Differences in Home-Range Size Computed in Commonly Used Software Programs

With the advancement of radiotracking techniques, there has been a dramatic increase in the quantity and quality of locational and movement data obtained for a variety of wildlife species. Automated tracking systems, in particular, produce enormous amounts of data. These data help researchers determine movements, home ranges, and habitat use by individuals and populations. One of many challenges is determining not only which home-range estimators to use, but also which home-range program will best fulfil study objectives. We used data from a moose (Alces alces) fitted with a test Global Positioning System (GPS) collar to compare home-range sizes estimated by 5 commonly used software packages (CALHOME, HOME RANGE, RANGES IV, RANGES V, TRACKER). We found large differences in calculated home-range sizes using minimum convex polygon, harmonic mean, and kernel estimators at 3 levels of resolution (95%, 75%, and 50% of locations). Comparing home ranges among different research studies can be misleading unless researchers report choices for software program, home-range estimators, user-selected options, and input values of required parameters.