Three scientists at the forefront of wolf ecology answer the same questions about wolf biology and management
interview with L. David Mech, Rolf O. Peterson, & Douglas W. Smith, as interviewed by Charissa Reid
In 1958, while a professor at Purdue University, Durward Allen began what continues to be the longest running predator-prey study ever conducted in the world at Isle Royale National Park. His first graduate student was David Mech, who was pursuing a PhD. In 1970, Allen's final graduate student, Rolf Peterson, also acquired his PhD as part of the Isle Royale Study. Dr. Allen turned the study over to Peterson in 1974, and Peterson continues to share leadership of the Isle Royale study 46 years later. Both Mech and Peterson went on to distinguished careers and are known as two of the foremost authorities of wolves in the world. Durward Allen died in 1997.
Doug Smith studied under Peterson and Mech, working on the Isle Royale Study from 1979 to 1994 and in Minnesota in 1983. Smith came to Yellowstone to work on wolf reintroduction as a project biologist in 1994 and eventually became the Wolf Project Lead, a position he has held for 20 years.
1. Do you have any memories of Durward Allen you'd like to share?
MECH: I was Durward Allen's first graduate student, and he assigned me the privilege of launching the Isle Royale wolf and moose study. He became a great mentor and friend. Besides our joint interest in the study, we both were keen on writing. "You really don't know how to write until you put a million words through the typewriter," he once told me. He had done so long before, having written several books and many articles. What I remember most about Durward was his wry wit and wonderful way with words. One particular winter evening at camp on Isle Royale, Durward was pecking away on an old Smith Corona typewriter, trying to finish one more article. After an especially bad bout trying to get the old machine to work, he looked up and dryly announced, "Ya know; this old typewriter would make someone a damn good boat anchor!" That typified Durward's wry utterances and forever made me think of him when I saw an old typewriter.
PETERSON: Durward Allen took up backpacking when he was nearing retirement age, primarily to get a glimpse of the interior of Isle Royale from the ground while writing a book on the island in the early 1970s. He was used to the canvas-and-leather era of camping in the Northwoods, and on his first solo backpacking trip he took along a bag of potatoes. But soon he adapted to the go-light routine of backpacking. In autumn 1972 he hiked 27 miles on a loop trail; and on the last night, still 10 miles out, he felt some tightness in his abdomen which he figured was from the waist-belt of the backpack, just a nylon strap. He hiked to Washington Creek campground the next day, his departure point for the trip back to the mainland in a few days. But he hardly slept that night because of continuing gut discomfort, and he was unable to arise in the morning. He crawled on all-fours a couple hundred yards to the ranger station, and a call was made to the air taxi to come right away to fly Durward to a hospital in Hancock, Michigan. He spent almost a week there as doctors puzzled over what his problem was–all the symptoms of appendicitis except one, as his white-blood-cell count was normal. Finally, a colleague from Purdue University drove to Hancock and took Durward home to Indiana, where doctors operated and found that his appendix had ruptured but only very slowly, and in fact there was nothing to remove. Durward concluded he was one of the lucky few people who might have survived appendicitis without the intervention of modern medicine–he often mused on how he might have gotten along if he'd been a mountain man 150 years earlier. But next time he backpacked, he had a padded waistbelt.
SMITH: I had heard a lot about Durward Allen before meeting him. First from Erich Klinghammer, who was a colleague of his at Purdue University, then later from Rolf Peterson, who was his student. I volunteered for Erich at Wolf Park in Battle Ground, Indiana, in the spring of 1979. Being from Germany (and a former student of Konrad Lorenz), he was impressed by anyone who had worked at something for a long time; some called it the "German alpha male effect." And that was Durward –an expert, a book author, and one of the pioneers in the nascent field of wildlife management, or I should say wildlife biology. In fact, I credit Dr. Allen for my educational interest in wildlife. In 1979, so many students were majoring in Wildlife Biology that one professor at Utah State where I interviewed called Wildlifers, as they were referred to at the time, "a dime a dozen." Then I met Dr. Allen at Wolf Park in Indiana. Nervous and almost clumsy, I spent part of an afternoon with him talking while watching a captive pack of wolves at Wolf Park. At one point I got around to the conversation at Utah State when I asked: Should I even major in wildlife given there were so many students doing so?, then I repeated the comment I heard by the Utah State professor. Quickly, almost interrupting, he said, "wildlife managers are a dime a dozen, wildlife scientists are not." I enrolled that fall in Wildlife Biology at the University of Idaho.
