Sistrurus miliarius is a small species with adults usually growing to in total length. The maximum reported total length is . Snellings and Collins reported a specimen of S. m. barbouri measuring, but it had been in captivity for over 12 years. The largest S. m. barbouri reported by Gloyd was a specimen measuring from St. Petersburg, Florida. Shine suggested that in some populations males may be larger than females, but a later study by Bishopet al. did not find sexual dimorphism of any kind in a population in Volusia County, Florida. At midbody, the rows of dorsal scales usually number 23. The dorsal pattern consists of a series of oval or subcircular spots with reasonably 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. Juveniles have a color pattern that is similar to the adults, although it may be paler or more vividly marked, and the tip of the tail is yellow.
Common names for S. miliarius include pygmy rattlesnake, ground rattlesnake, hog-nosed rattlesnake, little rattlesnake, miliar rattlesnake, North American smaller rattlesnake, oak-leaf rattler, pygmy ground rattlesnake, small rattlesnake, southeastern ground rattlesnake, southern ground rattlesnake, southern pygmy rattlesnake, spotted rattler, spotted rattlesnake, southern rattlesnake. Older common names might include bastard rattlesnake, nipple snake, Carolina ground rattlesnake, brick red rattlesnake, Carolina pygmy rattlesnake, Catesby's small snake, dwarf rattlesnake, eastern pygmy rattlesnake, grey rattlesnake, and ground rattler.
Geographic range
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 proposed that this be restricted to "Charleston, South Carolina".
Habitat
Sistrurus miliarius reportedly inhabits flatwoods, sandhills, mixed forests, and floodplains, and is also found near lakes and marshes.
Conservation status
This species is classified as least concern on the IUCN Red List of Threatened Species. Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. It was assessed in 2007.
Behavior
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. Some individuals are very aggressive and strike furiously, while others seem lethargic and do not even attempt to rattle. It does not dig its own burrows, but rather uses those dug by small rodents or gopher tortoises.
Feeding
The diet of S. miliarius includes small mammals and birds, lizards, insects, and frogs, as well as other snakes. Pygmy rattlesnakes also include giant desert centipedes in their diet, which they hunt by active pursuit, grabbing and flipping the centipedes around while simultaneously injecting venom to prevent injury by the victim. They also ambush lizards such as skinks by using their tails as lures, as is common in many other species of vipers.
Venom
Since S. miliarius is unable to produce much venom, it is unlikely to be able to deliver a fatal bite to a human adult. Brimley wrote that although it was too small to be really dangerous, its bite "will give the victim quite an unpleasant time for several days." However, bites involving children have resulted in prolonged hospitalization, with reports of necrosis. This snake produces cytotoxic venom that is strongly hemorrhagic and tissue toxic, but devoid of any neurotoxins. The venom was the basis for the development of the drug eptifibatide, which is used to prevent clotting during a heart attack. The venom is somewhat different in that it contains substantial amounts of serotonin and related tryptamine compounds. Antivenin does not appear to be effective in the treatment of bites of S. miliarius, although CroFab does seem to do a better job than ACP, at least in some animal models.
