Experimental Reintroduction of S.N.Yellow-legged Frogs to Restore Ecosystem and Visitor Experience
This experimental study would seek to restore the rapidly declining endangered Sierra Nevada yellow-legged frog (SNYF) Rana sierrae to high elevation lakes over a 3-4 year period. Habitat restoration of aquatic ecosystems in conjunction with reintroduction of the SNYF will provide critical information to wildlife managers for successfully managing the recovery of the SNYF. Standardized surveys for the SNYF at study locations will be conducted to determine success of restoration and frog recovery efforts. As a keystone species, recovery of the SNYF will indicate successful restoration of the aquatic ecosystem. Data collected will be used to develop restoration techniques for the Aquatic Resources Management Plan, which will be written beginning in 2008. Three of the lakes are adjacent to existing frog populations where natural recolonization is likely, whereas the other 3 lakes would need to have frogs reintroduced from a source population. This provides a pairwise test of habitat restoration and frog reintroduction techniques. Lakes were selected by the criteria that they contain relatively few fish, are little used by fishermen, and are within 10 km of the source frog population (for transportation by foot), or have an existing population nearby for natural recolonization. Predation by introduced non-native fish has contributed to the decline of the SNYF and has resulted in fragmentation of the remaining SNYF population across the landscape. More recently, the lethal effects of the fungal disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (B.d. or chytrid), found throughout the Yosemite landscape, has exacerbated the decline. Present frog populations are 95% below historical levels, and are declining at the rate of approximately 10% per year.