Polar Bears International

Aerial Survey of Southern Hudson Bay Polar Bears

9/30/2011 12:51:21 PM

Aerial Survey of Southern Hudson Bay Polar Bears

Polar bear in early fall setting
We conducted our survey of the Southern Hudson Bay population close to the time of a similar survey of the Western Hudson Bay population.

At the June inter-jurisdictional meeting on the status of the Southern Hudson Bay polar bear subpopulation held in Quebec City, Ontario agreed to conduct a distance-sampling aerial survey to determine the number of bears in the SH subpopulation. The survey would be run close to the timing of a similar survey to be conducted on the Western Hudson Bay subpopulation by biologists from the Nunavut Department of Environment and Manitoba Conservation.

Although aerial surveys don't provide the same information as traditional capture-recapture studies of polar bears, they're increasingly finding favour as a non-invasive research approach that's acceptable to aboriginal communities.

Unlike a simple line transect which might provide information on trend, distance-sampling aerial surveys are designed to yield an actual estimate of the size of the population under study. Since animals are not physically handled during an aerial survey, no information is collected on identity of individual or survival rates, and only coarse information on body condition. In addition, no samples can be collected for studies of contaminants, feeding patterns, stress levels, etc. Nevertheless, for some management purposes it may be sufficient to have an estimate of the number of bears in the population.

The Ontario Ministry of Natural Resources (OMNR) conducted capture-recapture studies from 2003-05 and 2007-09 that provided an estimate of the number of bears in the SH subpopulation (~900). Conducting this aerial survey will enable us to compare results from both methods. Funding for the survey was provided by OMNR's Species At Risk Branch, and the survey was designed by Martyn Obbard and Kevin Middel with the assistance of Seth Stapleton, University of Minnesota. The survey design is similar to that used in WH and involves a coastal transect and many perpendicular inland transects—these alternate between 60 km long and 20 km long. We're using this design in order to sample more intensively in the habitats closer to the shore of James Bay and Hudson Bay where we expect to find greater numbers of bears.

Polar bear in fall early fall
Aerial surveys are increasingly finding favor as a non-invasive rsearch method. They provide an estimate of the size of a polar bear population, but don't provide data on indiviidual bears and survival rates and only coarse estimates of body condition.

We began this field trip on Saturday, September 24th, when we travelled by helicopter from OMNR's hangar at the Gravenhurst airport in central Ontario, by way of Timmins and Moosonee, to Attawapiskat on the western shore of James Bay. The next day, Sunday, September 25th, was our first day of aerial survey. Since we were all new to this technique we were a bit apprehensive. However, we had consulted extensively with Seth Stapleton who designed the earlier Foxe Basin survey and the current Western Hudson Bay survey so we felt all would be well.

The first day went very well—the weather was sunny and unseasonably warm, so we had excellent conditions for aerial survey work and were able to complete our survey of Akimiski Island. We're using a Eurocopter EC-130 helicopter—a roomy and comfortable aircraft for survey work with large windows providing excellent visibility. We observed a total of 66 bears on the island, many of which were judged to be in excellent condition for that time of year. There must be lots of seals in James Bay! Mind you, these bears likely have a minimum of 2 ½ months to go before they can return to the ice of James Bay since it's the last to form in the Hudson Bay region. They will be much thinner by then.

 Bear along the shore
We counted 66 polar bears on Akimiski Island, most of which looked in excellent condition--there must be lots of seals in James Bay! But they still have at least 2 1/2 months to go before the ice forms and they can return to their seal-hunting grounds.

On Monday, September 26th, we surveyed up the James Bay coast from the Ekwan River to Hook Point, south of Cape Henrietta Maria. We saw few bears along the coast, and saw none on the few inland transects that we completed. These results confirm our decades-old impression that few bears summer on land in that portion of the James Bay shore. On Tuesday, September 27th, we'll complete the inland transects north of the Swan River to Hook Point and then will move on to Peawanuck on the shore of the Winisk River.

From the field in Ontario's Hudson Bay lowlands with Dr. Martyn Obbard, Research Scientist, Ontario Ministry of Natural Resources (OMNR); Kevin Middel, Analytical Biologist, OMNR and M.Sc. student, Trent University; Brandon Laforest, Ph.D. student, York University, and Doug Holtby, Helicopter Pilot, OMNR.

 

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