Santa Catalina Rattlesnake (Crotalus catalinensis)

The Santa Catalina Rattlesnake is endemic to Santa Catalina Island in the Gulf of California. It has a non-functional rattle and light-colored skin that blends with the rocky terrain. It is primarily active at night, feeding on small mammals, birds, and lizards. 

The lack of rattling ability was hypothesized to be a stealth adaptation during hunting if they are arboreal creatures1. Observations in their natural habitat debunked this theory since these rattlesnakes are mostly terrestrial creatures.

Unfortunately, the latest IUCN assessment categorized the Santa Catalina Island Rattlesnake as critically endangered. This is an effect of multiple causes, such as its single-location existence, past threats from feral cats, illegal trade, human persecution, and dependence on a single rodent species for 70% of its diet.