Photo: Pacific Southwest Region USFWS
Fewer than 400 endangered yellow-legged mountain frogs now remain from the thousands that once crowded hundreds streams throughout California’s San Gabriel, San Bernardino and San Jacinto mountain ranges. Fifty years ago frogs swarmed these streams competing for desirable mates, but are now reduced to surviving in five hard-to-find streams that still trickle down despite five years of heavy droughts.
Scientists have grown more concerned about the frogs’ survival with a nearby wildfire growing each day, the third major fire in a month to overtake the frogs’ habitat. If this most recently endangered patch of vegetation is destroyed, biologists fear winter storms could wipe out the only remaining streams where the frogs live with debris and ash from previous fires. “I’ve never seen things this dry here before,” said Adam Backlin, a U.S. Geological Survey biologist, regarding a population of around 20 frogs in San Gabriel Mountains’ Big Rock Creek. “The last thing these frogs need is drought and wildfire.”
Though wildfires in the area have been common for a long time, they are now coupled with a vast array of factors that would make it difficult for sparse yellow-legged frog populations to recolonize from neighboring populations, as they did in decades past. Now, existing populations have been pushed to the brink of extinction by disease, urbanization, and widespread invasive predators from crayfish to trout and bullfrogs. Backlin notes that many isolated mountain yellow-legged frog populations were already decimated after 2003’s Old fire, 2009’s Station fire, and 2013’s Mountain fire, and are incredibly weak in the face of the most recent fire.
Just three weeks ago, the Sand fire destroyed 40,000 acres of northwestern San Gabriel Mountain watershed, containing sections of Soledad Canyon, a shelter to both rare arroyo toads and federally endangered unarmored threespine stickleback fish. This week, biologists were alarmed to discover that the Blue Cut fire burned through over 37,000 acres across San Gabriel’s northeastern canyons. They are now rushing to study the fire’s impacts on the yellow-legged mountain frogs’ populations, and questioning whether captive breeding may be the only way to ensure the species’ continued survival.
Federal wildlife authorities started a recovery program for the frogs back in 2010 that involves trout removal, captive breeding, and banning public access to regions where frogs still survive. Authorities hope to keep the frogs alive in carefully monitored aquariums at the San Diego and Los Angeles Zoos, where “insurance colonies” are being maintained with the help of the U.S. Fish and Wildlife Service. Omaha’s Henry Doorly Zoo, the Memphis Zoo, and the Santa Ana Zoo may join the program within the next year. Everyone involved hopes these efforts will allow the yellow-legged mountain frog to survive long-term, if outside its threatened natural habitat.
Source: Sahagun, Louis. “California’s drought, wildfires threaten endangered frog.” LA Times. 20 August 2016.
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