The polar bear, Ursus maritimus, stands as the world’s largest land predator, adapted to the harsh environment of the Arctic Circle. These creatures possess a thick layer of fat and dense fur, which insulates them against the extreme cold. Discussing the size of this species requires separating the average animal from the truly exceptional, record-breaking individual. We must look at the standard size range to appreciate how massive the largest confirmed specimen truly was.
The Largest Confirmed Specimen
The largest polar bear ever recorded was a single male specimen documented in 1960. This bear was shot in the Kotzebue Sound area of northwestern Alaska. Its weight was officially recorded at 1,002 kilograms (2,209 pounds). This figure is an outlier, far exceeding the typical weight range for even the largest male polar bears.
This male measured 3.39 meters (11 feet 1 inch) in total length from nose to tail. When standing upright on its hind legs, the bear was said to have reached a height of nearly 12 feet. After its death, this record-holder was prepared and displayed at the 1962 Seattle World’s Fair, cementing its place in history.
Typical Size of Mature Adults
The standard size of a mature adult polar bear exhibits a high degree of sexual dimorphism. Adult males (boars) are significantly larger than females (sows), typically weighing between 350 and 680 kilograms (775 to 1,500 pounds). A large male’s body length generally falls in the range of 2.4 to 3 meters (8 to 10 feet). At the shoulder, an adult male stands between 1.3 and 1.6 meters (4.3 to 5.2 feet) tall when on all fours.
Mature female polar bears are noticeably smaller, with a typical weight range of 150 to 295 kilograms (330 to 650 pounds). The length of a sow usually measures between 1.8 and 2.4 meters (6 to 8 feet). Males can weigh two to three times as much as females. However, a pregnant female that has fed extensively can temporarily increase her body mass, sometimes reaching up to 500 kilograms (1,100 pounds) before entering her maternity den.
Factors Driving Size Variation
The wide range in polar bear size is driven by a combination of environmental and biological factors. Geographic location plays a significant role; populations in regions such as the Chukchi Sea near Alaska are often larger than those in areas like Hudson Bay. This difference is linked to the quality and availability of their primary food source: marine mammal prey.
The polar bear’s body mass is highly seasonal and relies on a hypercarnivorous diet consisting primarily of seals, particularly the fat-rich ringed and bearded seals. Access to sea ice, the platform for seal hunting, influences a bear’s body condition and overall size. Individuals that consume large amounts of seal blubber during peak hunting seasons accumulate substantial adipose deposits, which can account for up to 50% of their body weight.