Woolly Bears in the Mountains

By Claire Eamer 

No! Not those bears! I'm talking caterpillars.

Woolly bears are those fluffy, hairy caterpillars that look a bit like tiny plush toys. They're common from Mexico to northern Canada. You might have seen a woolly bear trundling along a warm sidewalk in summer or climbing a plant stem to munch on leaves. Eventually, the caterpillar will pupate and emerge as a moth.

So what's so special about woolly bears in the mountains? Actually, it's one particular species -- the arctic woolly bear, Gynaephora groenlandica. Arctic woolly bears weren't supposed to be crawling around in the Yukon mountains, but that's where Isabel Barrio found them during the summer field season of 2010.

Alpine tundra in the Kluane Range, Yukon. D. Hik photo

Until then, arctic woolly bears had been found only on the tundra along the edge of the Arctic Ocean, almost entirely in Canada's Arctic Archipelago and on the shores of Greenland. They emerge from hibernation for about three weeks in June, munch mainly on Arctic willow, and go dormant again until the next June, spending much of their lives tucked away among the tundra stones, frozen solid. They spend so little time active that it takes them a seven years to develop from egg to moth -- the longest of any butterfly or moth.

There's no way a caterpillar not much bigger than a jelly bean could travel from the Arctic Ocean to the southern Yukon in that short period of activity. And yet -- there they were, arctic woolly bears, crawling around an alpine research camp in the Kluane Range, fully 900 kilometres south of where they were supposed to be.

"Caterpillars are relatively common in the alpine and I had been watching them for years," David Hik, the leader of the research group, wrote in an email, "but Isabel was the one who really started looking at them more closely."

A Yukon arctic woolly bear in search of dinner. Syd Cannings photo.

Today, Isabel Barrio is a professor at the Agricultural University of Iceland, but in 2010 she was working on her doctorate under the direction Hik, a specialist in the alpine ecosystems of the southwestern Yukon. And she had a sharp eye for caterpillars.

Hik explained that there are two arctic species of woolly bear caterpillar -- Gynaephora groenlandica and Gynaephora rossii (the larval form of Ross' tussock moth) -- and they are easy to confuse. G. rossii, however, has a wide range all around the Arctic and in the high mountains farther south, so it was logical to assume the Kluane Range caterpillars were G. rossii.

When Barrio looked closely at the older caterpillars, however, she realized they weren't G. rossii. As improbable as it seemed, they appeared to be arctic woolly bears. The research group collected 30 caterpillars that summer to confirm the identification and to learn more about them.

What's your favourite? An experiment to see what the Yukon caterpillars like to eat. D. Hik photo.

That led to another surprise. Analysis of the caterpillars' genetic code showed that the Yukon woolly bears were slightly different from other arctic woolly bears. They were, in fact, a newly discovered subspecies: Gynaephora groenlandica beringiana.

That last word is important. It refers to the fact that they were found in Beringia, the area of northwestern North America that remained ice-free during the last major glaciation. That probably explains their presence in the alpine valley. These fuzzy little beasts were likely crawling over the tough tundra vegetation of Beringia when most of Canada was buried under kilometres of ice -- and they're still there.

G. groenlandica beringiana perched on top of its supper. D. Hik photo.

Since Barrio's first identification of them, the caterpillars have been found in a few other locations in the Yukon. David Hik suspects they are widespread throughout the alpine areas of Beringia. He hopes that new research projects in the region will turn up more confirmed identifications -- and more information.

"They are very cool, and there is so much more to learn about them," he wrote.