Critically Endangered Yellow-Legged Frogs Released to Bolster Wild Populations

Alex Wierbinski's picture

By Alex Wierbinski - Posted on 28 November 2018


Disease, Decimation, and Hope

High Sierra Yellow Legged Frog
High Sierra Yellow Legged Frog, by Roland Knapp.
Photo Credit: Elliot Lowndes

High Sierra Yellow Legged Frogs Translocation, Recovery Science, & Status

Location, location, location,
University of California - Santa Barbara, November 19, 2018.


Also Published by the
Sierra Nevada Aquatic Research Laboratory, with pics


The Problem
“…Sierra Nevada yellow-legged frog, amphibian residents of Yosemite National Park left devastated by the chytrid fungus Batrachochytrium dendrobatidis (Bd),...”

“ these frogs by reintroducing them to lakes from which they have disappeared because of Bd.”

Translocate Resistance Plan
“...devastated by Bd following its spread across these mountains...But a few populations survived and appear to be evolving some degree of resistance to this pathogen, allowing them to recover despite the ongoing presence of Bd. Using frogs from those recovering populations to reestablish populations that were previously eliminated by Bd — that hasn’t been done much before.”

Will it Work?
“...few examples exist in which reintroduced amphibians were able to recover in the face of ongoing Bd infection, Knapp said, describing the fates of these populations is critically important.”

Docs Think Yes...
“This paper shows that we can facilitate recovery by translocating frogs from places where they are recovering naturally to places where they were previously driven to extinction — either by disease or by fish or both.”

Building on Previous Successes
“They persist despite the disease and become established, at least in some cases. If you rely on natural recovery, success will be limited. We’ve shown that we can move the frogs to habitats to which they could never return by themselves (because of introduced predatory fish in interconnecting streams) and develop new populations. That’s an important advance.”

The Frog Docs
Prove Translocation
“The first two translocations of frogs were conducted more than 10 years ago, and Knapp and Joseph have been following those frogs ever since.”

Tracking Frogs
“By repeatedly catching the same frogs over several years, the researchers are able to track their health and survival, and determine whether the translocated populations are growing or shrinking.”

Main Measure
“…how infection load — a measure of how infected a frog is — changes over time...”

New Tools, Old Question
“We haven’t had the necessary computational tools to do that until recently. With today’s computational resources, we can better understand how differences among individuals affect the fate of populations — do they persist or do they go extinct?”

Two Populations, Two Outcomes
“Of the two frog populations detailed in the paper, one is persisting — with hundreds of new animals born since their reintroduction. The other has failed to thrive and appears on the verge of extinction. ”

Diminishing Threat
“Since the early translocations described in this paper, many additional translocations have been conducted in Yosemite and the majority of those populations show signs of becoming established.”

Work Ahead
“To facilitate recovery at a larger scale, across Yosemite and the entire range of the frog, we ultimately want to be able to predict in which habitats reintroduced frogs will survive. In the future, we hope to use the outcomes of all these translocations to identify the characteristics of sites that maximize the chance of successfully reestablishing frog populations. We are probably a decade away from that...”



August 30, 2017.

Critically Endangered Frogs Released to Bolster Wild Populations

Frog Inoculations


History of High Sierra Yellow Legged Frog Situation, an
Earlier Article featuring same researchers of current report.
Note: Causes of 93% reduction in frog populations: Fishing & Pathogen

Hope for endangered mountain yellow-legged frog, March 2017.


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