I investigated habitat use, home ranges, activity patterns, thermal bi
ology, and energetics of sympatric western diamondback (Crotalus atrox
), black-tailed (C molossus), and tiger rattlesnakes (C. tigris) in th
e Sonoran desert of southeastern Arizona. The three species differed s
ignificantly in their choice of habitats, and habitats used by snakes
were significantly influenced by season. Crotalus atrox used mainly cr
eosotebush flats, but switched to rocky slopes during winter. Crotalus
molossus frequented rocky areas, but during late summer and fall used
arroyos and creosotebush flats. Crotalus tigris was a strict rock dwe
ller during winter and spring, but used edges of arroyos during summer
. Crotalus atrox, C. molossus, and C. tigris had mean home range sizes
of 5.42 ha, 3.49 ha, and 3.48 ha, respectively. Over the year, snakes
traveled a mean distance of 12.94 km (C. atrox), 14.99 km (C. molossu
s), and 9.29 km (C. tigris) during approximately 95 h of surface activ
ity. During their active seasons, 1 March to 15 October, rattlesnakes
traveled, on average, 50.8 m/d (e. atrox), 42.9 m/d (C. molossus), and
32.9 m/d (C. tigris). All three species had mean activity temperature
s near 29.5 C. The three species showed no significant differences in
home range, activity distances, or body temperatures. Rattlesnakes had
standard metabolic rates similar to those of other Crotalus species,
but only 40% those of other squamate reptiles of similar mass. They co
uld fulfill yearly maintenance energy requirements with a prey quantit
y equivalent to 93% of their body mass; these energy demands could be
met with 2 to 3 large meals.