Polar Bear Adopts Unrelated Cub in Manitoba Amid Conservation Challenges

Researchers in Manitoba, Canada, documented an exceptionally rare instance of cross-fostering within the polar bear population near Churchill in November 2025. The sighting involved a female polar bear, identified as X33991, taking an unrelated cub under her protection. This event, which provides a rare look into the species' maternal behavior, marks only the thirteenth recorded instance of such adoption within the Western Hudson Bay subpopulation across 45 years of scientific study.

The adoption was confirmed by scientists from the Canadian Ministry of Environment and Climate Change and Polar Bears International following initial observations in the spring. Polar bear research scientist Evan Richardson noted that the mother was first seen emerging from a denning area in Wapusk National Park, south of Churchill, with one tagged cub, but was later observed traveling with two cubs. The adopted bear lacked the identification markings, such as a GPS collar, present on the biological offspring, though both cubs were estimated to be 10 to 11 months old. Staff scientist Alysa McCall of Polar Bears International suggested the behavior indicates that polar bears may actively look out for one another, possibly triggered by a strong maternal drive in response to solitary cubs crying out.

The adopted cub is expected to remain with the mother for approximately 2.5 years to learn necessary survival skills. This development offers a small, positive counterpoint to the significant environmental stress facing this specific group. The Western Hudson Bay population, one of the 19 global subpopulations, has experienced a substantial decline, estimated at approximately 30% over recent decades, which scientists directly attribute to the loss of sea ice caused by climate change. Studies link this decline to reduced hunting opportunities as the sea ice melts earlier and freezes later, thereby extending the bears' fasting periods.

This population segment, which depends on sea ice to hunt seals, is particularly vulnerable. A 2021 survey estimated only 618 individuals remained, reflecting a 27% drop in just five years from earlier counts. Extended ice-free periods force bears ashore, resulting in declines in body condition; for example, female polar bears lost an average of 39 kilograms during a period analyzed between 1979 and 2021. The successful adoption significantly improves the cub’s odds of surviving into adulthood, where the wild survival rate is only about 50%. Churchill, Manitoba, remains a critical hub for this research, as annual migrations bring the bears close to human settlements, necessitating ongoing monitoring efforts by institutions like Environment and Climate Change Canada.