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Rewilding the World
Dispatches from the Conservation Revolution
By Caroline Fraser Henry Holt and Company
Copyright © 2009 Caroline Fraser
All rights reserved.
ISBN: 978-1-4299-2452-8
CHAPTER 1
REWILDING NORTH AMERICA
Pluie
The proof was a wolf. In June of 1991, a five-year-old alpha female, perhaps searching for new territory, embarked on a two-year foray, roaming over five hundred miles through the Rockies, an area of around 40,000 square miles, twelve times larger than Yellowstone National Park. As scientists were learning, this is what wolves do.
She was wearing a radio collar fitted with a satellite transmitter, and Paul Paquet, a Canadian zoologist studying wolf movement for the World Wildlife Fund, was watching her. Paquet found and collared her in the rain, so he named her Pluie. He and a colleague, biologist Diane Boyd, tracked her with growing amazement as she inscribed an enormous circle, starting near Banff National Park in Alberta, Canada, heading south into Montana, skirting the southern boundary of Glacier National Park, swinging past Coeur d'Alene, Idaho, and Spokane, Washington, and then trekking north into British Columbia, making another pass at Banff. Paquet told a reporter, "We thought she was on a pickup truck for a while, she was moving so fast."
Pluie's journey provided key evidence substantiating the theories on which rewilding is based. In the early 1990s, rewilding as a conservation method was still in its formative stages, but Pluie helped move it from a collection of hypotheses to a specific set of recommendations. A perfect illustration of the cores-corridorscarnivores idea, Pluie's traverse showed a top predator traveling from one core area to another, using wilderness corridors to do it. Her journey made national parks look minuscule, highlighting their inadequate size, isolation, and fragmentation. Although Pluie utilized parks such as Banff and Glacier, she clearly needed a space many times their size, a space a dozen times the size of Yellowstone.
The corridors she used were passageways of remaining forest linking large wilderness areas. Some — particularly in the Bow Valley — were bisected by major highways and railroads, forming dangerous bottlenecks or breaks. Pluie's travels let scientists identify the movement corridors, which, once located, could potentially be protected or restored by fencing off highways and providing safe overpasses for wildlife.
Pluie's journey, Paquet told me later, "made very clear what kind of geographic scale we should be thinking of. We were able to show pretty definitively that these theoretical corridors that we imagined were actually there and being used." Now that scientists could watch elusive species like wolves traveling across the landscape, they could begin planning to manage, maintain, and even restore the necessary cores and corridors.
Pluie also demonstrated the contribution of "umbrella species," as biologists called wide-ranging animals: protecting the vast spaces they required could provide shelter for countless additional species. If conservationists were able to put in place a series of big enough protected areas linked by corridors, they would be protecting not only wolves but everything else under that umbrella.
In 1993, Pluie lost her collar, which was found with a bullet hole in it. The wolf herself was shot dead two years later, along with her mate and several pups. Her fate matched that of most wolves, bears, and other large animals in today's West: shot or hit by cars, trucks, or freight trains. She was lucky to have survived as long as she did. One of Paquet's graduate students enumerated the toll that traffic on the Trans-Canada Highway and the Canadian Pacific Railway near Banff National Park had taken on wolves:
In the last 15 years or so, 27 percent of the known wolf deaths have been from the railway, and 60 percent were on the highway. Just 5 percent were natural. ... The Bow Valley used to have three packs. Now it has one. In 1996, three of the four pups born to this pack were lost to the highway. The next year, none of the five pups born survived, and we know at least one was hit on the railway. During 1998, the pack had no pups and was down to three members.
Such figures — the rapidity with which an entire population of wolves can become roadkill — suggested the urgency of the need to find a way around these bottlenecks. Almost as soon as Pluie had run her course, the data gathered about the places she went and the routes she took were pressed into service to design a wilderness network. Most importantly, Pluie's movements inspired the first major rewilding project designed around cores, corridors, and carnivores, the Yellowstone to Yukon Conservation Initiative. Pluie's story, Paquet later said, "was the founding story of Y2Y. Really, the whole idea evolved out of it."
But we get ahead of ourselves. Before the projects, before Pluie, before the proof, there was a theory. Like Newton's falling apple, Pluie acted as inspiration and demonstration, but scientific journeys begin with questions, not answers. The origins of rewilding — the conservation method designed to slow a wave of human-caused extinctions — are rooted in the most important ecological theory of the twentieth century, a theory that examines the forces governing extinction, the theory of island biogeography.
