Wading through a mountain’s worth of videos, scientists are discovering more about the life of barren-ground caribou – and how it could change
The Porcupine Caribou herd, estimated near 200,000 animals, migrates massive distances between its wintering grounds to their summer grounds on the North Slope of Yukon and Alaska.
Barren-ground caribou have been roaming the tundra for a long time, and Mike Suitor wants to keep it that way. The Yukon Department of Environment’s North Slope and migratory caribou biologist says 3,000-year-old antlers gathered along the coastal plain of the Yukon and Alaska indicate a long history of calving there. (Female caribou lose their antlers within days of giving birth.)
Now, at the tail end of a five-year study, the Government of Yukon is learning more about how the behaviour of barren-ground caribou (specifically the Porcupine Caribou herd) could change alongside their habitat.
“We know climate change is going to have an impact,” says Suitor. “Most biologists think the impact will be negative, although there might be some positive impacts.”
Interest in this research is broad: partners include the Porcupine Caribou Management Board, Vuntut Gwitchin First Nation, Inuvialuit, Parks Canada, Environment and Climate Change Canada and the United States Geological Survey.
The Porcupine Caribou herd, estimated near 200,000 animals, migrates massive distances between its wintering grounds, where they forage in smaller groups throughout interior Alaska and between Old Crow and Dawson City in the Yukon, to their summer grounds on the North Slope of Yukon and Alaska.
In this treeless tundra, where caribou gather in unfathomably large numbers, researchers collected data from 126 cow caribou using cameras mounted on GPS tracking collars.
Collars recorded nine seconds of video every 20 minutes, giving biologists an incredible first-hand view of how these ungulates spend their time. The collars were deployed every spring starting in 2018 and retrieved every fall until the program’s conclusion in 2023.
Sorting through the hundreds of thousands of videos is ongoing, but scientists have already gleaned valuable information.
“I think we were able to capture every single calving event [from cows with camera collars], and usually within 20 minutes of the calf being born,” says Suitor. The GPS information reveals the location, while camera footage from the mother reveals if the calf survives the first month. After that, calves become more independent and the herd groups up, making it impossible to identify individuals.
As it captures life, the footage also shows death. A video sequence that Suitor describes as the most amazing he’s seen, starts with a caribou running and panting. Then, it’s dripping blood from its mouth and wading in a creek to evade its attacker — a wolf, caught on camera.
In a surprise ending, the caribou survives the wolf attack, at least temporarily, but the final frame reveals a grizzly bear standing over its carcass. The footage is visceral but, as Suitor explains simply, caribou are “born to die.” Their role is to feed and sustain the land.
The cameras also show researchers exactly what caribou are munching on, data they previously collected by literally digging through scat for plant debris. In one video, a caribou feasts on the newly emerged flowers of Arctic cotton grass, the most nutritious part of the plant.
Suitor says by comparing caribou’s preferential food sources with climate models predicting how vegetation could change due to warming temperatures and changes in precipitation, they can estimate where the best-quality habitat will be in the future.
He says the 1002 area in Alaska’s Arctic National Wildlife Refuge is already an important area for calving and feeding and they expect it to become even more critical in the future. This is significant, as the region is currently under consideration for oil and gas development.
More insights gleaned from the collars show how mosquitoes, warble flies and nasal bots harass caribou. The worst of these lay eggs in their fur and nose, causing the caribou to sneeze and produce mucus. The animals try to evade these pests by stomping, seeking out wind, or grouping close together and jockeying to limit their exposure.
Graduate student Will Hein is researching insect harassment of caribou and how insects react to warmer temperatures and a longer summer season, says Suitor. “We know insects are going to change over time. How is that going to influence the herd?”
Researchers are also developing an “activity budget” of how caribou spend their time. This offers more insight into how they could be impacted by development, which historically has been difficult to measure. Slight shifts in activity budgets, such as a decrease in eating because an animal is being vigilant and watching a perceived threat, can have significant effects on the herd and result in population declines.
All this information paints a more fulsome picture of caribou behaviour and ecology than ever before. Suitor says results from this breadth of research will start coming out this spring and continue over the next several years, shedding light on this ecologically and culturally important animal.To learn more about barren-ground and woodland caribou, join Yukon Wildlife Viewing for a “Ski-bou” at Mount Lorne this month. Yukon.ca/wild-discoveries.
