The truth about the gray wolf
RON SEELY
ISLE ROYALE – From an old and sagging log cabin on this island in the cold reaches of Lake Superior, Rolf Peterson and dozens of other biologists have made history and put to rest many of the persistent and wrongheaded myths about the island’s most famous resident: the gray wolf.
Peterson is a wildlife biologist who is the latest researcher working on what has become the world’s longest predator- prey study. Since 1970, Peterson has studied the relationship between wolves and moose on Isle Royale. He was just 9 years old when the research started in 1959. Eisenhower was president and Ford had just released the Edsel.
The long years of study have provided not only a wealth of information about the intricate connections between these two majestic mammals but also considerable insight into the relationship of the endangered gray wolf to the landscape in other northern states, including Wisconsin.
Peterson’s research, in fact, is proving a crucial tool for wildlife ecologists in Wisconsin as they fight an intensifying battle against misinformation about the timber wolf. Since the early 1970s, when wolves had nearly disappeared from the state, Wisconsin’s wolf population has rebounded to about 450 animals.
Adrian Wydeven, the wildlife ecologist who heads the state’s wolf program, said the Isle Royale studies have provided considerable information for the Wisconsin recovery effort. Most important, he said, have been accurate descriptions of wolf behavior to counter the long-held myths about wolves that are often perpetuated by those who are against the return of the predator to the state’s forests.
“Isle Royale,” said Wydeven, “represents the beginning of modern wolf research. The length of the study alone is valuable. We’ve gotten a lot of useful information and I think those studies are becoming even more important.”
To Wydeven, the studies are about truth-telling in the face of heightened criticism of wolves in Wisconsin. He cited, for example, a recent article in the Ashland newspaper titled “Wolves Threaten Our Northland Economy” that said wolves kill too many deer and frighten people.
On Isle Royale, science is bringing the wolf out of the shadows of lore and history. It is an ideal laboratory because of its insular population of wolves and moose. Moose swam to the island, perhaps in the early 1900s. Wolves crossed to the island on frozen Lake Superior in the late 1940s.
Years of patient tracking and observation have shown that, while it certainly is a deadly efficient predator, the gray wolf is an integral part of a natural web that is far more complicated than was once believed.
Peterson and other Isle Royale researchers have found that seeing the wolf’s role clearly, unclouded by myth, can help us better understand a landscape in its entirety, from the ups and downs of its animal residents to the fate of a cedar swamp.
This is the view that has coalesced from the cluttered environs of the famed Bangsund Cabin on the rocky shore of Isle Royale’s Rock Harbor. In 1970, Peterson, now a professor of wildlife ecology at Michigan Technological University but then a graduate student, first came to the cabin. He brought his wife, Candy, and together they started studying the bones of moose to better understand the secrets of wolf predation.
Inside the cabin is a pleasant jumble of old and comfortable chairs, wooden cabinets with doors askew, a table covered by a map of the island, a small kitchen stocked with battered pots and pans. Photos and clippings and headlines line the walls, a faded record of the many summers the Petersons have spent here. They watched their two boys grow up during all those seasons of research.
Candy, hosting guests one recent fall afternoon, served coffee from a tin pot atop the wood stove along with fresh- baked cinnamon bread. She recalled those early days, the joy of the wild island and of being close to the wolves.
“I remember feeling that they were all around us,” Candy said. “Being here in the cabin allows the wolves to live right here near us. We can be a part of it all . . . It’s just an absolute privilege to be here.”
Outside, the yard of the cabin is littered with moose bones – vertebrae and ribs and leg bones and backbones. They are from years of collecting. Many are labeled. A shed behind the cabin is filled from floor to ceiling and from wall to wall with moose skulls and antlers, interlocked in a puzzle of white bone. All of the bones tell a story; they are a calcified history of moose on Isle Royale.
“Ecology is actually a historical science,” Peterson said as he displayed several of the skulls he’s collected over the years. “That isn’t really appreciated. What we’re trying to do is understand the past.”
What are the lessons of history and bone? One of the most important findings, Peterson said, is that wolves are not indiscriminate killers. Instead, a study of the bones and teeth from wolf kills showed that the wolves prey primarily on the very old moose as well as on the sick and the young calves – these, after all, are the moose that are easiest to bring down. As Peterson pointed out in his 1995 book, “The Wolves of Isle Royale,” old moose were the wolves’ “bread and butter,” comprising about 85 percent of their diet.
There is more to this, studies on Isle Royale and elsewhere show, than meets the eye. By culling the weak and the sick from the moose herd, Peterson said, the wolves are actually serving as agents of positive change, assuring that the prey population remains healthy over future generations because only the strong and robust moose survive to rear young. As Darwin explained, nature selects for those characteristics that give a species its best shot at surviving and prospering.
“The wolf,” Peterson explained, “is the agent of selection.”
This important phenomenon happens in Wisconsin, too, though wolves are not nearly as major a predator on deer as people are. Wolves kill between 8,000 and 9,000 deer a year, according to Wydeven. People kill five times as many with their cars. Hunters kill more than 300,000 deer each year.
But Peterson said wolves, even in a place such as Wisconsin, can exert a positive influence on the overall health of a prey population. “Wolves,” Peterson said, “are probably having an effect on deer all across the upper Midwest.”
Peterson even speculated that wolves could play a role in stemming the spread of chronic wasting disease because of the same process of selection.
The long study of the relationship between wolves and moose on Isle Royale provided numerous surprises along the way, according to Peterson.
One of those involved the impact of wolf numbers on the health of the forest. It’s a simple thing, really, but something that shows the truth of nature being dependent on myriad connections.
Data through the decades of the 1960s and 1970s showed that wolves were the major force keeping moose in check. During that same time, there was a major regrowth of the forest on the island, especially balsam.
Similarly, in the 1990s, when moose numbers climbed again, the growth of woody vegetation was suppressed. The connection, once the changes in the forest were documented, was easy to make. Moose eat young trees. Wolves eat moose. More moose mean fewer trees while fewer moose mean more forest growth.
“Growth rates of balsam fir in the forest understory,” Peterson wrote in his book, “cycled in synchrony with the wolf population. When wolf numbers were high, the forest grew. What an impressive achievement for a couple of dozen wolves that were just doing what comes naturally!”
Such a finding is of special interest to Wisconsin biologists these days, according to Wydeven. Studies by researchers such as the UW-Madison’s Don Waller have shown that deer are decimating the understory of Wisconsin’s northern forests, especially cedar swamps. So studies are under way, Wydeven said, to understand the relationship between wolf predation and plant growth in Wisconsin’s forests.
If Isle Royale is any indication, the future of the cedar in northern Wisconsin could be dependent on the success of the wolf as a predator.
The wolves and the moose on Isle Royale have communicated myriad other secrets about our world over the years. In his book, for example, Peterson told the story of how the moose on the island even gave us important and unexpected information about carbon dioxide and climate change.
Back in 1989, Peterson said, when scientists were using the Oxford University’s accelerator mass spectrometer to date the Shroud of Turin, the next fellow in line to use the instrument was a geochemist named Jeffrey Bada. He carried small vials of gaseous extracts from Isle Royale moose teeth.
Bada, Peterson continued, found that moose teeth store carbon. More extensive study of 75 years worth of Isle Royale moose teeth, Peterson said, showed a steady increase in carbon, further proof of an inexorable rise in carbon dioxide due to worldwide combustion of fossil fuels.
Such unexpected findings lead Peterson to speculate about what mysteries could be solved in the future by the data that continue to be collected on the island.
What secrets, Peterson wondered, remain locked in the bones of Isle Royale?