California Red Legged Frog
by Michael Marchiano
The Calaveras Jumping Frog is a story written by Mark Twain in the 19th century. Contrary to popular belief, the frog in that story was NOT an American Bullfrog but rather California’s largest native, the California Red Legged Frog. The Bull frog (a non-native species) was not introduced to California until the turn of the 20th Century.
The Red legged frog, is a species in decline at this time due to habitat destruction (75 % of its historical range altered), fragmentation of its environment, water pollution, pesticides, mining, fertilizers, and the introduction of the bullfrog which eats red legged frogs and tadpoles as well as its food sources.
The Red legged frog can grow up to five plus inches (half the size of a bullfrog) and lives up to 8-10 years. The frogs are reddish brown, olive, or gray with black spots. The legs have a dark banding and a dark mask like steak runs from the shoulder to the front of the upper jaw.
Normally found near water it will often sit on the bank blending in to its surroundings. It will use its powerful hind legs to leap into the water when threatened or attacked by a predator.It takes two to three years to reach breeding age. Breeding takes place from December to March in seasonal ponds, streams, stock pools, and reservoirs. The female can lay up to 2000 eggs but only about one percent will metamorphosis into frogs. Tadpoles mature into frogs in three to seven months, often depending on the availability of water. Water sources with shore line growth of willows or cattails are ideal breeding locations, providing hiding place. In drought years many ponds that start out with breeding populations will dry up before metamorphosis is completed.
Although a riparian frog, it is capable of traveling several miles overland in rainy weather. During dry spells it often seeks refuge in leaf litter, animal burrows (especially ground squirrels and gophers) and under fallen trees. They must stay cool or wet enough so as not to dry out. Predators consist of the afore mention introduced American bullfrog, cats, garter snakes, raccoons, foxes, coyotes, egrets, bass, and introduced mosquito fish eat their eggs and newly hatched larva. Their food consists primarily of insects and other invertebrates but they have been known to eat tree frogs and small mice when available.
This very attractive amphibian is now protected under both State and federal law as a threatened species. Several populations of red legged frogs breed in Mount Diablo State Park but with our current drought situation many of their breeding sites are drying up before the frogs reach maturity thus causing a decline in their population.