Inside the Den: A Labyrinth of Tunnels & Rooms

4/4/2011 10:50:30 PM

Inside the Den: A Labyrinth of Tunnels & Rooms

While we take every precaution and follow a true and tried safety protocol, there is still something just a little unnerving about crawling down into a polar bear's den—I believe they call it instinct. Having had more experience in the matter, Rusty was quick to say, "You first." As the new guy on the team I couldn't say no, so down I went.

Biologist at entrance of polar bear den

After the bears have left (with after being the most important part) we have the chance to study and measure the maternal dens. We started with the den site of the very active bear family we had been monitoring the past month. Since they had been gone for some time, the entrance was blown in with a good deal of snow. We began to dig at the mouth of the den, only to uncover a labyrinth of tunnels and rooms spreading in all directions.

This was a very busy bear. At full length, the den stretched for almost 40 feet, making it the largest we have ever recorded. Though large in area, much of the den was cramped for height. Some of the main tunnels were 15 to 20 inches tall. As I lowered myself into the hole, I had to wait a few minutes for the claustrophobia to pass. Then I slid on my back with the ceiling pushing down on my chest and face the entire way. How a 400-pound animal moved back and forth through such tunnels for months is beyond my understanding.

Den entrance from inside

The living caverns were much larger, but hardly what I would consider roomy. Inside these rooms, light from above illuminated the ceiling, making the room shine blue like a mountain glacier. However, the large claw marks across the walls quickly reminded me of where I was. Tiny frosted hairs hung down from almost every inch of the ceiling, suggesting that the young cubs hardly sat still while cooped up inside.

Maternal den ceiling

This bear had surprised us earlier by digging a second den after the entrance to the first caved in a bit. We measured this smaller den as well. In these cramped quarters we twisted and squirmed, filling out data sheets and manipulating tape measures. While the information we collect is scientifically valuable in understanding maternal den structure and habitat needs, we can't help sometimes feeling less like biologists and more like young boys who have discovered the coolest of new forts.

Measuring snow den entrance

This week we received more good news. We returned to one of our cameras to find another open den in view, not too far from another active den we are currently monitoring. From what little we have seen of the video footage so far, neither of these families are very active at all and rarely leave their homes under the snow and ice. By our calendar, they are also a bit late. We expect most bears to be well on their way by now, but these two neighbors will not be rushed. We will be very lucky if we can obtain footage of these camera-shy bears as they sneak off to the sea ice.

Photos ©BJ Kirschhoffer.

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