hibernate. Feeding Previous theories suggested the tendency for this rattlesnake to climb into low bushes was connected to a dietary shift toward consuming birds. However, studies conducted from 2002 to 2004 revealed that stomach and fecal contents were 70% mammal (Santa Catalina deer mouse, Peromyscus slevini) and 30% lizard species (Santa Catalina desert iguana, Dipsosaurus catalinensis; Santa Catalina side-blotched lizard, Uta squamata; and Sceloporus lineatulus.) “We found no bird remains in scats or stomach contents of C. catalinensis in any year or season.” The diet of this rattlesnake is a fraction of the diet of its closest relative, the Red diamond rattlesnake, Crotalus ruber. C. ruber, like most rattlesnakes, frequently prey on lizards and small mammals such as mice, rats, and squirrels. C. ruber also is known to eat frogs, toads, birds, and other snakes. The restricted diet of the Santa Catalina Rattlesnake compared to its sister species is likely due to the limited prey diversity on the island. Small body size in the Santa Catalina rattlesnake may be an evolutionary response to their reliance on small-sized prey. For example, the main prey is the endemic Santa Catalina Deer Mouse, Peromyscus slevini, which are measured to 21 cm (8.3 in) in total length including the tail, which is 10 centimeters (3.9 in). Like other rattlesnake species from central and northern Mexico, the Santa Catalina rattlesnake has greater foraging activity during the summer and rainy season (July–October). Taxonomy Laurence Klauber (1972) suggested this species is closely related to C. scutulatus. However, a later study by Murphy and Crabtree (1985) used allozyme data to conclude the Santa Catalina rattlesnake shares its most recent ancestor with C. ruber. Most of the morphological, biogeographic, and biochemical data suggest the same. References Further reading Murphy RW, Crabtree B. 1985. Genetic relationships of the Santa Catalina Island rattleless rattlesnake. Acta Zool. Mex. (ns) 9. 16 pp. Ávila-Villegas, H. 2005. Aspectos ecologicos de la serpiente de cascabel de la Isla Santa Catalina, Crotalis catalinensis. Golfo de California, México. https://www.researchgate.net/publication/295919115_Aspectos_ecologicos_de_la_serpiente_de_cascabel_de_la_Isla_Santa_Catalina_Crotalus_catalinensis_Ecological_Aspects_of_the_Santa_Catalina_Island_Rattlesnake_Crotalus_catalinensis?ev=prf_pub External links catalinensis Endemic reptiles of Mexico Fauna of Gulf of California islands Endemic fauna of the Baja California Peninsula Snakes of North America Reptiles described in 1954 Critically endangered biota of Mexico Critically endangered fauna of North America