Camera traps have become increasingly popular as a monitoring tool to assess species diversity in wildlife surveys. Understanding diversity is essential to conservation and management efforts, and it is important to consider how trapping effort (i.e., the number of camera traps and sampling duration) affects the number of species detected and estimates of diversity. However, camera trap study design varies greatly from study to study. Species accumulation curves provide ecologists with a means to evaluate the efficiency of sampling methods to accurately quantify species diversity. From 2010 to 2012, we deployed 12 camera traps per study site at eight sites across the central and eastern United States. Camera traps were arranged in three arrays of four traps each, set along a 1-ha trapping grid. We performed species accumulation analysis to estimate the minimum trapping effort necessary to detect full species richness of medium to large-sized mammals at a site.
Our analysis showed that as the number of camera traps considered in the analysis increased, estimates of species richness were closer to estimates obtained by extrapolating species accumulation curves. However, 12 camera traps were not enough to reliably record all species present at each site, as none of the richness estimates reached the asymptotic maximum predicted by fitting the accumulation data to the Beverton-Holt model. Given the length of this study and the number of camera traps used, these results suggest that there may be other important factors, such as camera arrangement, that influence the efficiency of camera traps for estimating medium to large-sized mammal species richness. Nevertheless, we suggest that future studies should maximize the potential of camera traps to effectively capture species richness by increasing the number of camera placements when possible.