When in season, wolves choose salmon over deer
When in season, wolves choose salmon over deer
Jeremy Hance, mongabay.com
September 2, 2008
The popular image of hunting wolves is a pack bearing down on a deer, working in concert to make the kill. However, new research has discovered that when available, wolves largely forgo hoofed mammals for salmon.
To create an accurate picture of the relationship between wolves and salmon, researchers spent four years studying the feeding habits of wolves in British Columbia. “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,” Chris Darimont says, lead researcher from the University of Victoria.
The study found that for the majority of the year, wolves focus on deer. But every autumn, when the salmon come upriver to spawn, the wolves change their diet and feed on salmon.
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During spring and summer deer made up 90-95 percent of the wolves’ diet. In autumn, salmon averaged 40 percent and in some groups of wolves rose as high as 70 percent of their diet.
Past studies regarding the relationship between wolves and salmon hypothesized that wolves only hunted salmon when deer were scarce. “Our data show that this is not the case,” the scientists write, “salmon availability clearly outperformed deer availability in predicting wolves’ use of salmon.”
Darimont believes the wolves have good reason to pursue salmon when available: “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”.
 Courtesy of USGS |
The research further highlights the importance of the annual salmon migration.
“Salmon continue to surprise us, showing us new ways in which their oceanic migrations eventually permeate entire terrestrial ecosystems,” co-author Thomas Reimchen says. “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.”
Despite its importance, this great migration is endangered. According to Darimont threats to salmon include overexploitation by fisheries, habitat destruction, and disease from salmon aquaculture. The “threats to salmon systems have led to coast-wide declines of up to 90% over the last century,” Darimont says.
Loss of salmon not only affects their predators—such as bears, wolves, and humans—but entire ecosystems. Scientists have noted that salmon carcasses, eggs, sperm, and feces provide essential nutrients to river systems. A drastic decline in nutrients means a less productive ecosystem.
Chris T Darimont, Paul C Paquet, and Thomas E Reimchen (2008). Spawning salmon disrupt trophic coupling between wolves and ungulate prey in coastal British Columbia. BMC Ecology 2008, 8:14.
