Denning-area fidelity and mitochondrial DNA diversity of female polar bears (Ursus maritimus) in the Barents Sea

Polar bears ( Ursus maritimus Phipps, 1774) show fidelity to general denning areas in subsequent reproductive events. Studying the level and spatio-temporal scale of denning-area fidelity is critical to determine the adaptability of polar bears to climate change. We used mark–recapture data in conjunction with mitochondrial DNA (mtDNA) data to investigate the level of fidelity of polar bears from the Barents Sea population to five maternal denning areas. There was no differentiation in mtDNA haplotype frequencies between denning areas. The fidelity of females to denning areas is at a local geographic scale and small groups of neighboring females (3–13) shared similar haplotypes with higher probability than expected by chance. The transmission of denning-area fidelity is supported by the short distances (≤60.0 km) observed between capture locations of six (out of eight) denning mother–daughter pairs. Moreover, our results suggested that some females (3 out of 13) used different denning areas in subsequent denning events. This behavioral plasticity implies that females are likely to be able to change denning locations if unsuitable ice conditions prevent them from reaching their preferred denning areas. We consider this plasticity an important attribute of polar bears when facing climate change.