By Dr. Becker
Before the existence of many of the technological advances we enjoy today, the only way researchers could monitor wild animals for any purpose was to journey to their habitat – be it polar ice cap or rain forest -- and track them down.
Take polar bears, for example. Bears living in areas that are easily accessible to humans are well studied. But for those living in their natural range, relatively little data has been gathered.
Conducting surveys of Arctic animals like the big white guys, walruses, certain species of seals, and others, is quite challenging. The Arctic is a dangerous, isolated, remote location with unpredictable and potentially deadly weather conditions. Most wildlife monitoring in the region is done by airplane or helicopter, or less often, by ship. But this method of tracking is extremely costly and has its limitations in terms of detecting trends over a period of years.
Can Satellite Imagery Be Used to Track Wildlife?
A team of researchers at the U.S. Geological Survey led by Seth Stapleton decided to see if satellite imagery could be used as a more cost-effective way to monitor Arctic wildlife. In a study published earlier this year in PLOS ONE,1 Stapleton wrote:
“Remote sensing affords access to vast expanses of otherwise inaccessible sites, at potentially reduced costs, without concerns about human safety and disturbance to wildlife.”
Another benefit of satellites is that there are archived images going back at least a decade that can be used to establish population baselines for different species of wildlife.
Satellite Images and Aerial Surveys Returned Similar Results
Stapleton and his fellow scientists focused their research on Foxe Basin, Nunavut, which is in the eastern Canadian Arctic. The area has no ice or snow in late summer, and polar bears gather there to wait for the return of winter and ice.
The research team paid particular attention to Rowley Island, because it’s known to attract lots of bears during the summer. As a bonus, the white bears are relatively easy to see against the dark, flat landscape, creating a near-perfect environment to evaluate the use of satellite imagery.
The researchers discovered that satellite images provided information quite similar to data collected from aerial surveys. They counted 90 bears in the satellite imagery, compared with 100 spotted by helicopter. According to the researchers, their results demonstrated the utility and accuracy of satellite images to track the bears.
How Using Satellite Imagery to Track Wildlife Can Be Improved
There were two drawbacks to the use of the satellite images, however. One was that it took a long time for the scientists to study the images – over 100 hours in total. To be useful, the process must be made more efficient, ideally through development of a computer program that can analyze the images, followed by spot-checks by humans.
The other problem was that the ability to see the bears on satellite images varied greatly from one person to the next. The two researchers tasked with studying the images had different skill sets. One had experience interpreting satellite images, but no experience with polar bears. The other had some experience studying polar bears, but no experience studying satellite images. It was the “experience with bears” researcher who was better at spotting polar bears in the images.
The researchers concluded that “explicit search protocols and a rigorous training program including individuals with relevant, on-the-ground experience with the target species” would improve the usefulness and accuracy of satellite imagery.
Monitoring Penguin Poop from Space
Believe it or not, Emperor penguins can be spotted from space because they leave lots of poop behind on fresh snow. The dark brown stains are easy to see in satellite images of Antarctica, and once scientists locate a brown spot, they use satellite close-ups to actually count individual birds or make estimates of groups of penguins huddled together.
Satellite images have allowed scientists to more than double the number of known Emperor penguin colonies.