Nature’s oddest predator-prey relationship: Orcas hunting Moose

Yes, you read the story title correctly, orcas (killer whales) have been known to hunt and prey on moose, though it is a rare and fascinating phenomenon. This unusual predation occurs because of the unique behaviours of both animals.

Although documented cases are rare, evidence from Indigenous knowledge and occasional observations suggests that these interactions have happened, likely due to the moose's vulnerable state while swimming long distances.

Moose are excellent swimmers and often swim between islands, especially in places like Alaska and British Columbia. They can reach speeds of around 5mph. During the summer, it's not uncommon to see moose keeping cool in the water, and in the late summer season, they're known to forage for aquatic vegetation as deep as six meters underwater.

So, with moose enjoying time in the water and orcas enjoying hunting and eating, attacks have happened off the coast of Canada and Alaska. Specifically, near Vancouver, moose carcasses have been found with orca bite lacerations. It is unclear if these cases are opportunistic or just for fun. In such deeper waters, their swimming skills are no match for orca pods, which are masters of this environment.

Besides being the second-largest land mammal in North America (the largest are American bison), moose are also the tallest. Adult moose can reach a shoulder height of 6'11" and weigh as much as 1,543 lbs.

Orcas are apex predators with varied diets, including fish, seals, sea lions, and sometimes larger marine mammals. In areas where orcas and moose share overlapping environments, typically coastal waters, an orca might take the opportunity to hunt a swimming moose.

Among the largest creatures in the deep blue, these cetaceans can weigh up to 12,000 lbs and are the so-called "wolves of the sea," exhibiting diverse, adaptable hunting strategies and hunting in highly coordinated groups known as pods.

They use their speed in deep, narrow channels in fjords and deep inlets to rapidly close the gap between themselves and the moose and strike before it has a chance to return to the safety of the shore.

While this predation is not a natural part of killer whales' diet, these intelligent mammals will not stop hunting other prey when the circumstances align. For them, the moose is just another source of protein, much like seals and sea lions, and the opportunity for such a large, nutritious meal is hard to pass up.

In 1992, a pod of four orcas attacked a pair of moose swimming in Alaska, killing the larger moose and wounding the smaller one. In 1993, fishermen in southeast Alaska reported seeing a pod of orcas attacking a pair of moose, killing one and wounding the other.

Marine biologists and naturalists often consider these stories plausible, given the orca's adaptability and the moose's presence in overlapping habitats.

Though direct scientific documentation of orcas hunting moose is absent, stories from Indigenous communities and anecdotal accounts from hunters and locals suggest that such encounters may have occurred. Some have found evidence of partially consumed moose carcasses floating in coastal waters where orcas are known to hunt. Indigenous oral histories, especially among coastal First Nations in the Pacific Northwest, also suggest that orcas might opportunistically prey on swimming moose.