Calculating Probability of Site Use, Study Area Size, and Density of Wild Turkey Hens

Most researchers arbitrarily delineate study areas even though a quantitative estimate of study area size can be generated from capture and subsequent locations of radio-equipped animals. Arbitrary delineation may result in biased estimates of density. Density is often determined with capture-mark-recapture designs that do not include locational data from radio-equipped animals. We used logistic regression to determine probability of recapture of radio-equipped wild turkey (Meleagris gallopavo) hens based on pre-sample distances from bait sites for hens using and not using baited sites. We then used the posterior probability function from logistic regression analogously to the detection function from variable circular plot methods. Integration of this function provided effective radius of census (the radius around each bait site, within which all hens seen represent a complete census) and effective radius of sample (the radius around each bait site, within which the observed animals are a representative sample). A 1-ha cell grid was superimposed over the study area, and cells within these radii were summed. Effective area sampled corresponded with a study area size of 8,527 ha. Turkey hen density was compared using this study area size with several estimates of population size and a single observation period census corrected for sighting probability. Estimates were comparable and were biologically sound. The technique outlined enables effective use of locational data, provides an estimate of study area size, and provides density estimates that are easier and less expensive to obtain than other methods.

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