Santa Catalina Rattlesnake (Crotalus catalinensis). Field Museum of Natural History, Chicago. FMNH catalogue no. 1169. Conservation status: critically endangered. It is found only on Santa Catalina Island, located off the California coast at Los Angeles. The Catalina rattleless rattlesnake has evolved away from having a rattle because, according to one theory, it does not need a warning mechanism against predators. Its restricted range, the recent past presence of feral cats, the pet trade, killing by human encounters and its over-dependence on rodent food sources all contribute to its vulnerability. ..As biologists describe new species and add to our understanding of the interrelated nature of life on Earth, a species becomes extinct every 20 minutes (100 to 1000 times the background extinction rate as seen in the fossil record). Collections in natural history museums play important roles in conservation, education and research. Most of that work and the associated specimens are not on public display in museums? typically, less than five percent of specimens are exhibited.