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The Massasauga rattlesnake, or Sistrurus catenatus, is a member of the pit viper family. The eastern, western and desert subspecies live in prairies, woodlands, marshes and grasslands in parts of Canada, the United States and Mexico. They use their heat sensitive pits and tongues to seek prey, which includes small rodents, amphibians, other reptiles and birds. Females give birth to live babies and leave shortly after. Though their bite can be venomous, the snakes are shy and will only attack when threatened.
Wetlands, including swamps and floodplains, and meadows serve as the main habitat of the eastern rattlesnake during cold weather. They move to dry woodlands at higher elevations during summer. Their range includes southern Canada and the eastern and central United States. The western and desert subspecies live in prairies and grasslands, primarily in New Mexico, Arizona, Texas and Colorado.
The eastern Massasauga rattlesnake is the largest subspecies, measuring up to 30 inches (76 cm) in length. The western subspecies has an average length of 26 inches (66 cm), while the desert subspecies typically reaches a length of 21 inches (53 cm). All subspecies have a triangular head, pits near their nostrils and a rattle on the tip of their tail. The eastern Massasauga rattlesnake has the darkest coloring, ranging from gray to brown with black markings along its back. The western and desert subspecies are a lighter brown or tan color with white bellies.
Heat sensitive pits in the rattlesnake's head help it find warm-blooded prey in the dark, while its tongue picks up scent particles from other animals in the air. A swift strike with its fangs delivers enough venom to kill the shrews, mice, frogs, lizards, birds and other snakes that it feeds on. The fangs then fold up flat against the roof of the snake's mouth.
During the winter, Massasauga rattlesnakes go into a semi-hibernation state called brumation. They seek shelter in burrows or crevices in small groups or alone and emerge in the spring for the mating season. After mating occurs, the male leaves and the female carries eggs inside her for a period of two to four months. She lives off of fat reserves instead of hunting during this time to reduce the risk of being caught by predators.
The Massasauga rattlesnake uses sunlight to speed up gestation. The eggs hatch inside the female, who then gives birth to pale-colored babies measuring around 9 inches (23 cm) in length. The female does not remain with her young to raise them.
Habitat destruction has lead to the decline of Massasauga rattlesnake populations in most of their range. They are listed as endangered in Canada and considered threatened or endangered in many of the states they are found in. Although feared by humans due to their venomous bite, the snakes benefit their environments by reducing rodent populations.