January 25, 2011

Lessons from the Plight of Frogs in Southern California

Researchers and managers from California and Nevada held their annual Amphibian Populations Task Force meeting January 6-7, 2011, this time in Yosemite Valley. With more than 100 attendees, the meeting once again provided a great opportunity to hear about the status of myriad frog conservation projects and catch up with colleagues. For me, the most insightful talk was that by Adam Backlin, the USGS scientist who with Robert Fisher (also with USGS), has been leading efforts to restore southern mountain yellow-legged frog populations (Rana muscosa) in the Transverse and Peninsular Ranges in southern California. This group of populations was listed as endangered under the U.S. Endangered Species Act in 2002.

Starting with only 150 frogs scattered across several populations and mountain ranges, the efforts to keep southern California R. muscosa from going extinct have begun to produce promising results. The removal of non-native rainbow trout from a reach of Little Rock Creek has allowed the resident R. muscosa population to begin to expand. The recovery of this population is still in its early stages but the fact that this population has increased to approximately 50 frogs from just a handful since fish removal is a very promising start. 

Thanks to the efforts by staff at the San Diego Zoo, researchers now have access to captive-bred R. muscosa for use in reintroductions. Reintroductions using this captive stock were conducted for the first time in 2010 so it is still too early to know the outcome of these efforts. But just having the captive colony available to allow reintroductions is a huge step forward. 

The insight from Adam's talk that really hit home for me was the necessity of active management to restore R. muscosa. A hands-off approach of protecting habitat and hoping for the best wasn't sufficient to stem the decline of this group of populations. This decline was slowed only by very intensive interventions. As we try to halt the decline of mountain yellow-legged frogs in the Sierra Nevada, there is an important lesson to be learned from the southern California efforts. That is, we can't rely simply on a hands-off approach to accomplish our goal. Unfortunately, it has been my experience that the hands-off approach is increasingly the one being relied on. 

As the mountain yellow-legged frog in the Sierra Nevada has disappeared from more and more of its native range, the response by managers has been to increase the protections afforded the remaining populations. In some cases, that has meant that populations are off-limits for research. I understand and generally support these protections but they aren't enough. For example, it is critically important that we also continue to test reintroduction methods and conduct experiments to improve our understanding of the frog-chytrid fungus interaction. I fear that with the continuing decline of the mountain yellow-legged frog and its eventual listing under the state and federal Endangered Species Act, our ability to conduct this critical research will be increasingly restricted. 

I hope we can learn an important lesson from the southern California experience.

Back to The Mountain Yellow-legged Frog Site.