For more than 100 years, the US government has conducted lethal control of native wildlife, to benefit livestock producers and to enhance game populations, especially in the western states. Since 2000, Wildlife Services (WS), an agency of the US Department of Agriculture, has killed 2 million native mammals, predominantly 20 species of carnivores, beavers, and several species of ground-dwelling squirrels, but also many nontarget species. Many are important species in their native ecosystems (e.g., ecosystem engineers such as prairie dogs and beavers, and apex predators such as gray wolves). Reducing their populations, locally or globally, risks cascading negative consequences including impoverishment of biodiversity, loss of resilience to biotic invasions, destabilization of populations at lower trophic levels, and loss of many ecosystem services that benefit human society directly and indirectly.
You don’t have to look far to see the woolly influence of sheep on our cultural lives. They turn up as symbols of peace and a vaguely remembered pastoral way of life in our poetry, our art and our Christmas pageants. Wolves also rank high among our cultural icons, usually in connection with the words “big” and “bad.” And yet there is now a debate underway about substituting the wolf for the sheep on the (also iconic) green hills of Britain.
The British author and environmental polemicist George Monbiot has largely instigated the anti-sheep campaign, which builds on a broader “rewilding” movement to bring native species back to Europe. Until he recently relocated, Mr. Monbiot used to look up at the bare hills above his house in Machynlleth, Wales, and seethe at what Lord Tennyson lovingly called “the livelong bleat / Of the thick-fleeced sheep.” Because of overgrazing by sheep, he says, the deforested uplands, including a national park, looked “like the aftermath of a nuclear winter.”
“I have an unhealthy obsession with sheep,” Mr. Monbiot admits, in his book “Feral.” “I hate them.” In a chapter titled “Sheepwrecked,” he calls sheep a “white plague” and “a slow-burning ecological disaster, which has done more damage to the living systems of this country than either climate change or industrial pollution.”
The thought of all those sheep — more than 30 million nationwide — makes Mr. Monbiot a little crazy. But to be fair, sheep seem to lead us all beyond the realm of logic. The nibbled landscape that he denounces as “a bowling green with contours” is beloved by the British public. Visitors (including this writer, otherwise a wildlife advocate) tend to feel the same when they hike the hills and imagine they are still looking out on William Blake’s “green and pleasant land.” Even British conservationists, who routinely scold other countries for letting livestock graze in their national parks, somehow fail to notice that Britain’s national parks are overrun with sheep.
Mr. Monbiot detects “a kind of cultural cringe” that keeps people from criticizing sheep farming. (In part, he blames children’s books for clouding vulnerable minds with idyllic ideas about farming.) Sheep have “become a symbol of nationhood, an emblem almost as sacred as Agnus Dei, the Lamb of God,” he writes. Much of the nation tunes in ritually on Sunday nights to BBC television’s “Countryfile,” a show about rural issues, which he characterizes as an escapist modern counterpart to pastoral poetry. “If it were any keener on sheep,” he says, “it would be illegal.”
The many friends of British sheep have not yet called for burning Mr. Monbiot at the stake. But they have protested. “Without our uplands, we wouldn’t have a UK sheep industry,” Phil Bicknell, an economist for the National Farmers Union pointed out. “Farmgate sales of lamb are worth over £1bn” — or $1.7 billion — “to U.K. agriculture.” The only wolves he wanted to hear about were his own Wolverhampton Wanderers Football Club. A critic for The Guardian, where Mr. Monbiot contributes a column, linked the argument against sheep, rather unfairly, to anti-immigrant nativists, adding “sheep have been here a damn sight longer than Saxons.”
Mr. Monbiot acknowledges the antiquity of sheep-keeping in Britain. But the subjugation of the uplands by sheep, he says, only really got going around the 17th century, as the landlords enclosed the countryside, evicted poor farmers, and cleared away the forests from the hillsides and moorlands, particularly in Scotland. Britain is, he writes, inexplicably choosing “to preserve a 17th-century cataclysm.” The sheep wouldn’t be in the uplands at all, he adds, without annual taxpayer subsidies, which average £53,000 per farm in Wales.
