Range

North America is the native home of the southern mountain yellow-legged frog. Here they are confined to southern California in a trio of mountain ranges. They are considered extinct across large parts of their former range.

They live at altitudes between 1,066 and 3,658m (3,500 and 12,000ft).

Much of their current range is restricted to National forests and parks.

Habitat

They make their home in mountain streams and banks with suitable vegetation on the banks as well as lakes, ponds and marshes.

Reproduction

Breeding occurs from May to July. A male will grab on to the back of the female in a position called amplexus. She then lays her eggs and he fertilizes them as she does this.

A females egg mass can contain anywhere from 15-350 eggs. These are laid in globular clumps which are somewhat flattened.

These eggs will take 18-21 days to hatch and emerge as tadpoles who are confined to the water. These tadpoles may measure up to 7.62cm (3in) long. As a tadpole they have gills to breathe in the water.

The time between hatching and metamorphosis is variable between elevations. At lower elevations it can happen in the same season but at higher elevations it may take as many as four years.

During their metamorphosis they will lose the gills and develop lungs. The tail will shorten and be reabsorbed.

It may take between 5 and 8 years for sexual maturity to be reached in the wild.

Behavior

Mountain yellow frogs will hibernate over winter. In some areas they may only be active for three months of the year. Hibernation occurs underwater in lakes and rivers.

These frogs lack a vocal sac though they do make what is described as a flat ‘clicking’ sound. Males make a call to attract a mate.

They are active during the day. During the day they will bask in the sun to warm up their body.

Predators and Threats

Fish such as trout will prey upon southern mountain yellow-legged frog tadpoles and adults. Common garter snakes, raccoons, coyotes and birds also prey on them.

If threatened by a predator the mountain yellow-legged frog will emit a foul smelling odor (similar to garlic) in an attempt to ward them off.

Humans present a range of challenges to the survival of the southern mountain yellow-legged frog. These include habitat destruction and fragmentation, climate change and diseases such as chytrid fungus.

Due to the low population some instances of inbreeding have occurred and led to a decrease in genetic diversity.

A range of captive breeding programs exist which are working to release mountain yellow-legged frogs to the wild.

Quick facts

They are among the largest frogs found in North America.

As few as 200 mountain-yellow legged frogs are estimated to remain in the wild.