The Trouble with Islands
Nature is not a closed system. Since 1930, when a British botanist coined the term ecosystem to define the complex interrelationships between plants, animals, and microorganisms and the physical elements they interact with — rocks, soil, water, air — scientists began to recognize that wilderness cannot be preserved by sealing it off. To seal off is to interrupt processes that make life possible: natural selection, predation, competition. Because ecosystems contain such an extraordinary diversity of interactive species and processes, because they are not static, they have proved notoriously difficult to classify and study. Wrenched by larger environmental events — climate change, storms, fires, floods — they are capable of shifting, changing, evolving, and disappearing. Only within the past century have we begun to understand the laws that govern the evolution and transformation of ecosystems.
A momentous advance in understanding such systems came in 1967, when Robert H. MacArthur and Edward O. Wilson published The Theory of Island Biogeography. Wilson was thirty-seven when this epochal work appeared and would eventually become the most impassioned elder statesman of conservation, writing Pulitzer Prize–winning volumes about natural history and the need to protect biodiversity; indeed, his books popularized the term, a compression of "biological diversity." But in his early thirties, he was still a young Harvard biologist, albeit the world's greatest taxonomic expert on several subfamilies of ants in Melanesia, having spent years collecting in New Guinea and the islands of Fiji, as well as in Australia and South America. Over the years, he had noticed a pattern: the number of different ant species on any given island seemed to correlate to its size.
As told in Wilson's autobiography, Naturalist, and David Quammen's history The Song of the Dodo: Island Biogeography in an Age of Extinctions, Wilson discussed this pattern and other issues in the emerging, genetics-driven field of population biology with MacArthur, a young University of Pennsylvania mathematician and ecologist legendary for his ability to discern patterns from masses of data and to construct sophisticated mathematical models illustrating general principles. The theory Wilson and MacArthur shaped is an explanation of how natural forces act to control the number of species populating a given area. Paradoxically, the theory that launched a worldwide movement to protect enormous continental areas was inspired by the smallest of land units, the island.
As MacArthur and Wilson noted at the outset, an island "is certainly an intrinsically appealing study object. It is simpler than a continent or an ocean, a visibly discrete object that can be labelled with a name and its resident populations identified thereby. In the science of biogeography, the island is the first unit that the mind can pick out and begin to comprehend." But as they intuited, islands also provided useful information about the conditions that humanity was creating everywhere, even within continents. Islands were not only land masses surrounded by water; they were also isolated habitats surrounded by development. The principles of insularity — reduction and fragmentation — were going to apply "to an accelerating extent in the future" as habitats were "broken up by the encroachment of civilization."
To understand why size and distance were related to the number of species populating an area, the authors examined two crucial ways in which species rise or fall on an island: immigration and extinction. Using data on ants and other species, they worked out that, as new species arrived, a similar number of established species was becoming locally extinct, in a process of turnover. They set forth a mathematical model illustrating how an island's area and its distance from other islands or mainlands regulated the balance between arrivals and displacement. Their model allowed calculation of a number representing equilibrium — predictable and stable — that was based on those factors of area and distance. If the key factors changed, so did the equilibrium. According to the mathematical model, altering the factors of area and/or distance would cause the number representing equilibrium to reset. If a theoretical island grew smaller or more distant, the number reset downward; if it grew larger or closer to other land masses, the number reset upward. Although I have drastically simplified this explanation, leaving out discussion of additional factors (climate, location relative to ocean currents, initial species composition, etc.), the essence is this: the smaller the island and the more distant from other places, the fewer species it supports. As a rule, a 90 percent decrease in the area of an island results in a 50 percent decrease in diversity.
Equilibrium itself, and the species it represented, could vanish when an island or fragment became so small and isolated that immigration stopped occurring. This was known as "ecosystem decay" and could be seen in one illustrative example: MacArthur and Wilson reproduced a series of maps showing the reduction and fragmentation of a woodland in Wisconsin between 1831 and 1950; the maps clearly showed the progressive diminution of wooded remnants to tiny scraps that could support little variety of flora or fauna. As evidence supporting their theory, the authors looked at the famous volcanic eruption of Krakatau Island in 1883, which snuffed out all life under a sterilizing layer of searing pumice and ash. Although there were no comprehensive data on the flora and fauna prior to the eruption, there were for the subsequent "recolonization episode," in which insects, birds, and mammals returned to an island that had lost two-thirds its total area. MacArthur and Wilson calculated that the number representing equilibrium for bird species, based on its new area and distance from other islands, should have settled at roughly thirty species within forty years. The historical data on recolonization seemed to confirm their calculation.
