Nanu, a nine-year-old female polar bear, lives on the Hudson Bay lowlands, south of Churchill, Man. Her den, which she dug out of a stream bank before the ground froze, is nearly two metres in diameter and half a metre higher than the narrow exit tunnel. Air heated by Nanu’s body and breath forms a bubble of warmth that rises into the space. While the temperatures outside can be in the –20s in January, the well-insulated cave can be brought to just below freezing with nothing more than her presence.
Though she hasn’t eaten for six months, she’s able to nourish her cubs in utero and still keep her metabolism quiet enough to conserve energy for at least three more months of fasting to come. That’s because, in addition to her own considerable insulation—five centimetres of thick, downy underfur combined with a full mantle of long, hollow guard hairs—every bear has a layer of fat just below the skin.
To save energy, Nanu is able to lower her body temperature slightly from its normal 37°C. In her state of suspended animation in the darkened confines of the den, she delivers two blind, deaf, toothless, downy-haired young who are less than one per cent of her size, with no body fat to speak of.
The cubs, Sivu and Kingu, are immersed in the fur of her belly, where the sound of their mother’s heart is as present and familiar as it was when they were in utero. Mother’s milk, with 32 per cent fat, keeps these tiny, helpless newcomers alive and powers their exponential growth.
By the time they are three weeks old, their fine hair is replaced by a dense undercoat and longer guard hairs. After 25 days, the soles of their little feet start developing hair as well, completing the insulation they need for moving around the den.
ãã®èšäºã¯ Reader's Digest India ã® May 2023 çã«æ²èŒãããŠããŸãã
7 æ¥éã® Magzter GOLD ç¡æãã©ã€ã¢ã«ãéå§ããŠãäœåãã®å³éžããããã¬ãã¢ã ã¹ããŒãªãŒã9,000 以äžã®éèªãæ°èã«ã¢ã¯ã»ã¹ããŠãã ããã
ãã§ã«è³Œèªè ã§ã ?  ãµã€ã³ã€ã³
ãã®èšäºã¯ Reader's Digest India ã® May 2023 çã«æ²èŒãããŠããŸãã
7 æ¥éã® Magzter GOLD ç¡æãã©ã€ã¢ã«ãéå§ããŠãäœåãã®å³éžããããã¬ãã¢ã ã¹ããŒãªãŒã9,000 以äžã®éèªãæ°èã«ã¢ã¯ã»ã¹ããŠãã ããã
ãã§ã«è³Œèªè ã§ã? ãµã€ã³ã€ã³
Next Stop: Who Knows?
We wanted to do a once-in-a-lifetime trek in northern Laos. Just getting there became the adventure
ME & MY SHELF
Former director-general of the Delhi Policy Group, Radha Kumar is an academic, author and policy analyst. Her most recent book, The Republic Relearnt: Renewing Indian Democracy (1947-2024), explores the triumphs and the democratic decay of the Indian Republic.
The Journey Of The Kon-Tiki
Is it possible to cross the Pacific on a wooden raft? Natural scientist Thor Heyerdahl risks everything to prove it
Hot and (Un)bothered
Not that anyone in India needs to be reminded, but summer is here, and the collective energy dissipated by people complaining about the heat is making climate change even worse.
GOTCHA!
We asked for it: Whatâs the best prank you ever pulled?
Do More With Your Tech
You're undoubtedly missing out on cool features that can help make life easier, safer and even more fun
Why Water Workouts Work
Swimming and other aquatic exercises have special benefits
Surf's Up... Again
A Hawaiian helps victims of a devastating fire in the most Hawaiian way possible
HUMOUR in UNIFORM
I got sloppy with my shaving one morning and nicked my skin.
Leave the WILD Things Be
Wild animals have been made to serve a variety of human needs, including recreational ones. Itâs up to everyday folk to decry the use of animals for entertainment