Three Decades of Conservation: Protecting the Endangered Coachella Valley Fringe-toed Lizard, Uma in

Barrows, Cameron W.

University of California Riverside

Center for Conservation Biology

Riverside, California, USA

cbarrows@ucr.edu

Fisher, Mark

University of California Natural Reserve System

Philip L. Boyd Deep Canyon Desert Research Center

Indian Wells, California, USA

Muth, Alan

University of California Natural Reserve System

Philip L. Boyd Deep Canyon Desert Research Center

Indian Wells, California, USA

Securing protection for the Coachella Valley fringe-toed lizard, Uma inornata, has been a model for the practical application conservation theory on landscape that has shifted from an intact natural system prior to the 1960s to an anthropogenic quilt of habitat fragments by the late 1970s. The lizard’s listing as threatened in 1980 precipitated a first in the nation, multijurisdictional Habitat Conservation Plan in 1986, providing a framework to ensure the lizards’ survival. Here we report on over 30 years of identifying factors that explain their persistence or extinction on those remaining habitat fragments. In short, size matters. Populations occupying small, isolated dunes have gone extinct; a process catalyzed by multiyear droughts and off-road vehicle trespassing on unprotected habitat patches. Habitat fragments with persistent Uma populations range from 11-480 ha, whereas those where extinctions have occurred range from < 1-10 ha. Exceptions to the bigger is better paradigm were clusters of aeolian sand habitat patches captured on the leeward slopes and protected valleys of low-lying hills adjacent to the main body of sand habitat on the valley floor. There, 11 small habitat islands range from 0.05 – 6 ha in one cluster (12.4 total ha), and three islands ranging from 0.1-0.3 (0.7 ha total ha) in another. While individual habitat islands within each cluster have experienced periodic Uma extinctions and re-colonizations, each cluster has been able to sustain populations despite multiple droughts, and so have behaved as functional metapopulations. While size is a critical variable, so is habitat quality; the loss of connections to sand sources and invasive plant species degrade the naturally dynamic character of the aeolian sand fields where the lizards live. Increasing temperatures and drought intensity associated with modern climate change presents yet another threat, one that in defiance of models, this species has shown unexpected resilience.


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