r-Rdistance

Distance-sampling analyses estimate density and abundance of organisms in ecology when detection probability declines with increasing distance from the observers. Distance-sampling is popular in most branches of ecology and especially when organisms are observed from aerial platforms (e.g., airplane or drone), surface vessels (e.g., boat or truck), or along walking transects. Rdistance analyzes data collected on both point and line transects, estimates overall (study area) and site-level (transect or point) density, and allows users to specify regression-like formula (similar to lm or glm) for covariates. A large suite of classical, parametric detection functions are included along with some uncommon parametric functions (e.g., Gamma, negative exponential) and non-parametric smoothed distance functions. Custom (user-defined) detection functions can be implemented (see vignette). Measurement unit integrity is enforced with internal unit conversion when necessary. The help files and vignettes have been vetted by multiple authors and tested in workshop settings.