Press Release: Hunting by humans as big a threat as habitat change in ‘emptying the landscape’ of large herbivores
The decline or likely extinction of large herbivores such as rhinoceroses, hippos, zebras, camels and elephants threaten to create ‘empty landscapes’ in some of the world’s most diverse ecosystems.
“We are facing the prospect that in 20 years some of these large herbivores will have virtually disappeared from many of the world’s grasslands, savannah, deserts and forests, especially in India, Southeast Asia and Africa,” said Dr Thomas Newsome, from the School of Biological Sciences at the University of Sydney.
Dr Newsome is a contributing author to the research findings published in Science Advances on 2 May.
An international team of wildlife ecologists led by Professor William Ripple, from Oregon State University, conducted an analysis of 74 of the world’s largest herbivores, defined as animals over 100 kilograms who consume vegetation to survive.
As a group, herbivores encompass about 4,000 known species and live in many types of ecosystems on every continent except Antarctica.
The researchers looked at key threats, the likelihood of extinction and the ecological consequences of decline.
The twin threat for herbivores is habitat change and hunting by humans. Hunting is for meat consumption, with an estimated 1 billion humans relying on wild meat, and for the global trade in animal parts.
“Australia’s large herbivores including giant kangaroos and hippopotamus-sized marsupials went extinct about 40,000 years ago, soon after people colonised the continent,” said Dr Newsome.
“Overhunting by people, climate change and altered fire regimes are the most likely causes, and the loss of these large herbivores resulted in dramatic changes to Australia’s vegetation.”
“The widespread loss of herbivores alive today will have a similarly incalculable impact. It would include less food being available for large carnivores such as lions and tigers and more frequent and intense wildfires because herbivores won’t be controlling the vegetation through grazing.
“They also won’t be fulfilling their role of helping to disperse seed as they graze and travel which will lead to much less diversity in the landscape including loss of habitat for many smaller species.”
In 1992 researcher Kent Redford from the University of Florida coined the term ‘empty forest’ to discuss the decline of animals in tropical forests. The new term ‘empty landscape’ recognises that the threat of species loss extends well beyond that habitat.
The report notes that 25 of the largest wild herbivores now occupy an average of only 19 percent of their historical ranges. Competition from livestock production, which has tripled globally since 1980, has reduced access to land, forage and water and raised the risk of the spread of disease.
The researchers call for a coordinated research effort focusing on threatened species in developing countries and the essential involvement of local people in managing protected areas.
The paper is open access and can be viewed HERE
Source: The University of Sydney
CORVALLIS, Ore. – The decline of the world’s large herbivores, especially in Africa and parts of Asia, is raising the specter of an “empty landscape” in some of the most diverse ecosystems on the planet. Many populations of animals such as rhinoceroses, zebras, camels, elephants and tapirs are diminishing or threatened with extinction in grasslands, savannahs, deserts and forests, scientists say.
An international team of wildlife ecologists led by William Ripple, Oregon State University distinguished professor in the College of Forestry, conducted a comprehensive analysis of data on the world’s largest herbivores (over 100 kilograms, or 220 pounds, on average), including endangerment status, key threats and ecological consequences of decline. They published their observations today in the journal Science Advances.
The authors focused on 74 large herbivore species — animals that subsist on vegetation — and conclude that “without radical intervention, large herbivores (and many smaller ones) will continue to disappear from numerous regions with enormous ecological, social, and economic costs.”
Ripple initiated the study after conducting a global analysis of large-carnivore decline, which goes hand-in-hand, he said, with the loss of their prey. “I expected that habitat change would be the main factor causing the endangerment of large herbivores,” he said. “But surprisingly, the results show that the two main factors in herbivore declines are hunting by humans and habitat change. They are twin threats.”
The scientists refer to an analysis of the decline of animals in tropical forests published in the journal BioScience in 1992. The author, Kent H. Redford, then a post-doctoral researcher at the University of Florida, first used the term “empty forest.” While soaring trees and other vegetation may exist, he wrote, the loss of forest fauna posed a long-term threat to those ecosystems.
Ripple and his colleagues went a step further. “Our analysis shows that it goes well beyond forest landscapes,” he said, “to savannahs and grasslands and deserts. So we coin a new term, the empty landscape.” As a group, herbivores encompass about 4,000 known species and live in many types of ecosystems on every continent except Antarctica.
The highest numbers of threatened large herbivores live in developing countries, especially Southeast Asia, India and Africa, the scientists report. Only one endangered large herbivore lives in Europe (the European bison), and none are in North America, which, the authors add, have “already lost most of its large mammals” through prehistoric hunting and habitat changes.
The authors note that 25 of the largest wild herbivores now occupy an average of only 19 percent of their historical ranges. Competition from livestock production, which has tripled globally since 1980, has reduced herbivore access to land, forage and water and raised disease transmission risks, they add.
