A 1.9-Kilogram Fox Left Svalbard and Turned Up in Canada 76 Days Later

Back in 2018, a young female Arctic fox left Spitsbergen, the largest island in Norway’s Svalbard archipelago, on March 26. Seventy-six days later she was on Ellesmere Island in Nunavut, Canada, after covering a cumulative 3,506 kilometers.¹ She weighed about 1,900 grams, a little under two kilograms.⁷

Her route was not one long stroll across frozen ocean. It crossed sea ice, but also land and the ice sheet of northern Greenland.¹

The trip was described in a peer-reviewed paper by Eva Fuglei and Arnaud Tarroux, published in Polar Research on June 24, 2019, so this is not new. The authors say that, to their knowledge, it is the first satellite tracking of natal dispersal by an Arctic fox between continents and High-Arctic ecosystems. Natal dispersal is when a young animal leaves the place it was born to find a home of its own.¹

It matters beyond one fox’s itinerary. The authors say her trip supports genetic studies showing that Arctic fox populations mix across Arctic regions, including regions linked by sea ice only part of the year.¹

From Spitsbergen to Ellesmere Island

Researchers fitted her with a satellite tracking collar in July 2017, near her birthplace by a glacier on Spitsbergen. She stayed close to home at first, then ranged gradually farther before leaving the island.³ She left her natal area on March 1, 2018.¹

According to NPR, she reached Greenland on April 16, 21 days after leaving Spitsbergen.⁵ Her northernmost recorded position was on the sea ice off northern Greenland, at 84.7 degrees north.¹ The Weather Network puts her arrival on Ellesmere Island at June 10, after a brief stop in Greenland.⁴ The paper says she settled there by July 1.¹

How far she really went

Two big numbers float around this story, and they measure different stretches. The 3,506 kilometers covers the 76 days after she left Spitsbergen. Counting from when she left her natal area on March 1 to when she settled on July 1, her total tracked distance was 4,415 kilometers. The authors call that among the longest dispersal events ever recorded for an Arctic fox.¹

Neither number is a straight line. Measured directly, she ended up about 1,789 kilometers from where she was born.¹

For comparison, NPR noted that an adult female Arctic fox in the Canadian Arctic made a comparable trip in 2010, covering more than 2,800 miles over five and a half months.⁵

A record pace on the ice sheet

She averaged 46.3 kilometers a day. Her best day came on the ice sheet in northern Greenland, where she covered 155 kilometers.¹

“This is, to our knowledge, the fastest movement rate ever recorded for this species,” the authors wrote in the paper, as quoted by NPR.⁵

The researchers needed a moment to believe their own data. “We didn’t think it was true,” Fuglei, a researcher at the Norwegian Polar Institute, said in a release from the institute quoted by The Weather Network.⁴

A change of menu

She was a blue-morph fox, the darker color type typical of coastal areas without lemmings. On Ellesmere Island she settled into a food web that includes lemmings, so she changed ecosystems as well as countries.¹

What the tracking can’t tell us

This is one animal, so her trip shows what an Arctic fox can do, not what a typical one does. Her collar stopped transmitting in February 2019, and what happened to her after that is unknown.⁴⁶

Reuters, the BBC, The New York Times and others picked up the story, and it later inspired a children’s book, Anna across the Arctic, which Polar Research noted in 2021.⁷