Endangered Frogs Leap Back, 70 Mountain Yellow-Legged Frogs Reintroduced to Southern California Lake

Endangered Frogs Leap Back, 70 Mountain Yellow-Legged Frogs Reintroduced to Southern California LakeSource: Pacific Southwest Region USFWS from Sacramento, US, CC BY 2.0, via Wikimedia Commons
Kamal Jenkins
Published on November 16, 2023

In a significant conservation development, over 70 endangered mountain yellow-legged frogs have been reintroduced to a lake in Southern California, a first for this specific population. Previously, reintroductions were centered on mountain streams. The San Diego Zoo Wildlife Alliance and the Henry Doorly Zoo and Aquarium in Omaha, Nebraska, spearheaded this initiative in an effort to restore the declining species throughout its historic range.

Conservationists stress the importance of preserving suitable habitats for these frogs in light of climate change threats. "Lakes have the advantage of more permanent water that is less likely to dry up in a drought," notes Debra Shier, Ph.D., Brown Endowed Associate Director of Recovery Ecology at the San Diego Zoo Wildlife Alliance. "When water habitats like streams do begin to lose water, adult frogs may be able to move, but tadpoles can’t. It’s important that we’re identifying and preserving suitable habitats in the mountain yellow-legged frogs’ native range that can hopefully prove hospitable for this species for years to come—despite the increasing pressures brought on by climate change."

With a severely fragmented population and less than 200 adult mountain yellow-legged frogs left in their native habitats, the species has been categorized as endangered by the International Union for Conservation of Nature's Red List of Threatened Species. The major threats include disease, predators, wildfires, and drought exacerbated by climate change. Highlighting the importance of conservation breeding programs, this initiative is a concerted effort to protect species in their native habitats facing uncertain futures.

Derek Benson, an amphibian conservation researcher and lead keeper at Omaha's Henry Doorly Zoo & Aquarium, underscored the facility's unique capacity to serve as a remote head-start facility in this recovery mission, stating, "We have the unique ability to act as a remote head-start facility for the conservation recovery team and are committed to helping conserve these frogs."

The reintroduced frog populations were divided into two cohorts. The first group was settled into the protective habitat a week before the arrival of the second cohort. Now, researchers are assessing release techniques and other variables, seeking to understand the most effective reintroduction strategies for the frogs' survival. To monitor the frogs, each one was provided a microchip and is regularly observed by the San Diego Zoo Wildlife Alliance team through post-reintroduction surveys.

This recent release is a component of a broader conservation breeding and reintroduction research initiative launched by the San Diego Zoo Wildlife Alliance in 2006. What started as a salvage operation now includes genetic diversity management, disease management, assistive reproductive technologies, behavioral studies, field surveys, and statistical analyses. The partnerships have adopted a data-driven approach to expedite breeding and reintroduction for the species, contributing to the successful release of several thousand individuals into high-elevation mountain habitats and their subsequent monitoring.