In Canada, the woodland caribou is under threat from extensive logging operations.
Caribou use these large, sharp-edged hooves to dig through the snow and uncover the lichens that sustain them in winter months.
About one million caribou live in Alaska, and a comparable number live in northern Canada.
Caribou offer innumerable values for the ecosystem and humans.
Caribou hooves adapt to the season: In the summer, when the tundra is soft and wet, the footpads become spongy and provide extra traction.
The caribou of North America can run at speeds up to 80 km/h (50 MPH) and may travel 5,000 km (3,000 mi) in a year.
Biologists call this activity "cratering" because of the crater-like cavity the caribou’s hooves leave in the snow" (Rodden et al.
Wild caribou are still hunted in North America and Greenland.