He proposes an end to this artificial foundation for the “agricultural hegemony,” to be replaced by a more lucrative economy of walking and wildlife-based activities. He also argues for bringing wolves back to Britain, for reasons both scientific (“to reintroduce the complexity and trophic diversity in which our ecosystems are lacking”) and romantic (wolves are “inhabitants of the more passionate world against which we have locked our doors”). But he acknowledges that it would be foolish to force rewilding on the public. “If it happens, it should be done with the consent and active engagement of the people who live on and benefit from the land.”
Elsewhere in Europe, the sheep are in full bleating retreat, and the wolves are resurgent. Shepherds and small farmers are abandoning marginal land at an annual rate of roughly a million hectares, or nearly 4,000 square miles, according to Wouter Helmer, co-founder of the group Rewilding Europe. That’s half a Massachusetts every year left open for the recovery of native species.
Wolves returned to Germany around 1998, and they have been spotted recently in the border areas of Belgium, the Netherlands and Denmark. In France, the sheep in a farming region just over two hours from Paris suffered at least 22 reported wolf attacks last year. But environmentalists there say farmers would do better protesting against dogs, which they say kill 100,000 sheep annually. Wolves are now a protected species across Europe, where their population quadrupled after the 1970s. Today an estimated 11,500 wolves roam there.
Lynx, golden jackals, European bison, moose, Alpine ibex and even wolverines have also rebounded, according to a recent study commissioned by Rewilding Europe. Mr. Helmer says his group aims to develop ecotourism on an African safari model, with former shepherds finding new employment as guides. That may sound naïve. But he sees rewilding as a realistic way to prosper as the European landscape develops along binary lines, with urbanized areas and intensive agriculture on one side and wildlife habitat with ecotourism on the other.
In northern Scotland, Paul Lister is working on an ecotourism scheme to bring back wolves and bears on his Alladale Wilderness Reserve, where he has already planted more than 800,000 native trees. He still needs government permission to keep predators on a proposed 50,000-acre fenced landscape. That’s a long way from introducing them to the wild, on the model of Yellowstone National Park. Even so, precedent suggests that it will be a battle.
Though beavers are neither big nor bad, a recent trial program to reintroduce them to the British countryside caused furious public protest. (One writer denounced “the emotion-based obsession with furry mammals of the whiskery type.”) And late last year, when five wolves escaped from the Colchester Zoo, authorities quickly shot two of them dead. A police helicopter was deployed to hunt and kill another, and a fourth was recaptured. Prudently, the fifth wolf slunk back into its cage, defeated.
Rewilding? At least for now, Britain once again stands alone (well, alone with its 30 million sheep) against the rising European tide.
Social species, such as the African wild dog, require strict participation from group members to be successful. This strategy can enhance fitness benefits for the group, but also a higher critical threshold for extinction. Awareness of life history needs to guide management strategy. “Failure to consider the impacts of group dynamics may result in underestimation of critical threshold population sizes or densities required for population persistence,” the researchers write.
Carnivore management is not just a numbers game, Virginia Tech wildlife scientists assert in response to an article in the Jan. 10 issue of the journal Science that urged “minimum population densities be maintained for persistence of large carnivores, biodiversity, and ecosystem structure.”
“This type of approach may fail in social carnivore species,” said Kathleen Alexander, an associate professor of fisheries and wildlife conservation in the College of Natural Resources and Environment. “Predator management is incredibly complex and we need to be extremely cautious in applying blanket approaches which rely on securing some target number or density of individuals in an ecosystem.”
The research-based argument appears in a letter in the March 14 issue of Science and an article abstract in the October 2013 issue of the journal Population Ecology.
“Life history strategy, including number of offspring, lifespan, diet, and behavior that evolves from ecological pressures of the species in question should also guide management approaches,” wrote Alexander and Claire E. Sanderson, a postdoctoral associate in fisheries and wildlife conservation, in the Science letter.
The research published in Population Ecology evaluated 45 solitary and social medium and large carnivore species and their key life history attributes, population trends, and identified the presence of factors that increase the potential for extinction.
Disturbingly, 73 percent of carnivore species — both social and solitary — were declining, observed Sanderson, Sarah Jobbins, also a postdoctoral associate, and Alexander.
