Prairie or Western rattlesnake
The Prairie or Western rattlesnake, Crotalus viridis, is a venomous species native to the western United States, southwestern Canada, and northern Mexico. In Canada it occurs in Alberta and Saskatchewan; in the USA in eastern Idaho, Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, Texas, New Mexico, extreme eastern Arizona, in Mexico in northern Coahuila and northwestern Chihuahua.
The Western rattlesnake commonly grows to more than 39 inches long with the maximum recorded size being 59.6 inches long (Klauber, 1937). In Montana, specimens occasionally exceed 47 inches in length and this is typically the region where the longest of this species is found.
Photo by LA Dawson