The polar bear dens are difficult for humans to spot, but radar mounted on a drone can help prevent us from disturbing the hidden dens where the bears give birth.
Challenges Faced by Researchers
Pregnant polar bears work to build their dens by digging pits in the snow in early winter, crawling inside, and allowing fresh snow to cover the entrance. Inside, the bears give birth and protect their newborn cubs from the harsh elements of the Arctic. However, polar bear experts are concerned that these animals may be too good at hiding. For this reason, scientists at the Polar Bear International (PBI) contacted Jenssen and other engineers to collaborate on finding more effective ways to locate polar bear dens during aerial surveys before they are discovered by humans and inadvertently destroyed.
Using Drone-Mounted Radar
In winter, oil and gas companies transport equipment and other devices across polar bear habitats in Alaska. “Over the last two years, we’ve had four dens disturbed in the oil fields – all dens we didn’t know about until the bears suddenly appeared,” says Susanna Woodruff, a polar bear researcher with the U.S. Fish and Wildlife Service. As oil and gas exploration expands in the Arctic, the likelihood of den disturbances increases, raising the risks of harm to vulnerable cubs. For endangered species such as polar bears, these cubs are especially valuable.
Challenges Related to Using FLIR System
Current U.S. government policies require oil and gas companies to survey their sites for polar bear dens to avoid disturbing them. However, the tool that companies use for this purpose (known as Forward Looking Infrared or FLIR) only detects the heat of the animal in the snow and works only under specific conditions. Warm weather diminishes the heat signal from the polar bear, while deep snow or storms obstruct it. Additionally, using FLIR is somewhat like trying to scan the landscape through a smartphone camera – from an airplane. Users are sure to miss some areas.
Using Radar to Detect Polar Bears
The basic idea behind using radar to detect polar bears is simple. A radar device is mounted on a plane or drone that emits electromagnetic waves while flying over polar territories. When the waves hit the ground, some bounce back to the radar device, while others penetrate deeper. The time it takes for the waves to return indicates how far away a particular surface is. The quantity of reflected waves varies for different types of surfaces, such as rocks, dirt, snow, or water. Polar bears – which are essentially containers of water – will appear as an anomaly nestled within the snow.
Radar Testing in Svalbard, Norway
In 2021, PBI collaborated with radar specialists from Brigham Young University to test a radar device in Churchill, Manitoba, a town that has one of the world’s highest concentrations of polar bears. Although they only captured images of bears on the surface of the snow, the researchers demonstrated in a paper published in the journal Ursus in October that the radar detected 66 percent of the bears.
Testing Radar in Svalbard, Norway
The researchers wanted to test the radar’s ability to look inside dens in the Svalbard archipelago in Norway last spring. Svalbard has known populations of polar bears fitted with GPS collars, so the researchers had prior knowledge of the numerous den locations and were prepared to confirm the radar results. The PBI team was discussing details with Jenssen’s colleagues at NORCE on the day he joined the den project. Here, they learned that his drone-mounted radar platform was highly appealing to cover.
Results
Promising and Future Plans
During the journey, researchers flew a drone over the dens containing bears equipped with GPS tracking devices several times. Later, when analyzing the data, Jenssen selected the anomalies within the snow – and when compared with the known locations of the bears based on collar-mounted devices, the points matched. “The initial results are very promising that this works,” says Jenssen. However, he wants to gather more data before becoming too enthusiastic.
The team plans to go to Alaska in the winter of 2024, where the U.S. Geological Survey will mark new polar bears. This will give researchers the opportunity to test their radar platforms against FLIR. “We will finally be able to say with some certainty which tool is preferred or at least have a more robust discussion about the pros and cons of each option,” says York.
He has witnessed firsthand how better detection can keep dens safe. Several years ago, polar bears built a den next to an active road used by BP oil and gas company. PBI, the U.S. Fish and Wildlife Service, and BP monitored the den site and restricted drilling operations until the bear left. “It was a beautiful success story for everyone working together,” says York. “That’s the kind of outcome we’d like to see.”
Source: Andrew Chapman is a freelance science writer living in Truckee, California, covering life sciences and the environment.
Leave a Reply