“Social carnivores appeared to be particularly vulnerable with 45 percent threatened by infectious disease but only 3 percent of solitary carnivores similarly impacted,” they report. “In this, increased contact between individuals, disease-related mortality, and loss of individuals below some critical threshold seems to be the issue, pushing social carnivores closer to the brink of extinction.”
Reporting on their research on social carnivores, Sanderson, Jobbins, and Alexander said in the article, “Highly cohesive social species, like African wild dog, require strict participation from all group members … in all areas of life, including predator avoidance, reproductive success, hunting, and survivorship. This life-history strategy can result in enhanced fitness benefits for the group, but also a higher critical threshold for extinction.”
“The number of individuals in the group then becomes the critical factor influencing population persistence,” said Sanderson.
For example, rabies and distemper have caused local extinction of African wild dog in regions of Africa. Even in a large population, transmission of an infectious disease from only a few infected individuals can result in sufficient mortality to push groups below a critical threshold, ultimately threatening population persistence, the researchers report.
It has been found in certain ecosystems that when wild dog packs are reduced to less than four individuals, they may be unable to rear pups because of trade-offs between specialized roles, such as pup guarding and hunting.
“While aggregation of conspecifics may be beneficial for reproduction, hunting, and vigilance, social living is a disadvantage when it comes to transmission of disease,” according to Alexander’s research.
Also a wildlife veterinarian, she cofounded the Centre for Conservation of African Resources: Animals, Communities and Land Use, in Kasane, Botswana and has been conducting research in Africa since the late 1980s.
“Failure to consider the impacts of group dynamics may result in underestimation of critical threshold population sizes or densities required for population persistence,” Sanderson, Jobbins, and Alexander write.
Alexander and Sanderson conclude in their letter in Science, “We urge consideration of life-history strategy and social behavior in the development of carnivore management strategy.”
W. J. Ripple, J. A. Estes, R. L. Beschta, C. C. Wilmers, E. G. Ritchie, M. Hebblewhite, J. Berger, B. Elmhagen, M. Letnic, M. P. Nelson, O. J. Schmitz, D. W. Smith, A. D. Wallach, A. J. Wirsing. Status and Ecological Effects of the World’s Largest Carnivores. Science, 2014; 343 (6167): 1241484 DOI:10.1126/science.1241484
Claire Elizabeth Sanderson, Sarah Elizabeth Jobbins, Kathleen Ann Alexander.With Allee effects, life for the social carnivore is complicated. Population Ecology, 2013; DOI: 10.1007/s10144-013-0410-5
Virginia Tech (Virginia Polytechnic Institute and State University). “Preserving large carnivores in ecosystem requires multifaceted approach.” ScienceDaily. ScienceDaily, 13 March 2014. <www.sciencedaily.com/releases/2014/03/140313142447.htm>.
Last week the kids and I found a wolverine track in the snow, just a few kilometres from my home. The sun was shining, the air was crisp and life suddenly felt different. The silent forest around me became transformed, from a bland backdrop to a dynamic living ecosystem. The encounter was unexpected, a rarity, a treasure; something that transformed just another family outing to “the day we saw that wolverine track”.
As both a scientist and a conservationist I have worked with large carnivore related issues for almost my entire professional life. Studying their prey (roe deer), studying the predator species themselves (including Eurasian lynx, leopards and jaguars), and studying their interactions with people, has taken me to study sites all across Europe, from the Barents Sea to the Adriatic, and beyond to India and Brazil.
Large carnivores are not an easy career path. For the scientist part of me, they are difficult and expensive to study. Working on rodents would certainly have allowed me to gain more scientific kudos. For the conservationist part of me they are associated with a constant round of challenges and conflicts. So why do I do it?
Fascination is clearly amajor part of the answer. The more I learn about how these animals live their lives the more I appreciate them as masterpieces of evolutionary adaptation. They also trigger some emotional responses deep inside.
The combination of grace, power, silence, resilience and adaptability in such a beautiful packaging can only induce a sense of awe. These animals demand your respect simply by looking at you. They are also truly wild.
Completely independent of us humans, unapologetic about their actions, their persistence in our modern urbanised world provides a refreshing reminder that there is still some wildness left in nature. Predators above all other species remind us that nature is still something of a dynamic process and made up of interactions rather than just being static scenery. The idea that nature is something bigger than us humans and that it still not tamed provides a refreshing tonic to human arrogance and egotism.
