In 1995, eight wolves from a white truck that traveled 700 miles from Alberta, Canada, were released into Yellowstone National Park. They were the first to live in the park for 70 years, and the return of the world’s most fabulous predator to the world’s most famous national park has inspired research that will be present in ecology textbooks for decades.
A key account of this event is that wolves created a “landscape of fear” in the park, which marked the beginning of major habitat changes known as trophic cascades. This is an argument used to justify the release of wolves elsewhere. But more and more researchers are looking at the nuances of what happened in the decades after the introduction of wolves and challenging this approach.
The Wolves were reintroduced to Yellowstone Park in 1995. Photo: Jim Peaco / NPS
One of the key impacts of the Yellowstone wolves was to hunt grazing animals such as moose, whose overpopulation damaged the park. The number of moose in the northern range of Yellowstone rose from 19,000 in 1995 before wolves arrived, stabilizing at about 6,000 in the years after their reintroduction. With fewer moose, there was less pressure on vegetation such as willow and aspen, which allowed them to thrive.
Quick guide
Rewilding: what is it?
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What is rewilding?
Rewilding is the restoration of nature in places changed by human activity. From the release of top predators such as jaguars and wolves to the release of local pastures in urban areas, re-wilding can occur on a large or small scale. Although there are competing definitions, most are based on restoring sustainable environmental health, whether it is the return of algae forests off the coast of Sussex to England or the reintroduction of ridiculers in the Galapagos Islands.
Why did the term become so popular?
Rewilding captures the imagination of society, being an environmental movement and a science-based process at the same time. With visions of a wilder planet, high–profile conservationists such as David Attenborough and George Monbiot have inspired millions with pathways to a more biodiverse, environmentally healthy future. The success of the pioneers in rewinding around the world has shown what is possible: from the restoration of the Gorongoza National Park in Mozambique after the Civil War to the Knep estate in the South of England.
Is Rewilding Universal Support?
No. Critics of the restoration fear the term is being used to justify removing people from the landscape, especially farmers and local communities. In the United Kingdom, some have dismissed the concept as a fad for high-income landowners, while others fear it is being used to attack agricultural communities that have been cultivating for hundreds of years.
Can you rewind?
While the boldest re-wildlife initiatives are taking place on a landscape scale, small changes can have a big impact. Millions of people are changing the way they mow their lawn or let nature into their gardens, balconies and window sills can be added, providing more space to restore biodiversity.
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The wolves also indirectly changed the way their prey moves around the park. The moose became less inclined to graze large open river valleys for fear of attack. This meant that the new areas were able to regenerate, creating benefits that descend to ecosystems, leading to habitats for beavers, fish, small mammals, amphibians and insects, among many others.
A herd of moose in Yellowstone: the wolves made them change their grazing habits. Photo: Jane Gamble / NPS
“The aspen trees were the perfect visual way to demonstrate how well this reintroduction worked,” said Rick McIntyre, who was hired as a “wolf translator” in 1994, a year before the wolves arrived. Since then, he has been watching wolves almost every day and has published several books about them. He lives in the village of Srebarna Porta in the northeast corner of the park.
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In one place near the release basket, within a few years, the aspen went from continuous grazing to tens of thousands of shoots, creating a forest “almost as thick as a bamboo thicket,” he wrote in his book The Rise of the Wolf.
But the story was more complicated than that. The changes are partly due to wolves, but are also caused by other factors, such as the growing number of mountain lions and bears and the increase in human hunting in the northern part of the park, as well as climate change, McIntyre explains in his book. “I sympathize with the results that these people published in the first years. It made sense. That explained a lot during that time. But now, in some cases, we’re 20 years ahead and we’re doing better with all these other factors, “he said.
Aspen trees in Grand Teton National Park, Wyoming. Trees are increasingly affected by the climate crisis. Photo: Dominic Browd / Alami
Today, willow and aspen, which thrive along rivers, streams and swamps where many of these early studies have been done, have wrinkled because water levels have dropped, according to McIntyre. As the climate gets warmer, there is less snow cover, which means less moisture available for spring plant growth, which is a big factor in the health and survival of aspen and willow. “There are factors you couldn’t have foreseen that have been very influential and may reverse some of the documented changes,” he said.
Ecosystems are large and chaotic, making them difficult to study, and some of the techniques used may have had limitations. A paper published in 2021 looks at how sampling only the tallest aspen in Yellowstone means that researchers have overestimated how much it has regenerated at least four times compared to random sampling. The study concludes that “the results show the existence of a trophic cascade that is weaker than is often claimed.” Other researchers warn against summarizing the impact of wolves. In 2010, a document concluded that the trophic effects of wolves in Banff, Isle Royal and Yellowstone were different.
When the findings seem sensational, the media tends to stick to that optimistic vision, said Professor Dave Sword, a U.S. Geological Survey biologist who studies wolves. For example, a 2014 YouTube video, How Wolves Change Rivers, has been viewed 43 million times. But when these findings are challenged, most people don’t hear about it because complex and nuanced stories are less appealing. “Scientists are just people, and the reintroduction of wolves was such a popular thing and got a lot of publicity. It’s human nature, it’s not uncommon for people to jump to conclusions, “he said.
Two wolves are stalking a moose bull in Yellowstone National Park. The return of the predators created a “landscape of fear.” Photo: Minden Pictures / Alamy
In the UK, calls for the return of wolves and lynx – another top predator – have been controversial, especially among farmers, so it is important that advocates rationalize why they want to reintroduce these predators and what the consequences will be, writes Dr. Hugh Webster in British wildlife magazine.
Webster wants to emphasize that the arguments for reintroduction should not be based on the promise of ecological nirvana. “People can resell this myth, probably with the best of intentions,” says Webster. “You have to be so careful when you make such promises, and that worries me.
The study of the impact of lynx paints a complex picture. In Switzerland, the reintroduction of cats has led to a decline in deer and chamois populations, as well as changes in their behavior. In Sweden and Norway, however, the recolonization of lynx does not seem to affect the way deer move in the landscape, suggesting that the response of animals to these predators varies across ecosystems.
The United Kingdom is a country devoid of intact ecosystems, and the return of large predators is often seen as a way to reduce deer numbers, which are so high that they hinder natural reforestation. The United Kingdom has many deer because it has an abundance of habitat and food available – not just because there are no lynx and wolves hunting them.
Wild lynx taken from a remote camera in Switzerland. Research shows that the impact of the top predator varies across ecosystems. Photo: Nature Picture Library / Alamy
Webster believes conservationists should not justify reintroduction with arguments about the ecosystem services and trophic cascades they will create. “It’s a wonderful story and it captures the imagination, but science is not final for it,” he said.
A 2017 document, “Can we save large predators without losing the science of large predators?” Warned that researchers and conservationists are increasingly inclined to “ignore, neglect or devalue the basic principles of the scientific method” when communicating the role. which large predators play in ecosystems. This undermines public confidence in the science of large predators, the researchers said.
Europe is a better place when there are big, wild, furry animals … not because they will fix everything Prof. John Linall
Webster suggests that instead of arguing that reintroducing predators will solve complex environmental problems, it would be better to “championship their ability to excite and surprise us” by embracing their ability to enrich human experience. The fact that we can never be sure what their impact may be is part of the excitement, he said.
Professor John Linel, who studies conflicts between humans and wildlife at the University of Applied Sciences in Inner Norway, says it is essentially a debate about values and scientists may feel uncomfortable acknowledging its subjective nature. He says: “My personal values say that Europe is a better place when you have big, wild, furry animals. It is not because of this faith that they will …
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