J. T. Rotenberry, W. B. Kristan III, and M. V. Price. 2000. Distribution and community composition of birds and small mammals in southern California coastal sage scrub. California Southcoast Ecoeregion Conference, Pomona, CA.
Abstract. Between 1995-1997 we assessed distributions of birds and small mammals using surveys conducted at 238 points grouped into 22 sites throughout southern California coastal sage scrub (CSS) vegetation. At each point we also measured local vegetation and landscape compositional features. Analyses yielded several results. Although distinct at a regional level (compared to other southern Californian vegetation types), CSS is a heterogeneous plant community. Within CSS there were geographical gradients in local vegetation structure and composition, as well as landscape-level vegetation and land-use classification, mainly reflecting north-south and east-west gradients in climate and topography. Several of these gradients include patterns induced by human activities (e.g., exotic forbs and grasses, urbanization). Individual animal species responded to these gradients, with virtually all taxa showing significant associations with local, landscape, or geographical variables. Likewise, several species also exhibited significant urban "edge effects." However, the considerable heterogeneity of individual responses precludes generalization. Patterns of bird and mammal communities were associated with habitat variables, and were correlated with each other; however, species richness of birds and small mammals were uncorrelated. We conclude that a regional reserve system than spans the range of CSS conditions and geographical areas will be necessary if we are to preserve CSS species diverisity. However, any system of reserves cannot rely on the local diversity of any single taxonomic group as an indicator of appropriate design, but must be based on meeting the needs of multiple, independent species' criteria.