Polar Bears International

3/13/2014 2:17:08 PM

The Unpredictable Nature of Arctic Fieldwork

Doing fieldwork in any location will always have its challenges. Ask any field biologist out there! Arctic fieldwork is no exception to this rule. The frigid cold temperatures, mounds of snow, and icy winds make working outdoors very rugged indeed.

We started our spring field season in Churchill, Manitoba, approximately two weeks ago. Our goal is to locate as many family groups as possible before females begin to head far out on the sea ice with their young cubs. Weather conditions prevented us from flying for nearly a week though - frigid cold air temperatures hovered around -30 Celsius with even colder wind chills. This made working on cubs unsafe and so we decided to wait out the cold weather.

Today was our fourth day of flying through Wapusk National Park in search of females coming out of their dens and moving along the coastline. We spent much of our time searching for tracks and following them closely, making dips and turns in the air - a fun ride indeed! We did spot our first family group - a mom and her single cub - but they made a swift return to their safe and cozy den.

Despite our long hours coasting the skies (over thirteen hours so far), we have yet to see any more family groups. It may be that the frigid temperatures here are keeping moms and cubs in their dens a bit longer until conditions are less risky for the cubs, who have very low body fat at such an early stage in their life.

It is important for us to monitor polar bears during this time of year because it allows us to target a very special group: adult females and cubs. My research objectives are to determine the diet composition and body condition of this particular group and, using a 20-year historical dataset, identify potential shifts that may be occurring in this region due to declining sea ice coverage.

Adult females require a substantial amount of energy reserves, which they gather during the seal pupping period (April - May) far out on the sea ice. The fat and energy they store is then used to support pregnancy, birth, and especially lactation as polar bear milk is very high in fat. Using a small biopsy sample taken from the rump of each female, we can identify specifics in her diet and her overall body condition (or total fatness) and assess how this is reflected in her reproductive success (like litter size and cub mass) over a long-term scale. It is possible that an earlier sea ice breakup reduces the foraging window for female polar bears, meaning they will come ashore with less body fat and therefore less energy reserves to raise their cubs.

Our research objectives here in Churchill are ongoing. Each day that we get to head out in the field in search of family groups is very important, as every little bit of information we gather helps to create a clearer picture of what exactly may be occurring with the Western Hudson Bay polar bear subpopulation. We will continue to hope for excellent weather conditions and are eager to work on our first family group of this season.

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