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Researchers Confirm Rare Polar Bear Adoption in Western Hudson Bay

Genetic testing is underway to trace the cub’s mother, with scientists monitoring the collared family on sea ice.

Overview

  • Female X33991 was seen with one tagged cub in spring 2025 and with two similarly aged cubs in November, confirming she had taken in an unrelated cub.
  • This marks only the 13th documented adoption in roughly 45 years of study tracking about 4,600 bears in the Western Hudson Bay population.
  • Both cubs are estimated at 10–11 months old, appear healthy, and are expected to remain with the female until about 2.5 years of age.
  • Researchers collected genetic samples from the adopted cub to try to identify its biological mother, noting past cases sometimes involved accidental litter switching.
  • Scientists say a maternal caregiving drive likely explains the behavior; having a mother substantially improves a cub’s survival odds, though historically few adopted cubs have survived long-term.