California. The California red-legged frog is an important food source for the endangered San Francisco garter snake in San Mateo County. The California newt is often found with this species due to sharing habitat requirements and the newts eating their eggs. The California red-legged frog primarily eats earthworms, beetles, flies, and other winged insects. There have been instances where the species was viewed preying on juvenile snakes, small mammals such as mice, and other frogs and tadpoles. Breeding occurs from late December to early April. The male frog's advertisement call is a series of a few small grunts, usually given while swimming around under water. Choruses are weak and easily missed. The adult California red-legged frog is nocturnal, while juvenile frogs are both nocturnal and active during the daytime. The species inhabits dense, shrubby, or emergent riparian vegetation and still or slow-moving perennial and ephemeral water bodies that also serve as breeding sites. This species has been noted to utilize upland habitats as adults near aquatic areas (such as creeks). They often use these zones for basking and searching for prey. They prefer tall plants such as cattails for protection and to lay eggs. The tadpoles (larvae) of this species may metamorphose into frogs within about 7 months of hatching from the egg, or may overwinter, taking up to 13 months. This is a recent discovery, which may have management implications for the species, particularly when aquatic habitat undergoes modification. The California red-legged frog exhibits several behaviors when approached by predators. They either stay immobile, quickly leap into vegetation in an upland habitat or a water source nearby, or, rarely, give off an alarm call to indicate danger. They have also been seen demonstrating the unken reflex when caught. Conservation This frog is listed as threatened and is protected by federal and California law. One cause of the population decline is habitat loss and destruction, but introduced predatory species, such as American bullfrogs, might also be a factor. Their habitats are in close proximity to roads and trails, indicating traffic, runoff, pollution, and other human interference may be a significant threat to the species. The species has also been found thriving in undisturbed and isolated ponds in comparison. Vegetation diversity and surface coverage on smaller ponds indicate a greater likelihood of the species being present. 2006 After years of litigation initiated by land developers' organizations, specifically the Home Builders Association