From a helicopter, it can be difficult to spot a polar bear against the frozen tundra. So when polar bear biologist Jon Aars sets out on his annual research trips, he scans the landscape for flashes of movement or subtle variations in color – the slightly yellowish hue of the bears’ fur stands out. on the white snow.
“Also, very often you see the footprints before you see the bear,” Dr. Aars said. “And the bear is usually where the footprints stop.”
Dr Aars is part of a long line of polar bear researchers at the Norwegian Polar Institute, which has an outpost in Svalbard, an Arctic archipelago. Since 1987, scientists from the institute have been organizing annual field trips into the frigid wilderness to find and study polar bears on Svalbard.
Over the decades, these research trips have shed light on basic bear biology and ecology, and in recent years have helped scientists keep tabs on how the animals are coping with climate change. Rapid changes in habitat are already affecting their behavior; with the pack ice retreating rapidly, some bears now have to swim long distances to find places to hide. But so far, the bears themselves still appear hardy, Dr Aars said.
If that starts to change, however, as researchers fear it may, these annual field trips will help uncover problems earlier.
Here’s how scientists are doing it.
The trips often take place in the spring, when the bears emerge from their dens with new cubs and the sea ice is strong enough to support what can be a dangerous search. To maximize the study area – and the chances of finding bears – scientists are crossing the archipelago by helicopter. “And, of course, if you have a helicopter and you land on the ice and it’s thin, you might have an accident with the helicopter,” Dr Aars said.
Once airborne, the team, which usually includes two biologists, a veterinarian, a helicopter pilot and a mechanic, begin scanning the landscape for bears. When researchers spot one, they aim from the air with a tranquilizer dart. If they hit their target, it usually only takes a few minutes before the bear is flat on the ice.
Then the searchers land and get to work. They wrap a piece of cloth – a scarf or blanket works well, Dr Aars said – around the bear’s eyes to protect it from the harsh rays of the sun and set up equipment to monitor heart rate, energy levels blood oxygen and bear body temperature.
They take a variety of physical measurements, counting the length, girth and size of the animal’s skull. They also examine his teeth, which can provide a good approximation of his age.
“When you’ve done that with hundreds of bears, you know, you start to get pretty good,” Dr. Aars said. The bears are also weighed, a delicate maneuver that requires hoisting them into the air on a stretcher attached to two spring scales. (Male bears are too heavy to weigh.)
Then they take blood, fur, and fat samples, putting the blood sample in a pocket so it doesn’t freeze. “You just put it in your jacket, close to your body,” Dr. Aars said. Back in the lab, these samples will help scientists answer all kinds of questions about the animal’s life: what does it eat? (Sometimes a bear is covered in blood when researchers find it, a sign that it has just had a seal meal.) Does it have parasites? Has it been exposed to a lot of pollutants? They can also extract DNA from these samples to learn more about the genetics of the local polar bear population and draw sea urchin family trees.
Some of the bears are given satellite collars, which track their location and activity. A “salt water switch” on the collars activates when the bears fall into the water, allowing researchers to calculate how long the bears spend swimming.
Before finishing, the researchers give the bears several identification marks, adding an ear tag, implanting a microchip behind the ear and tattooing a number inside the lip. But they also add a more temporary mark, painting a number on each bear’s back. The number, which will disappear when the bear sheds its fur, prevents scientists from capturing the same bear in the same season in the field. “We don’t want to harass this bear twice,” Dr. Aars said.
The whole process takes about an hour for a single bear, longer for a female with cubs. When the researchers are done, the vet administers medication to help reverse the sedative.
Sometimes researchers wait for the bear to return, just to make sure it is standing and walking safely. They keep their distance, but for Dr. Aars the work has become routine and he doesn’t fear the bears as they wake up. “It’s not like the bear is saying ‘OK, I want to kill this guy,'” he said. “I think it’s more, like, see if you’re okay and probably get a little headache and think about other things.”
And then they’re back in the air, looking for their next bear.
Anna Filipova is an arctic-based photojournalist specializing in scientific subjects who has covered the polar regions for 10 years.