Polar bear mother and cub on sea ice, off the coast of Svalbard, Norway. Credit: Kt Miller/ Polar Bears International.

A new study has captured rare footage of polar bear cubs on the Norwegian island of Svalbard emerging from their dens for the first time.

Remote cameras were deployed in the Arctic mountains across nearly a decade, providing valuable footage of mothers and cubs emerging from dens. The results shed light on elusive polar bear reproduction.

Researchers from Polar Bears International, San Diego Zoo Wildlife Alliance, the Norwegian Polar Institute, and the University of Toronto Scarborough reveal the first detailed look at polar bear cubs emerging from their dens, captured through nearly a decade of remote camera footage in Svalbard, Norway.

This research marks the first combination of satellite tracking collars with remote camera traps to answer questions about polar bear denning, which is notoriously difficult to study as polar bear mothers build their dens under the snow in remote areas.

The researchers present new insights into the timing of den emergence and post-emergence behaviours alongside new tools to monitor polar bear dens across the Arctic.

Cub survival underpins species survival, and the denning period is the most vulnerable period of their life – less than 50% of cubs may make it to adulthood.

As industry expands in the Arctic, the study highlights the importance of undisturbed denning areas to protect polar bear populations. 

Lead author Dr Louise Archer, Polar Bears International Postdoctoral Fellow at the University of Toronto Scarborough, said: “Polar bear mothers are having increasing difficulties reproducing due to climate-driven changes, and are likely to face further challenges with the expansion of the human footprint in the Arctic.

“We’re excited to introduce new tools to monitor bears during this vulnerable time and to gain insight into their behaviour across the Arctic, so that we can work to protect cubs and therefore the species.

“Every den we monitored had its own story, every data point adds to our understanding of this crucial time and supports more effective conservation strategies.” 

A polar bear mother and cub. Taken on a vessel off the coast of Svalbard. Credit: Kt Miller/ Polar Bears International.

Rare glimpse

Dr Megan Owen, vice president of Wildlife Conservation Science at San Diego Zoo Wildlife Alliance, said: “This study provides a rare glimpse into one of the most vulnerable and critical periods in a polar bear’s life, offering insights that can help guide our collective conservation efforts.

“By combining innovative technology with long-term research, we’re gaining a deeper understanding of the challenges polar bear moms and cubs face in a rapidly changing Arctic.

“Protecting denning habitats is essential for population health, and this study provides invaluable insights that will help guide protective management.”

Dr Jon Aars, senior researcher at the Norwegian Polar Institute, said: “Studies including observational data at polar bear den sites have been few, and this study thus contributes significantly to our knowledge about denning ecology.

“Further, as the data from satellite radio collars were available for all the mothers, the observational data made it possible to tell how changes in activity and temperature recorded correspond with behaviour.

“This is of great value as a lot of data from collared females that have been in a maternity den is available.”

Svalbard’s mountains, viewed from the research helicopter. Credit: Kt Miller/ Polar Bears International.

Methodology

Female polar bears were fitted with GPS satellite collars that recorded their location, temperature, and activity.

Researchers used these collar data to locate dens, and they travelled through Svalbard’s mountains to deploy timelapse camera traps at thirteen den sites over six years (2016 – 2020 and 2023).

The study found that camera traps provided fine-scale insights into maternal den behaviour, while satellite collars are accurate and useful for monitoring bears over longer periods and in more remote areas. 

The newborn polar bear cubs are currently snuggled in dens with their mothers across the Arctic.

Polar bears typically give birth around New Year, at which point the cubs are blind, hairless, and just a 1/2 kg (or 1 lb).

They grow quickly, nursing on their mother’s milk which is 31% fat, reaching around 10kg – up to 20 times their birth weight – by the time they leave the den in spring.

Polar bears emerge from their birthing dens between February and April of each year, with the timing varying depending on where they live.

The duration of the denning period, timing of den emergence, and time spent at the den site after emergence all contribute to the survival of polar bear cubs. 

The study is published in the Journal of Wildlife Management.