Carnivore persistence in fragmented habitats in urban southern California

Abstract

We investigated the responses of carnivores to habitat fragmentation in urban southern California. We used scat, track, and remote camera surveys to determine presence and residence of carnivores on habitat fragments of various sizes (4.4-561.0 ha) and degrees of isolation (10-750 m). Fragment area explained a significant portion of the variation in all four measures of species richness (total species present, native species present, total species resident, and native species resident). Isolation was of secondary importance and was significant only for species presence. We suggest that fewer carnivore species at smaller or more isolated fragments resulted from foraging decisions based on lower food reward in smaller fragments and greater movement costs for more distant fragments. Carnivore species responded differentially to fragmentation. Bobcats Lynx rufus were fragmentation-sensitive and apparently required large fragments, thus they may be useful as focal species for conservation planning. In contrast, Coyotes Canis latrans were more fragmentation-tolerant and, along with smaller species such as Northern Raccoons Procyon lotor, Striped Skunks Mephitis mephitis, and Virginia Opossums Didelphis virginiana, can persist in smaller fragments. Our results suggest that most of the common carnivores can persist in fragmented urban habitat, provided that fragments are sufficiently large and in close proximity.