From: Editor, ENN
Published January 21, 2011 05:09 PM

New from From BBC Earth: Challenges at birth

Cute, cuddly but immediately plunged into a life and death situation, it's not easy for the grizzly bear cubs that are born at this time of year.

So not so grisly to start with, the cubs have to become hardened to the harsh winter, lack of food and other aggressive bears of Alaska and British Columbia fast.

Thousands of bear families emerge from hibernation under the snow in January and February every year. They have had nothing to eat during this time and will initially survive on their mother’s milk.

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It is this fat-rich milk and the mother's warm body to snuggle against that helps the cubs grow from their tiny initial weight of one pound. They are also blind for three weeks after being born. There are normally two cubs to every litter, and whether they live or die depends largely on the annual salmon run, which we’ve written about here.

But with the salmon run well over half a year away, chances of survival are no more than 50-50 for the cubs — usually around half die. And it's not just a lack of food that can trouble the bears.

Other adult males pose a serious threat to cubs, so their fiercely protective mothers will often take them to areas with small quantities of food or with a large human population. But this can risk conflict with humans.

When the bears do survive, they'll leave their mother at some point between being one and 4 years of age, the females having their own cubs at around six or seven.

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