Draft of Abstract for 2007 ESA meeting

The behavioral ecology of restoration: Island fox restoration and changes in the anti-predator behavior of island mice.

John Orrock, National Center for Ecological Analysis and Synthesis, University of California, Santa Barbara, California, 93101

Jim Reichman, Dept. of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, 93101

Cathy Schwemm, Dept. of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California, 93101  

Anti-predator behavior can alter the dynamics of prey populations and the stability of predator-prey interactions.  We capitalize upon the removal and subsequent reintroduction of the Island Fox, Urocyon littoralis, on San Miguel Island, California, to test whether rodent foraging behavior changes once foxes are reintroduced.  To examine rodent foraging behavior, we used foraging trays and seeds to measure giving-up densities in safe and risky habitats.  We found that, despite being free of fox predation for 8 years, island rodents rapidly respond to the presence of foxes by reducing their levels of overall foraging. As predicted by theory, the reduction in foraging was significantly greater in risky compared to sheltered habitats.  Moreover, the difference between risky and sheltered habitats continued to diverge as foxes became more abundant.  These findings suggest that anti-predator behavior is maintained in rodents despite the removal of foxes for many rodent generations.  Indeed, rodent behavior was well-matched to the number of foxes active near foraging trays, suggesting that rodents were capable of quantifying risk in a reliable way.  Our findings suggest that, in addition to the potential for cascading effects of fox-mediated changes in rodent density, manipulation of foxes may change the distribution of foraging by rodent granivores and thus their effects on plants.