Population substructure and space use of Foxe Basin polar bears

Abstract

Climate change has been identified as a major driver of habitat change, particularly for sea ice-dependent species such as the polar bear (Ursus maritimus). Population structure and space use of polar bears have been challenging to quantify because of their circumpolar distribution and tendency to range over large areas. Knowledge of movement patterns, home range, and habitat is needed for conservation and management. This is the first study to examine the spatial ecology of polar bears in the Foxe Basin management unit of Nunavut, Canada. Foxe Basin is in the mid-Arctic, part of the seasonal sea ice ecoregion and it is being negatively affected by climate change. Our objectives were to examine intrapopulation spatial structure, to determine movement patterns, and to consider how polar bear movements may respond to changing sea ice habitat conditions. Hierarchical and fuzzy cluster analyses were used to assess intrapopulation spatial structure of geographic position system satellite-collared female polar bears. Seasonal and annual movement metrics (home range, movement rates, time on ice) and home-range fidelity (static and dynamic overlap) were compared to examine the influence of regional sea ice on movements. The polar bears were distributed in three spatial clusters, and there were differences in the movement metrics between clusters that may reflect sea ice habitat conditions. Within the clusters, bears moved independently of each other. Annual and seasonal home-range fidelity was observed, and the bears used two movement patterns: on-ice range residency and annual migration. We predict that home-range fidelity may decline as the spatial and temporal predictability of sea ice changes. These new findings also provide baseline information for managing and monitoring this polar bear population.

Assessing polar bear (Ursus maritimus) population structure in the Hudson Bay region using SNPs

“…From a genetic and ecological perspective, these would reflect the genetic discontinuity within FB and SH and complement telemetry data from Obbard and Middel (2012) and Sahanatien et al. (2015), which together suggest support of a relationship between genetic differentiation and space‐use. As polar bear management initiatives shift toward conservation efforts, ecological and genetic perspectives that recognize behaviors and spatial organization on the sea ice during an important time of year when feeding and mating occur may be valuable for future assessments.…”

“…Sahanatien et al. (2015) detected population structure in the form of distinct movement patterns, demonstrating that bears of FB segregate into three patterns. One of these behavioral patterns corresponds to the genetic distinctiveness we detected in the northern area of FB (Figures 2 and 3).…”

“…For example, the split within FB that we found may be due to the pattern of sea‐ice breakup in Foxe Basin as the northern portion of the basin retains ice longer (Stewart & Barber, 2010) and the physical presence of Southampton Island may separate the bears for part of the year. Telemetry data of polar bears collared in FB indicate three space‐use patterns with individuals preferentially inhabiting either Hudson Bay, Foxe Basin, or Hudson Strait (Sahanatien et al., 2015). Similar to many other species, natal philopatry may also be a driving factor in the development of genetic structure (e.g., snow goose, Avise, Alisauskas, Nelson, & Ankney, 1992; prairie voles, McGuire, Getz, Hofmann, Pizzuto, & Frase, 1993; walleye, Stepien & Faber, 1998; Antarctic seals, Davis, Stirling, Strobeck, & Coltman, 2008).…”

Habitat‐mediated timing of migration in polar bears: an individual perspective

“…; Sahanatien et al. ) is suggestive of an underlying mechanistic relationship between sea ice melt and individual polar bear migration at finer spatial scales than have been measured. Quantifying the behavioral responses of polar bears to disappearing ice will prove useful when predicting ice concentration thresholds for suitable habitat under climate change scenarios (e.g., Durner et al.…”

Assessing spatial discreteness of Hudson Bay polar bear populations using telemetry and genetics

“…, Obbard and Middel , Sahanatien et al. ). Considerable overlap of bears from these three populations occurs while they are on the sea ice (Peacock et al.…”