Amphibians
California Red-legged Frog
Rana draytonii · also called red-legged frog, California red-legged frog
The California red-legged frog is the biggest native frog in the western United States, a handsome reddish animal of coastal ponds and creeks. It is also a literary celebrity — the frog Mark Twain made famous — and a conservation cautionary tale.
Overview
Rana draytonii lives in the coast ranges and foothills of California and just into Baja, in and around ponds, marshes, and slow streams with deep water and thick bankside cover. Adults reach 8–13 cm, with a red wash under the hind legs and belly. It hunts insects, snails, and small vertebrates from the water’s edge.
Twain’s frog
This is the species behind the 1865 story The Celebrated Jumping Frog of Calaveras County, Twain’s first hit. Calaveras County still holds a jumping-frog contest — now with farmed bullfrogs, because the red-legged frog is protected.
Hunted, then crowded out
Gold Rush-era San Francisco ate tens of thousands of red-legged frog legs a year, collapsing populations before the wetlands themselves were drained. Then the American bullfrog arrived — eating red-legged frogs, outbreeding them, and bringing disease. The frog was listed as Threatened in 1996 and named California’s state amphibian in 2014.
Recovery
Removing bullfrogs and non-native fish, restoring ponds, and reintroduction have brought the frog back to lost sites — including Yosemite Valley, where it returned in 2016 after a 50-year absence.
Status
Vulnerable and declining, gone from about 70% of its range, with recovery work concentrated on the central and southern coast.
California Red-legged Frog: common questions
Is this really the frog from Mark Twain's story?
Yes. Twain heard the tale of a rigged jumping-frog bet in the gold-mining camp of Angels Camp, Calaveras County, and published it in 1865 as The Celebrated Jumping Frog of Calaveras County. The native frog of that area, and the one people would have caught and raced, is the California red-legged frog. Angels Camp still runs an annual Jumping Frog Jubilee, but because the red-legged frog is now a protected species that may not be collected, competitors bring farmed American bullfrogs instead, which is an irony the event acknowledges.
Why did the California red-legged frog become threatened?
A sequence of pressures. First, commercial hunting for frog legs from the 1850s to the early 1900s removed huge numbers, especially large breeding females. Then most of California's lowland wetlands were drained, dammed, or built over. Into the depleted habitat came the American bullfrog, deliberately introduced as a food and game species, along with non-native predatory fish such as bass and sunfish, both of which prey heavily on red-legged frog eggs and tadpoles. More recently, pesticides drifting on the wind from the Central Valley have been linked to declines in Sierra foothill populations, and the amphibian chytrid fungus is present. The frog was federally listed as Threatened in 1996.
How can you tell it from a bullfrog?
Size is the first clue in reverse; a very large frog over 15 cm is almost certainly a bullfrog, as red-legged frogs top out around 13 cm. Look for a pair of raised skin ridges, the dorsolateral folds, running down the back from behind the eyes; the red-legged frog has them and the bullfrog does not. Flip the frog, carefully, and a red-legged frog shows red or salmon colour on the underside of the hind legs and the lower belly, while a bullfrog's underside is plain white or cream, sometimes with grey mottling on the throat.
Does removing bullfrogs actually help?
In the right circumstances, yes, and it is now a standard recovery tool. Projects that have systematically removed bullfrogs and non-native fish from a pond or a set of connected ponds, and kept removing them, have seen red-legged frogs recolonise and breed successfully, sometimes within a few years. It works best where a source population survives nearby and where the site can be kept fish-free, for example a pond that dries periodically. It is labour-intensive and has to be sustained, because a few bullfrogs left behind, or reinvading, can undo the gains.