Hidden Under Snow

2/12/2012 3:43:59 PM

Hidden Under Snow

How do bear scientists test the ability of the FLIR camera system to detect denning bears? Biologists Craig Perham and Dick Shideler set up two simulated bear dens to test the FLIR system: a polar bear den and a grizzly bear den. The scientists created the simulated bear dens last fall.

 Dick and Craig

For the simulated polar bear den, they dug a den in a 1.5 meter snow drift. Inside the den they placed a 120 watt heat source (equivalent to two 60 watt light bulbs), which is comparable to the heat emitted by a denning mother polar bear. Today we checked the simulated polar bear den to see if the heat source was working properly, including checking all of the electrical connections and power cords.

Checking a simulated den

I crawled in to check on the heat pad and all was good; it was giving off heat that was warm to the touch! It gives me chills of excitement to think that soon, in the month of April, I will be crawling into a real polar bear den instead of this simulated one!

Den heater

We also checked the grizzly bear den, but first we had to find it! This turned out to be a real challenge. Last fall, Craig and Dick dug the simulated grizzly bear den into the side of a river cutbank. Since that time they lost its exact location when the den marker became buried underneath mounds of drifting winter snow.

By careful analysis of photographs taken last fall, we finally locate the position of the den. After hours of shoveling snow, removing approximately 5000 kg (11,000 pounds) of snow, we found the den! By the time we did, we had dug a trench 3 meters deep, 6 meters long, and 1 meter wide; the equivalent of a dump-truck full of snow!

Digging out the buried simulated grizzly bear den

The grizzly bear den entrance was lined with beautiful hoar frost crystals which also form inside real grizzly bear dens. It's amazing to think that grizzly bears can hibernate under this much snow and be safe and warm during the long, cold winter!

Hoar frost at entrance to simulated grizzly den

Photos by April Cheuvront. Return to Scientists & Explorers Blog.

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