A recent study on polar bears in the Arctic Ocean’s Beaufort Sea came to a disheartening conclusion: Shrinking sea ice, caused by global warming, is forcing the lumbering predators to wander and swim farther to hunt the seals on which their bodies depend. That is causing them to lose weight during the spring months, when they should be packing on the fat they need to cope with cub rearing and the next harsh winter.
Researching the topic off the northern coast of Alaska required scientists to outfit nine female bears with high-tech collars made of leather and plastic that recorded activity levels and location. But these bear necklaces also held small cameras that, for the first time, afforded a polar bear’s view of their icy world. The resulting footage is remarkable: Beneath a fluffy white chin and dark nose at the top of the screen, we watch as the wearer interacts with other giant bears, plunges into frigid waters, and rips apart bloody — and nourishing — seals. To learn more about just what it takes to strap a body cam on a 400-pound carnivore, we talked to Anthony Pagano, a wildlife biologist with the U.S. Geological Survey, who was the study’s lead author.
This interview has been edited for length and clarity.
TWP: Why put cameras on polar bears?
Pagano: In the ’80s, the USGS started using satellite collars on polar bears to track movements, but there’s not very much that’s actually known about the behavior of bears in this area. Most of what’s known about the basic behaviors of polar bears on sea ice comes from research that Ian Stirling, a famous Canadian polar bear biologist, did. He made observations back in the 1970s and early 1980s from a cliff site in Canada, using a spotting scope.
Over the past decade or two, there’s been a number of studies on other species that have started to use some of these cameras. The technology has really improved to the point where the cameras can be quite small and the battery need has diminished. We really started to develop this project with the thought of both being able to measure the energy expenditure of the bears and being able to link that with the behavior of the bears on the sea ice.
TWP: How does one capture a polar bear?
Pagano: Typically we work from mid-to-late March to the end of April. We go out in a helicopter, flying over sea ice 60 miles off the northern coast of Alaska, and attempt to locate bears either by following tracks or searching over the sea ice habitat for them, which can be pretty challenging. They are, of course, white on a white surface. They’re hard to see.
Then we dart the bear from the helicopter using a dart gun. The sedative is similar to what’s used for dogs and cats, but in different amounts. We’ll land and then identify the individual bear for monitoring population numbers and survival, and we’ll take samples of a variety of things, looking at health and body condition. To weigh the bear, we have a metal tripod with a chain hoist that lifts the bear up off the ice.
TWP: So any bear you spot, you dart it?
Pagano: We only put collars on female polar bears. The males’ necks are actually wider than their heads, so they won’t retain a collar. It’ll just slip right off their heads. So what we know about polar bears is primarily based on females for that reason — their morphology.
TWP: It can’t be easy to find a camera that can withstand a polar bear’s lifestyle.
Pagano: The first year, 2013, we purchased two collars from a company that has been producing them primarily for caribou and other similar species, and they actually failed. The temperatures were too cold, and apparently the battery didn’t work. When we received the collars, they’d accumulated a large layer — probably an inch — of ice over the camera lens. So even if they had worked, we wouldn’t have had any useful footage. There was a metal O-ring that went around the lens, and we thought it served as a conductor for the ice.
We started talking to a camera engineer who works on a lot of different species, and he was willing to redesign this camera system specifically for this project. He modified the lens such that the issue of icing wouldn’t be a problem. He got rid of that metal O-ring. The other issue with the previous collar was that the lens was somewhat indented, and that was allowing snow and ice to get smushed up within that indentation. He shifted it closer to the edge of the collar and used Plexiglas in front to protect it. He also configured the camera so that it wouldn’t turn on if it was below -17 Celsius so the batteries wouldn’t get drained in those cold temperatures. We ended up putting out four of those that year, 2014, and did three more bears in 2015 and two bears in 2016.
TWP: How did the bears seem to feel about the collars? Are they heavy?
Pagano: For a polar bear, they’re not too bad. Typically, our satellite collars are meant to last for about a year, whereas these are for a week to two weeks. We could really scale back on the batteries. A female polar bear weighs around 400 pounds, and the collars are [about 2.5 pounds]. We didn’t really notice too much response to the collars based on the video footage, and we’ve done other work looking at the effects of collars on movement patterns and haven’t found any influence.
TWP: How much footage did you end up with?
Pagano: About 350 hours or so. They’re a large carnivore, so their primary behavior is resting. Typically, they’re locating an active breathing hole that a seal is using, and they’ll rest by that and attempt to catch a seal by standing or lying down or sitting by the breathing hole, which could last from minutes to hours. Or they’ll find a spot on the ice and just sleep. Certainly there was a lot of time just watching bears rest, which can get pretty arduous.
But it was really fascinating, really exciting to get a better idea of the behaviors of these bears. We were really blown away the second year, 2014, when we got the collars back and actually found that they had worked, and worked really well.
TWP: What were the highlights for you?
Pagano: On a basic level, just getting a detailed understanding of the basic behaviors of the bear — the time resting, walking, swimming, attempting to catch seals and how often they were successful. But on other levels, seeing the bears ‘still hunting’ … waiting and trying to pounce when they did detect a seal coming up to breathe. There was one bear that was actually trying to stalk seals from in the water. It appeared she was swimming toward some seals that were diving in the water.
A lot of it was just getting a view of the landscape from the bears’ perspective. There’s this common perception of the Arctic sea ice as flat and barren. But there’s also areas where the ice is being compacted and compressed upon itself, and the bears are moving up through large rubble ice fields.
Also, most of these bears were breeding females, so they were in estrus, and most of them were interacting with breeding males that were attempting to breed with them. It was really fascinating watching the courtship behavior.
TWP: Uh, what does polar bear courtship look like?
Pagano: For the most part, the females are not very receptive to the males, but it varied. Basically, the males would typically harass and hound the females until the females would submit. A male will approach the female and follow it, and the female at times could get aggressive and swipe or run at the male. The males are typically twice the size of the females, but the males didn’t show any kind of aggression toward the females — despite the aggression of the females.
TWP: You’re a scientist and probably try to avoid anthropomorphism, but did you get any sense of individual bears’ personalities?
Pagano: There did seem to be some differences in their foraging styles. Some bears were simply trying to still hunt; others were trying to stalk seals. Whether that was related to ice conditions or individual differences, it’s hard to say. Similarly with the interactions with the male bears, some of the females seemed much more receptive to the males than other females.
TWP: Did you find yourself cheering when they snagged seals?
Pagano: It was definitely a highlight when we would actually see them catch the seal. I could actually see the sequence where the bear is standing on her hind legs, and getting ready to pounce, and actually pouncing into the water and grabbing and catching the seal.