Polar Bears from Space: Satellite Imagery to Count Populations

Polar bears are about to be seen from space, as researchers from US Geological Survey (USGS) and other organizations used satellite imagery to survey polar bear populations in their remote Arctic habitats.

Satellites are a high-tech solution to a practical problem - most polar bears live in areas that are cold, barren and often inaccessible. The new project is an alternative to the aerial surveys already being conducted.

Keeping track of polar bears is part of an ongoing effort to help researchers better understand the effects of global warming, particularly the rapidly diminishing sea ice, according to a statement released Wednesday.

The technology is being tested at Rowley Island in Nunavut's Foxe Basin, Canada, during the summer, an ideal environment because of its flat terrain.

"We think satellite technology has the potential to open vast, remote regions of the Arctic to regular monitoring. It has tremendous potential to aid the circumpolar management of polar bears," study leader and former USGS scientist Dr. Seth Stapleton said in the statement.

US and Canadian scientists compared the applied satellite imagery technology to helicopter surveys also being conducted in the area.

"The remarkable consistency between our estimates of abundance derived from imagery and established aerial survey techniques suggests that bear identification using imagery was quite accurate," the authors wrote in the journal PLOS One.

Satellite imagery detected what was estimated to be 94 bears, while the aerial counts made by helicopter found 77 individuals, yielding a population estimate of 102 for the island when a model was applied, the study said.

There was "significant overlap" in the confidence intervals, but one limitation to satellite imagery is its inability to count cubs - presumably because they are too small to be detected.

Still, USGS scientists are hopeful that this technology will be useful in monitoring other Arctic animals, like musk oxen and caribou, which are dark and stand out against a white, snowy background, the study said.

Before that happens, the next step is determining if satellite imagery is just as effective at detecting polar bear populations over larger areas, including sites along coastal Alaska.

The satellite study is part of the ongoing USGS Changing Arctic Ecosystems Initiative.