Cumulative number of critical ice-free seasons given by individual polar bear populations in the Canadian Arctic Archipelago.

<p>Each color represents the contribution of events in each population to the total number of critical seasons in a given year. Starvation in adult males occurs at (A) ≥120 days ice-free; (B) ≥180 days ice-free. Reproductive failure in females occurs when (C) break-up occurs in July; (D) break-up occurs in June.