However, many of these characteristics are also the source of conflicts. The sources of my fascination can easily become another person’s frustrations or fears. Predators don’t always make easy neighbours, and many rural people living in their proximity experience very real problems.
Working for the conservation of these species involves confronting these conflicts and trying to find ways to minimise them. And the challenge of responding to this is probably my second motivation to work with these species. The challenge is even greater considering that most of my work is in Europe. Europe is a crowded continent, with 500 million people, and no true wilderness areas. There is no “over there” with more space. If we want large carnivores, they have to be “here”; in the same landscape where people live, work and play.
Integrating these species into the fabric of our modern landscape is probably the greatest example of land sharing that has ever been attempted in conservation. The Large Carnivore Initiative for Europe, of which I am a member, is trying to find ways to facilitate this integration of large carnivores into multi-use landscapes that simultaneously provide for the needs of human food production, recreation and biodiversity conservation.
And judging by present trends, the carnivores are succeeding, although there is still a long way to go. Many conflicts persist, and some are escalating. Finding solutions is going to require patience, ingenuity and a willingness to make compromises. Although research can provide some guidance, there is going to be a lot of trial and error because quite simply this experiment has never been tried before. For almost the entirety of human history we have been at a state of war with these species. We are now trying to find a way to coexist with them, although nobody knows how this coexistence is going to look in the end. Who could resist being a part of such a process?
John Terborgh, Research Professor in the Nicholas School of the Environment and Earth Sciences at Duke University; Director of the Duke University Center for Tropical Conservation
In this presentation, Dr. Terborgh draws on his decades of ecological research in the Neotropics to explain how biological interactions intricately regulate biodiversity. Hypotheses on the maintenance of tropical forest diversity abound, but it is becoming increasingly recognized that interspecific interactions are vital to sustaining the rich diversity the tropics are famous for. Dr. Terborgh offers ecological insights on the regulation of biodiversity and describe how interactions between primary producers, herbivores, and their predators contribute to the richness of tropical forests.
PGE’s interdisciplinary Spring conference, “Conserving More Than Carbon: Valuing Biodiversity in a Changing World”, addressed the current state of knowledge of tropical forest diversity and outlooks for its protection.
In addition to preserving biodiversity for future generations, the Natura 2000 Network provides a wide range of other important benefits to society and the economy via the flow of ecosystem services.
Healthy freshwater ecosystems, for instance, provide clean water and help remove pollutants from the surrounding countryside. Intact wetlands act as natural buffers against floods, soaking up excess rainwater. Peat bogs help fix and store carbon dioxide, the number one cause of climate change, whilst forests improve air and soil quality.
In addition, Natura 2000 helps to conserve natural pollinators, preserve landscape and amenity values, as well as support tourism and recreation. By offering attractive breathing spaces, it provides ample opportunities for economic activities based on these valuable natural assets.
Healthy and well-functioning ecosystems sustained within protected areas can increase not only the range of ecosystem services, but also the resilience of ecosystems to resist and adapt to natural disasters and disturbances (e.g. climate change) also beyond the site level.
However, for the Natura 2000 Network to deliver its full economic and biodiversity potential, it is essential that every effort is made to restore the sites to a more favourable condition. Positive conservation action is vital if we are to safeguard Europe’s biodiversity for future generations and maximise the socio-economic benefits that flow from healthy
As human populations expand and use the land differently, they are having an impact on the plants and animals that share that land with them. Conservation biologists have been working for decades to try and document the ways in which these changes are affecting species, and to try and develop indicators that can be used to monitor these changes over time. However, previous work has tended to focus on certain species (e.g. bats, birds), neglecting other important groups such as insects, and have been biased towards certain habitats (e.g. tropical rainforest).
A new project in partnership between University College London, Imperial College London, the University of Sussex, UNEP World Conservation Monitoring Center and Microsoft Research, aims to improve on previous studies and develop a model for understanding how whole biological communities respond to human pressures across the globe. Collating high-quality data from hundreds of peer-reviewed papers, in addition to unpublished data direct from field researchers, the PREDICTS team hope to investigate local patterns of biodiversity at a global scale, and improve our understanding of how whole ecosystems respond to human pressures such as land-use change.
