Information-theoretic model selection affects home-range estimation and habitat preference inference: a case study of male Reeves's Pheasants Syrmaticus reevesii

Reevess Pheasant Syrmaticus reevesii is a vulnerable forest bird inhabiting broadleaved habitats dominated by oaks Quercus spp. in central China. Identifying home-ranges and habitat associations is important for understanding the biology of this species and developing effective management and conservation plans. We used information-theoretic criteria to evaluate the relative performance of four parametric (exponential power, one-mode bivariate normal, two-mode bivariate normal and two-mode bivariate circle) and two non-parametric models (adaptive and fixed kernel) for estimating home-ranges and habitat associations of Reevess Pheasants. For parametric models, Akaikes information criterion (AICc) and the likelihood cross-validation criterion (CVC) were relatively consistent in ranking the bivariate exponential power model the least acceptable, whereas the two-mode bivariate models performed better. The CVC suggested that kernel models, particularly the adaptive kernel, performed best among all six models evaluated. The average core area and 95% contour area based on the model with greatest support were 6.1 and 54.9 ha, respectively, and were larger than those estimated from other models. The discrepancy in estimates between models with highest and the lowest support decreased as the contour size increased; however, home-range shapes differed between models. Minimum convex polygons that removed 5% of extreme data points (MCP95) were roughly half the size of home-ranges based on kernel models. Estimates of home-range and model evaluation were not affected by sample size (> 50 observations for each bird). Inference about habitat preference based on composition analysis and home-range overlap varied between models. That with strongest support suggested that Reevess Pheasants selected mature fir and mixed forest, avoided farmland, and had mean among-individual home-range overlaps of 20%. We recommend non-parametric methods, particularly the adaptive kernel method, for estimating home-ranges and core areas for species with complex multi-polar habitat preferences in heterogeneous environments with large habitat patches. However, we caution against the traditional convenience of using a single model to estimate home-ranges and recommend exploration of multiple models for describing and understanding the ecological processes underlying space use and habitat associations.