Studying Polar Bear Dens in Svalbard

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Steven C Amstrup, Polar Bears International

Reading Time: 3 minutes

Studying Polar Bear Dens in Svalbard

Guest Post By: BJ Kirschhoffer, Director of Field Operations at Polar Bears International

Last week, while most of my colleagues at Polar Bears International were busy preparing for International Polar Bear Day on February 27th, I was in a frenzy of packing for a polar bear den study in Svalbard. The sheer amount of gear required for staff working in subzero Arctic temperatures always boggles my mind—from warm sheepskin boots, gloves, and parkas to fur-lined hats, thermal underwear, and high-energy chocolate bars. 

This year marks the 8th year that we’re partnering with the Norwegian Polar Institute and the San Diego Zoo Wildlife Alliance  to study the behavior of polar bear moms and cubs when they emerge from their dens in spring. The long-term study is designed to add to our understanding of the needs of polar bear families during this vulnerable time in their life. 

Dmytro Cherkasov 341 Studying Polar Bear Dens in Svalbard
Dmytro Cherkasov, Polar Bears International

Polar bear moms give birth to their cubs in snow dens, nursing and caring for them until they’re strong enough to venture into the outside world. Our study involves deploying remote camera systems in late February or early March at known den sites in Svalbard to capture footage of moms and cubs during the period when they break free of their dens. Our cameras record when families emerge from their dens, how long they hang around the den site before heading for the sea ice, and the health and condition of the moms and cubs. 

Monitoring denning behavior is especially important in a warming Arctic. We already know that some polar bears are thinner due to sea ice loss, which reduces access to their seal prey. Polar bear mothers rely on stored body fat to withstand the months-long fast required to successfully den. Without adequate fat reserves, some mothers may choose to leave their dens before the cubs are ready. The longer the family can stay in the den, the better equipped the cubs are to begin a life on the sea ice.

Simon Gee 9402 Studying Polar Bear Dens in Svalbard
Simon Gee, Polar Bears International

Studies like this are long-term, but we’ve started to hone in on how many cubs are at the den site when they emerge versus how many are with their mom a month later. We also look at how much the cubs weigh compared to mom, and the height of each cub relative to other cubs in the litter and to their mom. We check how coordinated the cubs are, what differences there are between the cubs, and their general behavior. The study has the potential to answer a lot of basic questions in a rapidly changing ecosystem. It’s incredibly important information.

This year, we are also planning to test new den-detection technology—Synthetic Aperture Radar, or SAR—on known den sites on Svalbard’s snowy mountain slopes, part of a partnership with Brigham Young University, with tech support from ARTEMIS. We want to be able to find and map polar bear dens hidden under the snow so we can protect denning families from disturbances. This is critically important as more industry moves into the Arctic, threatening denning habitat and putting moms and cubs in harm’s way. Our earlier tests with SAR were quite promising and we hope to further refine those results. 

Steven C Amstrup 000025 Studying Polar Bear Dens in Svalbard
Steven C Amstrup, Polar Bears International

Working with moms and cubs for over a decade has given me a deep appreciation for the challenges denning families face in the Arctic. We hope you’ll join us in celebrating the bears on International Polar Bear Day—whether you donate in support of our den-detection study, tune in to one of our live events, or share information on social media, using the toolkit we’ve created. Together, we can help ensure the polar bears’ future and give moms and cubs the protection they need.

– On Sunday, February 27 you can check out the short film “Bear Witness” (By The Weather Network, featuring PBI scientist Geoff York, filmed in Churchill) on 
– Here’s a toolkit to get involved with International Polar Bear Day.

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