Gaps and links: San Francisco Garter Snake habitat assessment priorities

Abstract

A Geographic Information System (GIS) was used to map habitat elements for the San Francisco garter snake (Thamnophis sirtalis tetrataenia), an endangered species, in coastal San Mateo County.  The habitat included feeding sites and adjacent upland which was compared to the distribution of protected areas in order to calculate the amount of protected habitat, and to identify gaps and links as priorities for on-site assessment. Gaps, unprotected habitat complexes, were found throughout the study area. Links, habitat commplexes linking two or more protected areas, were found in several of the watersheds, the most notable ones in the Burleigh-Murray State Park/Purisima Creek Redwoods Open Space area; El Corte de madera/La Honda Creek Open Spaces area; Pescadero Creek County Park/Skyline Ridge Open Space area; and most significantly, in the Pescadero/Butano/Bean Hollow/Cascade-Año Nuevo State Parks Area.