Evaluating California’s Natural Community Conservation Planning Act (1991) for two target species

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Audrey Mayer, College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, MI

Background/Question/Methods: California’s Natural Community Conservation Planning (NCCP) Act of 1991 represented a bold experiment in species conservation, attempting to shift the target of conservation from species to habitats and thus fend off the need for additional listings under the Endangered Species Act. The first pilot program, focused on coastal sage scrub, used three flagship species to focus implementation: the coastal California gnatcatcher (Polioptila californica californica), the coastal cactus wren (Campylorhynchus brunneicapillus sandiegensis), and the orange-throated whiptail lizard (Aspidoscelis hyperythra). After the gnatcatcher was listed under the ESA in 1993, the question arose as to whether this new approach could forestall federal protection for the other two. A literature review and two databases were used to evaluate the success of the NCCP pilot program for the California gnatcatcher and cactus wren over time (North American Breeding Bird Survey and Christmas Bird Count for time series data); insufficient data exist for the orange-throated whiptail to assess the policy’s effectiveness.
Results/Conclusions: After 30 years, survey and genetic data reveal that the gnatcatcher has maintained stable and relatively well-connected subpopulations, but the cactus wren has exhibited population declines and population fragmentation. Data from the Breeding Bird Survey from the 11 routes within the NCCP pilot program’s area recorded variable but stable population dynamics for both species. However, CBC surveys in the region demonstrated stable gnatcatcher observations but a clear decline in cactus wren observations. A genetic study undertaken by USGS researchers revealed that the metapopulation of California gnatcatchers is relatively well-connected by few but long-distance dispersal events. However, the metapopulation of cactus wrens suggests increasing population fragmentation into isolated subpopulations. The focus of NCCP preserves along the coast have neglected important inland subpopulations of California gnatcatchers, which may be important as the species adapts to climate change. This evidence suggests that the NCCP policy can assemble functional and sufficient habitat preserve networks for species of concern, but cannot supplant the federal ESA.