Spatiotemporal variation in home range size of female polar bears and correlations with individual contaminant load

Abstract

We quantified the effect of multiple environmental and biological determinants on variation in home range size across multiple spatial (total-home range–core-home range areas) and temporal (seasonal and all seasons combined) scales for 22 adult female polar bears (Ursus maritimus) from Svalbard, Norway (2003–2011). We also evaluated if considering spatiotemporal variation in home range size and location is valuable to assess variation in concentrations of persistent organic pollutants (POPs). In general, home range size was negatively related to the proportion of land within the home range and sea ice concentration, but positively to snow depth. However, effects typically differed between seasons and total, and core-home range size, providing evidence that home range size is scale dependent in this large Arctic mammal. Females accompanied by dependent offspring had smaller home ranges during the breeding season and spring compared to solitary females, while age and body mass did not explain variation in home range size. Correlations between POP concentration and space use were marginally significant, but consistently stronger at fine spatiotemporal resolutions (i.e. core-home ranges during the breeding season) compared to coarse resolution (i.e. total-home ranges over the entire year). We also found that the geographic location of the home range is a stronger ecological correlate of POP concentration than home range size. To improve our understanding of the relation between POPs and animal space use, we recommend increasing the temporal frequency of POP measurements to evaluate how POP concentrations vary during a year and across areas.