Wild wolves used to roam freely across most of the United States, but when these wolves were hunted to extinction in areas like Montana and Wyoming, ecosystems quickly fell out of balance. Without natural predators, elk populations soared, eating away at trees and grasses, eliminating building materials beavers used for dams. Soon, the entire natural balance was thrown off. 

Fortunately, when Yellowstone made the decision to reintroduce wolves to the park in 1995, these ecosystems quickly returned to their former glory. Elk populations dropped and foliage began to recover. While willow tree planting efforts had been largely unsuccessful, researchers found that with lower elk numbers, willow tree biomass increased 10 times compared to growth achieved with transplanted trees. 

With more willow trees, the beavers returned to their long-abandoned rivers, providing optimal habitats for trout and other aquatic creatures. What occurred was essentially an entire cascade effect of environmental benefits triggered by the reintroduction of one key predator. To this day, this project remains one of the most successful examples of rewilding in the United States. 

What is rewilding? 

‘Rewilding’ is an increasingly popular term in the fields of conservation and habitat restoration. It refers to the process of reintroducing lost animal species to natural environments and leaving these habitats free from intensive human interference so they may restore naturally to promote ecological balance. 

First coined as an academic term in 1998 by American conservation biologists Michael Soulé and Reed Noss, the concept centers around the pillars of “cores, corridors, and carnivores.”

In addition to reintroducing native plants and animals, rewilding projects often include other steps such as providing connectivity between such different habitats for safe animal passage and protecting the area from human-related threats such as hunting, pollution, and development. Essentially, rewilding involves returning an area to as close to its natural state as possible. It operates under the fundamental assumption that “nature knows best” and if left alone, regions can successfully rebalance themselves independently. 

What are the benefits?

Natural ecosystems operate under a sensitive balance of interactions between organisms. Just like the flap of a butterfly’s wing can theoretically initiate a tornado, small changes in an ecosystem can wreak havoc. Speaking of butterflies, the loss of beavers in the southeast of the North American continent led to the loss of critical habitat and food sources for some of the rarest pollinators, which has impacts for other important plant and animal species, and ultimately can threaten even human food systems.  Rewilding attempts to restore nature’s balance to rectify these disruptions. 

In case studies, rewilding has been shown to have many benefits. One Cornell study found that allowing 30 percent of the world’s most precious ecosystems to be  fully restored could prevent 70 percent of expected species extinctions.  

Conservation biologist and butterfly researcher Nick Haddad points out that “restoration of the rarest butterflies will not happen if the focus is on the rare butterflies alone. They are part of complex, degraded ecological systems. The most positive outcomes for restoration and recovery of the rarest butterflies have come only after the restoration of whole systems.” In the case of the St. Francis Satyr, one of those rare butterflies that were near extinction, it was only after the reintroduction of beavers helped to restore the surrounding wetlands ecosystem that the butterfly’s population also began to rebound.

If the moral imperative to keep the Earth’s biosphere healthy and vibrant is not compelling enough, that loss of biodiversity is also a loss of potential new food sources, new medicines, or even new design innovations inspired by the tiniest creatures.  For example, we recently wrote about the rediscovery of a forgotten heat tolerant species of coffee that might prove critical to keeping the warming world caffeinated. Turning previously farmed land back to wild habitat also holds immense carbon sequestration potential. Rewilding is an essential tool in these efforts. 

Rewilding success stories

Our Yellowstone example is one of the most famous, but it’s not the only place rewilding has been successful. In Europe, the reintroduction of wild bison has been tremendously beneficial for many regions. In Spain, the grazing animals are reducing fire risk by eating brush and grasses. The organization Rewilding Europe is furthering this effort by providing training courses on how to implement the benefits of rewilding. 

Bison are considered a keystone species, one critical to the ecological balance of an ecosystem. They are a big part of rewilding initiatives in the US as well. In Oklahoma’s Tallgrass Prairie Preserve, 2,500 bison have been reintroduced to the area and their turning, rooting, and grazing of the land coupled with migration help give rise to greater biodiversity. They are also helping to bring back “lost crops.” These crops were once a vital resource for Indigenous communities, but colonization and modern agriculture have nearly driven them to extinction. Bison’s turning of the land has created an environment for seeds to thrive and promoted the growth of plants like barley (Hordeum pusillum) and maygrass (Phalaris caroliniana). 

Along with wolves and bison, elephants are another keystone species. When reintroduced to Virunga National Park in the Democratic Republic of the Congo, they helped destroy invasive growth and gave room for grazing animals and wild species such as buffaloes and warthogs to return to the park after a decades-long hiatus. Wes Sechrest, CEO and chief scientist at Global Wildlife Conservation says, “This is a really incredible example of rewilding our planet by giving nature a bit of help and then letting the elephants, in this case, take care of the rest.”

Even Chernobyl, famous as a site for human environmental disaster, is witnessing the power of habitat resilience in human-free conditions. The nuclear site will not be habitable for humans for thousands of years, but it is now home to thriving wild horses, foxes, deer, and boar. 

These successful trials have inspired other regions to look into rewilding as a viable environmental solution. Following success in Montana and Wyoming, Colorado has voted to reintroduce wolves as well and a movement is underway by the Scottish Rewilding Alliance to create policies that would push Scotland to become the world’s first “rewilding nation.”

You can even practice small-scale rewilding in your own backyard. Researchers from the University of Quebec at Trois-Rivières found that reducing the intensity of trimming lawns in urban areas can also reduce pests and weeds that cause allergies. It also provides a more bountiful habitat for insects like butterflies and bees that are facing serious habitat loss. 

Striking an Optimal Balance

Based on biologist E. O. Wilson’s pulitzer prize winning 2016 book, Half Earth: Our Planet’s Fight for Life, the Half-Earth project advocates the preservation of fifty percent of the Earth’s surface area, and has mapped it out.  Dr. Wilson, also known as the father of biodiversity, argues that if we want to preserve a vibrant ecosphere and keep our planet habitable for the majority of species alive today – including humans – this type of conservation effort is imperative.  While this seems like a massive undertaking and certainly has critics, putting habitat preservation and thoughtful stewardship into the center of our relationship to this planet, and having a specific, if audacious, goal can give us direction.  

Humans are a part of nature too.  In fact, indigenous cultures are often the best stewards of the land, and other thoughtful low-impact human uses of natural environments can lead to mutually beneficial biodiversity.  Dr. Jane Goodall explained this beautifully in a thoughtful essay reflecting on 2020.  She writes,  

As I learned in the rainforest, losing one small species may not seem to matter, but it may be the major food source of another species. And then you get a ripple effect that can lead to ecosystem collapse. We try to separate ourselves and live in a bubble, but whether we like it or not, humans are part of the natural world and depend on it.

It is time to end the thoughtless destruction and extractive development of the planet, and concepts like rewilding – returning degraded ecosystems to homeostasis by reintroducing keystone species into the wild – will help restore habitats and bring our planet into an optimal balance.