National Geographic News Watch
September 2, 2008
In a remote neck of Canada’s backwoods the deer catch a break during the fall. That’s when the wolves go fishing. “Although most people imagine wolves chasing deer and other hoofed animals, new research suggests that, they can, wolves actually prefer fishing to hunting,” researchers from the University of Victoria and the Raincoast Conservation Foundation, Canada, announced this week.
The study, published in the journal BMC Ecology, shows that when salmon is available, wolves will reduce deer hunting activity and instead focus on seafood.
Chris Darimont led the team that studied the feeding habits of wolves in a remote area of British Columbia. “Over the course of four years, we identified prey remains in wolf droppings and carried out chemical analysis of shed wolf hair in order to determine what the wolves like to eat at various times of year,” he said.
For most of the year, the wolves tend to eat deer, as the scientists expected. During the fall, however, salmon becomes available and the wolves shift their culinary preferences, they found.
“One might expect that wolves would move onto salmon only if their mainstay deer were in short supply. Our data show that this is not the case, salmon availability clearly outperformed deer availability in predicting wolves’ use of salmon,” Darimont said.
The wolves’ taste for fish is likely based on safety, nutrition and energetics, Darimont explained. “Selecting benign prey such as salmon makes sense from a safety point of view. While hunting deer, wolves commonly incur serious and often fatal injuries. In addition to safety benefits we determined that salmon also provides enhanced nutrition in terms of fat and energy”.”
The work gives researchers as much insight into salmon ecology as wolf ecology. “Salmon continue to surprise us, showing us new ways in which their oceanic migrations eventually permeate entire terrestrial ecosystems,” said Thomas Reimchen, also of the University of Victoria. “In terms of providing food and nutrients to a whole food web, we like to think of them as North America’s answer to the Serengeti’s wildebeest.”
National Geographic featured Darimont’s research a few years ago in a television documentary and a related National Geographic News story about Canada’s rain forest wolves. In that coverage our writer Stefan Lovgren noted that researchers found that wolves are excellent salmon fishers. “The wolves stand at the riverside or at estuaries, using their muzzles to make their catch. They eat only the head of the salmon, avoiding the body and viscera,” he wrote. The decapitated salmon play an important role in the ecosystem, Lovgren reported. “Scavengers will eat the body. Flies may come in and leave their eggs in the carcass.The eggs then turn into larvae, which are eaten by birds. In the forest canopy these birds later excrete the nutrients from the flies–nutrients that the flies got from the fish.”
Looking around Thomas Reimchen’s Web site, I came across the Salmon Forest Project . A coauthor of Darimont’s salmon-eating wolves research paper, Reimchen has been documenting the complex relationship between temperate rainforest and healthy populations of salmon and bears.
“Our research group has observed that black bears and grizzly bears throughout the British Columbia coast transfer large quantities of salmon carcasses from rivers into forests and these nutrients are incorporated into a broad diversity of plant and animal taxa,” a passage on his site notes.
The research uses nitrogen and carbon isotopes to quantify the uptake of salmon-derived nutrients by mosses, herbs, shrubs, trees, and insects.
“One of the results to emerge from our studies has been the detection of salmon signatures in the yearly growth rings of ancient trees, and this offers new opportunities for identifying historical salmon abundance.”
The relationship between salmon, predators [including wolves, we now know], scavengers, and the forests themselves once spread from California to Alaska, Darimont notes. But perhaps not for much longer. “There are multiple threats to salmon systems, including overexploitation by fisheries and the
destruction of spawning habitats, as well as diseases from exotic salmon aquaculture that collectively have led to coast-wide declines of up to 90 percent over the last century,” he says.
Read more about Raincoast’s Wolf Program