Svalbard polar bear body condition declined until 2000 then rose despite rapid sea‑ice loss

A study of 770 adult polar bears (1,188 captures) in Svalbard from 1995–2019 found body condition index declined until about 2000 and increased afterwards, and statistical models including sea‑ice metrics and the Arctic Oscillation did not show the expected negative effect of warming or habitat loss.

Researchers analysed polar bear body condition in the Svalbard area of the Barents Sea during 1995–2019 to investigate links with rapidly changing sea‑ice conditions. The Barents Sea has warmed faster and lost sea ice more quickly than most other polar bear regions. Svalbard hosts two main space‑use ecotypes: local bears that remain near the islands and pelagic bears that follow the sea ice. The study used a body condition index (BCI) measured from 770 adult bears across 1,188 captures in March–May. Key findings: - The dataset covered 770 individual adult bears and 1,188 capture events from 1995–2019. - Mean BCI declined up to about the year 2000 and increased after that, even as sea‑ice loss continued rapidly in the region. - Models that included sea‑ice metrics and the Arctic Oscillation did not support a clear negative effect of warmer conditions or habitat loss on BCI in this population. - The study notes ecological complexities: pelagic bears travel and swim longer distances and face higher energy demands, while local bears now spend more time on land and use more terrestrial food sources. - Authors mention increases in some prey (for example harbour seals, reindeer and walrus) that may partly offset reduced access to traditional seal prey, and caution against extrapolating results across polar bear populations. Summary: The study reports a non‑linear change in body condition for Svalbard polar bears with a decline until ~2000 followed by an increase despite continued rapid sea‑ice loss. Results did not show the predicted negative link between BCI and sea‑ice or Arctic Oscillation in the statistical models, indicating local ecological factors and prey dynamics are likely important. Undetermined at this time.