Meanwhile, herbivore hunting occurs for two major purposes, the authors note: meat consumption and the global trade in animal parts. An estimated 1 billion humans subsist on wild meat, they write. “The market for medicinal uses can be very strong for some body parts, such as rhino horn,” said Ripple. “Horn sells for more by weight than gold, diamonds or cocaine.” Africa’s western black rhinoceros was declared extinct in 2011.
“The causes of the decline of some large herbivores are difficult to remedy in a world with increasing human populations and consumption,” said co-author Taal Levi, assistant professor in Oregon State Department of Fisheries and Wildlife. “But it’s inconceivable that we allow demand for horns and tusks to drive the extirpation of large herbivores from otherwise suitable habitat. We need to intensify the reduction of demand for such items.”
The loss of large herbivores suggests that other parts of wild ecosystems will diminish, the authors write. The likely consequences include: reduction in food for large carnivores such as lions and tigers; diminished seed dispersal for plants; more frequent and intense wildfires; slower cycling of nutrients from vegetation to the soil; reductions in habitat for smaller animals including fish, birds and amphibians.
“We hope this report increases appreciation for the importance of large herbivores in these ecosystems,” said Ripple. “And we hope that policymakers take action to conserve these species.”
To understand the consequences of large herbivore decline, the authors call for a coordinated research effort focusing on threatened species in developing countries. In addition, solutions to the decline of large herbivores need to involve local people. “It is essential that local people be involved in and benefit from the management of protected areas,” they write. “Local community participation in the management of protected areas is highly correlated with protected area policy compliance.”
In addition to Ripple and Levi, co-authors include Christopher Wolf and Luke Painter of Oregon State; Rodolfo Dirzo of Stanford University; Thomas M. Newsome of The University of Sydney in Australia; Kristoffer T. Everatt and Graham I.H. Kerley of Nelson Mandela University in South Africa; Mauro Galetti of the Universisade Estadual Paulista in Brazil; Matt W. Hayward of Nelson Mandela University and Bangor University in the United Kingdom; Peter A. Lindsey of Panthera (nonprofit organization) and the University of Pretoria in South Africa; David W. MacDonald, Yavinder Malhi and Christopher J. Sandom of the University of Oxford in the United Kingdom; John Terborgh of Duke University; Blaire Van Valkenburgh of UCLA.
The paper is open access and can be viewed HERE
Source: Oregon State University
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University of Sydney Press Release 17/02/2015
Allowing dingoes to return to Sturt National Park in NSW and researching the results may be the key to managing the future of dingoes and many threatened native mammals, University of Sydney researchers believe.
“Our approach is purposefully bold because only an experiment on this scale can resolve the long-running debate over whether the dingo can help halt Australia’s biodiversity collapse and restore degraded rangeland environments,” said Dr Thomas Newsome from the School of Biological Sciences at the University of Sydney and lead author of an article published today in Restoration Ecology.
Written with Dr Newsome’s colleagues from the University of Sydney and other universities in Australia and in America, where he completed a Fulbright Scholarship, the article outlines how the experiment could be undertaken.
“Half the world’s mammal extinctions over the last two hundred years have occurred in Australia and we are on track for an acceleration of that loss. This experiment would provide robust data to address an issue of national and international significance,” said Dr Newsome.
“Our approach is based on dingoes’ ability to suppress populations of invasive predators such as red foxes and feral cats that prey on threatened native species. Dingoes can also control numbers of introduced species such as European wild rabbits, feral pigs and goats or native herbivores such as kangaroos, that in high numbers can contribute to rangeland degradation.”
“There are major challenges, including convincing livestock producers and local communities to support the experiment, but we currently have almost no understanding of the impact of increased dingo populations over large areas.”
“It took 20 years of debate in America before wolves were reintroduced into Yellowstone National Park and central Idaho – so let’s start having the conversation.”
The researchers suggest allowing dingoes to recolonise Sturt National Park in north-western NSW. One strategy to achieve this would be to realign a small section of the 5500 km dingo-proof fence on the northern and western sides of Sturt National Park and then rebuild it on the southern and eastern sides of the park. This would effectively place Sturt National Park on the northern side of the dingo-fence and allow dingoes to naturally recolonise from South Australia and Queensland where dingoes are more common.
NSW law currently requires the control of dingoes in Sturt National Park so that would have to change to allow the experiment to proceed. The park would be monitored before the realignment of the fence took place, to establish existing conditions. Afterwards the sites where dingoes naturally recolonise within the park would be compared to multiple sites outside the park without dingo populations.
“Large carnivores such as wolves, bears, lynx and wolverines are returning in many parts of the world, especially North America and Europe. The future survival of large carnivores will depend on our understanding of their potential to increase biodiversity, local tourism and the health and productivity of ecosystems,” said Dr Newsome.
“Just one possibility is that if dingo recolonisation to Sturt National Park successfully lowered numbers of feral cats and red foxes we could test whether this assists the reintroduction of locally extinct native mammals such as the greater bilby and burrowing bettong.”
The researchers also suggest it would be worthwhile considering reintroduction or recolonisation studies elsewhere, such as sites south of the dingo proof fence in South Australia.
You can view the paper
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