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The good news: Polar bears, imperiled by climate change, appear to have found something new to eat.
The bad news: It's dolphins.
Scientists studying bears on the Arctic shores of Norway found several of the white-coated predators feasting on the remains of white-beaked dolphins, which appeared to have become trapped under the ice of a fjord.
"This is the first record of this species as polar bear prey," the team recounted in a study published in the scientific journal Polar Research. "White-beaked dolphins are frequent visitors to Svalbard waters in summer, but have not previously been reported this far north in early spring."
The discovery occurred in April 2014 at a site just below 80 degrees north latitude. Scientists took several photos of the bears with the remains of the dolphins. At least one of the bears was notably skinny, with his ribs visible through his fur; he had finished off one carcass and buried a second one to save for later, said Jon Aars, a biologist with the Norwegian Polar Institute and the lead author on the study. A return trip in July found the remains of seven more dolphins in the area.
While the discovery may provide some help for the bears, dolphins aren't likely to replace the seals that are a staple of their diet, he said.
"It's a large population of bears, and it's not going to be that all of the bears in Svalbard can feed on dolphins," Aars told VICE News. "But it could be significant for some individuals for sure."
The bears are struggling with the same problem that's bringing the dolphins to the nearly 80-degree latitudes where Aars and his colleagues conduct their surveys: a warming climate that's making it harder for the thousand-pound predators to get enough to eat. The presence of the dolphins in the fjord where the photos were taken is itself a bit of a fluke, he said.
"Before we saw this, there was almost no ice," Aars said. Then a cold snap in late March and early April caused new ice to form, and the ice blew into the fjord. The dolphins had only a small hole through which they could surface to breathe, allowing the bear to catch them when they did, he said.
The bear appeared to have finished off one dolphin and buried the remains of a second in the snow for later — a common practice among some animals, but rare in polar bears, he said. Though the bear photographed in April was notably thin, other animals in the area were in better shape, he said.
Meanwhile, white-beaked dolphins — which typically live in the Atlantic waters between Europe and Canada — have been recorded ranging further northward. Around Svalbard, polar bears have been spotted feeding on the remains of dead sperm whales, which normally dwell in the North Atlantic, Andrew Derocher, a biologist who has studied polar bears for more than 30 years, told VICE News.
"What we're seeing is a lot more species that are normally found in lower latitudes drifting further and further north over time," said Derocher, a professor at Canada's University of Alberta. That's "a pretty common story" as global temperatures increase: Scientists have tracked northward shifts in the habitats of birds, butterflies, and other animals for some years.
And in the Arctic, which has warmed at more than double the rate of the rest of the globe, the disappearance of sea ice has created new habitat for other species, he said.
"They're not in their normal range, but of course they follow food," Derocher said. "And because there's no sea ice, they're happy to go into those areas. But the perils are that if the sea ice conditions change quickly, and they can … they get trapped."
Meanwhile, polar bears do best when the sea surface is more than half-covered with ice, which they use as a platform to scoop up seals, Derocher said. But as ocean temperatures off Svalbard have gone up sharply since 1970, the amount of sea ice in the area has gone down, the Norwegian study notes. Meanwhile, the seals that make up the bulk of their diet live on the sea ice and feed in shallow waters near shore. That puts their populations under pressure, and leaves the bears in a bit of a bind.
"We say, 'OK, these white-beaked dolphins are moving northward, why don't the polar bears just move northward?' The problem is once you get north of Svalbard very much, you get into the deep, deep Arctic Ocean waters," Derocher said. "Those are 2,000 to 3,000 meters (6,500-10,000 feet) deep. "They're not going to be habitat for seals, if it's not habitat for seals, then it's not going to be good habitat for bears."
And the loss of sea ice is also making it more difficult for bears to reproduce, Aars said. Female polar bears traverse the ice to reach the islands off the coast in late fall, making dens there to give birth. If the ice doesn't form, the bears don't make it — and scientists aren't sure yet whether they've found new places on the mainland, he said.
Follow Matt Smith on Twitter: @mattsmithatl