Grey Wolves on Prince of Wales Island Hunt Sea Otters

Have you ever pictured a wolf plunging into the sea in pursuit of food? On a secluded Alaskan island, that unexpected sight is now a reality.

Grey wolves on Prince of Wales Island have begun preying on sea otters-animals more commonly associated with kelp forests and shorelines than woodland predators.

The unusual behaviour has drawn scientific interest. Researchers are seeking to discover how a terrestrial predator can live partly from the sea, and what the shift could mean for the natural environment.

Grey wolves move into the ocean

Grey wolves normally pursue land-based prey such as deer and moose. However, on Alaska’s Prince of Wales Island, some wolves have added sea otters to their diet.

This dietary change may influence coastal ecosystems as well as the wolves’ own health. Scientists currently know very little about how wolves are able to capture such nimble marine prey.

Patrick Bailey, a PhD candidate at the University of Rhode Island, is leading the study. His work examines how coastal grey wolves rely on ocean-derived food and how their behaviour differs from that of inland wolf populations.

The project also addresses a broader ecological question. Wolves can profoundly influence terrestrial ecosystems by regulating prey populations, and Bailey thinks comparable connections may occur between land and marine environments.

“We do not have a clear understanding of the connections between water and land food webs, but we suspect that they are much more prevalent than previously understood,” said Bailey.

“Since wolves can alter land ecosystems so dramatically, it is possible that we will see similar patterns in aquatic habitats.”

Wolf teeth reveal dietary history

Sea otters were once abundant along the Pacific Coast, but the fur trade linked to colonial expansion caused their numbers to fall dramatically.

Although sea otters are still endangered, their populations are gradually recovering. Wolves preying on otters could signal the return of a predator-prey relationship that disappeared for many years.

To investigate this possibility, Bailey studies grey wolf teeth held in museum collections and taken from animals found dead in recent years. He applies stable isotope analysis, which can reveal an animal’s diet through time.

Like the rings of a tree, teeth form in layers. Every layer contains chemical evidence of the food the animal consumed.

“If large enough, we can individually sample each of these growth rings to track an individual’s feeding patterns over time,” noted Bailey. “When we gather enough samples across individuals we can then analyze how prevalent these dietary trends are throughout a population.”

The research allows scientists to determine when wolves started consuming marine prey and how widespread the practice has been between generations.

How wolves catch sea otters

Pursuing prey in the water presents challenges very unlike those encountered on land.

“Capturing and eating prey in the marine environment is very different from doing it on land,” said Sarah Kienle, who leads the CEAL Lab at the University of Rhode Island.

“We are super curious to see if these coastal wolves have behavioral adaptations that are different from terrestrial wolves.”

Accounts of wolves feeding on aquatic prey have been recorded for more than two decades, yet the details of the hunts themselves are still uncertain.

“What has not been explored, and what I am really interested in documenting, is how exactly wolves are able to capture sea otters,” said Bailey.

Earlier footage did not provide enough detail. New trail cameras offer a stronger opportunity to watch the behaviour, and Bailey placed cameras around the island during the summer.

“So far, we know that these wolves are consuming sea otters, and we are now staged to capture the details that have previously eluded us.”

Local support and unseen risks

Researching wolves in such an isolated location is difficult. The animals are wary and intelligent, while dense woodland and challenging ground make fieldwork harder still.

Prince of Wales Island became the project’s central study location through work with Alaska Department of Fish and Game biologist Gretchen Roffler and local research technician Michael Kampnich.

“I cannot emphasize enough how much these two have helped me,” said Bailey. “This project would not be possible without their input and guidance.”

Kampnich has contributed extensive knowledge of the local landscape and ecology. “Working with locals is so important because they have decades of experience and perspective that we as outside researchers simply do not have,” Bailey said.

Roffler’s research has also identified a further risk. Sea otters may contain high concentrations of methylmercury, a toxic compound that wolves can absorb when they eat the animals.

Liver samples from coastal wolves have recorded mercury concentrations up to 278 times higher than those in inland wolves.

“Methylmercury accumulation can cause a suite of problems related to reproduction, body condition, and behavioral abnormalities,” explained Bailey.

Beyond Prince of Wales Island

Bailey intends to broaden the research in the coming years, although limited resources currently restrict the work to Alaska. Another section of his dissertation compares the skull shapes of coastal and inland wolves from eastern areas.

“I am including historical east coast wolves in a separate chapter of my dissertation comparing skull morphology between coastal and inland populations,” he said.

The specimens are supplied by the Harvard Museum of Comparative Zoology and come from Canada, including Newfoundland and Labrador.

For the present, fieldwork remains focused on Prince of Wales Island, where Bailey plans to return next summer. Each discovery helps researchers better understand the unexpected links between land and ocean ecosystems.