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Wolves generally prefer to eat deer, moose, and mountain goats—ungulates are their food of choice. But when those prey are scarce or unavailable, new research shows that wolves in southeast Alaska switch to eating a wide buffet of alternate animals. Some have even switched to sea otters as their favorite fare, preferring them over deer.
The research, conducted by the Alaska Department of Fish and Game (ADF&G) and Oregon State University from 2010 to 2018, is the first large-scale, region-wide study of wolf diets in southeast Alaska, covering both its archipelago of islands and the mainland, across landscapes from estuaries to alpine tundra.
The study found about 55 different foods in wolf scat, including bald eagles, sandhill cranes, loons, marmots, minks, red squirrels, salmon, sculpin, rainbow trout, and marine mammals including sea otters. The findings indicate that the wolves of southeast Alaska, also called Alexander Archipelago wolves, may be much more adaptable and resilient than previously thought.
It was already known that wolves can and will hunt a wide variety of prey. But, until now, the assumption of wolf viability models was that the number of Sitka black-tailed deer largely drove the local abundance of wolves. The study suggests that might not be true at the regional scale.
Gretchen Roffler, a wolf biologist with ADF&G, and colleagues used DNA metabarcoding on 860 samples of wolf scat from 12 study sites. Their goal was to learn precisely what the elusive carnivores eat when their top menu items, ungulates, are unavailable or in low abundance.
On average across the majority of the islands, Sitka black-tailed deer made up 65 percent of the wolves’ diets; on the mainland, moose and mountain goats were preferred over deer. The story was different on some islands with low deer numbers, though.
On Pleasant Island, for example, where wolves arrived in 2013 and drove down deer numbers, sea otters are now the wolves’ favorite food. “We don’t know if wolves are killing sea otters or scavenging ones that already died. We just know they are eating them in pretty large numbers,” says Roffler. The researchers suggest that sea otters, which have rebounded in southeast Alaska after being reintroduced in the 1960s, could provide an important alternate food source for wolves in some areas.
All these details add to the big picture of Alaska wolf diets. “It’s pretty cool. It’s a much more complicated story than what we initially believed about wolves,” says Layne Adams, an Anchorage, Alaska–based wildlife biologist and wolf specialist with the US Geological Survey, who is not associated with the study. But the fact that the wolves switch to other prey isn’t in itself particularly surprising, he adds. “When you think of an animal like a wolf, it makes perfect sense that they would take advantage of whatever out there is available to them.”
The study results come as the US Fish and Wildlife Service considers a new petition to list Alexander Archipelago wolves under the Endangered Species Act.
Three groups filed the petition on July 15, 2020. They note that over the past 15 years, the monitored population of Alexander Archipelago wolves on Prince of Wales Island has declined by about 60 percent due to habitat loss from logging and road building, as well as from trapping and hunting.
Logging and road building remain the wolves’ biggest threat, says Patrick Lavin, Alaska policy advisor for Defenders of Wildlife, one of the groups that filed the petition. That includes proposed clearcuts in the Tongass National Forest, which have spurred intense conflict between loggers, land managers, and environmentalists.
Knowledge about what wolves eat in southeast Alaska could ultimately affect the conservation status of these animals, the study’s authors note. Cataloging exactly what the wolves are eating is valuable for those considerations, says Tom Schumacher, regional supervisor for ADF&G’s Division of Wildlife Conservation and Roffler’s supervisor. But more work remains to be done to determine if the wolves can get enough sustenance from their alternate menu over the long term. “If they eat a lot of small things, it may not provide the same number of calories as if they eat something big,” Schumacher says.