2. Are wolves in Yellowstone National Park different from other North American wolves, or do we just know more about them?
MECH: It depends on what you mean by different. Every population is different from other populations, but there is uniqueness to the origin of the Yellowstone wolves in that they were translocated from two fairly separated areas in Canada, meaning that their original gene pools were different. That differs from most colonizing populations of wolves in that ordinarily, the colonizers would all be from, basically, the same gene pool, whereas in Yellowstone they are from two separate gene pools. What practical difference this makes or what scientific difference this makes is certainly unknown and could be argued about, but I think that there's at least some reason to believe that because these two gene pools were merged in Yellowstone, that makes that population unique.
It's pretty clear that because of the great surplus of prey that was available to the population when it was first reintroduced, the kinds of things that we saw, like a pack of 37 wolves, were a result of there being that much food, which reduced the competition within the packs and between the packs during the first several years of reestablishment. The population that exists now is much more similar to other populations in that they have pretty much equilibrated with their prey. Actually, if you look at the, say, maximum pack size of the wolves in Yellowstone over all the years, the largest pack was in 2001, which was just six years after reintroduction. And, since that time, the maximum pack size has consistently decreased, such that the maximum pack size by 2015, was only about half of the maximum pack size in 2001.
The Yellowstone population from the beginning has been the most scrutinized wolf population in history anywhere in the world. The percentage of the number of wolves collared with even VHF radios and the amount of time that they've been observed from the ground has all produced tremendous amounts of data, which the biologists have turned into very informative publications. That means that things that we might not have been able to find in other wolf populations the biologists were able to find in Yellowstone. The question comes down to this: are some of the new findings a result of the increased scrutiny or are they a result of other factors like the fact that the population originated from two separate gene pools? That question hasn't been answered and may not even be answerable, so it does remain a question.
PETERSON: I don't think Yellowstone wolves are fundamentally different from other wolves in North America. The wolves introduced in 1995 were certainly placed in a unique situation, with extremely abundant prey in a large protected environment. Although one could never predict exactly what wolves would do in those circumstances, the general pattern of rapid population increase and then a leveling out is what one would expect (and hope for) in that situation. The unique features of their individual lives are fascinating, but they are no more unique than almost any other animal would prove to be if we invested the effort to learn about them with the same intensity.
SMITH: Wolves in Yellowstone are not different than wolves anywhere else. And I think a lot of people sometimes mention that they are…because, for one, we've learned so much about them that there seems to be a lot of different, new things about those wolves. Secondly, and perhaps most importantly, what really characterizes wolves in Yellowstone, and this is primarily the northern part of the park, the northern range, is that they occur at very high density. And that's unique across North America.
Wolves are an animal that lives in ecosystems at fairly low densities. Because of the very large elk herd that was present in Yellowstone at the time of reintroduction, wolf numbers built up to arguably the densest wolf population North America's ever seen. What's interesting is the northern range inside Yellowstone National Park is almost exactly 1,000 kilometers squared. The number of wolves we have in northern Yellowstone on the northern range is the unit of measure for wolves worldwide. Very typical wolf densities for, say, Canada is 10 to 15 wolves per 1,000 kilometers squared. In Alaska, it's not uncommon to have single-digits wolves per 1,000 kilometers squared. Where there's a lot of whitetail deer, say in Wisconsin or Minnesota, you might have 30 to 40 wolves per 1,000 kilometers squared. Here in Yellowstone, our peak density for several years was in the 80 to 100 wolves per 1,000 kilometers squared.
So what pervades a wolves' social behavior and ecology on the northern range of Yellowstone is this unique high density. Our wolf pack territories are 200 to 400 square miles. Arctic wolf pack territories being up to 1,500 square miles. What wolves do here in this very competitive environment is very different than what wolves do someplace else, but that doesn't make them different.
Secondly, and this is as important, we have had better looks at wolves. Our monitoring is more intense. We're probably one of the more intensive monitoring programs worldwide. And why is that? Because we have a road bisecting all the good wolf habitat in the park. Wolves up to this point in time have always been a remote wilderness species. They live in faraway places. And almost all the monitoring of them has been through radio collars and airplanes. Yellowstone is the best example of continuous year-round not only aerial monitoring, but ground monitoring as well. Rick McIntyre went out every day for fourteen years and saw a wolf 97 percent of the days he went out. There's nothing that can match that worldwide. Even though each day is just a little bit of information, you add all that up, we get great looks at wolves. This is also aided by the fact that we've been very successful radio collaring wolves.
