The old-fashioned way to keep tabs on polar bears is to capture and tag them, a difficult and potentially dangerous process for both the animals and the humans involved. But researchers with the U.S. Geological Survey are experimenting with a new tracking method: They're using satellites to watch the creatures from space.
Researchers used satellite imagery to count about 100 polar bears roaming Rowley Island, a small island west of Greenland, in the Canadian high arctic. The researchers then compared the images with data collected from helicopters and concluded that, yes, you can accurately track bears from space. The findings from the study were published last month in PLos ONE.
"It gives us a tool that is completely noninvasive," Todd Atwood, leader of the USGS polar bear research program, said in an interview this week.
It's quite a development, given that researchers have little information about six or seven of the 19 polar bear subpopulations, Atwood said, explaining: "It's too logistically difficult to get to them and sample them on a regular basis."
The method is also much cheaper than traditional tracking. The satellite observation cost an estimated $20,000 to $25,000, Atwood said; the full helicopter survey cost roughly $160,000.
The study is part of a USGS initiative to find better, less invasive ways to track animals. The idea to watch bears from space actually came from another study in 2012, when scientists conducted the first-ever emperor penguin count via satellite. It worked so well that researchers thought: Hey, why not polar bears, too?
First, they focused on white polar bears roaming a dark, mostly flat landscape; the island lacks ice during the summer, which is when the study took place.
"The biggest difference is that with penguins, they are trying to detect mostly dark animals on a white background," Atwood said. "We flipped it. We wanted to detect a mostly white animal on a dark background."
The real challenge will come when researchers try to track the bears in an icy, white environment. And the satellite images can't provide all of the information that traditional tracking does; researchers will have to continue to capture and tag some animals to get age and sex data, not to mention biological samples.
Still, getting basic census data on polar bears in remote regions has opened up a potential new research front for scientists, who don't have to face the cold in remote regions to figure out just how many bears are out there.