The southern coastal sage scrub is a distinctive plant community of southern California (Munz and Keck 1959, Mooney 1977). Beginning very narrowly in the Santa Barbara region, it is best developed in Ventura, Los Angeles, Orange, and San Diego counties, and ends in northwestern Baja California, where a different plant assemblage, the maritime desert scrub, begins (Thorne 1976). One very prominent feature of coastal sage scrub is thickets of cactus, including the Coastal Cholla, Opuntia prolifera, and two species of prickly-pears, Opuntia littoralis and O. oricola. The coastal sage scrub is the primary habitat of two birds, the California Gnatcatcher, Polioptila californica californica, and the San Diego Cactus Wren, Campylorhynchus brunneicapillus sandiegensis, that are declining rapidly because of loss of habitat to urbanization. (For explanation of variations in the spelling of the Cactus Wren’s scientific name, see Appendix 1).