Why Reintroduce Large Carnivores?

According to a report published by WWF, the UK is one of the most nature-depleted nations on earth, with only a fraction of its wildlife and habitats remaining after centuries of farming and industry.  Its large carnivores are long gone – the brown bear probably became extinct in the early medieval period, around 1,500 years ago, the lynx around the 16th century and the wolf in the 18th century, through a combination of persecution and loss of habitat.

Background to reintroduction

The idea of reintroducing wolves to the UK, specifically the Scottish Highlands (realistically the only place in Britain currently with enough space for a viable population) is not new. It was first proposed in the 1960s as a way of controlling the burgeoning deer population and encouraging regeneration of Scotland’s native pinewoods, suppressed by hundreds of years of overbrowsing. The idea gained wider publicity and support following the high profile reintroduction of wolves to Yellowstone National Park in the USA, in 1995.

Since then, due to a combination of legal protection and population-level conservation measures, aided by migration of people from rural areas to towns and cities, wolves have made a remarkable recovery in Europe, expanding from strongholds in eastern and central Europe and Italy to naturally recolonise France, Switzerland, Germany and in recent years, Denmark, the Netherlands, Belgium and even Luxembourg.  Lynx and brown bears have also increased in numbers and range, assisted by reintroduction programmes.   The UK is one of the last European countries without any large carnivores.

Rewilding

During this time, a new approach to conservation has developed alongside traditional methods; rewilding seeks to restore natural ecological processes, usually at landscape-scale, to rebuild resilient and self-sustaining ecosystems where minimal intervention is required. In Europe, this can be as simple as allowing large herbivores and their predators to recolonise  agricultural land abandoned as the human population becomes increasingly urbanised.  In Britain, where many keystone species (animals with a disproportionate influence on their natural environment) are extinct and prevented from returning naturally by its island geography, a more proactive approach is needed, including reintroduction of species such as the beaver.  As mainstream awareness of rewilding as a possible solution to the climate emergency and a worsening biodiversity crisis grows, and government policy on nature and the environment is reshaped following withdrawal from the European Union, public perception of how the countryside should be managed may change, increasing opportunities and support for reintroductions. What is the case for returning Britain’s lost carnivores ?

Trophic cascades and the landscape of fear

One of the main arguments often used in support of reintroducing large predators, particularly wolves and lynx, to Britain, is that they cause trophic cascades – by reducing the abundance and altering the behaviour of their prey, they release vegetation from browsing and grazing pressure, which has beneficial consequences for biodiversity.  A popular video entitled “How Wolves Change Rivers” has been circulating on the Internet for several years, claiming that reintroduction of wolves to Yellowstone has indirectly physically altered rivers, by reducing deer browsing pressure and increasing riverside vegetation, which in turn reduces riverbank erosion and allows beavers to recolonise, building dams which slow the water flow and create pools, benefitting a range of birds, insects, fish and animals. You can watch the video here.

The truth may be slightly different. Whilst elk numbers in Yellowstone have decreased since wolf reintroduction and aspen, cottonwoods and willows have recovered in some areas, it is not clear to what extent this is down to wolves. The reduction in elk may also be due to a combination of an increase in cougars and grizzly bears and severe droughts in the decade after wolf reintroduction, and human harvest of elk herds migrating out of the Park during unusually harsh winters.  Scientists also disagree on whether wolves have changed the behaviour of elk by causing them to spend less time in areas where there is a risk of being attacked (the ‘landscape of fear’). Similarly, research in Europe suggests that returning lynx do not always influence behaviour of roe deer.  In addition, the concept of ‘apex’ predators limiting numbers of herbivore prey species and indirectly benefiting vegetation etc. does not apply to all natural systems. In many situations, herbivores are kept in check by availability of food. Research suggests that large carnivores may not regulate populations of herbivores that are at carrying capacity (the maximum number that can be supported by their environment).

