When he developed a drone-mounted radar system that might penetrate a number of layers of snow, Rolf-Ole Rydeng Jenssen imagined utilizing it to measure snowfall or predict avalanches. Each functions could be useful in subarctic Tromsø, Norway, the place Jenssen works as an engineer on the interdisciplinary Norwegian Analysis Heart (NORCE). However one January evening a gaggle of researchers referred to as NORCE to ask a couple of very completely different use for the flying radar: discovering hidden polar bears.
Pregnant polar bears construct dens by digging holes within the snow in early winter, crawling in and letting contemporary snow cowl the doorway. Inside, the bears give beginning whereas the snow shelters them and their new child cubs from the cruel Arctic components. However polar bear consultants fear these animals could also be too good at hiding. That’s why scientists at Polar Bears Worldwide (PBI), a analysis and conservation group, gave Jenssen a name. PBI has since been collaborating with him and different engineers on more practical methods to search out polar bear dens throughout aerial surveys earlier than people stumble over and inadvertently destroy the dens.
Throughout the winter, oil and gasoline firms transport rigs and different equipment by way of polar bear habitats in Alaska. “Over the past two years we’ve had four dens that we know of that were disturbed in the oil fields—all dens that were previously unknown before the bears just popped out,” says Susannah Woodruff, a polar bear researcher with the U.S. Fish and Wildlife Service. As oil and gasoline exploration expands within the Arctic, the probability of den disruptions will increase; this ramps up the dangers of hurt to weak cubs. And for a threatened species comparable to polar bears, these offspring are particularly treasured.
U.S. authorities insurance policies at the moment require oil and gasoline firms to survey their websites for bear dens to be able to keep away from disturbing them. The instrument that firms usually use for this (referred to as a forward-looking infrared, or FLIR, system), nonetheless, detects an animal’s bodily heat amid the snow and solely works underneath particular circumstances. Heat climate weakens the warmth sign from a polar bear, and deep or blowing snow obscures it. Moreover, utilizing FLIR is a little bit like making an attempt to scan the panorama by way of a smartphone digicam—from an airplane. Customers are sure to overlook patches.
“When we looked back at how management agencies and industry were doing using this tool, the answer was ‘not that great,’” says Geoff York, PBI’s senior director of analysis and coverage. A 2020 research co-authored by York discovered that FLIR failed to spot 55 percent of polar bear dens. A part of the issue is that the perfect climate home windows for FLIR—which works higher throughout notably lengthy chilly intervals—at the moment are fewer and farther between due to local weather change. And even underneath the perfect circumstances, FLIR missed a few of its targets. “Ultimately, we need to find some method that’s going to do a better job at detecting dens,” Woodruff says.
York and two colleagues got here to the identical conclusion whereas engaged on the freezing tundra a number of years in the past. Pissed off with how the FLIR’s inaccuracy impacted their analysis, the trio began brainstorming. Radar finally emerged as a possible choice as a result of it really works nicely within the circumstances underneath which FLIR struggles. “They’re on the right track in terms of finding something that could maybe be used more frequently and isn’t weather-dependent,” says Woodruff, who isn’t concerned within the radar work.
The idea behind utilizing radar to detect polar bears is straightforward. The radar machine is connected to a airplane or drone and emits electromagnetic waves because it flies over the tundra. When the waves hit the bottom, some replicate again to the radar machine, and a few penetrate deeper. The time it takes waves to bounce again signifies how distant a floor is. And the amount of mirrored waves differs for several types of surfaces, comparable to rocks, grime, snow or water. A polar bear—which is actually a container of water—will seem as an anomaly suspended within the snow.
By means of a collaboration with radar specialists at Brigham Younger College in 2021, PBI examined a radar machine in Churchill, Manitoba, a city with one of many world’s highest concentrations of polar bears. Though they solely took photographs of bears on the snow’s floor, the researchers confirmed in a paper published in Ursus in October that the radar detected 66 % of bears.
Subsequent, the researchers needed to check the radar’s means to really peer inside dens in Norway’s Svalbard archipelago this previous spring. Svalbard has a well-studied inhabitants of GPS-collared bears, so the researchers already knew many den areas and have been thus ready to substantiate the radar’s outcomes. The PBI crew was discussing logistics with Jenssen’s colleagues at NORCE the day he joined the den mission. That’s after they realized his drone-mounted radar platform was too attractive to go up.
Jenssen’s system makes use of ultra-wideband radar, a sort that has comparatively excessive decision. Whereas the radar PBI examined in Churchill had a decision of round one meter, ultra-wideband radar might work on the centimeter scale. Jenssen had additionally particularly designed his machine to make use of frequencies that might penetrate snow and assess its traits, comparable to whether or not it was hard-packed or fluffy. The researchers agreed a instrument that gathered a lot info on snow layers may be higher than different radar platforms at detecting a polar bear’s signature in a den. One PBI researcher described Jenssen’s approach as a “slam dunk.” It was solely six weeks between when Jenssen introduced his analysis to PBI and when he left for Svalbard to check the radar. “I dropped everything else to do this,” he says.
Throughout the journey, the researchers flew the drone over dens housing GPS-collared bears a number of instances. Later, when analyzing the information, Jenssen picked out anomalies inside the snow—and after they in contrast these with recognized bear positions primarily based on the collars, the factors aligned. “The initial results are very promising that this works,” Jenssen says. Nonetheless, he needs to gather extra information earlier than getting too excited.
York says that in winter 2024 the crew plans to go to Alaska, the place the USA Geological Survey might be placing new tags on polar bears. It will give the researchers their first alternative to check their radar platforms head-to-head towards FLIR. “We’ll be able to finally say with some certainty which tool is preferred or at least have a more robust discussion of the pros and cons for each choice,” York says.
He has seen firsthand how higher detection might maintain dens protected. A number of years in the past a polar bear denned subsequent to an energetic highway utilized by the oil and gasoline firm BP. PBI, the U.S. Fish and Wildlife Service and BP monitored the den web site and restricted visitors oil drilling till the bear left. “That was a nice success story of everybody working together,” York says. “That’s the kind of outcome we’d like to see.”
