What Eats Polar Bears? Top Threats Facing Arctic Giants
Polar bears (Ursus maritimus) are apex predators of the Arctic. As adults, they have no natural predators and sit comfortably at the top of the Arctic food chain. However, life is still dangerous for polar bear cubs, and occasionally, vulnerabilities arise that allow other opportunistic predators to take them down.
This article explores what eats polar bears at different life stages.
Threats to Polar Bear Cubs
Polar bear cubs face threats in their first couple of years of life. They are small, vulnerable, and rely completely on their mothers for warmth, protection, and food. Cub survival rates vary greatly by region and sea ice conditions, but on average, only about 50% of cubs survive their first year of life, and mortality remains high for the next couple of years.
Other Polar Bears
Male polar bears are one of the biggest threats to young polar bear cubs. Unlike some other bear species, polar bear males play little role in rearing young. In fact, they often kill cubs to bring the female back into estrus so they can mate with her.
This typically happens when the mother emerges from her den in the spring with newborn cubs who have little strength or stamina, making them vulnerable targets.
Starvation & Exposure
Harsh Arctic conditions also take their toll on many polar bear cubs. Deep snow, frigid temperatures, and treacherous terrain all pose significant dangers – especially in the cubs’ first few months of life when they are still quite small, fragile, and vulnerable.
They rely entirely on their mother and her ability to hunt down enough seals to feed not only herself but also her fast-growing offspring. If prey is scarce or she is unable to adequately sustain herself and produce enough fat-rich milk, her cubs may starve to death.
Extended durations in open areas without shelter leaves cubs susceptible to hypothermia or frostbite as well. Falls into icy waters or drifting away on unstable chunks of ice can also be fatal if the mother cannot rescue them.
Predation from Other Animals
While apex predators, polar bear cubs do occasionally fall victim to other opportunistic predators of the Arctic region:
Arctic Foxes: These omnivorous canids will scavenge polar bear carcasses and may also prey on vulnerable cubs if given the chance. They do not actively hunt full-grown bears.
Walruses: On rare occasions, walruses have been observed preying on small cubs when bears venture too close. They use their long tusks to impale the young cubs. Generally, however, walruses only attack in self-defense when necessary.
So, while polar bear cubs face their share of dangers from a variety of sources, they have the distinct advantage of having a very protective, experienced mother to increase their chances of survival. As long as she is healthy and able to procure enough food, she can defend them from most threats until the cubs mature and gain strength.
Threats to Adult Polar Bears
Once polar bears reach adulthood, the tables turn considerably in their favor. Their immense size, strength, and predatory skills make them truly the kings of the Arctic ice. However, outside of humans, there are still a few natural predators that occasionally threaten full-grown polar bears.
Killer Whales (Orcas)
As Arctic waters warm due to climate change, killer whales may increasingly gain access into polar bear habitats for longer periods, resulting in more frequent dangerous interactions between the species.
Other Polar Bears
As with cubs, adult polar bears may attack and kill other adults of their species under certain situations. These typically involve disputes over territories, mating rights, or suddenly available food sources like carcasses.
Polar bears generally avoid contact with one another by choice to steer clear of such dangerous conflicts. But both males and females have been known to assert their dominance through aggressive battles at times that occasionally result in the death of one of the combatants.
Packs of Wolves
While a single wolf poses little threat to a polar bear, a coordinated pack attack can occasionally take one down. Wolves occasionally venture out onto Arctic sea ice in search of food.
If a polar bear happens into a large pack of wolves on a hunt, they may attack defensively as a group to subdue the deadly predator in their midst. These scenarios are quite rare, however, and typically only occur inland during the summer months when the sea ice retracts, and polar bear movements are more confined to land.
Walruses, Seals, and Other Prey
Just as wolves may attack a polar bear as an extreme defensive measure, walruses, seals, and similar prey may counter-attack a hunter that poses an immediate threat.
Usually, polar bears rely on ambush tactics to surprise and overwhelm their much slower prey before it has a chance to fight back. But if the tables are turned and a polar bear is injured, exhausted from swimming, or otherwise compromised in its attack, the intended prey may gore the bear with its long tusks or teeth in efforts to escape.
A pack of walruses can be especially dangerous if they decide to attack simultaneously in defense.
