Polar Bear Food Chain in the Arctic
They’re the kings of the Arctic, living on top of the world and occupying the top of the Arctic food chain, but why are polar bears such an icon of the high north? Curious wildlife enthusiasts, trying to get a glimpse of this fierce and fluffy predator in their natural habitat, only get to see a small part of polar bear behavior. What’s the life of an apex predator like the polar bear like? Read our fact sheet about polar bear basics, their fatty diets and what makes them perfectly adapted to the harsh northern climates.
Polar Bear Characteristics
Less than 500,000 years ago, polar bears evolved from the brown bear species and began their evolution toward the hard-core Arctic survival masters they are today. A thick layer of fat up to 10 cm (4 inches), small ears and a tail prevent heat loss. Thick fur, paddle-like paws, webbed toes and a relatively slim body with a long neck make this apex predator the perfect dweller of the high north. Their short but sharp claws and long teeth with sharp molars are the perfect tools for hunting and devouring their meat-heavy diets. As the largest land predator, males reach a length of 2.6 meters (8.5 feet), while females are a little shorter at up to 2.1 meters (6.8 feet). Polar bears are heavy fellows, with adult males ranging from 300 to 800 kg (660-1,700 lbs.) and females between 150 and 350 kg (330-770 lbs.).
Diet and Prey
Energy-rich ringed seals are the perfect food for adult polar bears and cubs alike. While ringed seals are preferred, polar bears will also feed on harp, hooded and ribbon seals. The nutritious fat of seals serves as an excellent food source and if prey is plenty, adult polar bears will only feed on the fat. When necessary, polar bears aren’t picky eaters and the carcasses of marine mammals, including beluga whales, bowhead whales, walruses and grey whales, are also a welcome meal.
Whenever food sources become scarce, polar bears will venture ashore to feed on reindeer, muskox, small rodents, bird eggs, berries and, sadly, even human garbage. With their excellent sense of smell, polar bears can locate food up to 32km (20 miles) away. With sea ice patterns changing, polar bear habits and diets change as well. Losing access to their typical seal-based meals, they are forced to step ashore and shift to other types of food. This also increases human-polar bear encounters and possible attacks.
Hunting Strategies
Polar bears master the art of patience and energy efficiency! Rather than dashing after their prey, they wait for hours or days on the ice next to the breathing holes of seals until they emerge. Sharp claws and teeth await the surfacing seal, ripping it apart. Having a keen sense of smell, polar bears will sniff out seal’s birth lairs. Jumping on the snow-cover above to collapse the lair’s entrance and prevent the escape of mother and pups, polar bears then break through the roof to devour their prey.
Perfecting polar bear hunting strategies takes time; hence adolescent polar bears will often scavenge on leftover carcasses until they master the art of the hunt. Most of the polar bear’s energy reserves come from the late spring and early summer feeding, which helps them sustain throughout the times of the year when prey is scarce. Polar bear stomachs can hold volumes of up to 20% of their own body weight and their digestive systems absorb 84% of the consumed protein and 97% of fats.
Reproduction and Lifespan
Polar bears can live to a mature age of 30 years in the wild. While females start mating at around four to six years of age, males need a little longer to mature, breeding from around eight to 10 years. Polar bears are loners, enjoying a solitary life, until it comes to mating. Late spring and early summer is the time to find a partner and males will pick up the scent of willing females. Just as in other species, fights may occur if a female attracts two suitors. Couples stay together for only around a week before they go their own ways. Come summer, pregnant females stock up their fat reserves to prepare for giving birth. In regions with scarce sea ice, pregnant females may scavenge for bird eggs and other prey ashore or, in some cases, live off their existing fat reserves until the prey is plentiful.
To ensure the survival of their offspring, polar bears go through delayed implantation. Fertilized eggs do not implant before autumn and only then if the female has enough fat storage to ensure survival of herself and the cubs. It takes around 200 kg (441 lbs.) of female weight gain to trigger a successful pregnancy. This period may take up to eight months, though embryos need only four months to develop.
Digging a den in snowdrifts in autumn to birth their cubs (usually singles or twins), mothers and cubs emerge from their shelters during March or April. Born at only around half a kg (16-24 oz.) and around 30cm (12 inches) long, they grow fast thanks to the high fat content (33%) of their mother’s milk. After two years, they separate and young polar bears continue on their own.
