This study explores how local density affects contact rates among Channel Island foxes (Urocyon littoralis) through two pathways: changes in home range size and changes in home range overlap. This study was motivated by concerns about how best to manage disease risk for canine distemper virus (CDV) after an 85% decline of the closely related Channel Island fox population on Santa Catalina Island, California, due to a CDV epidemic.
Fox densities on San Clemente and San Nicolas Island are unusually high, making this population particularly susceptible to the spread of a novel virulent disease. Furthermore, fox densities vary among habitats within each island in ways that influence home range behaviors, making it difficult to predict the outcome of a disease introduction. By use of radio collars, the goals of this project were to determine how density mediated changes in fox behaviors affect disease spread through changes in the frequency of contact among neighboring foxes, and 2) to use that information to inform a spatially explicit epidemic model which can then be used to evaluate effective monitoring, vaccination, and response strategies to minimize the impact of diseases likely to infect island foxes.
This report details the second year of a project demonstrating an efficient method for tracking daily survival of a large number of island foxes on San Nicolas Island, CA. The first goal of this project was to demonstrate a labor-saving novel technology to efficiently monitor the daily survival of a large sample of island foxes. The second goal was to develop mortality thresholds which trigger increasingly intensive management response when natural mortality rates are exceeded.
This report details an innovative radio-telemetry system for monitoring San Nicolas Island foxes through a DoD Legacy funded research and demonstration project on San Nicolas Island off the coast of California. It describes monitoring efforts and accomplishments using this system, summarize the results of the first year of intensively monitoring fox survival, and develop a preliminary set of monitoring-based criteria to trigger management actions based on these results. Includes a discussion of ways in which the system can be improved and new developments to be implemented in the second year of this project.
This report characterizes the Island fox, Urocyon littoralis, A Species at Risk and how to manage for it.