So, while polar bears reign supreme throughout their Arctic habitat, other animals do occasionally claim victory during particularly fierce battles and defensive countermeasures. Yet overall, the massive white bears have remarkably few true natural predators hunting them for food once they reach adulthood. Humans remain the single most dangerous predator, endangering polar bear survival into the future due to hunting and climate change. But regarding the natural food chain hierarchy, polar bears confidently stand at the top in the harsh environments they call home year-round.
Frequently Asked Questions
Are polar bears prey for killer whales?
Killer whales generally inhabit more southerly ocean waters and only rarely venture into the Arctic seas. Most documented killer whale and polar bear interactions have occurred closer to shore when the bears were either swimming or temporarily on land. In their own icy domain atop the sea ice, polar bears do not typically cross paths with orcas.
So, while killer whales could pose a threat if encountered and may occasionally prey on polar bear cubs, they do not actively hunt full-grown polar bears.
Why don’t polar bears eat each other more often?
While males do kill cubs, and adult bears occasionally fight to the death, most polar bears actually avoid other polar bears when possible.
Fatal conflicts require expending much time and energy with no guarantee the polar bear will come out victorious. It is a safer bet for polar bears to hunt more passive prey like ringed seals that offer greater caloric rewards with fewer risks and energy expenditures.
Plus, polar bears have very low reproductive rates. The species cannot afford substantial losses of breeding-age adults to intra-species predation and still thrive.
These factors all help minimize polar bear cannibalism rates overall.
Do grizzly bears eat polar bears?
Grizzly bears and polar bears both occupy remote northern regions and occasionally encounter one another near shared habitats. But as larger and more powerful predators, polar bears typically dominate in conflicts between the two bear species.
Their chances are even better when battling on the sea ice where polar bears rule supreme. More often than not, grizzlies avoid direct interactions with polar bears altogether when possible due to their lethalness.
How do polar bears catch seals and attack prey without getting hurt?
Polar bears rely heavily on stealth and surprise when ambushing seals. This allows them to inflict lethal wounds before the seals are able to put up much of a fight in return.
They quietly creep up to seal breathing holes or birth lairs within the ice, often waiting patiently for extended periods for the right moment to strike with a rapid, explosive lunge the moment the seal surfaces for air. Or they may burst through thin ice or snow cover in a sneak attack at resting seals above.
Polar bears leverage their immense strength and relatively large size advantage against more modest-sized ringed and bearded seals to overwhelm them quickly during such calculated assaults.
Ringed and bearded seals make up the bulk of the polar bear’s diet. One study found that seals comprise about 90% of a polar bear’s total diet.
Staying injury-free is not always possible, but their tactical hunting approach helps minimize risks when attacking dangerous prey.
How do larger prey like walruses manage to injure or kill polar bears?
Walruses pose greater risks for polar bears based largely on their imposing size and formidable tusks. Weighing up to 1.5 tons as adults, walruses can reach 10 feet long and match polar bears in terms of raw strength. Those bone-crushing tusks stretch up to 3 feet in length on large males.
While polar bears typically attempt to attack younger, weaker walruses hauled out on ice, the much faster bears can still fall victim to counterattacks if they are stabbed by the razor-sharp tusks during the tense conflict.
Each species tends to avoid the other when possible, but challenging weather and food scarcity pressures sometimes bring them into deadly clashes initiated by the bears. The outcomes can go either way.
Do Arctic foxes hunt polar bear cubs?
While Arctic foxes mainly subsist on smaller prey like lemmings, birds, eggs, and carrion, they are opportunistic feeders and will attack vulnerable polar bear cubs if the chance presents itself. However, they do not actively hunt cubs as a primary food source. Because cubs stay with their mothers for extended periods, foxes would be outmatched if they directly threatened a cub being actively protected and defended by an adult female.
More often, foxes may prey on injured, unattended cubs, or scavenge the remains of cub carcasses killed by other predators rather than orchestrating their own attacks. So, they pose more of an opportunistic threat than a predatory one.
Conclusion
Polar bear cubs face the most natural predators, especially from other adult male polar bears. But once polar bears reach maturity, they become essentially apex predators in their Arctic domain, with few species daring to hunt them for food.
Their biggest threat remains humans and our role in greenhouse gas emissions driving disruptive climate change throughout polar bear habitats.
Understanding how we impact predator-prey dynamics can hopefully motivate greater environmental stewardship to protect majestic polar bear populations for generations to come.
