Species Fact Profile: Massasauga (Sistrurus catenatus)

                                                               Massasauga

                                           Sistrurus catenatus (Rafinesque, 1818)

Range: Central North America, from southern Canada south into northern Mexico

Habitat: Lowland Forest, Wetlands, Prairies

Diet: Rodents, Lizards, Amphibians, Invertebrates

Social Grouping: Solitary

Reproduction: Mate in late summer, giving birth about 1 year later.  Females may have 5-20 young, born live.  Depending on food availability, they may reproduce anywhere from every year to every three years.  Sexual maturity is reached at 3-4 years old

Lifespan: 15-20 Years

      Conservation Status: IUCN Least Concern

• Short, thick-bodied snake, average adult length approximately 60 (range 46-76) centimeters.  Weigh 310-425 grams, with females being larger than males. 
• The head is flattened and heart-shaped, with the eyes having vertical pupils.  The tail terminates is a series of keratin rings, forming the rattle.  An additional button is added to the rattle every time the snake sheds its skin, though older segments can become brittle and break off.  Newborn snakes start life with a single button at the end of their tail
• Adults are gray or light brown with large chocolate-brown blotches, edged with lighter-colored scales, down the center of their backs, smaller blotches on the side.  The underside is solid black, or solid black with some light mottling.  The tail has alternating bands of light and dark scales.  Young snakes are similarly marked, but with more vivid colors.  Solid black melanistic individuals have been documented
• Most active by day, shifting towards more crepuscular during the peak of the summer
• During the spring and summer, the snakes migrate towards drier upland habitats.  Will only migrate short distances, occur most commonly in areas of habitat with variable elevations
• Unlike many other rattlesnakes, massasaguas hibernate alone, taking shelter in crayfish burrows, small mammal burrows, or under logs and tree roots, just below the frost line.  Most active between April and late October in the northern parts of their range.  Use the same hibernation den year after year
• Young snakes may lure prey close to flicking their tail to attract frogs and other animals.  Adults feed primarily on rodents, juveniles on reptiles.  Prey may be detected by sight, by smell, or in response to the heat or vibrations that animal gives off
• Natural predators include larger snakes, herons, hawks, skunks, raccoons, and foxes, with eggs and the young being especially vulnerable.  If approached, they will vibrate their tail as a warning, though with their small size the display is less audible than in other rattlesnakes, sometimes likened to the buzzing of an insect
• The venom is a cytotoxin, which destroys tissue and disrupts blood flow, preventing clotting and causing internal bleeding in the prey.  The snake bites its prey, then withdraws to safety while the venom kills the prey animal
• Only two reports exist of persons dying of massasauga bites, both individuals who were not given proper medical treatment.  Many hospitals do not carry their specific antivenin, which is considered difficult to acquire.  Bites on humans are very infrequent, with about 1-2 reported a year in Ontario and Michigan (the strongholds on this species), with other states reporting fewer than 1 bite a year.  Anywhere from ¼-1/2 of these bites are dry bites
• “Massasauga” comes from the Chippewa for “Great River Mouth,” probably referencing their preferred habitat in wetlands
• Three subspecies – the nominate, or eastern massasauga, which is the largest; the desert massasauga S. c. edwardsii (extreme southern US into northern Mexico, also occurring on several barrier islands);  and the western massasauga S. c. tergeminus (of Nebraska south to northern Texas).  The eastern subspecies is sometimes considered a separate species, with the other two subspecies recognized as S. tergeminus.  The eastern massasagua is the subspecies/species that is cooperatively managed in AZA member institutions
• The only other species in the genus Sistrurus is the pygmy rattlesnake (S. miliarius) of the southeastern United States
• Listed as endangered in several states and is a candidate for federal listing under the Endangered Species Act.  Primary threat is loss of habitat due to deforestation and wetland draining; the species does not make large-scale movements, so populations are easily isolated from one another.  Invasive plants disrupt their habitats, and efforts to control these plants through proscribed burning may kill snakes.  Also persecuted out of fear of being a venomous snake, though they are legally protected throughout their range