Polar bears spend winter months in maternity dens nursing cubs. Denning success is critical for cub welfare and is threatened by climate-driven changes to Arctic conditions.
Polar bear cub welfare during the denning period is entirely dependent on adequate maternal body condition, appropriate den snow conditions, and freedom from disturbance. Female bears that enter the denning period with insufficient fat reserves produce less milk, resulting in smaller, less viable cubs with reduced survival prospects. Climate warming is making the snowpack needed for stable den construction less predictable in some regions, particularly around Hudson Bay where sea ice loss forces early den entry with inadequate fat reserves. Industrial activities in the Arctic — oil exploration, seismic surveys, and shipping — near denning areas cause disturbance that can lead to den abandonment. Protecting denning areas from human disturbance through seasonal exclusion zones is a practical welfare intervention.