Inside the Untamed World of Polar Bears

In this month’s blog post by Dr. Owen Slater, we explore rarely discussed facts about these fascinating marine mammals. Let’s get started!

Chill Time: The Social Lives of Male Polar Bears

Typically, adult male polar bears are thought of as being solitary carnivores that wander the vast sea ice on their own in search of seals and other prey. While this is largely true for many months of the year, when circumstances are right, they can be social with other adult male bears and at times seem to seek each other out for company.

Adult male polar bears playing together along the shores of the Hudson Bay in Churchill. Image credit: Owen Slater

Breeding age males will often come together in the fall around Churchill while they wait for the early season sea ice to return along the shores of the Hudson Bay. During this time, males will hang out with other male bears and are often observed playing and practicing sparring techniques together. This play behaviour typically happens when the ambient temperature is at or below zero Celsius, as anything warmer results in the bears quickly overheating due to their thick coat of fur and underlying fat. The cool mornings are the best time to observe these behaviours, but even on warmer days, males are often spotted resting near each other and travelling along the shoreline and frozen inland ponds together.

Classic Canadian Tour guests have been lucky to witness this firsthand over the years, including last year when 3 males entertained us on several trips with their playful antics close to the Tundra Buggies.

The Ultimate Polar Bear Potluck

There are also occasions when large congregations of polar bears can happen, including both males and females and sows with cubs. These occur when whale carcasses wash ashore and there’s a big enough feast for many bears to take advantage of. In one instance in 2017, upwards of 230 polar bears were spotted on Wrangel Island in close proximity to each other as they all got a chance to feast on a bowhead whale carcass! No doubt the smell of the whale wafting through the air brought in bears from tens of kilometers away and provided a large enough buffet that sharing was tolerated.

In these instances, the largest males feed first but as long as other bears display submissive behaviour towards them, with their heads lowered and relaxed body posture, they too are allowed at the buffet table. Even the largest adult males get full eventually and need to rest. These open spots at the dinner table don’t take long to be filled. 

Polar bears feast on a bowhead whale carcass while others rest and digest on land or wait their turn. 

Image credit: Alexander Gruzdev/Wrangel Island State Nature Reserve 

From Sparring to Scarring

Once the sea ice returns, the males return to their solitary ways until the spring mating season, which is occurring now and spans from April through June. The previously playful sparring and friendly behaviour between males turns to fierce battles between rivals for the chance to mate. Standing on their hind legs at an average of about 10 feet tall, this is when the males often acquire the scars on their noses from the claws of other males and break their canine teeth while fighting for mating privileges. During our fall tours, we look for these battle scars and the condition of the canine teeth to help determine the sex of a bear and get a rough estimate of a bear’s age. Based on a recently published study, scarring and canine teeth breakage are highest in males, especially once they reach prime breeding age, which is between the ages of 11-17 in the Western Hudson Bay population (Tremblay et. al., 2025). 

Two large males sparring together while a third male takes a break to cool off on a frozen lake in Churchill. Note the scars on the muzzle on the bear on the right just behind the nostrils. Image credit: Owen Slater 

Bear Facts Aren’t Black & White

A curious cub peers out from behind mom. Note the dense fur and slightly off-white colour. Image credit: Owen Slater 

Some facts are black and white, but that’s not always true for polar bear skin and fur. Black noses, and footpads of polar bears gives a good hint that the skin under all that fur is also black. This is true for most of the bear’s life but like many facts, there can be exceptions. In this case, the exception applies to the newborn cubs, which are born in late December to early January and start off their lives with pink skin. As they nurse and grow over the next several months and prior to den emergence in March, melanin accumulates in the dermal layer and by the time they exit the den with mom, their skin has turned black. There are a couple theories for why it might be advantageous for polar bears to have black skin. One thought is the black skin helps them absorb heat from the sun to keep them warm during the long, cold winters. However, with little to no sun in the high Arctic during the coldest parts of the year, it seems less likely this is an adaptation exclusively to stay warm. The other, and more likely theory is to reflect the harmful UV rays emitted from the sun and reflected off snow, ice and water. With high levels of melanin, their exposed skin is at much less risk of UV damaged that could lead to higher risk of burns and cancer if they had lightly coloured skin. This is true for a wide range of animals that live in parts of the world with high levels of solar radiation. 

As for the fur, polar bears have the densest fur of any of the 8 bear species, which is not surprising given they need to stay warm throughout the long Arctic winters. There are two types of fur, one of which are the long guard hairs that are hollow and translucent. The hair is not actually white, but the hollow hair shafts reflect the light of the surrounding environment, giving polar bears a white appearance during certain times of the year. These guard hairs also help protect the inner, soft layer of fur that provides insulation from the cold and wind. The colour of the fur can vary, with polar bears being whitest just after the summer molting period, when bears replace their coat with new fur. At other times of the year, bears will have a yellow appearance, particularly in spring after they have feasted on many seal pups that are high in fat. The oils that accumulate in the fur are oxidized by the sun, which creates the slightly yellow appearance. 

A Side of Kelp Goes a Long Way

During our fall trips, we often see bears eating kelp while either bedded down or walking along the shoreline of the Hudson Bay. We aren’t sure why they do this but speculate it could help provide them with important nutrients and support healthy gut bacteria. Kelp is high in iodine, which is essential for proper thyroid function. It also contains many other important trace minerals like iron, several vitamins and is high in omega 3 fatty acids. These could help boost immune function and support overall health. In people, seaweeds are known to reduce the feeling of being hungry and it could serve a similar function during fasting before the polar bears can return to consuming their essential diet of ringed seals and other marine mammals. 

A large male polar bear nicknamed Victor for the V shaped scar on his nose, eating kelp as he walks towards our Tundra Buggy. Image credit: Owen Slater