For over a decade, the Yosemite toad has been recognized as a federally threatened species, after experiencing a 50% population decline during the Rim Fire of 2013.
The wildfire, which encompassed a mass of land near Yosemite National Park, made the amphibian species especially vulnerable in its home habitat.
Native to the Sierra Nevada, the toads play a key role in the area’s ecosystem — and conservationists stepped in to secure their future.
In 2017, the San Francisco Zoo’s conservation team began working with the National Park Service, Yosemite Conservancy, U.S. Fish & Wildlife Service, California Department of Fish & Wildlife, and the U.S. Geological Survey.
The goal of all of these stakeholders? To raise their own Yosemite toads, re-establishing a self-sustaining population in the wild.
“Over the past several years, SF Zoo’s conservation team has been busily raising hundreds of these small but significant amphibians from tadpole stage, a species found only in the Sierra Nevada, for the purpose of reintroducing them to an area of Yosemite National Park where it was last seen 11 years ago,” the zoo shared on social media.
By 2022, a group of toads were deemed ready for release — and at the end of June of this year, 118 toads were flown via helicopter back to their habitat.
“It’s the first time anyone has ever raised this species in captivity and released them to the wild,” Rochelle Stiles, field conservation manager at the San Francisco Zoo, told SFGATE. “It’s just incredible. It makes what we do at the zoo every day worthwhile.”
Over the past two years, these toads were fed a diet of crickets and vitamin supplements and were examined individually to ensure they were ready for wildlife release.
Zoo team members inserted a microchip into each toad to identify and monitor its health. In addition, 30 of the toads were equipped with radio transmitters, allowing their movements to be tracked using a radio receiver and antenna.
The project doesn’t end with this single wildlife release; it’s slated to take place over the next five years, as conservationists continue to collect data about the toads’ breeding conditions and survivability in an ever-changing climate. They will also continue to raise future toad groups at the zoo’s wellness and conservation center.
Living in high elevations over 11,000 feet, experts do have concerns about how the toads will fare, since they require pools of snowpack runoff and spring recharge, which are in decline as temperatures rise.
These bumpy-skinned, yellow and green amphibians need ideal moisture conditions in their native meadows to allow tadpoles the chance to metamorphose.
While the future of the Yosemite toad is still up in the air — and the uncertainty of climate change makes this a particularly audacious leap of faith — the reintroduction of these amphibians could have positive ripple effects for all of Yosemite.
Their re-entry could restore the population balance of invertebrates and small vertebrates that the toads consume, as well as balance the food web, serving as prey for snakes, birds, and other local predators.
“Zoo-reared toads can restore historic populations,” Nancy Chan, director of communications at the San Francisco Zoo, told SFGATE.
Stiles continued: “This is our backyard, our home, and we want to bring native species back to where they belong.”
Header image courtesy of Beau Rogers (CC BY-NC 2.0)
