In a recent paper we explored whether the expansion of golden jackal populations in Europe is linked to the widespread extirpation of the grey wolf.
Below is a copy of the abstract and you can view the open access paper HERE
Top-down suppression by apex predators can limit the abundance and spatial distribution of mesopredators. However, this phenomenon has not been studied over long time periods in human-dominated landscapes, where the strength of this process might be limited. Here, we used a multi-scale approach to analyse interactions between two canids in the human-dominated landscapes of Europe. We tested the hypothesis that the range expansion of golden jackals (Canis aureus) was triggered by intensive persecution and resulting decline of the apex predator, the grey wolf (Canis lupus). To do so, we (1) reviewed literature to reconstruct the historic changes in the distribution and abundance of the two canid species on the continental scale, (2) analysed hunting data patterns for both species in Bulgaria and Serbia, and (3) surveyed jackal persistence in eight study areas that became re-colonized by territorial wolves. The observed trends were generally consistent with the predictions of the mesopredator release hypothesis and supported the existence of top-down suppression by wolves on jackals. We observed inverse patterns of relative abundance and distribution for both canid species at various spatial scales. In most (seven out of eight) cases of wolf re-colonization of jackal territories, jackals disappeared or were displaced out or to the periphery of the newly established wolf home-ranges. We suggest that wolf extermination could be the key driver that enabled the expansion of jackals throughout Europe. Our results also indicate that top-down suppression may be weakened where wolves are intensively persecuted by humans or occur at reduced densities in human-dominated landscapes, which has important management implications and warrants further research.
The arguments focused on two key points:
- That dingo reintroduction proposals have been inspired largely by the reintroduction of wolves into Yellowstone National Park.
- That unstable climates in Australia will make if difficult for dingoes to exert strong effects on ecosystems via trophic cascades.
(see here for a definition of a trophic cascade, and below for an example of a dingo-induced trophic cascade).
In a paper published in the journal Food Webs, we responded to these criticisms and argued that (1) the case for dingo reintroduction has never been solely based on the reintroduction of wolves into Yellowstone National Park, and (2) that the climatic circumstances under which dingoes can provide net positive effects on ecosystems via trophic cascades are those that typically prevail in Australia.
We concluded that the case for dingo reintroduction in Australia remains strong, and urge managers and decision makers to consider the mounting evidence that dingoes can have positive effects on ecosystems before deciding whether or not to reintroduce dingoes into ecosystems where they have been extirpated by humans.
A dingo-induced trophic cascade (solid arrows).
If dingoes suppress large herbivores (e.g. kangaroos and emus), then grass and herb biomass is expected to increase. If dingoes suppress lower order predators (e.g. foxes and cats), then numbers of small mammals (e.g. mice), reptiles (e.g. goannas), and birds (e.g. parrots) are expected to increase. Invertebrates also may respond to improved vegetation conditions and contribute to soil quality. However, the strength of all interactions may be influenced by the extent of rainfall and fires (hashed arrows). Numbers represent the predicted sequence of events based on trophic cascade theory.
Since my last post I have been a co-author on two research papers on feral cats.
1. Legge S, et al (including Newsome TM) (2017) Enumerating a continental-scale threat: how many feral cats are in Australia? (Biological Conservation)
In this paper we found that feral cats cover over 99.8% of Australia’s land area, including almost 80% of the area of our islands.
“Australia’s total feral cat population fluctuates between 2.1 million when times are lean, up to 6.3 million when widespread rain results in plenty of available prey,” explains the lead author Dr Sarah Legge from The University of Queensland.
Furthermore, cat densities were found to be the same both inside and outside conservation reserves, such as National Parks, showing that declaring protected areas alone is not enough to safeguard our native wildlife.
This paper has now become the most heavily ‘e-cited’ paper in the journal Biological Conservation.
A full summary of the media generated can be found HERE
2. Molsher R, Newsome AE, Newsome TM, Dickman CR (2017) Mesopredator management: effects of red fox control on the abundance, diet and use of space by feral cats (PLOS ONE)
In this paper we investigated interactions between red foxes and feral cats in south-eastern Australia.
We used a fox-removal experiment to assess whether foxes affect cat abundance, diet, home-range and habitat use.
The results provide little indication that cats responded numerically to the fox removal, but suggest that the fox affects some aspects of cat resource use. In particular, where foxes were removed cats increased their consumption of invertebrates and carrion, decreased their home range size and foraged more in open habitats.
