Behavioral Response of the Coachwhip (Masticophis flagellum) to Habitat Fragment Size and Isolation in an Urban Landscape

—Habitat fragmentation is a significant threat to biodiversity worldwide. Habitat loss and the isolation of habitat fragments disrupt biological communities, accelerate the extinction of populations, and often lead to the alteration of behavioral patterns typical of individuals in large, contiguous natural areas. We used radio-telemetry to study the space-use behavior of the Coachwhip, a larger-bodied, wide-ranging snake species threatened by habitat fragmentation, in fragmented and contiguous areas of coastal southern California. We tracked 24 individuals at three sites over two years. Movement patterns of Coachwhips changed in habitat fragments. As area available to the snakes was reduced, individuals faced increased crowding, had smaller home-range sizes, tolerated greater home-range overlap, and showed more concentrated movement activity and convoluted movement pathways. The behavioral response shown by Coachwhips suggests, on a regional level, area-effects alone cannot explain observed extinctions on habitat fragments but, instead, suggests changes in habitat configuration are more likely to explain the decline of this species. Ultimately, if ‘‘edge-exposure’’ is a common cause of decline, then isolated fragments, appropriately buffered to reduce emigration and edge effects, may support viable populations of fragmentation-sensitive species. Habitat fragmentation occurs when human land use alters continuous, natural landscapes leading to a reduction of total area, changes in patch configuration, and isolation of habitat remnants. Habitat fragmentation threatens the viability of populations (Saunders et al., 1991; Fahrig and Merriam, 1994; Laurance et al., 2002) and worldwide biodiversity (Wilcox and Murphy, 1985; Wilson, 1992). Early interpretations of empirical studies indicated habitat loss has a larger impact on ecological systems than does habitat configuration (Fahrig, 2003; Turner, 2005). However, because habitat loss and configuration covary, the regression-based approaches used in these earlier studies can produce opposing conclusions (Koper et al.,