Prairie Massasauga (Massasauga Rattlesnake)

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Massasauga (Massasauga Rattlesnake)

photo of a massasauga
Sistrurus tergeminus tergeminus
Viperidae (venomous snakes) in the order Squamata (lizards and snakes)

Medium-sized, dark rattlesnake with a short, thick body. Gray to gray-brown, with dark brown blotches down the middle of the back and along both sides. Head is a thick diamond shape with dark stripes extending back from the eyes. Tail has a stubby rattle. Like other venomous snakes, they have “pits” on the sides of their heads, and the pupils are diamond-shaped (not round). The other rattlesnake of north Missouri, the timber rattlesnake, grows much larger and has a rusty stripe down its back.

Length: 18–30 inches, not including the rattle.
Habitat and conservation: 
Mainly found in bottomland or wet prairies dominated by cordgrass, sedges, bullrushes, and smartweeds, and lowlands by rivers, lakes, and marshes. They require wetlands associated with river floodplains of north Missouri. Populations have declined because of habitat loss as floodplains were converted to farmland. Restoring wetlands along rivers, improving existing wetlands, and protecting this snake from being killed are the keys to the survival of this species.
Massasaguas feed primarily upon rodents (especially voles and deer mice) and small snakes such as gartersnakes. Most of the hunting occurs during the day, except in the hottest part of the summer, when this species becomes more active at night.
Distribution in Missouri: 
Small numbers survive in north-central and northwest Missouri. Recently recorded in only Chariton, Lynn, and Holt counties.
What were formerly two subspecies of "eastern massasauga" (Sistrurus catenatus) have been split into separate species. Our population of massasaugas are a subspecies of western massasauga (S. tergeminus) called the prairie massasauga (S. tergeminus tergeminus). The eastern massasauga (S. catenatus), a candidate for federal endangered status, is extirpated from Missouri. Both species are listed as endangered in Missouri. None can be injured, killed, or taken from the wild for any use.
Life cycle: 
In summer, massasaugas live along the edges of wet prairies. They overwinter in burrows in moist lowland areas. They emerge from winter dormancy in mid-April. In early October, they migrate back to overwintering areas, in some cases traveling distances of over 1½ miles. Female massasaugas are believed to reproduce every other year. Mating occurs in late summer, and females give birth to an average of 4 to 10 live young.
Human connections: 
Many of us fear rattlesnakes, so it’s a natural impulse to want to kill them — however, as we increase our understanding of how these snakes fit into the balance of nature, our knowledge and appreciation of these disappearing snakes makes us concerned for their survival.
Ecosystem connections: 
Massasaugas hunt voles, mice, and other rodents, plus smaller snakes, keeping their populations in check. As a resident of marshy areas and moist prairies, this efficient predator thus has an important predatory niche within those habitats.
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