Roland Knapp works to recover frog population in the Sierras

An Unexpected Recovery

Biologist Roland Knapp works to restore a once-vanishing frog population in the Sierras

For more than two decades, UC Santa Barbara biologist Roland Knapp has been working with mountain yellow-legged frogs in the Sierras. Based at the UCSB-managed Sierra Nevada Aquatic Research Laboratory, he has seen and studied drastic changes in frog populations, watching their numbers dwindle from many thousands to nearly zero at some locations. And now he’s seeing them return. 

Aiming to rebuild rapidly disappearing populations of this California native species, Knapp has collaborated with other scientists, wildlife agencies and even zoos to rescue and recover the mountain yellow-legged frogs. Their efforts are paying off: In late 2016, the results of a 20-year study conducted at hundreds of sites in Yosemite National Park showed a seven-fold increase in frog abundance over the study period.

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