Polar Bear

Polar bears are found all over the ice-covered waters of the circumpolar Arctic; their distribution is based on the availability of food and the quality of the sea ice. They are most frequently found where seals gather and where sea ice meets open water. Polar bears depend heavily on sea ice as their main living space, using it for various crucial activities such as hunting and consuming seals, finding partners and reproducing, travelling long distances, reaching land-based denning areas for mothers, and occasionally for denning itself. Polynyas, which are open water areas surrounded by ice due to changes in wind, tide, or current, are locations where marine mammals and birds gather in large numbers and are vital for polar bears.

Polar bears primarily prey on ringed seals, but they also hunt bearded seals, walrus, and beluga whales, and scavenge on beached carrion such as whale, walrus, and seal carcasses found along the coast. These bears frequently consume just the skin and blubber of seals, leaving the rest of the body for other animals to feed on and therefore, playing an essential part in the Arctic's ecosystem.

Reproduction occurs on the sea ice typically in April or May. After mating, the female needs to build up enough fat reserves to survive and care for her cubs from late October to mid-November when she enters the maternity den until the family emerges in spring for feeding. Cubs are born in snow dens from late November to early January, the timing differs based on region and population. Due to their fragility at birth, cubs stay in the den where the temperature is close to freezing. They nurse in the den until late February to mid-April, depending on the location.

The term Nanuq, derived from the Inuktitut language, signifies a polar bear as a creature deserving of immense admiration, and respect, symbolizing the nomadic nature, strength and adaptability. For Inuit communities, polar bears hold profound spiritual and cultural importance.

Polar bears are well-known globally as a symbol of the Arctic, however, for the Inuit people who have long coexisted with them for centuries, these are deeply intertwined with their way of life, homeland, and traditions. The harvest and trade of polar bears provide essential resources and income to support the livelihoods of northern communities. For generations, the Inuit people have been hunting polar bears for sustenance and practical use: the meat provides ample protein, niacin, vitamin A, riboflavin, and iron. The sturdy hide is used for garments, covers, and carpets; it can also function as a platform for standing on during seal hunting near air holes. Body fat was historically used for fuel, and claws and teeth were fashioned into tools, art and jewelry. In Nunavik, participating in a polar bear hunt can be a rite of passage for youth, as part of traditional Inuit practices that connect them to their culture, skills, and the land.

Additionally, the polar bears are important in Inuit arts and sculpture. Inuit artists transform ordinary stones into realistic sculptures of polar bears. For years, they have been known for their beautiful sculptures connecting them to the Arctic and depicting their way of life and surroundings.

Canada is home to approximately 60% of the global polar bear population. Polar bears are listed as a species of Special Concern under Canada’s Species at Risk Act (SARA) and are also protected by provincial and territorial laws.  As the Arctic warms and sea ice melts, polar bears are among the species most vulnerable to environmental change. The shrinking sea ice has affected polar bears' usual hunting range, forcing them to seek alternative food resources such as birds' eggs on land. It is also responsible for the increased human-polar bear conflicts in the Arctic. Previously, where sea ice has been extensive, this has facilitated large-scale migrations. Sea ice variability has led to fragmentation and isolation of some polar bear populations, incurring genetic costs (reduced genetic variation within regions impacted by sea ice loss).

Polar Bears International emphasizes the compounding impacts of climate threats on polar bears and Arctic communities. Longer ice-free periods have extended fasting times for polar bears, contributing to population stress in some areas. Conservation strategies, including community-based wildlife management and regulated harvesting, aim to prevent overharvesting and ensure sustainable use. Coordinated management, information exchange, population monitoring, and research all support these efforts.

For the polar bear co-management, the Nanuk co-management boards were established comprising representatives from the federal, provincial, and territorial governments and Inuit work for collaborative decisions about harvest levels. Through their work in the Eastern Arctic, representing the Nunavut Agreement (established 1993), and the Labrador Inuit Land Claim Agreement (established 2008), they work on polar bear management and support polar bear and Inuit health and well-being. Also, the Nunavik Wildlife Management Board and the Nunavik Marine Region Wildlife Board have prominent roles in the management of the polar bear harvest management.

Since 2016, the research initiative BEARWATCH has been studying the effects of Arctic climate change using polar bear behaviour, genomics, and Traditional Ecological Knowledge in and around the Inuit community of Gjoa Haven, situated on the southeast coast of King William Island, above the Arctic Circle. The project's team has created non-invasive tools for analyzing the molecular makeup of bear feces to monitor the polar bear population more effectively and to assist Indigenous community-led monitoring efforts.

WWF, Canada advocates for the protection of polar bears across the Arctic and supports polar bear studies including satellite telemetry studies to understand the movements and habitat requirements. In addition to climate change, there are other threats such as oil and gas exploration, pose potential risks to polar bear’s health, reproduction and access to prey.

Polar bears are among the most iconic and well-studied Arctic species. Research on their genetics began in the 1970s, and since then, numerous studies have explored their genomics across North America and beyond. These studies help us understand their evolutionary history, adaptations to the Arctic environment, and the impacts of climate change on their populations.

There are several genomic studies which have examined bear speciation and population history and the evidence of ancient admixture between brown bears (Ursus arctos) and polar bears (Ursus maritimus). Recent paleogenomic work has revealed extensive ancient gene flow from polar bears into brown bears (Wang et al., 2022), complementing earlier findings of admixture (Cahill et al., 2015; Lan et al., 2022).

Researchers at the University of Buffalo discovered a potential genetic adaptation that gives polar bears an increased ability to survive in the harsh Arctic environment. They studied the mitochondrial and nuclear genomes of 23 polar bears and compared them to corresponding genomes of black and brown bears and found that there is a difference in genes related to the production of nitric oxide which has a vital role in the metabolic process. This adaptive thermogenesis results in the cells producing heat instead of energy. These intercellular nitric oxide levels may be one of the key factors for the adaption of polar bears to the extreme environment (Welch et al., 2014). By gaining more insight into polar bears' ability to adjust to various environments, including their natural Arctic surroundings and other locations, we can enhance our comprehension of their capability to cope with ongoing climate change and may also explain how their adaptations impact the overall Arctic ecosystem.

Genomics has uncovered significant levels of population-level structuring within Arctic Canada as a whole and regionally (e.g., within Hudson’s Bay, for example). Genomic data and genetic analyses have been used to detect mating patterns and to determine differential dispersal of males and females, and to infer the occurrence of multiple parentage (i.e., promiscuity and non-monogamy) in certain populations.

Studying whole genomes offers insights into both the past and the future since the genetic variation in the polar bear genome could be crucial for the species' potential future adaptation. With the genetic architecture of the polar bear genome now identified by scientists, upcoming studies can determine how certain genes impact important biological functions such as handling contaminants and enduring periods of fasting. This will help improve our understanding of how polar bears can adapt and survive in the face of new environmental challenges. Evaluating, comprehending, and preserving genetic diversity in the polar bear subpopulations worldwide will be crucial for ensuring the species' long-term conservation.

Environmental DNA (eDNA) has also been found for the polar bear, offering a target for novel tool development: for example, Hellström and colleagues (2023) demonstrated that eDNA taken from footprints in the snow can be used to identify individuals by comparing the genetic profile of polar‑bear DNA extracted from the print.