12/20/2012 3:32:44 AM
Snug in Their Dens
At this rather hectic time of year, it's amazing to ponder that deep under the snow all over the Arctic, the miracle that brings us a new generation of polar bears is upon us. Hundreds of pregnant females have "settled down for a long winter's nap," snug in their dens with their cubs. It's amazing to me that an animal so large gives birth to cubs not much larger than the blocks of butter we use to make shortbread. It's just as amazing that the mother has milk richer than any cream you can buy to fatten up these tiny bears that will one day roam the Arctic without fear of any creature.
The mother bears of Churchill will be far inland nestled along the banks of the creeks and lakes. Most of these bears started their denning season in a den dug deep into the thick peat banks. By now, enough snow has accumulated that most will have moved into the pristine snow that is easier to keep clean. Bears at higher latitudes will be snuggled amongst the hills wherever they can find enough snow to build their den. Some will be within sight of the sea ice that are they are longing to return to, while others are deep in valleys away from overly curious or potentially dangerous adult males.
It must be an interesting event for the mother as the silence of her den is transformed into a nursery. We don't know a lot about polar bear behavior in the dens, but we know the cubs are cuddled up close to the mother where a drink of milk is never far away. Such tiny cubs probably nurse often but with such a small stomach, likely only a tablespoon or two are taken in at a time by the youngest cubs. It's a tough world, though, and it won't be long before competition between siblings kicks in. Mothers don't seem to have much control over which cubs gets milk so despite this being the season of giving, in this case, the greedy cub gets more.
It's not all sleeping and tending to cubs for the mother. Snow is a good insulator so keeping warm isn't the problem, but ice forming on the roof of the den is an issue. If there's too much ice, the oxygen flow drops and the family could suffocate. Periodic scraping at the ceiling keeps things in order. If a big dump of snow comes, the mother will dig the den closer to the surface by pushing the snow backward into the old den. A bit like Christmas presents, there's no peeking allowed at the outside world for the mother. The den is kept well locked up to keep it warm: amazingly, it's usually still a bit below freezing but much warmer than it is outside.
Polar bears are special: perhaps it's the idea that they live in such a faraway place that gives them some magical spot in our lives: a bit like the North Pole being the home of a Jolly Elf renowned for his tendency to rotundness. Just like Santa who likely added a few too many pounds eating all the cookies left out for him, mothers in their dens had to be lucky (more likely skilled) last spring on the sea ice when hunting. Given that these mothers haven't eaten in five or six months and won't eat for another three months, one has to wonder if they have "visions of ringed seals dancing in their heads."
As we all settle down to ponder this special time of year, it's worth reflecting on what polar bears mean to us all. The greatest gift we could ever give anyone is a healthy Arctic. Those that came before us gave us this gift. It is now up to us to nurture it for the next generations of both children and polar bears.