These snakes are listed as Endangered and a Species in Greatest Conservation Need by the State of Minnesota.
This is a small rattlesnake that measures 17 - 39 and 1/2 inches in length. It is VENOMOUS! There is a row of black or dark brown mid dorsal blotches on a lighter brown or gray background. There are two or three rows of small spots on the sides. All blotches and spots may be outlined in white. The blotches usually turn into bars on the tail; the last bar being a complete ring. There are usually five bars that are 3 - 3 and 1/2 scales wide and 1 and 1/2 scales apart. There is a rather broad dark stripe from the eye past the angle of the jaw. The belly is mostly black with irregular white or yellowish marks. Melanistic specimens are known; these are uniformly black dorsally and ventrally. There are usually some light markings on the chin and throat that remain, however.
Massasaugas are stout bodied snakes with a triangular shaped head. The pupils are vertically elliptical and there is a heat sensitive pit located between the eye and nostril. This pit is larger and positioned lower on the face than the nostril. There is a rattle at the end of the tail. The rattle is comprised of a series of interlocking keratinous - like segments that make a buzzing noise when the tail is vibrated. The scales are keeled and the anal plate is single.
The eastern massasauga, Sistrurus catenatus catenatus, is the only subspecies in Minnesota.
Although the eastern massasauga is listed as species found in Minnesota, there is great speculation as to whether or not a population of this species even exists in Minnesota. I have included it only for the sake of consistency with past authors. There have been numerous unsubstantiated reports of these snakes occurring in southeastern Minnesota, but a 1993 search yielded no massasaugas. There is one preserved specimen from Wabasha County and others with disputed origins from Minnesota. These snakes are good swimmers and possible border crossings should not be discounted, especially during a flood. In any case, massasaugas are exceedingly rare in Minnesota and their status should be Endangered if it is a resident of Minnesota. If you see a massasauga in Minnesota, try to take a good picture of it. Do not attempt to catch or move it and, most importantly, give clear and exact locality documentation of where you saw it, and report it to the DNR, the Minnesota Herpetological Society, or
Most authors seem to agree that massasaugas prefer low, swampy areas close to marshes, lakes, and rivers. They seem to elevate themselves from the borders of such habitations, but do not wander a great distance from a particular body of water, except in summer, when specimens may be found in open grasslands, meadows, or dry open woodlands.
I have no data on the habits of massasaugas in Minnesota. The information is supplied from accounts from Iowa and Wisconsin, and literature from Wisconsin, Indiana, and other sources. Some references state that massasaugas are slow, sluggish snakes that are quite passive and slow to rattle or strike. They rely on their coloration for camouflage to avoid detection. One may almost step on this snake before provoking a reaction from it. I have found that they are diverse in their behavior as some will rattle at the least provocation and strike repeatedly, but most do not.
This snake is generally diurnal except during extremely hot weather. They seem to enjoy warm overcast weather as this is the condition under which many specimens were found. Mornings are a good time in which to look for basking massasaugas. They take shelter under rocks, logs, pieces of bark, under piles of brush, muskrat houses, or in crayfish burrows. They breed in the late summer or fall and sometimes in the spring. They may only breed every other year or less and are sexually mature at the age of three or four. They give birth to living young (ovoviviparous). The young number from 5 - 24 and are about 5 - 7 inches in length. The young are equipped with fangs and are venomous as soon as they are born. They are usually brighter colored than the adults. Instead of overwintering communally, like many species of snakes, they overwinter alone in crayfish burrows, or, rarely, mammal burrows, crevices or rock piles close the water, and other areas they can gauge the water line. It is reported that they emerge with the spring flooding and basically follow the water line during this time.
Massasaugas diets are comprised largely of small mammals, but small birds, lizards, frogs, toads, and other snakes are also consumed. While adults usually feed upon mice, small snakes are an important food item for young massasaugas. It is interesting to note that this snake will bite and release adult mice then search them out and swallow them after they are dead. When birds and lizards are to be consumed, they are held in the snake's jaws until the venom takes effect.