Squamata suborder Serpentes
Sistrurus catenatus -- Massasauga
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Purple shade indicates vouchered specimens. Light blue (cyan)
shade indicates photographic records. Yellow shade indicates verified
sighting. Slanted hatch indicates pre-1980 records only
NOTE: Not all specimens upon which these maps are based have been verified.
Key Characters: Nine large symmetrical plates on top of head; elliptical pupil; pit between eye and nostril; light-edged dark blotches on back and sides; rattle or horny button on tail tip; 4 head stripes; back scales strongly keeled; anal plate not divided.
Similar Species: Timber rattlesnake, fox snake. What's the difference between a fox snake and a massasauga?
Subspecies: Eastern massasauga, S. c. catenatus.
Description: Medium-sized (up to 100 cm TL) venomous snake. Back gray to light brown with 29-40 light-edged dark brown or black blotches down the middle. Three rows of smaller, alternating dark blotches along each side. One black head stripe behind each pit, two on top. Belly black with irregular white or yellow markings. Newborn tail tip yellow, but darkens with age.
Habitat: Old fields, floodplain forests, marshlands, and bogs.
Natural History: Active April through October, often suns on clumps of grass, in branches of small shrubs, or near crayfish burrows. Feeds on small rodents. Breeds spring and autumn with 4-20 young born late summer or early autumn. Newborn 20-30 cm TL. Main predators are hawks, predatory mammals, and other snakes.
Status: Endangered in Illinois. Formerly common over northern two-thirds of the state, prior to drainage of prairie marshes and intensive agriculture. Once known from 24 widely scattered relict populations, now thought to occur at only 6-8.