Polar Bears – Icon of the Arctic

By Jessica Shepherd

Polar bears drift like vagabonds on ice floes or amble along shore-fast ice, thriving where frozen sea and open ocean converge.

When my oldest granddaughter was seven or eight, she looked up at me with concern in her wide blue eyes and said, “Did you know, Grandma, that polar bears will go extinct in my lifetime?”  What do you say to that?

Polar bears are, as their Latin name Ursus maritimus implies, a marine mammal. They drift like vagabonds on ice floes or amble along shore-fast ice, thriving where frozen sea and open ocean converge. Patient and stealthy, they primarily hunt ringed and bearded seals. In a pinch, they’ll make due with carrion, bird eggs or small mammals. Being excellent swimmers, they also hunt walrus and beluga whales. I can picture them under water, huge paws extended, wrestling an aquatic animal half again their size. Globally, approximately 20,000 polar bears range the circumpolar regions of Alaska, Canada, Greenland, Russia, and the northern islands of Norway. Of the 19 separate populations of polar bears, two of them reside in Alaska: the Southern Beaufort Sea population, and the Chukchi Sea population. In May, 2008, the U.S. Government listed the polar bear as a threatened species.

The largest among Earth’s eight species of bears, mature polar bear males can exceed 1,500 pounds (three times larger than our neighborhood black bears), while mature females weigh upwards of 500 pounds. They survive Arctic winters and freezing waters thanks to a thick layer of blubber and a water-repellent outer coat supplemented by a dense undercoat. Their skin is black and absorbs warmth from the summer sun as it passes through their fur, which is clear despite its white appearance. 

Generally solitary, males will seek out females for breeding in the spring by following their scent. Gestation is delayed during the summer when hunting and weight gain are critical. Come late fall, males head out to the pack ice while pregnant females find suitable nearshore sea ice or come ashore to den. Here they give birth and overwinter, living off the fat reserves they put on during the summer while their cubs (usually two) nurse and grow. 

Weighing around one pound at birth (about the size of a newborn golden retriever pup), the cubs nurse for at least a year and learn to hunt alongside their mothers until they are about two-and-one-half years old. At this point the mother drives them off to breed again. 

Females reach reproductive maturity between four and eight years of age. Thereafter they breed once every three to four years. Given an average lifespan of 20 - 25 years in the wild, the number of cubs born to a female is in the range of 8 - 12. But breeding success is declining as sea ice forms later in the year and bears have to swim and range farther in search of food.  Weight loss in females is linked to reduced pupping success while predation by male bears further reduces these numbers. 

The Southern Beaufort Sea population, along the northern coast of Alaska and into Canada, is threatened by the recent move to open the Arctic National Wildlife Refuge (Refuge) to oil exploration and drilling. Population studies indicate an estimated 900 bears in the region, a 40 percent decline since 2010. 

Despite their protected status, on December 7th of this year the United States Fish and Wildlife Service proposed an incidental harassment authorization clearing the way for seismic surveys on the Refuge set to begin in January, 2021. The authorization states that seismic activity would have “no more than a negligible impact” on denning bears in the area. 

Seismic testing involves driving 90,000 pound vehicles across fragile tundra in an extensive grid pattern.  Tracks still persist from smaller scale testing done during the winter of 1984-85, and the impacts of further seismic testing on permafrost is worthy of concern. As they move, the vehicles (referred to as “thumper trucks”) produce a vibration that creates seismic waves which penetrate deep into the Earth before reflecting back up. The reflection is picked up by sensors which provide data that can be used to create a detailed three-dimensional underground map. Geophysicists then analyze the waves to suss out the depth and size of subsurface oil and gas reserves. 

With an estimated 19 – 29 female bears denning each year on the Refuge’s Coastal Plain, the scale of disturbance proposed by the Kaktovik Inupiat Corporation (Corporation) is likely to have more than just a “negligible impact”. The Corporation has indicated that it will use areal infrared surveys to detect den sites and plan around these sites. But prior infrared studies identified only 12, or about 50% of active den sites. Moreover, the physical proximity to massive equipment and crew camps, along with the unsettling vibrations produced by the seismic testing is likely to drive some mothers and their cubs from the warmth and safety of their dens with potentially fatal results. 

Given the continued warming of the Arctic due to the burning of fossil fuels, scientists estimate a two-thirds decline in world populations by 2050, or sooner if melting accelerates as many scientific models predict. Oil exploration and drilling will only exacerbate climate change and speed the decline of the Southern Beaufort Sea polar bear population by the outright death of bears in the den and displacement of females and their young during the denning season.  

It’s all too easy to imagine a future when only a dozen or so adult female bears roam the Arctic Plain. Too weak or too old to raise cubs, these will be the last survivors, collard and tagged and studied until their extinction. That’s not the future I want for my granddaughter.