The last chapter of The Theory of Island Biogeography described how further testing might be done by reproducing "miniature 'Krakataus'" — eliminating all species or all of a particular class of organisms (insects, fish) from a series of small islands or lakes, either "manually or by poisoning," and monitoring their return. Wilson and one of his graduate students, Daniel Simberloff, re-created the sterile island experiment, performing an exacting census of all species of insects on several tiny mangrove islands in the Florida Keys, then hiring exterminators to tent and fumigate them. Over the following year, Simberloff monitored their return. "To my absolute delight," Wilson later told Quammen, "we watched the numbers of species rise to what was obviously equilibrium within about a year." The experiment confirmed the theory as it related not only to area but also to distance: the most remote of the experimental islands was the slowest to return to equilibrium, and with the lowest number of species.
The havoc that equilibrium would play in small, remote protected areas was immediately obvious to biologists. By extrapolation, the smaller and more isolated an area is, the farther it is from the nearest wild area — the more islandlike it is — the more likely it will exhibit the characteristics of an island, including reduced diversity of species and a higher rate of extinction. Quammen distilled the issue of scale to a single, unforgettable metaphor. What do you get when you take a beautiful Persian carpet, he asked, and cut it into thirty-six pieces? Thirty-six separate carpets? Or thirty-six worthless, fraying scraps? Substitute ecosystems for carpet, he suggested, and you begin to see the problem.
In a 1972 paper inspired by the equilibrium theory, the ornithologist Jared Diamond, who had done extensive fieldwork in New Guinea, directly addressed how equilibrium would affect protected areas that were too small and too islandlike. He observed that the government of that country was in the process of setting aside small rain forest "tracts" as preserves. While the intentions were good, Diamond wrote, the outcome was likely to be the opposite of what they planned. The governments of New Guinea and other tropical countries were creating islands within islands, surrounded by "a 'sea' of open country in which forest species cannot live." Diamond argued that the diminution and fragmentation would cause a "relaxation to equilibrium." The size of the preserves would inevitably trim the number of species they protected to a lower number than the forests initially held, undercutting their very purpose. In yet another paper, Diamond set forth initial suggestions for the size and design of nature reserves, the first to be based on the equilibrium theory. Large is better than small, he argued, and reserves grouped together or, better yet, connected to one another would support more species.
Given the evidence already available, many biologists were quick to agree that when it comes to preserving ecosystems, large is better than small, connected is better than isolated, and whole is better than fragmented. But some were resistant, arguing against a rush to judgment, suggesting that protected areas in the real world might prove vastly more complex, each with unique characteristics that might affect the outcome. The intellectual debate over the subject became so vituperatively colorful that David Quammen made it a central focus of The Song of the Dodo. The arguments were heated, he explained, because what was at stake was nothing less than saving the planet: "At a time when humanity was cutting forests and plowing savannas at a rapid pace, when habitat everywhere was becoming fragmented and insularized, the equilibrium theory embodied minatory truths. It was not just an interesting set of ideas — it was goddamned important. If heeded and applied, it might help save species from extinction."
The most prolonged and violent debate to come out of island biogeography, a veritable "pissing match," as one biologist put it, was the debate over "SLOSS": "single large or several small." Are single large protected areas better than several small ones? Jared Diamond strongly defended the idea that a single large reserve would tend to preserve more species. Large reserves, he argued, would preserve large carnivores, which need more space; they would provide more protection in the event of extreme climate change. Others thought that the theory had yet to be proved and, ironically, the most adamant critic of the "single large" camp was Daniel Simberloff. He pointed to cases in which officials in Costa Rica and Israel, in a position to make decisions about conservation, nearly threw out plans for reserves that seemed too small and therefore — or so they thought — useless. Small parks might target hotspots of endemism; the conviction that big is better, Simberloff said, is "a cocktail-party idea" with the "trappings of science."
The SLOSS debate eventually wound down, as more and more scientists and conservationists moved toward the big-is-better-than-small hypothesis. Looking around, they could see that national parks, protected areas, and reserves in the United States and around the world were small, fragmented, isolated. As anyone who has driven to Yosemite or Yellowstone knows, parks have indeed become islands of protected land in a sea of development — motels, shops, restaurants, malls, homes, roads — that washes right up to the entrance gates. In addition, many were poorly placed to preserve biological diversity. "National parks," conservation biologists argued, "are essentially square. Few conform to watersheds, mountain ranges, or other ... features that define natural regions. Most parks are too small." Moreover, those dating back to the nineteenth century revealed the tastes of their creators in their emphasis on aesthetic grandeur — Yosemite's cliffs or Glacier's peaks — a criterion now derided by biologists as "rocks and ice," habitat notably short on biodiversity.
(Continues...)
Excerpted from Rewilding the World by Caroline Fraser. Copyright © 2009 Caroline Fraser. Excerpted by permission of Henry Holt and Company.
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