Sunday, February 29, 2004

The Great Arctic survivors
Nutan Shukla

A female polar bear lives off her body fat during the harsh Arctic winter
A female polar bear lives off her body fat during the harsh Arctic winter

LARGEST of the terrestrial carnivores and one of the most powerful predators in the Arctic, the polar bear (white bear) females are highly caring mothers. To escape the severity of harsh polar winters these mammals dig out a big den in the ice where cubs are born between November and December. Although an adult polar bearís thick white coat keeps it warm even in the severest cold, the cubs are born blind with short, sparse hair, not sufficient to protect the in the open.

While most animals of the polar region migrate to warmer places to escape the harsh winter, this handsome animal stays back and hibernates in the cold desert . As the chilly season approaches, the female seeks out the previous seasonís snow for digging ócompacted and dry after several months of settling. With her huge paw she digs an entrance tunnel some two metres long in a snowdrift and at the end of it makes a raised threshold and a vaulted chamber. Sometimes other rooms are also added; in one case a 13-yard long den was found with five chambers.

During winter, the Arctic temperature often plummets below minus 30 degrees C but the inside of the den remains up to 21 degrees C higher because of the body heat released by the bear. In this cozy fortress of ice, the female gives birth to one or two cubs, each about 25 cm long and weighing up to a kilogram. In the initial months, it is only the inside of the den the cubs know about where they play, fight and suckle their mothers. While the mother spends most of her time sleeping, she does not forget to keep the den clean. She herself passes very little urine or faeces when inside, for although she drinks by scraping ice off the ceiling, she does not eat but lives off the body fat built up by eating as much as possible during autumn. Since the cubs are on motherís milk, they also pass very little excreta, which the mother covers with snow scraped from the ceiling.

After winter, the days start becoming longer by March and as summer approaches, the temperature also starts rising. Stimulated by the increasing amount of light penetrating through the ice ceiling, the mother bear is ravenous after having exhausted most of her fat reserves to keep the cubs and herself alive. She breaks open her fortress to come out and heads straight to the sea to hunt for seals, her favourite food, followed by her cubs for whom it is an entirely new experience.

These carnivores are supremely independent and during the Arctic winter males mainly hunt seals that come out of the ice holes to breathe. In the icy desert, their snow-white coat and habit of hunting alone helps them in blending well with their surroundings while silently approaching the prey.

When in a mood to hunt, a bear sits by an ice hole, still and silent, flat on the ice almost in a lying posture with forelegs outstretched and eyes fixed, waiting for the prey to poke its head out of the breathing hole. As the seal breaks surface and before it realises the danger on the edge, the bear smashes down with a powerful, double-pawed blow. A swift, scooping movement with its long sharp claws, and the unconscious sealís limp, bloody body is lying on the ice.

This feature was published on February 15, 2004