Comments: Habitat encompasses arid and semiarid regions, from plains to mountains and from sandy flats to rocky uplands, including desert, grassland, shrubland, woodland, open pine forest, river bottoms, and coastal islands (Degenhardt et al. 1996, Tennant 1998, Werler and Dixon 2000, Stebbins 2003, Campbell and Lamar 2004). In southeastern Arizona, this snake is more numerous in desert scrub than in semidesert grassland (Mendelson and Jennings 1992). It hibernates in rock crevices or cavities or sometimes in animal burrows or under other cover (Ernst 1992). Hibernation sometimes occurs communally in brushy upland ridges. A population in southeastern Arizona used mainly creosotebush flats but switched to rocky slopes during winter (Beck 1995). This primarily terrestrial snake sometimes climbs into vegetation or enters water.