© Madison Stevens/Polar Bears International
11/6/2017 7:13:25 PM
What's on the Polar Bear's Dinner Menu?
Polar bears evolved several hundred thousand years ago when the first grizzly bears wandered out onto the sea ice and began to hunt marine mammals. Since then polar bears have become highly adapted to the Arctic marine environment. They specialize in living off the fat of their primary prey, ringed seals and bearded seals.
Polar bears have evolved to digest fat efficiently, allowing them to absorb much of the dietary energy from their calorie-rich prey. This ability helps polar bears survive fasting periods, which for pregnant females in the den can last more than eight months. But are ringed seals and bearded seals the only thing that polar bears eat? The short answer is no.
Eggs and other land-based foods
Polar bears are known to hunt a variety of other marine mammal prey including walrus, whales and other seal species (harp seals, hooded seals, harbor seals). But what happens when the sea ice melts and polar bears are forced on to land and no longer have access to marine mammals? For the most part bears remain inactive and try to conserve their energy until the sea ice begins to reform in the fall. But if bears are thin and hungry they will often go looking for food on land.
Long-term research has shown that in years when the sea ice breaks up early bears make greater use of the terrestrial food resources and in particular are more likely to visit seabird colonies in central and northern Hudson Bay to eat seabird eggs.
A young polar bear patrols a rocky coastline in Nunavut, Canada, his paws and muzzle stained from eating eider duck eggs. Photo copyright Evan Richardson.
Although bears can eat large numbers of eggs in a relatively short period of time the number of eggs available to bears simply isn’t enough to sustain them in the long term. In addition, research into how polar bears digest plant material shows that bears get very little nutritional value from eating berries that would sustain other bears species such as black bears and brown bears.
Polar bears have also been seen chasing and eating caribou/reindeer in different parts of their range. Just the other day, we observed a polar bear hunting voles in the kelp along the coast of Hudson Bay.
Although polar bears can make use of alternative prey resources in terrestrial environments, these little morsels of food are just not sufficient to offset the energetic losses polar bears are experiencing as a result of climate-induced reductions in sea ice and reduced access to their marine mammal prey. So please help do your part to help combat climate change and make sure that seals stay on the menu!