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.transectsA data.frame containing 72 rows and 5 columns. Each row represents a site or transect surveyed. Column descriptions:
siteID: Factor, the site or transect surveyed.
length: Number, the length of each transect. Use the same units for all distance measurements.
observer: Factor, an example categorical covariate with 5 classes. Identity of the observer who surveyed the transect.
sagemean: Number, an example continuous covariate. The mean sagebrush cover (%) at each transect.
sage: Factor, an example categorical covariate with two classes. Class is "Low"" when sagemean is < 10%, "High" otherwise.
Carlisle and Chalfoun, unpublished data