Pygmy Rattlesnake

Sistrurus miliarius is a small species, but bulky in width, with adults usually growing to 40–60 cm (16–24 in) in total length (including tail). It is the smallest species of rattlesnake on the North American continent. The maximum reported total length is 78.8 cm (31.0 in) (Klauber, 1972). Snellings and Collins (1997) reported a specimen of S. m. barbouri measuring 80.3 cm (31.6 in), but it had been in captivity for over 12 years. The largest S. m. barbouri reported by Gloyd (1940) was a specimen measuring 63.8 cm (25.1 in) from St. Petersburg, Florida. Shine (1978) suggested that in some populations, males may be larger than females, but a later study by Bishop et al. (1996) did not find sexual dimorphism of any kind in a population in Volusia County, Florida. It is currently theorized that the lack of sexual dimorphism in the species is due to the fact that both males and females experience selective pressures to be of a larger size. At midbody, the rows of dorsal scales usually number 23. The dorsal pattern consists of a series of oval or subcircular spots with somewhat regular edges. The spots on the flanks are mostly round and not much higher than they are wide. Belly pigmentation towards the rear is more limited to indistinct blotches found on pairs of adjacent scales. …

Sistrurus miliarius is found in the Southeastern United States from southern and eastern North Carolina, south through peninsular Florida and west to East Texas and Oklahoma. The type locality given is "Carolina". Schmidt (1953) proposed that this be restricted to "Charleston, South Carolina".

Sistrurus miliarius is usually seen in the summer sunning itself or crossing the road late in the day. The tiny rattle makes a buzzing sound that can only be heard from a few feet away. The unusually small rattles of the pygmy rattlesnake is suggestive of the early stages of rattle evolution. Some individuals are very aggressive and strike furiously, while others seem lethargic and do not even attempt to rattle. Some research has shown that a larger portion of these rattlesnakes are usually reluctant to bite. It does not dig its own burrows, but rather uses those dug by small rodents or gopher tortoises (Gopherus polyphemus). These snakes typically don't move far from their "home burrows" and studies have shown that males may move farther than females. Pygmy Rattlesnakes are generally solitary but become social only during the breeding season. During this time, male pygmy rattlesnakes become agonistic towards each other, with fighting, challenge displays, and mate-guarding behavior all being observed.

The specific name, miliarius, is derived from Latin and means millet or millet-like, perhaps referring to the blotched patterns described in the species.