Louise Archer, University of Toronto / Polar Bears International

Maternal denning plays a vital role in the development and survival of altricial polar bear cubs by providing protection from external conditions. However, the denning period remains challenging to study and monitor because polar bear dens are often remote and difficult to access. Denning is typically inferred from satellite telemetry data, yet the accuracy of these measures in capturing important denning behaviors that are relevant to management and monitoring is unclear. We installed trail cameras and custom-built continuously recording cameras at 17 maternal den sites in Svalbard, Norway, over a 10‐year period to monitor polar bears emerging from maternal dens. We combined observations from cameras with telemetry data (location, temperature, and activity levels) obtained from satellite collars worn by the denning bears. Den emergence phenology was variable across individuals, with mothers and cubs remaining at the den site for between 2 and 31 days post den breakout. Behaviour during the emergence period was influenced by external environmental temperature and the amount of time since den breakout; bears were more likely to emerge and stay outside longer when temperatures were warmer and as more time had passed since their initial emergence from the den. We also describe fine scale behaviours and activity patterns of mothers and cubs before their final departure from the den site. Our study highlights the importance of the post‐emergence period for cub acclimatization and development. We also provide new monitoring tools to study polar bear denning behavior, which is increasingly vulnerable to disruption in a rapidly changing Arctic.