The polar bears of Western Hudson Bay, Canada, are the most studied in the world, yet researchers there still encounter surprises.
As we mark International Polar Bear Day, a time dedicated to celebrating and protecting polar bear families, one recent observation highlights both the vulnerability and resilience of moms and cubs in the Arctic.
Late last year, during the annual polar bear gathering near Churchill, Manitoba, Canada, a female polar bear was filmed exhibiting a rare behaviour: the adoption of a cub that is not her own.
Confirming a Remarkable Adoption:
Researchers from Environment and Climate Change Canada first encountered the mother, known as bear X33991, in the spring of 2025 as she emerged from her maternity den with a single cub. When the team observed her again in the fall, she was accompanied by two cubs: the one they had tagged, and an unknown, adopted cub!
Polar bear adoptions are considered very rare. The Western Hudson Bay subpopulation, one of 20 polar bear subpopulations, has been studied for more than 45 years, with researchers tracking over 4,600 individual bears. This recent observation marks only the 13th known case of adoption in this extensive dataset. To learn more, researchers collected genetic samples from the new cub and are currently analyzing them in hopes of identifying its biological mother.
Supermom on Ice:
You can track this polar bear mom, known as bear X33991, on Polar Bears International’s tracker. Now that it’s February, they’re out on the ice, learning how to hunt. The cubs are just over a year old and will stay with mom until they’re about two to two and a half years old. Polar bear moms are supermoms, nursing the cubs and teaching them how to survive in an incredibly harsh environment. International Polar Bear Day shines a light on this early stage of life, which is the most vulnerable period for polar bears. While only about half of polar bear cubs reach adulthood, having a mother significantly improves the adopted cub’s chances. A mother’s care during these first years is critical.
Celebrating Polar Bear Families on International Polar Bear Day
On International Polar Bear Day, stories like this underscore why protecting moms and cubs matters. While climate change remains the greatest overarching threat to polar bears and the sea ice they depend on, research, monitoring, and collaboration with Northern communities and governments are essential to safeguarding the bears that are here today, especially moms and cubs.
That’s why Polar Bears International invests in denning research, working to understand this critical time for polar bear families so that we can better protect them. We recently teamed up with the Norwegian Polar Institute, San Diego Zoo Wildlife Alliance, and the University of Toronto Scarborough to deploy remote camera traps at polar bear den sites in Svalbard, Norway, to study the crucial period of maternal den emergence. The project paired remote cameras with GPS satellite collars to capture rare footage of mothers and cubs. The resulting research and remarkable footage of polar bear families emerging from their dens provide new insights that help inform improved wildlife management and conservation efforts.
If you want to celebrate International Polar Bear Day, we’d love for you to join in– here are some ways to get involved:
- Join the conversation: Tune into live chats with scientists on PBI’s Facebook at noon ET pm on February 27, and follow Polar Bears International on Facebook and Instagram for updates.
- Use your voice: Stand up for moms and cubs with the latest science about polar bear families, reproduction, and denning. And be sure to check out Polar Bears International’s Arctic Advocacy toolkit.
- Track polar bear moms across Hudson Bay using Polar Bears International’s tracker, like the mom who adopted a cub this winter (Follow bear X33991 on the tracker).
- Donate to protect moms and cubs: Your gift will support research to protect future generations of polar bears.
- Show your love for polar bear families by purchasing “Protect Moms and Cubs” merch.
- Enjoy the Northern Lights Live Cam, streaming from the Churchill Northern Studies Center in Churchill, Canada, thanks to a partnership between Polar Bears International and explore.org, a direct charitable activity of the Annenberg Foundation.
- Learn More About Moms and Cubs in this video.
- Spread the polar bear love:
- Download graphics and learn all about polar bears with the International Polar Bear Day Toolkit
- Get social with #PolarBearDay #ProtectMomsAndCubs
As polar bear females across the North prepare to emerge from the den with their newborn cubs, we’re thinking of all the polar bear moms – from the ones who adopt, to the ones who rear twins out on the ice – and continuing to work to safeguard the future generations of polar bears.
