Wolves are the primary predator of adult caribou, but grizzly bears actually kill more calves during the critical first days of life. Beyond these two dominant predators, caribou face threats from a surprisingly long list of animals, including golden eagles, black bears, coyotes, wolverines, and even lynx. The full picture depends on the caribou’s age, the season, and where it lives.
Wolves: The Main Threat to Adults
Gray wolves are the single most important predator of adult caribou across their entire range. Wolves hunt caribou year-round, but winter is when caribou are most vulnerable. Deep snow slows caribou down while wolves, with their broad paws and cooperative hunting strategy, can maintain pursuit over long distances. A wolf pack will typically target individuals that are old, sick, or separated from the herd.
Wolves also kill calves, accounting for roughly 29% of newborn deaths in one well-studied herd in Denali National Park, Alaska. But their real impact is on the adult population, where no other predator comes close to matching the toll wolves take over the course of a year.
Grizzly Bears Dominate the Calving Season
For newborn caribou, grizzly bears are the most dangerous predator by a wide margin. In Denali National Park, grizzlies were responsible for 49% of all neonatal deaths, nearly double the share caused by wolves. The window of vulnerability is remarkably narrow: most of these kills happen within the first eight days of life, and bears rarely take calves older than 10 days. After that, calves are fast enough to escape.
The numbers paint a stark picture of early life for caribou. About 39% of radio-collared calves in the Denali study died within their first 15 days, and 98% of those deaths were caused by predation. Calving season is essentially a gauntlet, and grizzly bears are the biggest obstacle. This is one reason caribou herds often migrate to remote calving grounds far from areas with high bear density.
Golden Eagles as Calf Hunters
Golden eagles are an underappreciated threat to caribou calves. Caribou remains regularly turn up at eagle nests on Alaska’s North Slope, and immature golden eagles are frequently spotted feeding on caribou. Some researchers have suggested that eagles could be more significant predators of calves than bears or wolves in certain areas, though the data to confirm that is still limited.
Eagles hunt calves by diving at high speed and striking with their talons, targeting animals too small and young to outrun an aerial attack. Arctic ground squirrels appear to be their most common prey overall, but during calving season, the sudden abundance of vulnerable newborns on open tundra creates an easy opportunity.
Black Bears, Coyotes, and Other Predators
The full list of animals known to prey on caribou is longer than most people expect. In North America, documented predators include black bears, mountain lions, wolverines, coyotes, Canada lynx, arctic foxes, red foxes, bald eagles, and even common ravens (which can kill very young calves). Polar bears may also take caribou where their ranges overlap, though no confirmed kills have been observed.
Wolverines deserve special mention because of their fierce reputation, but in practice, they’re far more scavenger than hunter when it comes to caribou. During winter, wolverines rely heavily on the remains of moose and caribou killed by wolves or by hunters, or animals that died of natural causes. A wolverine can kill a caribou in the right conditions, but these events are rare. Their real role in the caribou ecosystem is as a cleanup crew.
Coyotes, on the other hand, are a growing concern. In the Gaspésie Peninsula of eastern Quebec, a long-term study spanning nearly three decades found that rising coyote numbers were the main driver behind declining calf survival in the endangered Atlantic-Gaspésie caribou population. Coyotes have expanded northward into caribou habitat as logging and other human activity opened up the landscape, creating a predator threat that historically didn’t exist in those areas.
How Habitat Loss Makes Predation Worse
Predation is the direct cause of most caribou deaths, but it doesn’t tell the whole story. Logging, road building, and other industrial development fragment caribou habitat in ways that tip the balance toward predators. When forests are cut, shrubby regrowth attracts moose and deer into areas where caribou live. More moose and deer support larger wolf and bear populations, which then spill over into caribou range and kill caribou at unsustainable rates.
This chain reaction, sometimes called apparent competition, is considered the ultimate cause of caribou population declines across much of Canada. The caribou aren’t losing a fair fight. They’re dealing with artificially inflated predator numbers driven by habitat changes that benefit other prey species. In central British Columbia, some mountain caribou populations were nearly wiped out through this process before recovery efforts began.
Humans as Caribou Hunters
People have hunted caribou for thousands of years, and the harvest continues today. In Alaska, both Indigenous communities and sport hunters take caribou under a regulated permit system. Alaska’s 2024 registration hunt data shows thousands of permits issued across multiple hunt areas, with harvest totals ranging from zero in some small hunts to 580 caribou in the largest. Success rates varied widely, from 9% to 80% depending on the area and herd.
Indigenous subsistence hunting remains culturally and nutritionally vital for communities across the Arctic. In many remote Alaska and Canadian villages, caribou is a dietary staple that no store-bought alternative can realistically replace. These harvests are managed separately from sport hunting and are given priority under subsistence regulations, reflecting the deep dependence of northern communities on caribou herds.