Use of Population Viability Analysis to Evaluate Management Options for the Endangered Lower Keys Marsh Rabbit

We conducted a population viability analysis (PVA) for the federally endangered Lower Keys marsh rabbit (Sylvilagus palustris hefneri). We estimated parameters via livetrapping, radiotelemetry, and fecal-pellet counting during a 2.5-year study. Historically, this subspecies ranged throughout the Lower Keys of Florida, but today the marsh rabbit is limited to 41 subpopulations occurring in 3 distinct metapopulations. To evaluate this subspecies' risk of extinction, we used VORTEX, a simulation modeling program, that combined deterministic and stochastic birth and death events, differing migration rates based on spatially explicit patch structure, and extinction and recolonization. Our simulation calculated the chance that each metapopulation would go extinct under current conditions and several management scenarios. Under current conditions, the model predicted there is a 100% chance that all metapopulations will go extinct. The metapopulation with many small patches went extinct faster than the metapopulations with fewer, larger patches. The most effective strategy to decrease the risk of extinction of all 3 metapopulations was to increase the survival rate in several age and sex classes by eliminating predation by domestic cats.