By Nicholas Bakalar, The New York Times, June 27, 2011Humans are a much bigger problem than wolves for a caribou herd in the oil sands area of Alberta, Canada, scientists reported last week in Frontiers in Ecology.
Studies of scat of moose, caribou and wolves in the area showed that caribou accounted for only 10 percent of the animals consumed by wolves. Eighty percent of the wolves’ diet was deer, with moose making up the remainder. Wolves’ preference for deer, the researchers conclude, draws them away from the areas where caribou thrive.
But the oil sands contain the second largest reserve of petroleum in the world, and so they face a heavy human presence as they are developed. And by looking at hormone levels in caribou scat, the scientists found that when humans were most active in an area, caribou nutrition was poorest and psychological stress highest. When oil crews left, the animals relaxed and nutrition improved.
The scientists reported that removing wolves, favored by government and industry, could do serious damage to the ecosystem, and fails to help preserve the caribou. (The study was paid for by Statoil Canada, an energy company with oil leases in the area.)
The scientists said if development trends continue, within 30 years the caribou herd on the east side of the Athabasca River will be no more.
The Alberta Caribou Committee, a government and industry group, views removing wolves as the most effective way to protect caribou. And killing wolves has already started in the range of one herd.
The researchers used dogs to find the scat of caribou, moose and wolves in the oil sands area, then analyzed the material to determine the animals’ range and habits. The weather during the three winter collection periods in 2006, 2007 and 2009 was extremely cold, perfect for instantly freezing the scat and preserving it for laboratory analysis. And dogs are very good at finding scat. According to Samuel K. Wasser, a professor of biology at the University of Washington, the lead author, they are able to detect it in deep snow as far as a quarter mile away. The group collected more than 3,400 samples.
Caribou, the scientists found, graze on lichen, their chief winter food, in flat wetlands, partly because the open landscape makes it easy for them to see and hear predators, including humans.
Researchers found the caribou population larger than recent estimates, and moose, wolf and caribou populations were steady during the study period. They emphasize that this does not mean that these caribou are free from risk. But they say management of human activity, not wolf control, is the still best way to minimize it.
Some experts still believe that killing wolves is essential. Stan Boutin, a professor of biology at the University of Alberta, believes that three steps are required if the caribou are to survive: protection of areas where there is little or no human activity; restoration of areas humans have altered; and culling the wolf population, which has exploded in recent years with changes in vegetation and the resulting proliferation of deer. “People don’t enter into predator control lightly,” Dr. Boutin said. “It has huge implications. But without actually shooting wolves, the only other way is vegetation control. That takes a long time to work.”
Still, the authors of the study believe that adjustments in the ways oil exploration is done can allow the work to go on without harming the caribou, and that killing wolves is neither necessary nor desirable. Dr. Wasser said that the primary problem is the presence of high-use roads in flat open areas.
“It would be better to move the roads to more complex terrain,” he said, “areas that go up and down in elevation where you can’t see far. That will create a buffer so that the caribou can eat without being disturbed. Everything we’ve done suggests that wolf removal is not the best approach to this problem.”
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