Whilst Yellowstone is a near pristine ecosystem where wolves and other large predators are largely free from conflict with humans and can fulfil their ecological role, European conservation integrates biodiversity and human activity rather than setting aside wilderness areas, even in National Parks.  As a result, numbers of wolves, bears and lynx are usually limited by ‘social carrying capacity’ (the number that will be tolerated by human communities) rather than at ecologically functional levels, and therefore do not significantly influence numbers of deer and other prey species. Under these conditions, there is no strong evidence that the presence of large carnivores benefits biodiversity. 

This is likely to be even more apparent in Britain, where there is limited space and National Parks are largely managed as cultural landscapes rather than for conservation of nature. With deer populations estimated to be higher than at any time since the last Ice Age, it is unlikely that  populations of predators large enough to serve the ecological functions desired of them could become established without causing intolerable conflicts with humans - the presence of large carnivores is not compatible with unattended grazing of livestock as currently practiced in Britain. Whether justified or not, there is also concern for human safety. Wolves and lynx may not be the ecological panacea that many people think them to be.

Benefits of reintroduction

If wolves and lynx (brown bears have not so far been seriously considered as a candidate for reintroduction, primarily because of concerns about attacks on people, but also lack of suitable habitat with adequate food and undisturbed winter denning sites) will not significantly reduce current deer numbers, what would be the benefits of reintroduction of these species?

Regulating deer populations

Although returning wolves and lynx would not reduce numbers of deer to the extent that is needed, evidence suggests that where herds are culled to levels at which natural regeneration of woodland can take place, as is already happening on some estates in Scotland, reintroduction of large carnivores may help to stabilise the ecosystem by preventing deer numbers from returning to their former abundance.  The emphasis on returning other large herbivores (such as wild boar, bison and European elk) as ecosystem engineers as part of large-scale rewilding also requires a method of keeping numbers of these species relatively stable at ecologically beneficial levels, and the return of their natural predators may reduce the need for intensive management.

Landscape scale conservation

The requirements of wolves and lynx for large territories and adequate prey would provide a focus for restoring large areas of connected wild or semi-wild land. Such large areas have been shown to be crucial for maintaining biodiversity. Within these areas, smaller reserves can be managed for conservation of specific species. 

Mesopedator control

Wolves and lynx sometimes kill smaller predators such as red foxes, which may be seen as competitors, and may cause them to alter their feeding and territorial behaviour.  In the absence of large carnivores in the UK, these ‘mesopredators’ have a significant negative impact on species of conservation concern, such as ground-nesting birds. However, the conditions under which large carnivores limit mesopredators are not fully understood, and in some studies the presence of an apex predator actually increased numbers of foxes, possibly through increased availability of carrion.

Economic benefits

It is widely predicted that reintroducing wolves and lynx would benefit the economy through increased ecotourism, as has been demonstrated in Yellowstone (in 2017, the annual economic benefit of wolf restoration was estimated at over $65 million) and in parts of Europe where lynx have been reintroduced. The environmental benefit of thousands of people being able to visit Scotland to try and see wolves and lynx, instead of taking international flights to the USA and Europe is also worth considering.

Repairing the damage

Perhaps the greatest motivations for the return of large carnivores are aesthetic and ethical. In a Scottish context, wolves and lynx are unlikely to restore self-sustaining ecosystems and increase biodiversity on their own, but they have a symbolic value – embodying a concept of ‘wild nature’ that is highly desirable to many people. Returning these species is seen as restoring that wildness, and an ethical act of undoing the damage to our native flora and fauna caused by centuries of human activity.  Large carnivores are the ultimate test of our ability to coexist with nature - can we truly rewild without restoring our lost predators?

 

Interested in finding out more?  We recommend these books:

Yellowstone Wolves - Science and Discovery in the World's First National Park, edited by Douglas W. Smith, Daniel R. Stahler and Daniel R. McNulty. University of Chicago Press, 2020.

Large Carnivores and the Conservation of Biodiversity, edited by Justina C. Ray, Kent H. Redford, Robert S. Steneck & Joel Berger. Island Press, 2005.

Rewilding, edited by Nathalie Pettorelli, Sarah M. Durant and Johan T. du Toit. Cambridge University Press, 2019.

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Large carnivores are the ultimate test of our ability to coexist with nature - can we truly rewild without restoring our lost predators?