Prairie rattlesnakeCrotalus viridis
VENOMOUS 
Photo: Graham Zephirin
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Map accurate as of 1/31/2024
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Habitat In Colorado this species lives in plains grassland, sandhills, semidesert shrubland, riparian zones, piñon-juniper woodland, and montane woodland habitats up to 9,500 ft in elevation.
Activity Most activity takes place April - September. Prairie Rattlesnakes retreat and remain inactive in winter dens December-February. During mild weather in spring and fall this species is active during the day, becoming more nocturnal during hot summer months.
Diet Adults primarily consume small mammals, though they will also feed on lizards, frogs, toads, insects, birds, eggs, and carrion. Juveniles primarily feed on lizards.
Predators In Colorado, known predators include Golden Eagles, Northern Harriers, hawks, and North American Racers. Humans are likely the most important predator of this species throughout the range.
Defensive behavior When approached Prairie Rattlesnakes may remain motionless and rely on their camouflage to escape detection. They may also attempt to quietly crawl away to cover. At other times they will coil defensively or raise their body, rattling and striking readily when approached too closely. If harassed for an extended period they may attempt to hide the head beneath the body.
Reproduction This species usually mates mid July - early September, with females storing sperm through the winter and giving birth the following summer. Males likely mate every year, while females typically reproduce every 2-3 years. Males sometimes engage in wrestling combat over reproductive access to females. Pregnant females bask and shelter at rookeries alone or in groups in order to incubate their young. Young are born from late summer to early fall and mothers remain with and defend their offspring until the young disperse.
Conservation and status This species has experienced local declines and extirpations but remains locally abundant in much of its Colorado range. The Prairie Rattlesnake is a small game species in Colorado that may be taken from June 15–August 15, with a daily bag limit of 3 and a possession limit of 6. Colorado State Statutes state that "any person may kill rattlesnakes when necessary to protect life or property" [33-6-107(9), C.R.S.]. Live venomous snakes may only be possessed pursuant to a Commercial Wildlife Park License issued by Colorado Parks and Wildlife, and noncommercial possession or the possession of a live venomous snake as a pet is prohibited.
Diet Adults primarily consume small mammals, though they will also feed on lizards, frogs, toads, insects, birds, eggs, and carrion. Juveniles primarily feed on lizards.
Predators In Colorado, known predators include Golden Eagles, Northern Harriers, hawks, and North American Racers. Humans are likely the most important predator of this species throughout the range.
Defensive behavior When approached Prairie Rattlesnakes may remain motionless and rely on their camouflage to escape detection. They may also attempt to quietly crawl away to cover. At other times they will coil defensively or raise their body, rattling and striking readily when approached too closely. If harassed for an extended period they may attempt to hide the head beneath the body.
Reproduction This species usually mates mid July - early September, with females storing sperm through the winter and giving birth the following summer. Males likely mate every year, while females typically reproduce every 2-3 years. Males sometimes engage in wrestling combat over reproductive access to females. Pregnant females bask and shelter at rookeries alone or in groups in order to incubate their young. Young are born from late summer to early fall and mothers remain with and defend their offspring until the young disperse.
Conservation and status This species has experienced local declines and extirpations but remains locally abundant in much of its Colorado range. The Prairie Rattlesnake is a small game species in Colorado that may be taken from June 15–August 15, with a daily bag limit of 3 and a possession limit of 6. Colorado State Statutes state that "any person may kill rattlesnakes when necessary to protect life or property" [33-6-107(9), C.R.S.]. Live venomous snakes may only be possessed pursuant to a Commercial Wildlife Park License issued by Colorado Parks and Wildlife, and noncommercial possession or the possession of a live venomous snake as a pet is prohibited.
Suggested citation Colorado Partners in Amphibian and Reptile Conservation. 2018. Prairie Rattlesnake (Crotalus viridis) Abbreviated Species Account. Compiled by Andrew M. DuBois. http://www.coparc.org/prairie_rattlesnake [accessed date here].
Last updated 4/25/2022 by Rémi Pattyn
Last updated 4/25/2022 by Rémi Pattyn
Resources
Ernst, C. H. and E. M. Ernst. 2012. Venomous Reptiles of the United States, Canada, and Northern Mexico: Crotalus. Vol. 2. JHU Press, Baltimore, Maryland.
391 pp.
Hammerson, G. A. 1999. Amphibians and Reptiles in Colorado. 2nd ed. University Press of Colorado, Boulder, Colorado. 325 pp.
Stebbins, R. C. 2003. Western reptiles and amphibians. 3rd ed. Houghton Mifflin Company, New York, New York. 352 pp.
Young, M. T. 2011. The Guide to Colorado Reptiles and Amphibians. Fulcrum Publishing, Golden, Colorado. 170 pp.
391 pp.
Hammerson, G. A. 1999. Amphibians and Reptiles in Colorado. 2nd ed. University Press of Colorado, Boulder, Colorado. 325 pp.
Stebbins, R. C. 2003. Western reptiles and amphibians. 3rd ed. Houghton Mifflin Company, New York, New York. 352 pp.
Young, M. T. 2011. The Guide to Colorado Reptiles and Amphibians. Fulcrum Publishing, Golden, Colorado. 170 pp.
