- Scientists have captured rare footage of female polar bears and their newborn cubs emerging from maternal dens in the Arctic.
- Using remote cameras and satellite collars, researchers were able to track down polar bear dens in Norway’s Svalbard region and get insights into their behavior.
- On analyzing the data, researchers found that the bears typically stayed in and around the dens for 12 days after first emerging from them; they were also found to abandon the dens earlier than previously thought.
- Polar bear denning and the subsequent den emergence is a crucial period during which cubs transition from the warm environment of the dens to the harsh environment outside; the amount of time cubs spend in the dens is believed to have implications for their survival.
To a layperson, it’s footage of adorable polar bear cubs with their moms against the backdrop of endless Arctic snow. For researchers who study the animals, however, it’s a rare and incredibly important observation that could potentially inform conservation strategies.
Scientists have captured rare footage of female polar bears emerging from maternal dens with their cubs for the first time. The clips give them a glimpse into a rarely observed life stage that has critical implications on the survival of polar bear cubs and, therefore, the species.
A study published in the Journal of Wildlife Management details how researchers combined data from satellite collars and remote cameras to understand den emergence behaviors and trends among polar bear families in Svalbard, a remote archipelago in Norway. The work was done as a collaboration between the nonprofit organization Polar Bears International, the Norwegian Polar Institute, San Diego Zoo Wildlife Alliance, and the University of Toronto Scarborough.
Polar bears (Ursus maritimus) give birth in dens that they dig up deep beneath the snow. After birth, the cubs remain in the den for many months and grow as much as 20 times their birth weight. The dens, typically about 20° Celsius (36° Fahrenheit) warmer than the external ambient temperature, keep the cubs warm in the first few months of their life. “It’s almost like an extension of the womb where you have this very stable environment that allows cubs to develop,” Louise Archer, lead author of the study and postdoctoral researcher at the University of Toronto Scarborough, told Mongabay in a video interview.
The emergence of the mother and her cubs from the dens and the days that follow mark a crucial period during which the cubs acclimatize to the harsh and cold environment in the Arctic. Archer called it “quite a stark transition period” that, according to previous studies, has a significant impact on cub survival.
“The first step in protecting the cubs starts with giving female polar bears and their offspring the best chance to be able to make it through this crucial development period and move on to the sea ice to begin hunting,” Archer said.
In the past, researchers have monitored polar bear denning behavior in some locations with the help of binoculars and cameras. However, this hasn’t always been easy, due to the remote nature of the dens, the poor lighting and the harsh terrain. Scientists have increasingly used satellite tracking collars to tell if a female bear has been stationary for a long time. Higher temperature recordings from sensors in the collars have also indicated that a bear might be denning. But the method has its limitations, especially when it comes to giving nuanced insights on animal behavior.
“It’s difficult to validate what you’re seeing from collar data without having eyes on the ground,” Archer said. “And there’s typically no way you can say a signature that the collar is indicating is a particular behavior, like bears coming out of the den or a bear moving on the surface.”
Scientists have addressed this concern by deploying remote cameras along with satellite collars. Starting in 2016, Archer’s team deployed time-lapse camera traps for six years at 13 denning sites. Once the satellite collar data indicated that the bears might have gone into their dens, the team went into the field, accessing the sites on foot or on skis while transporting the equipment using sleds. After setting up the cameras about 200-500 meters (660-1,640 feet) from the dens, they left the site, returning a few months later to retrieve the cameras once the collars indicated the bears had left their dens.
Videos captured by the cameras have not only helped scientists verify satellite collar data but have also given them more insights into post-emergence behavior. The team found that polar bear families in Svalbard emerged from their dens around March 9 every year. They were found to stay in and around the den site for around 12 days after that.
They also found that polar bears in Svalbard abandoned their dens earlier than previously thought. “This is a trend we’re interested in monitoring,” Archer said. “To see if it is something related to the changes in the environmental conditions in the region.”
With the help of the footage, they also discovered that the time it took for the animals to leave the area after first emerging from their dens varied from family to family. For instance, one family was found to leave two days after emerging from the den, while another stayed around for 31 days. “What that tells us is that there’s unlikely to be a one-size-fits-all approach to protecting polar bear dens during this time,” Archer said. “It’s important to account for this individual variability.”
The team has also built predictive models by linking data points from the satellite collars — such as temperature and movement — to corresponding images from the cameras. These models, Archer said, will help them predict polar bear behavior based solely on collar data. “Cameras aren’t necessarily feasible or practical to be deployed widely, but collars are something that are regularly used by researchers,” Archer said. “Having a predictive tool to more accurately infer behavior from collar data puts us in a good position to monitor bears.”
The work is, however, becoming increasingly challenging. The rising rate of snowmelt in the region has made it harder for researchers to transport equipment using sleds. That challenge, Archer said, along with the rapid increase in human expansion and infrastructure projects in the Arctic, underscores the urgent need to protect polar bear habitats.
“Our hope is that this data is taken on board by policymakers and decision-makers,” Archer said, “and used to protect bears and give them the best chance at survival.”
Banner image: Polar bears give birth in dens beneath the snow where the cubs remain for many months; their emergence from dens marks a crucial period during which the cubs acclimatize to the harsh environment in the Arctic. Image by K T Miller/Polar Bears International.
Abhishyant Kidangoor is a staff writer at Mongabay. Find him on 𝕏 @AbhishyantPK.
Citation:
Archer, L. C., Kirschhoffer, B. J., Aars, J., James, D. K., Miller, K. M., Pilfold, N. W., . . . Owen, M. A. (2025). Monitoring phenology and behavior of polar bears at den emergence using cameras and satellite telemetry. Journal of Wildlife Management, 89(3), e2275. doi: https://doi.org/10.1002/jwmg.22725
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