Although not restricted to wetland habitats, this species always selects moist refuges. Sustained movements by adults primarily occur during, or just after, rains. Tadpoles require standing water for periods long enough to complete their aquatic development, which varied from a month at warmer localities, to three, or more, months at high elevations in the Sierra. Associated with permanent or temporary water of all kinds in all California habitats, except dry desert types. At high elevations in the Sierra, diurnal activity is common.
Individuals are active all year except during cold or dry periods.
Migrations to and from breeding localities occur at night, usually during or just after rains. Except for migration to and from breeding sites, movements usually do not exceed a few meters except on rainy nights when longer distances may be traveled. Females only remain at breeding sites for one or a few nights during the breeding season, while males stay there from 2 weeks to over 2 months. Individual females may lay a total of 700 eggs. Pacific treefrogs and their tadpoles are preyed upon by introduced sunfishes, bullfrogs, garter snakes, a variety of birds, and some nocturnal mammals.