Polar bears are large apex predators uniquely adapted to life in the harsh Arctic environment. Their existence depends on a specialized diet that allows them to thrive in extreme cold and support their significant body mass. Understanding what these powerful animals consume reveals the intricate ways they interact with their icy habitat.
The Primary Diet: Seals
Seals form the majority of a polar bear’s diet, providing the energy needed for Arctic survival. Ringed seals (Pusa hispida) and bearded seals (Erignathus barbatus) are particularly important prey species for these bears. The high blubber content of seals is important, as it provides a concentrated source of fat and calories necessary to build and maintain the thick layer of insulating fat polar bears possess. This fatty diet enables them to meet their substantial energy requirements, which can exceed 12,000 calories per day for an active adult bear.
The fat from seals is metabolized efficiently, providing both energy for hunting and a thermal buffer against frigid temperatures. Without this high-fat intake, polar bears would struggle to maintain their body condition and reproductive success.
Hunting Strategies
Polar bears employ several specialized hunting techniques to capture their primary prey on the sea ice. One common method is “still-hunting,” where a bear patiently waits by a seal’s breathing hole in the ice. When a seal surfaces to breathe, the bear quickly seizes it. This strategy requires patience and an acute sense of smell to detect seals beneath the snow-covered ice.
Another effective technique is the “stalk-and-rush,” where a bear slowly approaches a seal basking on the ice, using terrain for cover, before launching a sudden charge. Polar bears also hunt by breaking into snow lairs, which are snow caves where ringed seals give birth and nurse their pups.
Alternative Food Sources
While seals are the preferred food source, polar bears opportunistically consume other items when seal availability is low. These can include young or sick walruses, beluga whales, or narwhals, often scavenged from carcasses. Birds and their eggs are also consumed during the summer months when bears are on land.
Smaller mammals, such as arctic foxes or lemmings, offer minimal caloric value compared to seals. Polar bears may consume some vegetation, such as berries or kelp, but these provide negligible nutritional benefit. These alternative foods generally do not offer the same high-fat content or energy density as seals, making them less ideal for sustaining a polar bear’s health and energy demands.