3. What has been Yellowstone's most significant finding or contribution to wolf research or management?
MECH: I don't know any other place in the world one could get such information that the MacNulty papers have produced on the effect of pack size and the wolf –individual wolf ages and sizes, how they affect wolf hunting behavior. I don't think that kind of information could ever have been obtained anywhere else in the world. And it is unique and I think very significant to the whole field of wolf/prey interactions. We didn't know anything like this before, and so I think that those findings were some of the most important.
The recent findings related to pack size and composition affecting the winning of pack interactions, aggressive interactions, comes a close second, I would say. We've known from many populations that wolves kill each other, but we certainly had no idea about the level –or we certainly had no level of detail similar to what Kira Cassidy has found in Yellowstone with the wolf packs attacking each other. That's pretty unique information.
What's most surprising to me has been many of the observations of the multiple breeding in some individual groups of wolves that we don't even–they're not even family packs; that is, there's groups of wolves that get together, like several males getting together;or there's one female that I think was observed breeding with five males and that type of thing. That's really surprising to me. I wouldn't have envisioned any of that; and it's one of the things, incidentally, I wonder about as to whether it's a result of some of the differences in genetics or whether it's a result of the more intense scrutiny that these packs have had. I wouldn't be able to answer that question myself.
PETERSON: I think the ecosystem role of the wolf that has been demonstrated in Yellowstone will prove to be the most important lasting contribution. Although the top-down significance of wolves is not a unique scientific result from Yellowstone alone, the huge audience that is paying attention makes the findings from Yellowstone all the more important. Prior to the introduction of wolves to Yellowstone, the long-running controversy over elk management had been referred to as the biggest controversy in wildlife management of the 20th century. Perhaps that is arguable; but in any case wolf predation played an important role, along with recovery of grizzly bears and cougars, in reducing a hyperabundant elk population.
SMITH: We've had a great window into ecosystem functioning. "How do ecosystems function?" has been the hottest scientific debate going. A lot of the trophic cascades arguments are a window into how ecosystems work. And that's been a really vibrant debate. We're coming out with new information on that.
The second thing that we've learned is how wolves work in the absence of human exploitation. And really, this is why we establish national parks. There are two things we've discovered, and it probably does not occur in wolf populations outside of protected areas like Yellowstone. And that is, one, wolves have organized themselves into matrilineal groups. The other thing that we're finding, and this is even more evolving science, is there appears to be an interaction between a coat color, whether you're a black wolf or a gray wolf, and disease immunity and aggression. Those two things are currently being studied.
Early wolf biologists, all males, thought the supreme leader of the pack was the alpha male. It appears that it's the female. Female offspring tend to stay in the pack. It's called philopatry. Male offspring tend to leave. They disperse. And they do this because wolves don't want to inbreed. When you have a tendency for males to leave and females to stay, the daughters are within the pack waiting for their opportunity for mom to die.
Second finding: There appears to be a relationship between coat color and disease immunity. And what that means is black coat color is dominant to gray coat color in wolves. If you get a black and a gray allele, the black allele is dominant and you're gonna be a black wolf. But you're heterozygous black. So you maintain the possibility to have gray offspring because you're carrying that allele. It's just masked by the dominant gene. So that's one way to get a black wolf is you get a black copy of the gene and you get a gray copy. And it always comes out black. You could also get two recessive gray alleles. That's the only way to get gray. So you get two gray alleles, you get a gray wolf. And then you could also be black because you get two copies of the black allele and that wolf is black. What we're finding out is if you get both copies of black, you have a higher probability of dying from a disease.
Homozygous black wolves die at a higher rate when they're born, right after they're born, than heterozygous black or gray wolves; but heterozygous black wolves have a survival advantage, probably because of an immune system gene. We're trying to figure out what they're dying from.
