The Sierra Nevada yellow-legged frog, or Rana Sierrae, has been one of the most endangered species in Yosemite’s National Park. Researchers have been surveying the frog’s prevalence during the past decades to control its extinction.
The Rana Sierrae’s population has been decreasing in the national park for the last 100 years, due to non-native predatory trouts that were put inside Yosemite’s rivers for commercial and recreational fishing during the 19th century.
The predatory trout ate the frog’s tadpoles and snack on their primary food sources, endangering the Sierra Nevada yellow-legged frog and reducing over 93 percent of its historical range. During the 1970’s a chytrid fungus appeared in the park, affecting the frog species.
However, a team of researchers from the University of California has been studying the frog’s population at Yosemite’s national park and has concluded that the numbers of yellow-legged frogs have been incrementing.
“This was not a rare species that became rarer. This was a really abundant species that became really rare,” said Ronald Knapp, lead author of the study and biologist from the University of California at Santa Barbara, to the Christian Science Monitor.
A recovering species
Two years ago the Sierra Nevada yellow-legged frog was added to the endangered species list by the U.S Fish and Wildlife Service to improve its life conditions and avoid the species from its extinction.
According to Knapp’s team of researchers, the species has been recovering, and the population has had a surprising increment to the team of specialists, and it is all thanks to a change in Yosemite’s environment.
The recent study published in the journal of the National Academy of Sciences, based in over 20-year data and records from Yosemite’s Park, informs that a change in the environment and the removal of non-native species were the secret to recovering the species.
Yosemite’s managers decided twenty-five years ago that the park’s environment should go back to its natural environment and started to remove all non-native species, including all of the fishes in the rivers, including the predatory trout.
Knapp and his team noted in the park’s data, that when the fishes started to be removed from the park, the frog’s population started to go back to its normal levels as they began to be more visible.
The yellow-legged frog also managed to adapt itself to the dangerous fungus that had been endangering its species, resisting to its effects but the reasons of why the species managed to do it, remains a mystery for researchers.
The recent discovery provides a new approach to saving endangered species and how to handle non-native animals from affecting another environment.
“If we do care, and we do provide protection to the species, and we so stop doing activities like stocking non-native trout on top of the frogs, then it does matter, and we can recover species,” said Noah Greenwald, director of the endangered species at the Center for Biological Diversity.
Source: New Scientist