| While movement and habitat heterogeneity are of increasing theoretical and conservation interest, few studies have addressed the effect of seasonal inter-habitat movements for communities utilizing two adjacent habitats. I assessed the importance of such movements for Microtus californicus , a common herbivorous rodent, and its avian predators, across a salt marsh and grassland landscape in coastal California. I experimentally limited movement of voles and measured their demographic responses over a 28-month period. To assess whether predation influenced seasonal habitat use by voles, I conducted a one-year study of the foraging patterns of avian predators across the two habitats. Further, I utilized stable isotope analysis to determine if predator success changed temporally across the marsh-grassland landscape. Using a simulation modeling approach, I asked if short-term movements of voles translated into increased population growth.; Seasonal habitat use by voles was evident in the control plots, with individuals preferentially inhabiting grassland during the winter and spring. As the grassland senesced during the summer and fall months, use of the marsh habitat increased. When access was limited in the experimental barrier plots, vole populations experienced reduced survival and reproduction, particularly during the fall period.; As the rodent populations shifted from dry grassland into salt marsh during the summer, raptors also increased their movements into this habitat, although not as strongly as predicted by vole abundance. Additionally, N isotope composition in vole bone collagen reflected their diet, allowing a classification of their habitat origins along a gradient from salt marsh to grassland. Isotope values of predated voles indicated that a higher percentage of voles were taken from grassland in the spring/summer period than expected. Thus, the marsh provided a temporal refuge from predation during the summer.; The importance of inter-habitat access was supported by the modeling simulations, with long-term population growth higher in connected landscapes than in isolated ones. This study demonstrates that marsh-grassland linkages provide increased resources for voles, translating into an increased prey base for the broader predator community that depends on this species. Thus, efforts to preserve or restore these habitats must consider policy mechanisms that conserve the natural connectivity of these communities. |
