Polar Bears are Eating Dolphins, Probably Thanks to Climate Change
A warmer winter lured a pod of white-beaked dolphins north but then ice trapped them, sealing their fate as a polar bear’s meal
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A group of researchers studying polar bears on the islands of Svaldbard, Norway, recently noted behavior never before attributed to the top Arctic predator. An adult male was noshing on the bodies of two dolphins, reports Matt Smith for Vice.
The dolphin-eating bear was spotted in April 2014, and the prey choice was unusual because, as the researchers write in the journal Polar Research, white-beaked dolphins don’t usually spend much time that far north in the spring. He had eaten most of the first dolphin and was busy trying to cover the second with snow, presumably to save some for later.
Both dolphins were near a hole they must have used to breathe — it appears they were trapped by ice and easy prey for the male bear, who was very skinny when the researchers found him.
Typically, the fjords and coastlines in Svaldbard are choked with ice in the winter, but 2013 to 2014 the coast surrounding Spitsbergen, the largest island of the archipelago, was ice free. During that time, a pod of dolphins must have wandered farther north than they usually do. When fierce northerly winds blew through in mid-April and packed ice into the fjords. "We speculate that this event led to the entrapment of white-beaked dolphins, including the two we found dead," the researchers write.
Over the following summer and fall the researchers saw at least six more polar bears scavenging the carcasses of seven other dolphins, likely from the same pod as the first two.
The incident is just one anecdotal observation, but if ice-free seas created by a changing climate tempt other dolphins farther north, it’s likely that future polar bear encounters will end in carnage. The bears are used to hunting and eating small white whales and narwhals. They also scavenge larger whales. A white-beaked dolphin probably wouldn’t look (or taste) that differently to them. Smith reports for Vice:
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.
The dolphin eating could just be the latest change these large bears are facing — along hybridization with grizzlies and pollutants that make their penis bones more fragile. At least this change might mean some easier meals, at least until the ice melts too much and there’s none left to trap dolphins at all.