In the far north, spring is an event more than it’s a season. In central and northern Alaska, we call it “breakup.” The transition from winter to summer is rapid. Just a week ago, in early May, I was staring at about a foot of snow outside my office window. Today, fresh grass is shooting up in the lawn and the leaves on the birch trees are popping. In a couple days, everything will be green.
The term “breakup” refers not just to the rapid melting of the snow, but the violent breaking of the river ice. Breakup sometimes has its oddities too, and a recent video posted by Brenda Frost of Old Crow, Yukon, shows several caribou standing on ice sheets that are being swept downriver.
Understanding River Breakup
When spring hits, many rivers still have ice that’s more than two feet thick. Rather than a gentle thaw, the ice is lifted and broken into pieces by the runoff-fed, rapidly rising river. The ice is then flushed downstream in massive rafts. Breakup is often violent, and on smaller rivers, you can sometimes see its scars where huge sheets of ice have been pushed up into the willows and have gouged the banks. Often, ice jams cause flooding, especially on bigger waterways like the Tanana and Yukon rivers in interior Alaska. This spring, houses have been washed away by rivers in several Alaska communities.
Caribou Catching a Ride
Old Crow, where this video was shot, is located on the Porcupine River, about 31 miles east of the Alaska Border. The Porcupine River flows into Alaska and eventually into the larger Yukon River.
The large Porcupine caribou herd, last estimated at over 200,000 animals, historically winters in and near the Old Crow flats, then migrates north of the Brooks Range and into Alaska to calve in and near the Arctic National Wildlife Refuge. They’ll travel as far west as the Dalton Highway in the summer and fall, before migrating back east into Canada. Caribou often cross frozen rivers during their migrations, but this group apparently didn’t get the timing right as the ice went out. They weren’t the only ones, as you can hear Frost say: “A few just went by just before this.”
Caribou are excellent swimmers, and it’s likely that the caribou in this video escaped to safety. But still, a powerful, fast-flowing river full of massive ice chunks and sheets is a precarious situation for any critter to be caught in. It’s just one of many hazards in the North.
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