California Red-Legged Frog

The California red-legged frog (CRLF) (Rana draytonii) is normally found in lakes and ponds, and often in grazed areas. It lays eggs in large masses, usually attached to dense, submerged vegetation, from February to April. Tadpoles normally mature by the end of summer and transform into immature frogs in September and October.

This species can travel miles overland, moving between water bodies or using refugia far from water. It was known to occur a short distance away at the Fairfield Osborne Preserve but had never been observed on the Mitsui property until September 2010 (Wilcox, in press), when newly metamorphosed frogs were seen sheltering in cow-hoof depressions along the shore at Dolcini Pond (This pond is bereft of vegetation, and therefore a typical habitat for the species). A nightlight-shine survey was conducted right away and four adults were observed. These sightings were reported to the California Natural Diversity Database.

Surveys conducted during research for this report have turned up more newly transformed CRLF this year, as well as up to six adults at Dolcini Pond, one at Turtle Pond, and one at Poplar Spring.

Statewide, the largest threats to California red-legged frogs are habitat loss and predation by bullfrogs. This species would be in much greater peril if it were not for numerous stock ponds built by cattle grazers in the last century.

CLRF-eggs

California Red-Legged Frog