6/13/2013 8:24:26 PM
Time to Go
In 30 years of polar bear research, I’ve had good seasons, great seasons, and wonderful seasons. I’ve never had a bad field season, but some are scientifically more productive than others. I once spent three weeks sitting in fog at a camp waiting to start a season, so this year was good in a relative sense.
I came to Viscount Melville Sound to help out on a study and see a part of the Arctic I’d not seen for over 20 years. This area was estimated to be improving for polar bears as the multiyear ice has melted and now forms as annual ice (i.e., ice that freezes and melts away in a single year). Annual ice should be much better polar bear habitat because it's good seal habitat; multi-year ice can be too thick for seals to create breathing holes.
In the end, though, I was left with the impression that there are precious few polar bears in the area that we were working. There are probably more bears farther east but another helicopter crew (Evan Richardson and Jodie Pongracz) was working that area. I hope to return next year, but we’ll see what happens. What I saw (or didn’t see) was incredibly interesting, but a single year is far too brief a window to understand what is happening in an area. This is why our best insights come from long-term studies.
Data is what we need and the combination of polar bear captures, satellite collars, and other insights from our samples will tell us a lot more about what is happening up here. My former Ph.D. student Péter Molnár, now a post-doctoral fellow at Princeton, is looking at what can happen when polar bear populations get too small. One might think that a population left to its own devices would just grow if left alone. It turns out this isn’t always the case. Any population can suffer troubles if it gets too small. Technically it’s called an Allee effect and it might be one of the reasons passenger pigeons and Carolina parakeets went extinct. (Excessive hunting and habitat loss are other reasons.)
I still feel ripped off that we no longer have this colorful little parrot in the eastern U.S. In the case of polar bears, we suspect that once a population gets too small, males have problems finding females and this can mean fewer cubs being produced than one would expect. Think about the old song (from 1916) with the famous lyrics “If you were the only girl in the world and I were the only boy, nothing else would matter in the world today.” Granted it’s a corny song, but in the case of polar bears, the last boy bears have to find the last girl bears—and for the polar bear world to continue, they’d have to have some baby bears.
Studying Allee effects has management implications. In the past, managers only considered the females in a polar bear population. They assumed that there would be enough males to ensure all females available to breed would indeed find a mate. This normally makes sense because female polar bears typically mate once every three years because they spend 2.5 years with cubs, but males can breed every year. Thus, there should be lots of males to find every female available to mate.
But in small populations at very low density, it turns out that you need to watch the male harvest as well. In many harvested polar bear populations, 2-4 males are killed for every female killed. This occurs for a variety of reasons, but mainly because females are protected when accompanied by cubs. In addition, a skin from a male will be larger and worth more. Are we seeing an Allee effect in Viscount Melville Sound? It will take more fieldwork and analyses to figure this out.
It will also take some more fieldwork to put together a holistic picture of the population. Harvest continues in this part of the Arctic and we met two hunters on the sea ice who had made the trip all the way from Ulukhaktok. I’d met the hunters a year earlier when we were based in their community.
This year, there were few bears around Ulukhaktok. This fits with our satellite collar data, which had the bears much further west this spring. The hunters hadn’t seen any bears in Viscount Melville Sound and were working their way eastward. Both hunters are community elders and know where to find bears: I had to ponder what it means when they weren’t finding many bears. Management is trying to integrate science with local knowledge. It can improve the management system, but it’s a new way of doing things and we’re all learning how to integrate perspectives. These hunters have many years of experience and are fully aware that some years are better for bear hunting than others. Polar bear scientists are similarly cognizant of the ups and downs in the Arctic.
Our last outing was a push towards the Emerald Isle once more. We saw few tracks and few polar bears (two adult males), no seals, no seal kills, and a lot of white ice and snow. Flying close to Melville Island, I spotted two rock ptarmigan flying along the cliffs. It’s hard to imagine how these hardy birds can eke out a living year-round up here.
We ended the season with only nine polar bear captures: eight males and one female. We saw tracks of only one female with newborn cubs. The weather had something to do with the low number of bears, but my impression is that there just weren’t many bears about. Will spring 2014 be different? Hmm…
We spent our final day packing and cleaning up the cabin. Consultation with the weather office by satellite phone suggested we had a window of about six hours to head south and then another storm would hit. While the Polar Bear Cabin is nice enough, the costs associated with being weathered-in were more than my polar budgets could bear (excuse the pun). We have to pay for four hours of flying whether we fly or not. This cost is averaged over the contract, but it’s hard to catch up if you get a few days of bad weather, especially at the end of a trip.
So we loaded up and took off for Sachs Harbour. Once again, the helicopter was rather full on our return south. The weather was a tad dodgy once again but we picked our way along, sometimes using muskox herds for ground reference and made it to Sachs. A quick refueling had us on a straight-line run for Tuktoyaktuk and then Inuvik. It was a tad ironic that heading out from Sachs, we spotted sic bears in less than 40 minutes (a female with two yearlings and three independent bears). The habitat in the northern Beaufort Sea is dramatically more productive than Viscount Melville Sound.
We made the run to Inuvik. The next day, we set about getting our gear ready to be shipped south. There were only a few seats on the plane south, but Nick and I got seats and were soon back in Edmonton experiencing what felt like desert temperatures. Everyone in the airport was wearing sandals and shorts while we emerged in winter boots and parkas.