The spread of chronic wasting disease toward Yellowstone’s famed game herds alarms wildlife lovers, but two top researchers think biologists will discover a powerful ally in an old frontier villain.
Wildlife managers have never controlled a major outbreak of chronic wasting disease, a fatal neurologic malady of deer and elk first discovered in a captive Colorado mule deer herd in 1967.
No one knows for sure if wolves would target CWD-infected deer and elk, but wolves’ uncanny ability to spot vulnerable animals may make them the best natural control for the disease, researchers say.
Even in its early stages, CWD makes its victims distracted and unwary as it eats tiny holes in their brains. That’s a fatal liability in the presence of a running predator like the wolf, National Park Service biologist Douglas Smith said.
“Wolves show up and say, ‘Let’s see what you’ve got,”‘ said Smith, who helped lead the program that returned wolves to Yellowstone in 1995 and 1996. “And if you don’t have it, they laser in on you like a fighter pilot. The things they pick up on are incredibly subtle.”
While the theory is still unproven, Colorado’s top wildlife manager says it is worth factoring in to the blistering debate over how to manage wolves that may soon migrate into the state.
“Every idea should get a fair hearing and I think disease management is a fair question for a biologist to ask,” said Russell George, director of the Colorado Division of Wildlife.
Some scientists are skeptical of wolves’ ability to contain CWD. David Mech, a biologist with the United States Geologic Survey who is considered the world’s top wolf expert, cautioned that until wolves and wasting disease actually interact, such theories are just speculation.
“But that is a reasonable possibility,” he said.
The speculation isn’t simply academic.
CWD was first identified in a Fort Collins wildlife research station in 1967. By the 1980s, it spread across a 30,000-square-mile area of northeastern Colorado and neighboring Wyoming. In the late 1990s it appeared in Nebraska and South Dakota. But the real shock was in 2002, when CWD was discovered in Wisconsin and on Colorado’s Western Slope.
Many consider CWD the biggest single threat to wildlife in North America.
No one has been able to study whether wolves single out CWD-infected animals because the range of predator and disease have never overlapped.
But over the next few years, that will likely change.
This summer, an infected mule deer was discovered in Bighorn Basin north of Cody, Wyo., on Yellowstone’s doorstep.
Some Wyoming biologists fear CWD will move into the Greater Yellowstone ecosystem in the next year or two.
But Mike Miller, a CWD expert and research veterinarian for the Colorado Division of Wildlife, thinks northwestern Wyoming’s robust wolf population will eliminate infected deer that try to move into the park.
“No one knows for sure,” Miller said. “But I think wolves could help the disease from becoming established to begin with. Sick animals just won’t survive that long.”
The earlier infected animals are killed, the less opportunity they have to transmit the disease.
Colorado has plenty of CWD but no wolves, although it’s just a matter of time before they migrate here from Yellowstone, experts say.
Predation by mountain lions and coyotes appears not to have slowed the spread of the disease in Colorado and Wyoming. But wolves are a different kind of hunter, Smith and Miller said.
Mountain lions are ambush specialists: They attack any deer or elk that they can surprise. Coyotes are too small to hunt adult deer, although they kill fawns and can severely injure adults.
By contrast, wolves constantly test potential prey, including elk, deer, moose and bison, looking for weakness. Sometimes wolves kill healthy adults, Smith said, but most of the time they find some vulnerability in their victim.
It could be a calf or fawn separated from its mother, a bull or buck worn out from the rut, a doe caught in deep snow, a cow elk with arthritis.
This hunting style, Smith said, seems perfectly tailored to removing sick animals.
“Wolves are probably the single best way to stop the spread of CWD,” he said. “Chronic wasting disease causes animals to act weird. Wolves kill animals like that.”
University of Calgary professor Valerius Geist, an expert on deer and elk, is also convinced.
“Wolves will certainly bring the disease to a halt,” he said. “They will remove infected individuals and clean up carcasses that could transmit the disease.”
Scientists still don’t know if CWD is a naturally occurring brain disease or if it jumped to deer and elk from sheep, which get a similar brain disease called scrapie. In the 1980s, scrapie jumped to British cows that were being fed sheep bits as a source of protein. The result was a huge outbreak of mad cow disease, which killed 100 Europeans who ate infected beef.
Deer and elk naturally gnaw on bones to obtain needed minerals. Researchers suspect the animals may contract CWD by eating brains or spinal tissue of dead animals, or grazing near their carcasses.
Geist and Princeton University biologist Andrew Dobson theorize that killing off the wolf allowed CWD to take hold in the first place.
A federal predator control program in the 1920s eliminated the last prairie wolves in the region, according to Michael Robinson of the Center for Biological Diversity.
While CWD was first identified in 1967, its prevalence in Colorado and Wyoming suggests it appeared several decades before that.
“Remove the wolves and 20 to 50 years later you have a problem,” Dobson said.
Federal wildlife officials are considering whether to reintroduce the wolf to Colorado’s San Juan mountains. Rocky Mountain National Park is also evaluating wolf reintroduction to deal with an overpopulation of elk.
And experts expect the animal will naturally make its way down from Yellowstone.
Colorado officials are drafting a wolf management plan, outlining if and where it would be appropriate to have wolves in the state.
Two polls in the past 10 years show two-thirds of Coloradans would like to see the wolf returned to the state.
But stockmen, who fear wolf attacks on their herds, and hunting groups worried that wolves will take game meant for hunters, vociferously oppose the notion.
“We don’t think CWD will annihilate a herd, but there are several instances of herds that we think were annihilated because of the wolf,” Wyoming outfitter Maury Jones said. “Wolves will be far more devastating to a herd than CWD.”
Wolf researchers say those claims are false, but at the Division of Wildlife, George wonders whether Coloradans could tolerate enough wolf packs to reduce clusters of CWD infection on the Western Slope, where the overall infection rate is about 1 percent of animals.
“How often would a wolf be in proximity to an animal in a stage of the infection that made it vulnerable?” he asked.
It’s a different situation in Yellowstone, which is considered fully occupied by the 17 wolf packs living there.
Veterinarians have managed to control small CWD outbreaks on captive game ranches, but only by slaughtering every animal in the exposed herds – at a cost of more than $12 million in Colorado alone. Wisconsin is trying to eliminate all 25,000 white-tailed deer in a 1,150- square-mile area near the state capital, Madison, in a desperate attempt to eliminate an outbreak discovered in 2002.
In a limited trial, Colorado biologists are testing the tonsils of every deer in a herd and killing the infected animals.
Wolves would essentially do the same culling work for free, the theory goes, although they would likely also kill livestock and pet dogs.
Researchers may well have a chance to study how effective wolves can be in stopping the disease. Waves of wolves radiating out from Yellowstone are approaching the northern borders of Colorado and Utah. And in Wisconsin, wolf packs are within 70 miles of the CWD zone.
But retired Wyoming Game and Fish veterinarian Tom Thorne thinks animosity against wolves will be tough to overcome.
“Emotions against wolves are so strong that I’m not sure this potential benefit, which I agree might be there, would sway the opinions of many folks,” he said. “I think it would be a long, long time before people are used to wolves enough to admit they might be doing a bit of good.”