© BJ Kirschhoffer/Polar Bears International
3/20/2019 3:54:48 PM
Svalbard Maternal Den Study
By Barbara Nielsen, Director of Communications
Sometimes a giant chocolate bar is just the perk a polar bear researcher needs in the frigid conditions of Svalbard in February.
“We bring a lot of high-calorie food with us: chocolate bars, cheese, freeze-dried food, reindeer sausage,” says BJ Kirschhoffer, our director of field operations. “A giant chocolate bar is something to get excited about when it’s that cold.”
For our den study team in Svalbard, bone-chilling cold, difficult terrain, and unpredictable storms are all part of the challenge of conducting field work on the remote archipelago.
This February marked the fourth year that we partnered with the Norwegian Polar Institute and the San Diego Zoo Institute for Conservation Research to study the behavior of polar bear mothers 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 period in their life cycle—research that’s more important than ever in the face of a warming Arctic.
In contrast to the mostly flat terrain in many of the Arctic regions where our researchers conduct field work, Svalbard is characterized by towering mountains and numerous fjords.
“Svalbard’s landscape is unreal, the scale is absolutely amazing,” Kirschhoffer says. “It’s a place of snow, mountains, and glaciers. It’s incredibly beautiful but also feels vast and empty in winter, with no trees and very little wildlife—just a few small reindeer running around and some arctic fox and ptarmigan.”
To study polar bear families after they emerge from the den without disturbing them, the team sets up remote trail cameras powered by solar panels, aiming them at locations where GPS collars indicate that female bears are hidden under the snow. Some of these sites are halfway up steep mountain slopes or tucked into cornices at the top of a tall mountain.
Team members prepare to set up a trail camera on one of Svalbard's snowy slopes, aiming it at an adjacent slope where a polar bear family is denning. The camera will record the family's behavior from the time they emerge until they depart for the sea ice. Photo copyright BJ Kirschhoffer/Polar Bears International.
“It’s incredible that a polar bear would den there,” Kirschhoffer says. “These are places where I would not venture on a pair of skis for fear of an avalanche or a cornice breaking off.”
Even though the team uses GPS coordinates to locate dens, Kirschhoffer says it’s still not easy figuring out exactly where to aim the cameras given that the dens are blanketed by snow and the terrain is incredibly complex. “There’s not a big arrow on the side of the mountain saying, A polar bear den is here!” he explains.
Instead, researchers ski past locations multiple times with GPS in hand, triangulating where the den might be. Sometimes they’re lucky and can see a den opening. At other times they make their best guess based on incongruities in the snow’s surface. They won’t know if they’ve guessed correctly until after the families depart to hunt seals on the sea ice. Then, the Norwegian Polar Institute team led by Dr. Jon Aars will retrieve the cameras and the San Diego Zoo team led by Dr. Megan Owen will analyze the footage.
Advances in technology allow team members to ski to den locations, fitting needed equipment—from trail cameras to solar panels—into their backpacks. Photo copyright BJ Kirschhoffer/Polar Bears International.
With the polar bear maternal den emergence project now its fourth year, the team continues to collect data even while analyzing footage from previous years. Among the questions they address, are:
- When families emerge from the den and how long they remain at the den site after emergence before departing for the sea ice
- How the emergence and departure times correlate with regional weather conditions and sea ice patterns before, during, and after denning
- Whether rain/freeze events took place during the denning period and how these may have affected the den’s stability
- How the changing climate may affect cub readiness outside the den
“Long-term projects like these are incredibly important,” Kirschhoffer says. “It’s only with time that meaningful patterns emerge.”
Special thanks to San Diego Zoo Institute for Conservation Research, Ouwehands Dierenpark, Zoo Berlin, and St. Louis Zoo for providing funding for the project.