07/18/2026
On April 5, 2017, researchers on the tundra of northern Alaska found wolverine tracks running alongside the tracks of two caribou. They followed the trail for 31 kilometers. At the end, one caribou was dead. The wolverine had pursued it for 19 miles without stopping, and the tracks in the final hundred meters showed it had attempted to jump onto the caribou's back several times before the animal went down. There was relatively little struggle at the kill site. The caribou had simply run out.
Audrey Magoun and colleagues published six documented wolverine-caribou pursuit kills from northern Alaska in the Canadian Field-Naturalist in 2018. The pursuit distances ranged from 4 to 62 kilometers. In one case, a wolverine followed a caribou for nearly 39 miles before killing it. The researchers tracked each pursuit by following the physical evidence in the snow: the spacing of the tracks, the depth of the hoofprints, the point where the caribou's stride shortened, and the place where the wolverine finally closed.
A wolverine weighs 25 to 40 pounds. An adult caribou weighs 250 to 400. On firm ground, the caribou wins every time. It is faster, taller, and carries enough mass to kick or trample a wolverine that gets too close. The wolverine does not attempt to match the caribou's speed or overpower it. It outlasts it.
The mechanism is in the feet. A wolverine's paws are disproportionately large for its body, broad and flat with semi-retractable claws that spread the animal's weight across the snow surface. The foot loading, the ratio of body weight to paw area, is low enough that a wolverine can travel on top of snowpack that a caribou punches through to the shoulder. Every step costs the caribou more energy than it costs the wolverine. The caribou is wading. The wolverine is walking. Over 10 kilometers, 20 kilometers, 30, the energy deficit compounds until the caribou cannot maintain its pace. The wolverine does not speed up. It does not need to. It just does not slow down.
The Animal Diversity Web at the University of Michigan states it directly: wolverines are capable of bringing down prey five times their size, but generally only under conditions that leave large ungulates stranded in deep snow. On hard ground, ungulates outrun wolverines without difficulty. The snow is not an incidental advantage. It is the entire strategy. A wolverine that encounters a healthy caribou on windblown tundra with minimal snow cover does not attempt a pursuit. It scavenges, hunts rodents, digs out cached food, and waits for conditions to change. When the snow is deep enough and soft enough to swallow a caribou's legs while supporting its own broad paws, the wolverine becomes something the caribou cannot escape.
Magoun's team noted that snow conditions appeared to be a decisive factor in only one of the six documented kills. In the other five, the caribou were pursued across relatively firm tundra and the wolverine still prevailed. The researchers attributed those kills to the wolverine's extraordinary endurance rather than snow advantage alone. A wolverine can travel 24 kilometers in a day as a matter of routine. It has one of the highest metabolic rates relative to body size of any large carnivore. Its body is built for sustained effort in cold conditions: short legs minimize heat loss, thick fur insulates at temperatures far below zero, and the broad feet function as snowshoes even when the snow is not deep enough to fully trap ungulate prey.
The kill itself is fast. Once the caribou is exhausted and can no longer run, the wolverine bites the back or front of the neck, severing tendons or crushing the trachea. The caribou drops. The wolverine feeds and then caches whatever it cannot eat immediately, burying sections of the carcass in the snow for later retrieval, the same hoarding behavior documented in the Arctic fox egg-caching studies but applied to 300-pound animals instead of goose eggs.
Image is for illustration purposes only
Source: Magoun et al. (2018), Canadian Field-Naturalist / Animal Diversity Web / Smithsonian Magazine / Craig Medred / Facts and Details.
