Mountain Yellow-Legged Frog Project


The mountain yellow-legged frog, which once hopped throughout California’s upper elevations have dropped more than 90 percent in the past decade due to chytrid, a skin fungus that thickens the frog’s skin so they can’t breathe.  Researchers at University of California, Santa Barbara and the Oakland Zoo are collaborating to create an inoculation procedure against the fungus.  Frogs who have received inoculations are then released back to the wild and monitored by Fish and Wildlife biologists.

Challenges to Conservation

The Mountain Yellow Legged Frog was once one of the most numerous animals in the alpine habitats of the Sierra Nevada. It is now on the verge of extinction due to the decimating effects of the chytrid fungus. This fungus attacks the permeable skin of susceptible amphibian species, rapidly reducing populations of frogs to nearly zero within a few weeks.  Chytridiomycosis, the disease caused by the chytrid fungus, is a global pandemic and has been called the greatest loss of biodiversity ever caused by a pathogen. Once the chytrid fungus is present in the environment, the chance of infection is very high. This can hamper the success of reintroduction efforts of unaffected frogs back into the wild.

Conservation Approaches

There is hope for the recovery of the Mountain Yellow-Legged Frog, and other species affected by chytrid, through the pioneering work of the University of California, Oakland Zoo, and other partners which make up the High Mountain Lakes Project. This project studies the natural resistance of survivor populations of the Mountain Yellow-Legged Frog, investigating potential antifungal skin bacteria, antifungal skin peptides, and even genetic resistance.  

At the Oakland Zoo, we study an inoculation procedure which includes infecting the frogs with a controlled amount of fungus and allowing their immune systems time to recognize the pathogen before treating them with antifungal baths to cure them.  We hope that this controlled infection will allow their immune systems to recognize and fight off the fungus if they encounter it again after they have been released to the wild.

Oakland Zoo Takes Action...

Conservation & Treatment

The Zoo supports the conservation of these frogs in their native habitat by head starting and inoculating frogs in our Biodiversity Center before releasing them back to their native habitat in the high Sierras.  This gives them a head start on life and hopefully leaves them better prepared to face the challenges they may encounter.  

Oakland Zoo also supports the Rapid Response Team both financially and with skilled team members.  The Rapid Response Team should be able to mobilize fast – within a few days, of a biologist identifying a new outbreak in the wild.  Since chytridiomycosis kills fast, it is important to treat as many frogs as quickly as we can in the field.

Oakland Zoo educates the public about yellow legged frogs and the global pandemic of chytridiomycosis that affects frogs all over the world.  

Habitat Preservation

The zoo maintains a habitat for local frogs at the Arroyo Viejo Creek, located within Oakland Zoo’s 500-acre Knowland Park.

...And So Can You!