Rdistance contains two example datasets, i.e., sparrow.detections and sparrow.transects. These datasets demonstrate the type and format of input data required by Rdistance to estimate a detection function and abundance from distance sampling data collected by surveying line transects. Only the data in sparrow.detections is needed to fit a detection function (see F.dfunc.estim), but both sparrow.detections and sparrow.transects are needed to estimate abundance (see F.abund.estim).
Data come from 72 transects, each 500 meters long, surveyed for sparrows by the Wyoming Cooperative Fish & Wildlife Research Unit. Observers recorded the sighting distance and sighting angle to each sparrow group detected.
See the package vignettes for an Rdistance tutorial using these datasets.
sparrow.detectionsA data.frame containing 356 rows and 5 columns. Each row represents a detected group of sparrows. Column descriptions:
siteID: Factor, the site or transect where the detection was made.
groupsize: Number, the number of individuals within the detected group.
sightdist: Number, the distance from the observer to the detected group.
sightangle: Number, the angle (in degrees) from the transect line to the detected group.
dist: Number, the perpendicular, off-transect distance from the transect to the detected group. This is the distance used in analysis. Calculated using perp.dists.
Carlisle and Chalfoun, unpublished data