Evaluation of wolf density estimation from radiotelemetry data

John W. Burch, National Park Service, 201 1st Avenue, Fairbanks, AK 99701, USA; Layne G. Adams, U.S. Geological Survey, Biological Resources Division, Alaska Biological Science Center, 1011 East Tudor Road, Anchorage, AK 99503, USA; Erich H. Follmann, Eric A. Rexstad, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA

Density estimation of wolves (Canis lupus) requires a count of individuals and an estimate of the area the wolf population inhabits. With radiomarked wolves, the count of wolves is straight forward but the estimation of area is more difficult and often not given adequate attention. The population area, based on the mosaic of pack territories, is influenced by sampling intensity in a similar manner as individual home ranges. If sampling intensity is low, the population area will be underestimated and wolf density estimates will be inflated. Using data from studies in Denali National Park, Alaska, we investigated these relationships using Monte Carlo simulation to evaluate the effects of radiolocation effort and the number of marked packs on density estimation.

We report that as the number of adjoining pack home ranges increase, fewer locations are necessary to define a given percentage of population area. We evaluated the utility of nonlinear regression to adjust for biases associated with under sampling and present recommendations for monitoring wolves via radiotelemetry.