Using species distribution models to guide conservation at the state level: the endangered American burying beetle (Nicrophorus americanus) in Oklahoma

Abstract

The goal of the Endangered Species Act is to improve the chances of listed species’ survival by increasing population levels (US Fish and Wildlife Service in American burying beetle (Nicrophorus americanus) recovery plan. Newton Corner, MA, p 80, 1991). If successful, a species will be delisted, but in order to achieve the goal of species recovery the demography, habitat preferences, reproductive biology, and cause of the species decline must be understood. Like many rare invertebrates, information about the endangered American burying beetle (Nicrophorus americanus) prior to listing consisted of the taxonomic description and morphological characterization. Surveys for N. americanus provide data that can be integrated into spatial models to help predict suitable habitat. Our objective was to model the potential distribution of N. americanus and to evaluate these models ability to generate maps of potential habitat, thus focusing recovering efforts. We chose six modelling algorithms that utilized both presence and absence data from beetle surveys conducted throughout eastern Oklahoma. Using area under the curve (AUC) as our evaluation statistic, we found that ten of the twelve models performed within the AUC index category of “potentially useful” (AUC 0.7–0.9). Models utilizing presence only data performed well compared to models built with presence/absence data. This may indicate the weakness of using absence data to indicate unsuitable habitat. Lack of integration into the model of biotic interactions may also be affecting model performance. To improve model performance, the causes of N. americanus’s endangered status and its population shrinkage should be considered. Although the best models were not highly accurate, the map of suitable habitat can help to inform conservation biologists of areas with a likelihood of N. americanus presence. Overgenerous models can mislead conservation planners in thinking that more areas are highly suitable. If resources are limited for planning preserves and areas of reintroduction, it may be better to be conservative and to limit consideration to the most suitable habitat.