Life Lessons From a Coastal Wolf Pack

Pleasant Island is two miles from the town of Gustavus, Alaska, and less than 30 miles from where we’d anchored. A wolf pack arrived there in 2013, after swimming across the narrow channel from the mainland. Initially, they did what wolves typically do: eat every ungulate they could clamp their jaws around. After they’d decimated the island’s limited deer population, their next act seemed obvious: The pack would move, or starve. Several decades earlier, an ill-fated and ethically dubious ecological experiment on Alaska’s far-flung Coronation Island demonstrated what happens when introduced wolves eat all the local deer and have nowhere else to go: In the absence of prey, the wolves starved, resorting to cannibalism before eventually dying out entirely.

But, as Juneau-based biologist Gretchen Roffler and her colleagues revealed in a pair of studies published in 2021 and 2023, the Pleasant Island wolves found another way. When deer disappeared from the menu, the pack shopped around, and did so with remarkable success.

Roffler’s first glimpse of a Pleasant Island wolf eating a sea otter seemed like an anomaly. But when she observed the same behavior again, she suspected a larger phenomenon might be at play. To test this, she and her colleagues began the unglamorous work of scooping poop from the island’s beaches and forested trails. By analyzing the scat using a technique called DNA metabarcoding — akin to a prey fingerprinting tool for feces — Roffler, Taal Levi and other partners at Oregon State University could determine whether the wolves were eating terrestrial herbivores, like deer, or marine predators, like seals or otters. Combining this research with on-the-ground field observations and GPS collars that tracked the wolves, they found that the pack was not merely sampling otters; they were devouring them en masse. Despite being fierce adversaries, with sharp teeth and claws, otters provided the wolves with a reliable alternative to venison.

The sea otters were relative newcomers themselves. After near-extirpation throughout much of the North Pacific, otters were reintroduced to the outer islands of Southeast Alaska in the 1960s, and their population rapidly expanded. Whether the first Pleasant Island otter meal was a lucky accident or the result of a strategically planned hunt, the pack wasted no time in capitalizing on this now-abundant resource. In 2015, wolf scats collected from the island consisted of approximately 98% deer; by 2018, deer had disappeared entirely and sea otters made up more than two-thirds of their diet.

Though what wolves eat for lunch might not seem revolutionary, this demonstration of their flexibility is, particularly when it comes to shaping our scientific understanding of their lives. Wolves are known to be opportunistic, but this pack’s quick and dramatic prey shift sent shock waves through the wildlife world: in just three years, they’d upended classic predator-prey dynamics and bent the supposed “rules” of their lives.

Most wolves specialize on ungulates, including deer, moose and elk. Pleasant Island’s wolves seemed no different until they amended the core tenets of this long-standing exchange, and did so in a matter of just a few years. By crossing a dietary threshold, they had propelled themselves across ecotones and trophic levels — switching their primary food source from a bottom-up terrestrial herbivore (deer) to a top-down marine carnivore (otters). This isn’t just a matter of semantics; conserving the health of wildlife populations requires knowledge about what animals eat, where they live, and what they might do next. And these island-hopping wolves were full of surprises. (...)

The idea that carnivores’ dietary habits can influence their environments isn’t new. However, as our awareness of wolves’ ability to shift what they eat — quickly and sometimes dramatically — grows, so does the need for a more nuanced scientific approach. Traditionally, ecological theory has prioritized models that simplify relationships in the wild: Wolves dine on ungulates, predators need prey, and the lives of deer, beavers and otters have little in common. However, otter-eating wolves and other so-called exceptions may actually be teaching us just how capable some species are of responding rapidly when the need arises. Ecologists sometimes refer to this potential to pivot as “adaptive capacity;” i.e., how fast a species can change the rules of its own game.

by Caroline Van Hemert, High Country News |  Read more:

Image: Nature Picture Library/Alamy

[ed. Taking down a full grown otter would be quite a feat. They can grow up to nearly 5 ft. long and 100 lbs., with clam cracking jaws. Here's one (below) being cleaned of oil (took six people to hold him down, even moderately sedated):]

Image: markk