4. What is the most pressing issue or conservation challenge facing wolves in Yellowstone?
MECH: Yellowstone wolves are pretty well protected. I don't see any major problems affecting their conservation. I would be very, very surprised if that population didn't persist for as long as the park persisted. I don't see any big threats to their conservation. In the long term, I see that the relationship between the number of wolves and the number of prey being something that should be followed for a very long period. Each predator/prey–or let's say each wolf/prey population is unique, and Yellowstone's wolf/prey population, or wolf/prey system, comprises or is comprised of elk and bison and sheep and deer and moose and pronghorn and all; and it will be very interesting over the years to see any changes in the proportion of all these different prey animals that make up the wolf kill. I mean that's going to shift as numbers of the different prey animals change. So, for example, the elk population has dropped considerably and now we're starting to see wolves taking more bison. Sooner or later, they're going to be taking more pronghorn, I believe, and probably preying a little harder on the sheep and deer. A really good, close look at the changes in that dynamic over the years would be pretty valuable.
PETERSON: From the human standpoint, the key conservation challenge is to preserve and protect the Yellowstone ecosystem, with the national park at its core. The presence of wolves gives an important boost to this challenge; but the fundamental challenge has been there for many decades, as Yellowstone is an island in a sea of human-dominated ecosystems that press on Yellowstone from all sides. For the wolves themselves, I think their special challenge is to become specialized predators of bison –everyone hopes that will happen.
SMITH: Social science. I sometimes say–wolves are one of the most studied mammals in the world and that's because they're controversial. The real frontier for wolves is human attitudes. But people are the tough part. For us in the park it's tough because people come here from all over the world to see them and love them. Then wolves cross the line, and two of the three states want to reduce the wolf population. They have a different group of constituents that have different demands on wildlife than our people do. The boundary issues are going to be very pressing.
To be honest, it's been difficult, but it's ended up going well. You've got wolves far from Yellowstone that Yellowstone has no business commenting on. And then you've got wolves in the park, which is all our business. And then you've got wolves in between. And those are the wolves that we have to reach some kind of compromise about. And I think, in general, we have.
Montana has responded to our request to reduce harvest right next to the park. Wyoming has small hunt units with limited quotas. We talked to them. So it's going well. Maintaining that balance into the future is going to be a challenge.
5. Why did you choose to dedicate your professional career to the study of wolves?
MECH: As a teenager I was always interested in fur trapping, and the most challenging animals to trap are carnivores, and so I became interested in carnivores. And before graduate school, I had the opportunity to help with some research on black bears, and in that process I also ended up catching some coyotes and bobcats, and so the larger carnivores interested me a great deal and I worked with some professors on them. And when the Isle Royale Wolf Moose Project became available, it was actually offered to me as a graduate project. I jumped at it and was hooked on wolves ever since because of the challenges involved both in studying the wolves and the challenges that the wolves face in their lifestyle.
PETERSON: It wasn't just wolves as a focal species that interested me, it was wolves in the complete context of an ecosystem, where wolves influence the abundance of their prey, which in turn impacts a myriad of plants and other animal species, including impacts that we probably aren't clever enough to measure or even guess about.
SMITH: I've been interested in wolves since I was about twelve, thirteen years old. I have two older half-brothers; they're 20 and 25 years older. For Christmas one bought me Dave Mech's book The Wolf. I still have it. That book came out in 1970. And my brother who saw this interest that I had I think just randomly saw this book on a bookshelf. In those days there was no Amazon.
At fifteen, and I know this well–at fifteen I started writing wolf biologists. And this is back in the day of pen and paper or typewriter. And oddly, again, that was unique to the age. I was fifteen in 1975. They all wrote back typed letters, not form letters. At fifteen, everybody said, "No thanks."
So at eighteen I wrote them back again. I wrote all the same wolf biologists back. Dave Mech, Rolf Peterson, Lloyd Keith, Lu Carbyn, Erich Klinghammer, the big five, and said, "I don't want a paid job;I don't want a volunteer job. I just want to hang out with you. I just want to observe what you're doing. And it's for an educational project. I'm a senior student. I want to go for a school project for six weeks." And so to this day, I have a soft spot in my heart because I get two or three either high school or college kids every year wanting to do the same thing. And I can't bring myself to say no because one of those five wrote me back and it was a captive study.
Erich Klinghammer. He was doing behavioral research on captive wolves associated with Purdue University. I drove over there in the middle of the winter with my mother. My father had died. He just wanted to look at me in person and see is this some kind of wacko high school kid. At the end of the interview he said, "You can come." And so in the spring of 1979 I went to Wolf Park to hand rear wolf pups.
It's been a love of my life to study them. I am tirelessly still loving it.
Last updated: July 10, 2016