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Crotalus concolor facts for kids

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Crotalus concolor
Crotalus oreganus concolor 01.jpg
Scientific classification
  • Crotalus concolor
    Woodbury, 1929
  • Crotalus confluentus decolor Klauber, 1930
  • Crotalus confluentus concolor – Woodbury, 1930
  • Crotalus viridis concolor
    – Klauber, 1936
  • Crotalus viridis decolor
    – Gloyd, 1940
  • Crotalus viridis decolor
    – Klauber, 1956
  • Crotalus viridis concolor
    – Klauber, 1972
  • Crotalus oreganus concolor
    – Ashton & de Queiroz, 2001

Crotalus concolor is a venomous pit viper species found in the western United States. It is a small rattlesnake known for its faded color pattern. Other common names include midget faded rattlesnake, faded rattlesnake and yellow rattlesnake.


This snake grows to a maximum length of 75 cm (29 12 in). The smallest gravid female measured was 52.2 cm (20 12 in).

The color pattern of this species consists of a pinkish, pale brown, yellow-brown, straw-colored, reddish, or yellow-brown ground color, overlaid with a series of brown elliptical or rectangular dorsal blotches. However, most specimens are gray or silvery. In juveniles, the pattern is distinct, but becomes faded in adults, almost to the point where it is indistinguishable from the ground color.

Geographic range

Found in the United States in the Colorado and Green River basins. This area covers southwestern Wyoming, Utah east of long. 111° West (excluding the southeastern corner) and extreme west-central Colorado. The type locality given is "King's Ranch, Garfield Co., at the base of the Henry Mts [Utah]."


This species possesses the most toxic venom of the C. oreganus / C. viridis group, although apparently considerable variability exists among local populations. It is even one of the most potent venoms found in North America, and according to LD50 studies, the venom is many times more potent than that of an Asiatic cobra. It is characterized by the presence of a presynaptic neurotoxin, referred to as concolor toxin, the amount of which varies in individual snakes.

  • Hubbs, Brian, and Brendan O'Connor. 2012. A Guide to the Rattlesnakes and other Venomous Serpents of the United States. Tricolor Books. Tempe, Arizona. 129 pp. ISBN: 978-0-9754641-3-7. (Crotalus oreganus concolor, pp. 32–33.)
  • Woodbury, Angus M. 1929. A new rattlesnake from Utah. Bull. Univ. Utah 20 (1).
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