Endangered species protection and evidence-based decision-making: Case study of a quarry proposal in endangered turtle habitat

Abstract

Surface mining practices can negatively impact turtles through degradation of wetlands and surrounding upland habitat, alteration of movement corridors, increased risk of nest and turtle predation, and direct mortality. These impacts, in turn, can cause changes in sex ratios and population demography, which may ultimately lead to population declines and extirpation. Using radio-telemetry, GPS data loggers, and capture-mark-recapture surveys over two field seasons, we described the demography of, and identified critical habitat for, a population of endangered Blanding's turtles (Emydoidea blandingii) inhabiting an area of interest for development of a trap rock quarry in Ontario, Canada. We captured 56 turtles and estimated population size to be 80±18 turtles, and density to be 1.84 turtles/ha, which is among the highest reported densities for the species. Daily distances moved and home range sizes were generally smaller than conspecific values reported in the literature, suggesting that habitat quality was high as turtles did not need to move much to acquire necessary resources. We identified 15 nesting sites and 12 wetlands that housed overwintering turtles, both considered by government to be critical habitats with lowest tolerance to destruction. We mapped our spatial data based on the application of legislated provincial and federal recovery guidelines, and the results indicate that the quarry proposal should be rejected if the spirit of the law is upheld given that at least 63% and at most 100% of the proposed quarry area is categorized as endangered species habitat. Keywords: Canada, Critical habitat, Endangered species act (ESA), Home range, Nest site, Ontario, Overwintering site, Population size, Spatial ecology, Species at risk act (SARA)