Canada's Rain Forest Wolves a Link to Past
for National Geographic News
|October 1, 2004|
From the inland fjords to the windswept outer islands, the north and
central archipelago of British Columbia in Canada has been largely
untouched by time. In the thick temperate rain forest, wolves reign
supreme, just like they have for millennia.
To Chris Darimont, a University of Victoria Ph.D. student, the rugged and remote islands are "the home of the truly wild." Since 2000 he has been studying, among other things, the foraging behavior of wolves in the Great Bear Rainforest to learn more about the little-known ecology of the islands.
The wolves play an integral part in the ecosystem in the archipelago, and their diet can offer scientists important clues about the dynamics between predator and prey.
Investigating the feces of the elusive wolves, Darimont found that their diets consist to a large extent of black-tailed deer. But he also found that their diets vary greatly depending on location. On the outer islands, for example, wolves are far less likely to have a deer for lunch than on the inner islands.
These findings suggest that wolves can deplete resources in isolated areas, making the link between the predators and their prey more delicate there.
The information is important for understanding not only island ecosystems, but also for conservation efforts. If scientists can understand how species behave on isolated islands, they may be able to figure out how the species will behave in other places that are becoming more fragmented.
"Our planet is turning out to be a series of islands for wildlife and nature," said Darimont, who is halfway through his Ph.D. in conservation biology. "Instead of oceans and waterways separating habitable landmasses, we have highways, farms, and cities. The more we learn about island ecology, the more we can apply this information to the rest of the world."
Darimont's research is described in an upcoming article in the Journal of Biogeography. His project is also featured in a forthcoming National Geographic film called The Last Stand of the Great Bear, which will air on PBS on November 3 in the U.S.
Much of the British Columbia archipelago is uncharted territory, because the islands are so inaccessible. Visitors must either fly or boat in. The weather is often unpredictable, and waters can turn very rough in the winter.
"It approximates what the coast used to look like, from southeast Alaska to northern California," Darimont said. "We can observe ecological and evolutionary processes here that are largely unaffected by humanity. It's a good opportunity to learn about how ecosystems used to work."
Scientists had virtually no baseline information on the wildlife in the area. With the logging industry threatening to move north into the pristine rain forest, Darimont says the urgent need was to "go out there and see what we have."
Wolves made an ideal entry point for the study. "They are flagship animals," he said. "They can answer important questions about island ecology, inspire debate, and also help us advocate for the preservation of these forests."
But the foraging behavior of wolves is difficult to study because they are so elusive. Their hunting techniques are a mystery. Some research suggests that wolves kill by ambush.
Wolf and deer encounters sometimes involve water. Although wolves can swim for several miles, deer are better swimmers. If a deer is swimming in the water, wolves may spread out on shore to wait for it to get out once it gets cold and tired.
Unable to witness directly how the wolves make their living, the researchers did the next best thing: They picked up what the wolves left behind.
During two five-week trips in the summers of 2000 and 2001, Darimont's team collected almost 600 feces samples over a 60,000-square-kilometer (23,000-square-mile) area. The expanse is three times the size of New Jersey.
While black-tailed deer form the majority of the wolves' prey, Darimont was surprised at the diversity of their diet and how it varies depending on where the wolves are.
On the relatively species-rich mainland, wolves hunt deer, but also moose, mountain goats, and smaller mammals. On the inner islands, the best habitat for deer, the wolves' diet is almost completely dominated by deer.
On islands farther out in the archipelago, across water channels that may run several miles wide, deer make up about 50 percent of the diet. On the extreme outer islands, the number drops to below 20 percent.
"Isolation is a really important factor in determining how wolves make their living," Darimont said. "Predators can run out of resources in isolation."
This suggests that wolf populations are more vulnerable further out to sea, in greater isolation. When animals depart from their main prey, they are taking greater risks.
The findings may have important implications for the design of protected areas for wolves and other carnivores. What happens on coastal islands is likely to happen in parks. "In a better connected park system the predator-prey association is less likely to be affected," Darimont said.
The Food Web
The researchers have also 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.
The decapitated salmon, however, play an important role in the ecosystem. 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 fliesnutrients that the flies got from the fish.
"There are such incredible linkages in the food web," Darimont said.
The coastal wolf project has also shed further light on the genetics of wolves. Wolves are more widely distributed than any known large mammal. This strongly suggests they have a lot of genetic variability, which allows the predators to adapt to different environments, from deserts to high mountains.
Researchers say that wolves in the coastal region are much more genetically variable than wolves elsewhere in North America. This may be because their populations have not been decimated from hunting as they have been elsewhere.
"We may be looking at the historic wolf rather than the modern wolf," said Paul Paquet, a biology professor at the University of Calgary who initiated the coastal wolf project.
Because of their greater genetic variability, the coastal wolves may be more adaptable and resilient than other wolves, Paquet said.
Darimont views the wolves as great ambassadors for the coastal rain forest. "To have an area still in the world where we see wolves in historic numbers, living like they did millennia ago, is amazing," he said.
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