When veterinary nurse Brittany Semeniuk went to Manitoba, Canada, in November, she and her vet partner were looking to photograph polar bears. They visited a place called Mile 5 Sanctuary, outside the town of Churchill.

There Semniuk saw a chained-up sled dog—and a massive polar bear was approaching it.

"I had no idea what was going to happen," Semeniuk says. "I was worried for the dog."

But then, the bear started playing with the dog. It began nudging the canine with its nose and poking it with its paws; the dog even appeared to be in on the bear's playful game.

This seemingly benign behavior continued for about 15 minutes. After that, the bear walked away to mosey around looking for food, leaving the dog unscathed.

"When the bear left, the dog seemed to be totally fine," Semeniuk says. "[The interaction] was a bit rough because a polar bear doesn't know his own strength."

CAN(NINE) WE BE FRIENDS?

Churchill has been called "the polar bear capital of the world," because in the fall before the ice on the Hudson Bay freezes, the bears often come through the town searching for food. Locals can see dozens of the animals meander through the area, rummaging through garbage in search of food. The bears are often not afraid of humans.

Interactions with polar bears don't always end the way it did in the above video, especially when the animals are hungry. In November 2016, another video showing a polar bear apparently petting a chained-up sled dog at the same location went viral. Soon after, a Canadian news outlet reported that three polar bears had been removed from the location after killing and eating other dogs.

Dog owner Brian Ladoon has been accused of feeding the polar bears, according to a comment a Manitoba conservation officers’ spokesperson made to the Canadian Broadcasting Company. Ladoon told the CBC that the 2016 attack occurred on “the only day we didn't feed the f--king bears, the only night we didn't put anything out.”

Ladoon is a controversial figure in Churchill, where he runs Mile 5 Dog Sanctuary and charges tourists to come see and photograph the polar bears. (Semeniuk says she did not pay for access.) National Geographic tried reaching out to Ladoon for comment but has not heard back.

“Brian overfeeds his dogs in that one area, which inadvertently lures in the bears or as some people would call it—baiting,” says National Geographic Society program officer Sandra Elvin, who used to guide polar bear expeditions in Manitoba and is familiar with Ladoon’s operation. “Being intelligent and amazing, polar bears have learned to associate dogs with extra food, and have realized that without dogs, there is no food. Thus, the bears do not kill the dogs.”

She likens it to how orcas have been known to toss seals around before deciding whether to return them to land or eat them.

POWERFUL PLAYERS

As strong predators with no natural enemies, polar bears can be fearsome. They're the world's largest land carnivore and can charge at nearly 25 miles per hour. They can weigh anywhere from 900 to 1,600 pounds, can measure up to eight feet tall, and have sharp 2-inch claws paired with 42 teeth. The bears normally prey on seals, but they're also opportunistic scavengers that have been known to consume whale carcasses and other flesh.

"I've seen the polar bears before but I've never seen the bears interacting with the dogs in that way," Semeniuk says.

In addition to being incredibly dangerous, bears have a "curiosity quotient" and ask questions with their teeth and paws, Polar Bears International scientist Tom Smith told the Washington Post in reference to the 2016 video. It's possible that when the bear approached the dog this time around, the canine became submissive and the bear saw that as an opportunity for a playmate.

"This interaction was fascinating to see, but it's also incredibly dangerous for these dogs," Semeniuk says. "They have no choice but to interact with the bear."

Rachael Bale contributed reporting to this story.