Improving PVAs to better guide conservation management and monitoring

Expanding population viability analyses (PVA) to encompass the interrelated processes of population demography, monitoring, and management can increase the relevance and usefulness of PVA as a conservation tool by allowing managers to evaluate current population conditions as indicators of future extinction risk. We linked a demographic population model to submodels of different monitoring and threat management tactics to aid in setting recovery criteria and designing monitoring systems for the endangered Channel Islands fox (Urocyon littoralis). We simulated survival and abundance monitoring for this recovering species as well as management actions to abate its primary threats – eagle predation and epidemic diseases. We then compared the monitoring intensities required to limit extinction risk to acceptable levels given different potential management actions. We found that moderate, highly feasible survival monitoring is adequate to evaluate eagle predation risks, but that these efforts must be paired with rapid and effective control measures. We also assessed two approaches to management of disease outbreaks— the traditional monitoring of sentinel animals and initiating a large-scale vaccination response in the event of an epidemic vs. prophylactic vaccination of a subset of individuals with and without disease surveillance efforts. Even in the absence of monitoring, pre-emptive vaccinations of a moderate number of individuals appears to be a far more effective strategy for disease control. Overall, our work suggests that the modification of traditional PVA methods to more directly address management and monitoring problems is a necessary and feasible way to bridge the gaps between viability analyses and on-the-ground conservation problem-solving.