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Reptiles and Amphibians of North Dakota

Prairie Rattlesnake (Crotalus viridis)

species distribution map JPG -- Species Photo


These are North Dakota's only poisonous snakes. Found west of the Missouri River, they commonly reach a length of three feet, although specimens have been recorded as long as five feet.

Their color varies from greenish-gray to greenish-brown. They have dark oval blotches surrounded by white markings. Rattlesnakes are found in the grasslands and sagebrush areas of North Dakota as well as the high rocky ledges of buttes.

In the early spring and late fall prairie rattlesnakes hunt for food during the day. In the hot summer months they take shelter from the heat by finding a shaded area or rocky outcrops. There they stay till evening when they begin their nightly hunt for small mammals.

The unique feature that gives rattlesnakes their name is the rattle. These rattles are shaken by the snakes in order to scare and warn potential predators. The number of rattles or buttons increases each time these snakes shed their skin. Because of this you can only approximate the age of rattlesnakes by the number of buttons on the tail.

The females mate in March to May and in the early fall they give birth to live young. An average-size litter contains about 12 young but this can vary from 4-21. The young are able to fend for themselves and no parental care is given by the mother.

In the winter these snakes will hibernate together in prairie dog burrows or rocky crevices.

Rattlesnakes are pit vipers. They use specialized organs to detect heat. These pits, found below and in front of the eye, are placed at different positions on either side of the snake's head. This makes it possible for the snakes to line up their prey in total darkness.

The fangs are covered by a protective sheath of tissue, and are normally folded back against the roof of the mouth. Rattlesnake fangs are hollow and are connected to a venom gland which lies behind the eye. Fangs are replaced at regular intervals whether they are broken or not.


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