Mountain yellow-legged frogs reintroduced to wild

Mountain yellow-legged frogs reintroduced to wild

The endangered mountain yellow-legged frog will take a major step in its recovery this week when, for the first time, scientists reintroduce its eggs to its former habitat. This reintroduction will occur at University of California Riverside’s James San Jacinto Mountains Reserve, part of the UC Natural Reserve System, and will be done in collaboration with the U.S. Geological Survey, U.S. Forest Service, U.S. Fish and Wildlife Service, the San Diego Zoo Institute for Conservation Research and the California Department of Fish and Game.

Once common throughout much of southern California, the mountain yellow-legged frog has been decreasing in numbers since the 1970s due to what scientists call the “perfect storm” that is affecting frog populations around the globe—decreasing habitat, increasing pollution and invasive species, the spread of the deadly chytrid fungus and the effects of climate change. Today, only a small wild population of less than 200 individuals can be found in the San Gabriel, San Bernardino, and San Jacinto Mountains.

In 2006, scientists collected mountain yellow-legged frog tadpoles from the remaining wild populations in the San Jacinto Mountains and took them to the San Diego Zoo Institute for Conservation Research where, for the first time, specialists were able to establish a captive breeding program for the species. This year’s reproductive season at the Zoo has been so successful that scientists have decided to attempt a reintroduction into the wild.

There are 61 mountain yellow-legged frogs at the San Diego Zoo Institute for Conservation Research. Scientists attempted to spur breeding in January by putting half of that population into a cooler that mimicked high mountain winter conditions. The chill caused the frogs to hibernate. About two weeks ago the frogs were taken out of the coolers and began displaying breeding behaviors within a few days. “Three months ago the San Diego Zoo started an experimental procedure of chilling these frogs to see how it would effect breeding. It has been wildly successful and as a result today we can reintroduce about 500 eggs into the San Jacinto Mountains,” said Jeff Lemm Research Coordinator for the San Diego Zoo Institute for Conservation Research. “This is a momentous day—the first ever reintroduction of these endangered frog eggs back into their natural habitat and the San Diego Zoo is thrilled to be a part of it”. The James San Jacinto Mountains Reserve was selected for this reintroduction because it is a protected area with ideal habitats in the species’ former range.

The mountain yellow-legged frog is one of three Southern California frog or toad species on the Federal Endangered Species List. Biologists from the USGS will be responsible for the initial phase of the reintroduction, and will be releasing egg masses into deep permanent pools, followed by the additional release of tadpoles later in the year. They will then closely monitor the health and success of the reintroduction. It will take two years for the tadpoles to morph into adults and as they are not a migratory species, the frogs will stay in the creek within the bounds of the protected reserve where they can be easily monitored. “This is an amazing first step in the recovery program for this wonderful frog, and we are looking forward to having the frogs here for a long time to come,” said Becca Fenwick, Director of the James San Jacinto Mountains Reserve.


The James San Jacinto Mountains Reserve is one of thirty-seven University of California reserves throughout the state protecting over 280,000 acres, and making them available for research, university level instruction and public outreach. http://www.jamesreserve.edu/

U.S. Fish and Wildlife Service is working with others to conserve, protect and enhance fish, wildlife, plants and their habitats for the continuing benefit of the American people.

The San Diego Zoo’s Institute for Conservation Research is dedicated to generating, sharing and applying scientific knowledge vital to the conservation of animals, plants and habitats worldwide.

Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communication
119 National Center
Reston, VA 20192

Adam Backlin (USGS)
Phone: 714-508-4702

Dani Dodge Medlin (San Diego Zoo)
Phone: 619-685-3291

Becca Fenwick (James Reserve)
Phone: 951-827-6835

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