Re-wilding - How far is too far?

The U.K media's gone a bit re-wilding mad in the last couple of weeks after notoriously outspoken environmentalist George Monbiot published both this article and accompanying animation on the subject. He highlights the fact that "lions hunted reindeer across the frozen wastes of Britain until 11,000 years ago" and promotes re-wilding as a chance to reverse man's destructive impact on the natural world by reintroducing lost species and then "stepping back and letting nature get on with it".

The subject has provoked both excitement at the prospect of seeing some of our arguably more charismatic native species returned, as well as conflict over his suggestions to convert "unproductive" farmland to wilderness. Some have even criticized the motivations of his enthusiastic re-wilding promotion as being little more than "a cure for ecological ennui".

Re-wilding proposals range from bringing back extant species such as wild boar (hunted to extinction in the U.K in the 13^th Century), to as far back as the Pleistocene epoch, where the ancestors of African species such as elephants and lions once roamed Europe.

So which "wild" do we aim for, and how far back is too far for modern day landscapes to take?

The three C's

So what's different about re-wilding?

Well, the main contrast to your regular restoration practices, which typically seek to reverse relatively recent damages such as logging or heavy grazing, is that re-wildling works on a broader historical timescale, with an emphasis on reinstating large mammal species.

The practice of re-wilding is to reintroduce extant species (either captive bred or wild caught) back into their indigenous habitats. The focus is on restoring species that were extirpated from a region in historical times, meaning within the last several hundred years¹.

The defining features of re-wilding are described by Soulé and Noss as the "three C's":

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This stems from the theory that the structure and resilience of ecosystems is largely sustained by "top down" trophic interactions - the presence of Carnivores.

Then, because predators are typically wide-ranging, large areas of protected land - "Cores", are required in order to accommodate their foraging behaviours and seasonal movements.

Finally, because existing protected areas are often too small to adequately support certain megafauna, these cores must be linked by Corridors so that wide-ranging species do not become restricted to areas which are unable to sustain them.

From a less scientific perspective, re-wilding also addresses the aesthetic and ethical issues of our relationship with wilderness. Many would argue that we have a moral responsibility to try to repair some of the damage that we have inflicted on our environment. With re-wilding, this refers in particular to our almost total eradication of large carnivores from much of their natural ranges.

If we want to restore the "wild", however, we must first decide what we mean by that - which is no easy task! "Wilderness" has become more of a psychological term than an ecological one, and it's a concept that has been contemplated and debated over by some of the greatest minds of the environmental movement.

Emotions aside, however, determining the level of re-wilding that you want to achieve is not so much a case of what wild is, but when.

Re-wilding originated, and is still largely rooted in North America, where the commonly used benchmark for restoration is the arrival of Columbus in 1492.

So where do the lions and elephants come into this? Well, some scientists make the bold argument we should rewind even further than this: to the prehistoric era, and the late-Pleistocene arrival of the very first Americans...

The Pleistocene was characterized by the presence of an impressive range of megafauna, such as mastodons, sabre-toothed cats, giant ground sloths, dire wolves, and huge teratorn birds with 25-foot wingspans. All of these (and the majority of other megafauna) went extinct at the end of the Pleistocene.

The loss of these large mammals dramatically shaped subsequent ecological and evolutionary processes resulting, some would argue, in a serious imbalance in our current fauna⁷.

Pleistocene re-wilding is, therefore, the attempt to return ecosystems to their 13,000 year old state by reintroducing large vertebrate species.

You may have noticed a slight issue with this in that, most of these megafauna are extinct...so instead the idea is to reintroduce either:

This is already being attempted in some locations, such as the Siberian Pleistocene Park experiment which began in 1988 by introducing mega herbivores such as wood bison, Yakutian horses and musk oxen to an area of 16 square kilometres, with the hopes of recreating the grassland ecosystems of the Pleistocene⁹.

This all sounds quite reasonable, a few grazing species that used to be around there keeping the grass in check, probably not doing anyone any harm...but what if you throw a few lions into the mix...

Workable or laughable?

The real Pleistocene re-wilding controversy kicked off when Donlan et al. published a paper in Nature which outlined proposals to translocate African and Asian megafauna to North America to replace their extinct Pleistocene counterparts. The process would begin with modest restorations of surviving Pleistocene species such as the Bolson Tortoise to their prehistoric range, with a potential end goal of introducing species such as African cheetahs, Asian and African elephants, and lions into vast "Ecological History Parks" in economically depressed parts areas of the North American plains.

These seemingly outrageous suggestions sparked an inevitably fierce backlash.

Some claimed it was "only a slightly less sensational proposal" than Jurassic Park, and that both the modern-day proxies and the ecosystems into which they are reintroduced are "wrong", in that neither come close enough to resembling the animals or habitats that would have been present in the Pleistocene.

A key criticism was that merely recreating species compositions does not guarantee the restoration of ecological processes. The biggest concern therefore was not of failing to replicate Pleistocene ecosystems, but of generating new unexpected, and unwanted ecological interactions - resulting in "Frankenstein-like ecosystems" that now resemble neither a healthy present nor Pleistocene landscape^8,11.

Then you have the dangers of introducing novel parasites and diseases⁸, the costs of fencing and managing reserves, the costs of salaries for scientists and practitioners to run trial introductions, the potential of reducing ecotourism in Africa and Asia, the diminished appreciation of native fauna in favour of exotic species¹², the list goes on...

So what other defences do Donlan and his colleagues offer? Well, for one, they aim to revolutionize the current "doom and gloom" of wilderness preservation with a more proactive, "hands-on" approach to twenty-first century conservation biology. This is driven, in part, by the ethical responsibility of humans to redress not only our current eradication and detrimental effects on large vertebrates, but also our potential involvement in the Late Pleistocene extinctions. They see the preservation of our "global megafauna heritage" as a chance to rekindle some of the lost evolutionary and ecological potential that was lost 13,000 years ago.

It also provides opportunities to ensure the long-term survival of large mammal species by increasing worldwide populations, offering them greater potential to generate new phenotypic and genotypic variants, helping to bolster populations' abilities to adapt to global environmental change.

In terms of the dangers and logistics of such large-scale re-wilding, they outline much more detailed plans and justifications involving carefully managed ecosystem manipulations, extensive trial introductions, and case-by-case species and location evaluations a more extensive article here.

However, there is one problem which even the most dedicated supporters admit may be insurmountable - would the public ever really accept living in proximity to large predators? One only has to look at the situation with wolves in the U.S to see the strong polarity of opinions over the protection, reintroduction and culling of predatory species. If this is a problem in North America where there are still large areas of relatively uninhabited land, imagine the potential conflicts of returning large predators to the U.K...

Only in our wildest dreams?

Back in 1998 Soulé and Noss stated that "the greatest impediment to rewilding is an unwillingness to imagine it". But it seems to me that we're very keen to dream about it, and not so keen to do.

As is so often the case with environmental issues the main barrier has never really been the science but the politics. The key challenge will be in convincing farmers, landowners, planners, politicians, pressure groups and local and visiting public, and even some conservationists to accept living alongside large predators once again.

So whilst it's hard to envisage elephants roaming our relatively small island here in the U.K, perhaps we could find room for a few wild cats in the highlands?

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