors fading with age. The tail tip ends in a medium sized rattle.

Habitat
The massasaugas are primarily a snake of the open prairies and other grasslands of North America. In north Texas, the massasauga is commonly found around the small streams and canyon lands that cut through open grasslands. These riparian habitats usually support stands of post oaks and cottonwoods, and so they may be found among these small groves. The massasauga also is associated with the steep and rocky hillsides found around most of North Texas, because these areas are perfect winter hibernacula. Much of the former tall grass prairies in Texas are now overgrazed cattle pastures and the massasauga has adapted somewhat to these areas. Because of this, they often make use of the typical cover that can be found around barns and farmhouses; tin, boards, bails of hay, farming equipment, etc.


Feeding
These snakes feed on many different species of frogs, especially treefrogs (Hyla) and their relatives the chorus frogs (Pseudacris) and cricket frogs (Acris). They have even been known to feed on toads (Bufo), which many snakes find unappetizing. Lizards also make up a large part of their diet, including Great Plains Skinks (Eumeces obsoletus), Prairie Skinks (Eumeces septentrionalis), and Whiptail Lizards (Cnemidophorus). In addition to this reptile and amphibian smorgasbord, they also feed upon insects, centipedes, snakes, small birds, mice, shrews, and rats.

A curious feeding behavior, found in many juveniles, is the practice of caudal luring. Caudal (= tail) luring is a practice that some snake species use to attract prey within striking distance. The whole process usually entails the snake curling up in a coil along side some trail often used by lizards or amphibians. When curled up, the tail is usually placed close to the head. The tail is then twitched about very slowly and methodically, resembling a worm or insect larva, while the rest of the body is held still. When a curious frog or lizard gets to close, the animal will strike and envenomate the prey. The bright green or yellow tail of the juveniles presumably helps enhance the appearance of the lure.


Reproduction
Members of this genus, like all rattlesnakes, are viviparous, or live bearing. Breeding often takes place early in the springtime, but can occur throughout the summer and into the fall. The gestation period varies with the time of mating, but probably lasts somewhere around 6-9 months. Rather than just quote many of the captive-bred statistics, I have also given some of my own first-hand observations of this species in the wild.
Massasaugas usually breed shortly after coming out of hibernation in February or March. I personally observed courtship between a small male and large female in Weatherford, TX on March 10, 2001. In addition, I have found young massasaugas, with buttons only (the first segment that a rattlesnake is born with and has for only a short time), from late September through late October. The litter size varies from 2-8 with as many as 13 observed in one litter from a large female (Tennant, 1985).

Relative abundance
The Western Massasauga has declined drastically in numbers over the past few decades. Twenty years ago it was a common sight to see upwards of 50 of these snakes in a single night on the roads of suburbs, such as Benbrook (personal communications with Jonathan Campbell and Michael Smith). Now one must travel much further and much more often to see a few road killed animals and occasionally a live specimen. Man has created many of the problems facing the massasauga. A major concern has been the overgrazing of the tall grass prairies by cattle ranchers. This has severely altered the natural habitat of the massasauga. In addition, many of the traditional den sites of this snake have been dynamited or otherwise destroyed. This has proven detrimental to the species as many snakes return, year after year, to the same den sites where they were born. Many roads now criss-cross the prairie grasslands that the massasauga calls home. This invariably brings the massasauga into contact with passing cars resulting in many dead snakes every year. Finally, for years commercial collectors have found it easy to collect massasaugas off of the roads at night or around their winter dens. Because of this easy accessibility, some populations have been over collected.

Husbandry
The keeping of venomous reptiles is a touchy subject among reptile hobbyists, researchers, and governmental officials and is outside the scope of this article. However, a couple of things should be pointed out. First, one must always abide by federal, state, and local laws. Many of the cities in the Metroplex have ordinances making it illegal to keep venomous reptiles (as well as snapping turtles and some other herps). In addition, anyone thinking of keeping a venomous reptile should only do so after mentoring with a zoo or private individual for an extended period of time. Some states, such as Florida, require 1000 hours of mentoring under a licensed individual in the particular snake or lizard family that will be kept. Despite Texas not having any state laws governing this, I feel this is a good guideline for anyone thinking of keeping these potentially dangerous animals. In the meantime, the Western Massasauga can best be enjoyed in their natural environs.


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