11/18/2011 8:37:42 PM
What if It All Means Something?
It's always hard to "know" how a population of polar bears is doing. Numbers give us some insights: scientists love numbers and hard data. Looking at polar bears from Tundra Buggies® provides another window on their world, but it's difficult to put this year's bears into perspective with last year's bears (or with earlier years for that matter). Looking at polar bears is a bit like remembering the weather: we remember the warm days and try to forget the cold ones (but don't forget that polar bears probably think the opposite).
One of the problems with casual observations is a phenomena called a shifting baseline. Simply put, we're comfortable with commenting on changes we observe over our own time frame, but miss the idea that someone that observing before us might have had a very different baseline. Shifting baselines are particularly common in fisheries where older fishermen see the decline in fish stocks over the course of their careers, but new fisherman start from a lower level of abundance than the previous generation. All in all, such a situation leads one to yearn for the good old days.
The good old days for polar bears? Well, it was clearly well back in the 1980s when the bears were fat and fecund—triplets abounded. With the recent discovery of two dead bears on land in the last weeks, it's impossible for scientists to do anything with the numbers. From my perspective on the bears, this seems like a new event and one that doesn't have much of an existing baseline. Polar bears have always died on land but it seems that we are now seeing such events with greater regularity. Nonetheless, this isn't science but a gnawing sense of realization that it might be an indicator.
Our energetics models tell us that a longer ice-free period will stress more and more bears with each passing week: mortality is predicted to increase with a longer ice-free period. Is this what we're observing or is it something else? Hard to say. What is clear is that the bears are in desperate need of sea ice and yet Hudson Bay is mostly open water. On November 5th, the Canadian Ice Service reported that the eastern Arctic (including all of Hudson Bay) had about 2% ice cover; the normal amount for that date is closer to 12%. We won't know what it means until the ice forms and the bears leave.
On the plus side, I've seen many bears this year looking in good condition and several females with offspring: this bodes well. On the flip side, two dead bears, some very lean bears, polar bears scavenging the grain screenings piled up near the old dump, and lots of problem bears near Churchill don't bode well. The singers-songwriters Chantal Kreviazuk (born in Manitoba) and Raine Maida wrote a well-known hit called "What if It All Means Something?" after visiting Churchill with Polar Bears International. We don't know for sure, but perhaps the bears are telling us it does mean something.
Top photo ©Frontiers North; bottom ©Randy Kokesch.