Assessing raccoon (Procyoun lotor) habitat use and predicting potential corridors for rabies spread with maximum entropy and circuit theory modeling.

摘要

The USDA, APHIS, Wildlife Services National Rabies Management Program (NRMP) has led a cooperative oral rabies vaccination (ORV) campaign to prevent the spread of the raccoon (Procyon lotor) variant of the rabies virus into mid-western states and Canada since 1997, with an ultimate goal of elimination. Given the overlap of this rabies variant's enzootic range with the most heavily populated portions of the eastern United States, the public health implications of effective ORV by NRMP and cooperators is considerable. Remote sensing (RS) technologies are playing increasing roles in infectious disease eco-epidemiology investigations. NRMP raccoon density index (RDI) information is critical to ORV planning and RDI for pine- (Pinus sp.) dominated landscapes are generally among the lowest observed among habitats used by raccoons. After a thorough review of the scientific literature on remote sensing and potential infectious disease applications, an Information-theoretic model selection approach was used to better understand variables that may influence raccoon density on these pine-dominated landscapes based on model Akaike weights (wi) through the Akaike Information Criteria procedure for small sample sizes (AICc). Maximum Entropy (Maxent) and circuit-theory (Circuitscape) modeling provided habitat suitability assessments and risk visualization tools for an increased understanding of raccoon habitat use and to assist in delineating potential habitat corridors for raccoon rabies spread. The current RS products remain the best available technologies for NRMP needs. RDI assessments (15 from 11 pine-dominated sites in 6 eastern states) during 2007-2012 produced RDI ranging from <1-3.3 raccoons/km 2. Of seven candidate models comprised of landscape and other variables, the model that included habitat edge (edge)(Akaike wi = 0.58) ranked the best. The top most influential variables in teinis of raccoon habitat suitability from the Maxent procedure were annual mean precipitation (Massachusetts) annual mean temperature (Florida) and soil type (Alabama). Maxent probability surface maps ingested into Circuitscape provided conductance visualizations which identified potential areas of connectivity for raccoons, and hence, risk for the movement of rabies. Incorporating these results into current and future ORV planning should result in substantial cost-savings to the NRMP, cooperators, and the public, with potential applications to other rabies management activities.