Publication Date

Fall 2010

Degree Type


Degree Name

Master of Science (MS)


Biological Sciences


Jerry J. Smith


foothill yellow-legged frogs

Subject Areas

Biology; Ecology


Visual encounter surveys, mark-recapture technique, and telemetry were used investigate breeding, movement, growth, habitat preferences, and predators of foothill yellow-legged frogs on Coyote Creek in Santa Clara County, California, from March 2004 to March 2006. The main stem and tributaries were intermittent in summer in all three years. Thermal conditions for breeding initiation were alike during 2004, 2005, and 2006. Breeding occurred in the main stem on descending limbs of the hydrograph. No breeding occurred in the middle main stem reach, which is ephemeral. Breeding occurred at less than an order of magnitude greater than base flows. Typically, larger females bred earlier, and egg mass size decreased as the breeding season progressed during 2004 and 2005. Males arrived earlier and remained in breeding areas longer. Resident tributary frogs moved greater distances than main stem frogs to breed. Females tended to travel farther than males and occupied habitats farther from the breeding areas. Frogs on Coyote Creek showed faster growth during their first year than Sierra Nevada and north Coast Range populations. Both sexes preferred pools and boulder-dominated habitat on both the main stem and tributary. Santa Cruz garter snakes were the most frequently encountered predator in the study area. However, all diurnal predators were scarce on the tributaries. Perennial water is a limiting factor within the study area, as illustrated by the movement patterns and timing of breeding.