You might presume a sea otter mainly lives in fear of a lethal bolt from the blue in the form of an orca or white shark. Turns out, though, that some threats come on four legs.

A recent paper in Ecology underscores the dietary (and strategic) versatility of the gray wolf – historically among the most widely distributed large carnivores on Earth – and, more specifically, just how marine-oriented the menus of coastal wolves along the Pacific margin of northwestern North America can be.

The research, conducted along the seacoast of Katmai National Park and Preserve in southwestern Alaska, was partly prompted by an observation from May 2016. That’s when National Park Service (NPS) rangers saw a white wolf trotting along a Katmai beach with a dead sea otter in its jaws. (Sarah Keartes wrote about this sighting for Earth Touch News at the time.)

Image: National Park Service/used with permission

Among the questions the researchers set out to investigate were whether Katmai wolves were preying on or simply scavenging sea otters, and how common the behaviour was.

The effort yielded evidence that wolves of the Katmai coast appear to actively hunt sea otters where the animals haul out. Not only that, but the study authors report on the observation (also in 2016) of a male gray wolf attacking and killing a harbor seal near the mouth of an intertidal creek over the course of about half an hour.

The research suggests that wolves here may target marine mammals at haul-out sites and other vulnerable shoreline areas particularly during low tides.

“Our observations indicate that solitary wolves may successfully ambush seals and sea otters on the Katmai coast and may have developed unique hunting and foraging strategies compared with their interior counterparts,” the study authors wrote.

A significant rebound of sea-otter numbers off southern Alaska following drastic reductions during the historical North Pacific Rim fur trade may be giving coastal wolves new options for carnivory. Indeed, another recent paper – this one published last year in PNAS – showed that sea otters can even become a primary prey, as they apparently did for a wolf pack on southeastern Alaska’s Pleasant Island after a major die-off of black-tailed deer (a standard go-to quarry for wolves in the region).

“This just kind of adds to the body of evidence that wolves are definitely impacting the nearshore environment and potentially marine mammals and their populations,” Kelsey Griffin of the NPS, part of the group that saw the 2016 otter-hauling wolf, told Daba Kobilinsky for The Wildlife Society.

Moving from Katmai farther eastward and southward down North America’s Pacific seaboard, in the realm of the world’s most extensive tract of temperate rainforest, a unique coastal form of gray wolf, widely called the “sea wolf,” readily swims between offshore islands and pursues a diet that may be as much as 85 percent marine-based.

These sea wolves, found from southeastern Alaska to British Columbia’s Vancouver Island, will also hunt harbor seals and sea otters – plus scarf the brains of spawning salmon (perhaps to avoid a potentially fatal bacterium found in salmon kidneys and muscle tissue), crunch clams and mussels, and scavenge all manner of beachwrack, whale carcasses included. Their menus can be strikingly distinct from interior mainland gray wolves not all that far away (as the raven flies), which subsist mainly on ungulates such as moose, deer, and mountain goats.

Speaking of ungulates, though, they are indeed generally the most important gray-wolf chow across the global domain of Canis lupus: all manner of deer (from little roe deer to huge wapiti and moose), wild boar, antelope (such as blackbuck and saiga), wild goats, various mountain sheep, wild asses, muskoxen, and more – ranging in size up to bison – are on the menu.

This is the classic image of the gray wolf: a pack coursing swiftly after a gangly moose or fleet-footed stag through the woods, or stampeding a caribou herd out on the tundra.

But wolves are adaptable opportunists, and sea otters and harbor seals are far from the only non-hoofed meat they’ll go after. Arctic hares and rodents help round out the diet of Arctic wolves, northernmost of all wolves. Wolves in Pakistan may snatch rhesus monkeys and palm civets along with marmots, pikas, and Cape hares, while red foxes and European badgers appear to be preyed on by wolves in parts of Europe with some frequency. In spring, wolves in northern Minnesota’s Greater Voyageurs Ecosystem pounce on spawning suckers – a freshwater fish – in similar fashion as sea wolves do salmon. Small mammals and reptiles are primary wild foods of the imperiled, little-known Arabian wolf, smallest and most exclusively desert-adapted of all gray-wolf subspecies.

In parts of boreal North America, including eastern Canada and the Minnesota Northwoods, beavers can be a significant prey item. Research in the Greater Voyageurs Ecosystem shows that wolves may employ a catlike ambush strategy – sometimes lying in wait for 12 hours or more – to catch beavers coming ashore. A brand-new study reveals beavers here are especially vulnerable to wolf predation while commuting on longer feeding trails, which take them farther away from the protection of water to cut trees.

Earlier this year, the Voyageurs Wolf Project shared some rare, super-lucky trail-cam footage showing wolves hunting – and, in one case, catching – beavers:

Beaver-hunting is often the pursuit of solitary wolves, and this points up the seasonal variation in gray wolf diet and hunting behaviour. Wolves in, say, the Great Lakes forests of the Upper U.S. Midwest and Canada may spend the winter pack-hunting adult white-tailed deer and moose. In summer, though, with such ungulates in peak physical form and a hungry denful of pups demanding loads of nosh, wolves here often split up as singletons or pairs to prowl for hidden-away newborn deer fawns, beavers, snowshoe hares, and other smaller prey.

And while gray wolves are among the most hypercarnivorous of canids, they will scarf plant material. Indeed, ripe berries and fruits may be significant seasonal menu items in some areas, such as parts of Europe as well as in the boreal forest, where blueberries can be an important summertime food

The seafood-fond wolves of the Katmai Coast, like their brethren the sea wolves, inhabit an extremely productive, fauna-rich landscape with only a small human footprint. Many gray wolves in other parts of the world – in lower-productivity biomes and, especially, where the impacts of humanity on ecosystems are heavier – face a different situation. Especially where land modification and other anthropogenic impacts have reduced populations of wild prey, wolves may be forced to rely more heavily on livestock and other domestic animals as well as refuse.

One study in central Iran found that gray wolves there, “with a relatively high abundance of anthropogenic foods and a moderately low abundance of wild prey,” subsisted mainly on poultry, domestic goats, and garbage. In Israel’s Negev Desert, Arabian wolves seem to primarily rely on agricultural forage and garbage and are strongly associated with human settlements, cropland, and roads.

It goes without saying that wolves setting their sights on goats or cows or sheep are unlikely going to be popular with the local human populace. But evidence suggests that the resourceful and opportunistic Canis lupus is, where it has the opportunity, more disposed to hunt wild prey than domestic animals. A study comparing the feeding habits of Iberian wolves in northern Portugal, for instance, found that in a natural park with abundant wild prey – roe deer, red deer, and wild boar – wolves mainly targeted those species. By comparison, in another park more intensively modified by human activities and with low availability of wild ungulates, wolves survived on livestock.