Polar Bear Populations and Habitats
The Ursus Maritimus (aka polar bear) calls the Northern Hemisphere its habitat and stocks (groups of polar bears) roam the Arctic regions. Polar bears live in areas of northern Canada, Alaska, Greenland, Russia and Northern Europe, relying on sea ice to hunt, breed and mate. Worldwide there are 19 sub-populations of polar bears, with 22,000-31,000 animals in total. When studying polar bear habitats and population behavior, looking closely at the movement of sea ice is crucial. Migration patterns, feeding habits, the availability of prey (bearded and ringed seals) and changes in the body weight of the animals are influenced by environmental changes.
Sea ice presence determines the migration patterns of polar bears in the Arctic. While some regions in northern Canada (such as the Gulf of Boothia, Kane Basin, Lancaster Sounds and Norwegian Bay) feature a year-round ice cover, habitats further south (such as Baffin Bay, David Strait, Southern and Western Hudson Bay) feature a seasonal ice cover and melt during the summer. In areas with seasonal ice cover, polar bears are forced to live ashore and sustain on their fat reserves until the ice returns with the onset of winter. In East Greenland, ice cover remains along the shore throughout the summer, allowing polar bear populations to stay on sea ice year-round.
State-of-the-Art Polar Bear Research
How do you study a dangerous predator that roams remote habitats far north and prefers to keep private? In the past, researchers would camp outside dens to observe female polar bears and their cubs, as BJ Kirschhoffer from Polar Bears International Field Operations remembers. Nowadays, technological developments have revolutionized polar bear conservation studies, making it a high-tech research field. It’s all about GPS tags, remote cameras, satellite tracking, aircraft, laser-based body condition measures, fecal and DNA samples.
New technology doesn’t only benefit the research team, limiting cold nights out in remote camps, but also the bears. Remote camera systems are less invasive, limiting interaction between humans and wildlife. And it’s only after the polar bear’s departure that scientists retrieve the camera footage. Serious polar bear research doesn’t show quick results. With a lifespan of up to 30 years in the wild, results take time and conclusions about trends may take decades.
Polar Bears and Climate Change
Hunting, mating and breeding – polar bears do it right on the Arctic sea ice, which has been gradually declining at a rate of around 12.2% per decade (according to NASA Climate Science). This endangers the sea ice ecosystem to which polar bears, seals and other wildlife belong. Polar bears, as well as other Arctic animals, rely on sea ice to hunt, forage, rest and reproduce. While scientists have observed polar bears trying to adapt to sea ice decline by foraging on land and increasing their swimming efforts while hunting in the ocean, these activities burn more energy than their regular hunting techniques. And even their food source is at risk. Their prey (such as ringed and bearded seals) isn’t immune to the threats of the warming Arctic.
Polar Bear Encounters on Arctic Cruises
We know that polar bear sightings are a highlight for our Arctic travelers. Polar expedition cruises are real wildlife expeditions and, while we know the best spots to see polar bears, we cannot guarantee any sightings. A good time to see polar bears in the Arctic is from early to late summer, and we time our cruises to match prime viewing season. To make such an encounter safe for our expeditioners and the polar bears, we follow strict safety protocols on our cruises. We inspect possible landing sites for polar bear activity and change them whenever necessary. Trust us, you wouldn’t want to run into this Arctic predator and, after all, safe sightings from aboard our open deck are the best way to observe the bears’ unique way of life.
FAQ
What food chain is a polar bear in?
As apex predators, polar bears are on top of the Arctic food chain.
What animals do polar bears eat?
Polar bears eat ringed seals, as well as bearded seals, waiting for them on the sea ice to surface through their breathing holes. Additionally, they supplement their diet by looking for alternate prey ashore such as muskox, bird eggs, waterfowl, small rodents, reindeer, fish, shellfish and whale carcasses.
What are the predators of the polar bear?
Polar bears are high on the food web and have no natural predator, though humans and climate change pose a threat to polar bears’ lives, as well as walruses, which can cause fatal injuries to them.
Do polar bears eat meat or fat?
When seals (such as ringed and bearded seals) are plentiful, polar bears will only feed on the fat, leaving the carcasses for scavengers.
Do polar bears eat fruit?
In the wild, polar bears, like other bears of the Ursidae family (bear family) will supplement their diets with berries, in captivity you may see them being fed seasonal fruit to provide them with additional vitamins and nutrients.