Long-Distance Movement of a Female Polar Bear from Canada to Russia

Jodie D Pongracz,Andrew E Derocher,Amy C Johnson

doi:10.14430/arctic4641

Abstract

Polar bears (Ursus maritimus) display fidelity to large geographic regions, and their movements are influenced by sea ice distribution. Polar bear subpopulations are moderately distinct from one another, and long-distance movements between subpopulations are rare. We describe and analyze the movements of a female polar bear tracked by satellite telemetry from spring 2009 for 798 days. This female traveled an exceptionally long distance (totaling 11 686 km) from the sea ice off the Yukon Territory, Canada (Southern Beaufort Sea subpopulation) to Wrangel Island, Russia (Chukchi Sea subpopulation). In comparison to other polar bears in this study, this bear traveled farther, moved faster, and had a much larger home range in the first year. Furthermore, the calculation of the home range size by two different methods demonstrated that the commonly used minimum convex polygon method overestimated the home range compared to the less biased Brownian bridge movement model. This female’s long-distance movement was unusual and provides additional evidence for gene flow between subpopulations. Monitoring polar bear movements is useful to track such events, which is especially important at present because sea ice loss due to climate change can affect subpopulation boundaries and influence management.

Highlights

Site fidelity, migration, and long-distance movements are all important for understanding the ecology and dynamics of a population
Polar bears (Ursus maritimus) are distributed across the circumpolar Arctic in 19 subpopulations in close association with the distribution of sea ice over the continental shelf where they forage for their main prey, the
Polar bear location data were collected from females in the Canadian region of the southern Beaufort Sea from 2009 to 2011 (Fig. 1)

Summary

Introduction

Migration, and long-distance movements are all important for understanding the ecology and dynamics of a population. Movement of animals can result in gene flow and may influence population fluctuations (Slatkin, 1987; Ranta et al, 1997). Movement of individuals within the context of meta-population structure (Hanski and Gilpin, 1997) is important for species conservation (Esler, 2000; Webster et al, 2002). For highly mobile species, understanding spatial connectivity between populations is relevant. Polar bears (Ursus maritimus) are distributed across the circumpolar Arctic in 19 subpopulations in close association with the distribution of sea ice over the continental shelf where they forage for their main prey, the Northwest Territories X0E 0T0, Canada © The Arctic Institute of North America.

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Conclusion