Within the 2.5 million acres of the Yukon-Charley Rivers National Preserve in Interior Alaska, wolves and other majestic animals are protected. But animals like wolves do not respect lines drawn on a map. And a recent study suggests that efforts to limit populations of these predators outside those borders is having negative effects on wolves living within the preserve.
The study, published in June in Wildlife Monographs, suggests that when Alaskan authorities were limiting wolf populations outside the Yukon-Charley preserve, survival rates of wolves within the preserve were lower than usual. The findings highlight the notion that managing wildlife within human-imposed boundaries requires communication and cooperation with authorities beyond a preserve's boundaries, and could have implications for wildlife management programs elsewhere.
Since the 1990s, the Alaska Department of Fish and Game has spent millions of dollars, first sterilizing wolves, then shifting to shooting and killing hundreds of the animals from helicopters (independently, it announced the planned suspension of the program next year). The wolves were targeted as part of an intensive predator management program in the Upper Yukon-Tanana region aimed to increase the population of the Fortymile caribou herd in lands surrounding the preserve. Once estimated to number in the hundreds of thousands, the caribou herd fell to just 6,000 in the 1970s and now generally peaks at about 50,000 to 60,000. And evidence has built up suggesting that these efforts may be ineffective at increasing caribou in this area.
After 22 years monitoring wolves in the preserve using radio collars, the researchers, led by John Burch, a wildlife biologist for the National Park Service, were not surprised to find that wolf survival rates decreased during lethal management outside the preserve in the Upper Yukon-Tanana Predation Control Area. "Every single wolf pack went outside the bounds of the preserve," Burch said. The state never shot wolves inside it, but many wolves that left the boundaries of Yukon-Charley were shot and killed.
What was surprising, however, was the intricate story that unfolded of how the wolves responded to control efforts. Surviving wolves inside the preserve tended to have more pups — but not enough to immediately offset those killed during predator control efforts.
"Even though they were adding more members to the pack, they were losing more than that, so in the average year, they ended up behind," said Josh Schmidt, a biostatistician who led the population analysis. "They were not self-sustaining and were dependent on dispersing individuals coming in from other areas from outside of the area most likely."
The targeted caribou herd, which was increasing before these efforts began, has reached more than 50,000 and is showing signs of nutritional stress, according to a study published in The Journal of Wildlife Management in January. It suggests that food availability, rather than wolf predation, could be limiting the size of the caribou population.
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Predator management, particularly of wolves in Alaska, has a long, contentious history. For thousands of years, many Alaskans living in remote areas have relied on hunting and trapping caribou for sustenance, and state laws require the maintenance of this food source, whether through improving habitat or killing predators. These laws can come into conflict with the conservation mandate of the National Park Service, a federal agency. Polarized emotions around wolves further complicate things.
"Some people just hate wolves," said Kyle Joly, the lead wildlife biologist at Yukon-Charley Rivers National Preserve, pointing to hunters who see them as competition for caribou. "Other people on the other side think wolves are things that can do no harm. They're just angelic."
To Joly, neither view is particularly accurate.
"They're just another wild animal trying to make a living, and they do it by killing ungulates and other things," he said.
Darren Bruning, an Alaska Fish and Game official involved in management of the Fortymile caribou herd, is familiar with these conflicting views and hopes for improved cooperation with federal authorities responsible for Yukon-Charley in the future.
"Ultimately all the public, and people with numerous and diverse values for wolves, will benefit from increased knowledge that we can gain from learning about wolves in the Yukon-Charley Rivers area," he said.