Biodiversity Declines Major global loss of biodiversity is underway, and we have good reason to believe humans are responsible. The current extinction rate of species is estimated to be 1000 times higher than long-term historical averages, although large fluctuations in this in the past were also common. Humans have altered the world enormously, converting forests and savannas into farmland and housing. Virtually all ecosystems have been changed substantially – most biomes have lost between 20 and 50% of land to human uses. Humans have also exploited natural resources for wood, food, medicine and social reasons, and in many cases overexploitation has lead to major species declines and extinctions. Globally, it is estimated that 12% of bird species, 23% of mammals and 32% of amphibians are threatened with extinction, with many of these species suffering population declines and a reduction in genetic diversity, which may exacerbate the effect of human impacts. Even optimistic projections indicate continued human pressure on biodiversity from a range of different sources including hunting and habitat destruction. Many of the pressures currently placed on global biodiversity, such as land-use change, pollution and the introduction of invasive species, are set to continue or intensify over coming decades.
Biodiversity is a valuable asset to humans for many reasons, not least its considerable economic value. Biodiversity contributes to human well-being by providing ecosystem services such as food (crops and livestock), fresh water, timber, natural hazard protection, air quality, climate regulation, prevention of erosion, as well as cultural benefits such as the aesthetic and recreational use of biodiversity. The exact relationship between biodiversity and ecosystem services is still relatively poorly understood, as it represents a complex interaction of many factors, which may vary from habitat to habitat. Many researchers suspect there may be threshold effects, with a sudden collapse of ecosystems, and a consequent loss of the services they provide, once a threshold number of species is lost. Others suggest certain ‘keystone’ species may be more important for ecosystem function. What is clear, however, is that healthy, functioning ecosystems are key to human health and well being. A greater understanding both of how biodiversity contributes to ecosystem function and ecosystem services, and of how biodiversity is likely to respond to continued anthropogenic pressures is sorely needed.
Improving Indicators One central issue to studying and increasing our understanding of how ecosystems respond to human pressures is selecting species, populations or ecosystems to act as indicators of overall trends. It is simply not possible to monitor all populations of all species, and conservationists have traditionally relied upon indicator species and ecosystems as a measure of the overall health of biodiversity. In many cases these indicators were initially selected out of convenience meaning that well-studied species, communities and biomes are hugely overrepresented in the data available. However, species’ traits are likely to influence how they respond to human pressures, and a broader geographical and taxonomic view is needed to take the next step in our understanding.
Projecting Responses of Ecological Diversity in Changing Terrestrial Systems
The PREDICTS project aims to address some of these issues by performing a meta-analysis of species responses to different human pressures, covering as broad a taxonomic and geographical data set as is available. The PREDICTS team are collecting data from published papers; however, they also hope to draw on rich datasets held by ecologists which are simply too large to have been published in full. If you are an ecologist and believe you may have data that could be used for this project, please visit the PREDICTS website to find out more. They have already collated over 800,000 biodiversity records covering more than 15,000 species. These data are being combined to form a database that will be used to answer a number of key questions about biodiversity and anthropogenic change. In particular, the PREDICTS project is interested in investigating how different taxonomic groups respond, how responses differ in different biomes and with different intensities of human pressure. They also plan to investigate how different measures of biodiversity (e.g. species richness, evenness, abundance etc) may respond differently in different species, regions and for different human pressures.
By combining data from many species and sites, across a variety of different intensities of human pressure, PREDICTS hopes to develop a deeper understanding of how different factors interact to determine species responses. From this they hope to make predictions about how biodiversity may respond to different projected future scenarios, and thus provide insights for science policy.
Turning Science into Policy
We are faced with an increasingly difficult global situation, as human populations expand, the climate changes and biodiversity declines. What makes this situation more difficult still is that we need to make decisions now and over the next few years that will impact a generation, but for which we still have insufficient data to know for sure what’s best. Making projections for climate change, human population expansions and changes in the exploitation of biodiversity is difficult. Making projections for how biodiversity will respond to those changes is even more difficult still, but it is a task we must attempt if we are to make informed decisions about the future of our planet. PREDICTS hopes to utilise what data we do have to make synthesise a more in depth and holistic understanding of how ecological communities respond to human impacts, which can be used to make predictions that will help inform science policy makers globally.