Polar Bears and Arctic Sea Ice
Polar bears (Ursus maritimus) are in an ecological race to adapt to a world with less ice fast enough or face extinction on this rapidly warming planet. Polar bears are tied to the sea ice. They live on it, breed on it, and hunt on it. The Arctic is seeing faster warming and higher relative temperatures than the rest of the world. One estimate predicts that summer sea ice will be completely gone by 2035. As ice melts, the dark water absorbs more of the suns heat than the white ice, increasing warming. The more ice that melts, the more water is exposed, and the faster waters warm- melting more ice. Having intact sea ice is key to polar bears survival. As sea ice disappears, polar bears have less area to hunt on. As more sea ice melts each year, the bears have to swim farther to find intact ice that may have their prey such as ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus). They spend more time swimming and searching, burning up precious energy. Polar bears are primarily ambush predators and rely on their powerful sense of smell to help them locate distant prey and the breathing holes they use. The bears then use the camouflage of their white coat and patience to lay in wait for an unsuspecting seal to resurface at these breathing holes in the sea ice. With less ice, the polar bear will have to change hunting tactics or choose new prey altogether.
The sea ice is home to the polar bear. It stretches to the horizon until it bleeds into the Fata Morgana that the Arctic is known for.
The ice bear uses scent to find prey but also to find, or avoid, other bears. This young female rolls in her own urine to lock in her scent which may help other bears know to keep their distance.
Polar bears have the most powerful sense of smell in the animal kingdom. They use this super power to find prey such as seals from miles away, sometimes buried below 3 feet of snow, across the expansive sea ice.
A polar bear can smell prey like these bearded seals (Erignathus barbatus) from over 20 miles away.
As polar bears are forced off sea ice and onto land, they lose their advantages such as camouflage and surprise. This hungry male has little chance of running down a free swimming beluga (Delphinapterus leucas) rather than ambushing it at a breathing hole.
Mother polar bears face challenging dicisions when they have to move to a different ice flow across open ocean- swim and risk their cub freezing or stay on a flow with limited food options.
Polar bear cubs are not born as adapted to Arctic waters as their mothers. They don't have the necessary fat layers to stay warm when wet and their fur isn't as thick as their mothers. They prefer to jump between ice flows rather than swim, keeping their less protective fur dry and retaining more body heat.
Cubs use the time on large flows to practice the skills they will need when their mother leaves them.
This play behavior helps cubs learn to hold onto prey. They learn how to stalk breathing holes and ambush seals on the ice flows by watching their mothers.
As this cub grows up, the expanses of open ocean between flows will widen, forcing the cub to either adapt or face starvation.