Density and Abundance from Distance-Sampling Surveys
Distance-sampling ()
is a field survey and analytical method that estimates density and
abundance of survey targets (e.g., animals) when
detection probability declines with observation distance.
Distance-sampling is popular in ecology,
especially when survey targets are observed from aerial platforms (e.g.,
airplane or drone), surface vessels (e.g., boat or truck), or along
walking transects. Analysis involves fitting smooth (parametric) curves to
histograms of observation distances and using those functions to
adjust density estimates for missed targets. Routines included here
fit curves to observation distance histograms, estimate effective
sampling area, density of targets in surveyed areas, and the abundance
of targets in a surrounding study area. Confidence interval estimation
uses built-in bootstrap resampling. Help files are extensive and have been
vetted by multiple authors. Many tutorials are available on the package's
website (URL below).