The results suggest that fox control programs could lead to changes in the way that cats interact with co-occurring prey, and that some prey may become more vulnerable to cat predation in open habitats after foxes have been removed.
The paper was featured in the NRM Research and Innovation Network weekly updates.
Below is a copy of the press release for our new paper titled:
“Bushmeat hunting and extinction risk to the world’s mammals”
Contact: Nick Houtman, 541-737-0783, firstname.lastname@example.org
Source: William Ripple, 541-737-3056, email@example.com
Links to photos are at the end of this story.
CORVALLIS, Ore. — The ongoing decline of more than 300 species of animals is having significant environmental impacts and posing a food security threat for millions of people in Asia, Africa and South America, according to the first global assessment of the hunting and trapping of terrestrial mammals.
Species of large wild ungulates, primates and bats are threatened primarily due to unregulated or illegal hunting, according to data collected by the International Union for the Conservation of Nature (IUCN), a nongovernmental organization. An international research team led by William Ripple, distinguished professor of ecology at Oregon State University, analyzed data on the IUCN Red List to reach their conclusions.
The animals at risk range across the spectrum from large (grey ox, Bactrian camels, bearded and warty pigs) to small (golden-capped fruit bat, black-bearded flying fox and Bulmer’s fruit bat). Hunting endangers more primate species — 126, including the lowland gorilla, chimpanzee, bonobo and many species of lemurs and monkeys, than any other group.
Populations of other species are declining and similarly threatened: Javan and black rhinoceroses, tapirs, deer, tree kangaroos, armadillos, pangolins, rodents and large carnivores, all of which are hunted or trapped for meat, medicine, body parts, trophies or live pets.
Scientists reviewed IUCN data on 1,169 of the world’s terrestrial mammals that are listed as threatened with extinction. These animals represent 26 percent of all mammals for which data exist to determine whether or not they are endangered. The research team published its analysis today in Royal Society Open Science, a professional journal.
Forests, grasslands and deserts in the developing world are now lacking many species of wild animals and becoming “empty landscapes,” the authors wrote.
The researchers suggested five broad steps for effectively addressing the threat:
- Laws could be changed to increase penalties for poaching and illegal trafficking and to expand protected habitats for endangered mammals.
- Property rights could be provided to to communities that benefit from the presence of wildlife.
- Food alternatives can help shift consumption to more sustainable species, especially protein-rich plant foods.
- Education could help consumers in all countries understand the threats to mammals that are hunted or trapped.
- Assistance in family planning could help relieve pressure on wildlife in regions where women want to delay or avoid pregnancy.
The researchers suggest that, to curb this overhunting crisis, more logistical and financial support will be needed from the richer developed countries. They conclude that only bold changes and political will can diminish the possibility of humans consuming many of the world’s wild mammals to the point of extinction.
“Our analysis is conservative,” said Ripple. “These 301 species are the worst cases of declining mammal populations for which hunting and trapping are clearly identified as a major threat. If data for a species were missing or inconclusive, we didn’t include it.
“Our goal is to raise awareness of this global crisis. Many of these animals are at the brink of extinction,” he added. “The illegal smuggling in wildlife and wildlife products is run by dangerous international networks and ranks among trafficking in arms, human beings and drugs in terms of profits.”
People across much of the globe depend on wild meat for part of their diets, the researchers noted. For example, they wrote, “an estimated 89,000 metric tons of meat with a market value of about $200 million are harvested annually in the Brazilian Amazon, and exploitation rates in the Congo basin are estimated to be five times higher….” Loss of these mammals could affect the livelihoods of millions of people, the researchers said.
Overhunting of mammals is concentrated, they added, in countries with poorer populations. As hunters find it harder to feed their families, it is likely they will switch to less preferred species, migrate or suffer from malnutrition and disease.
Not all wild meat is consumed for subsistence, the researchers noted. Much of it is sold in markets and as delicacies in urban restaurants. In 2010, another team of scientists found that about five tons of bushmeat are smuggled weekly in tourist luggage through the Charles de Gaulle airport in Paris.
Large carnivores and herbivores (bigger than 10 kilograms or 22 pounds) comprise a small percentage of all mammals listed but tend to be impacted more severely by overhunting, the researchers reported. By dispersing seeds and controlling smaller animals such as rodents, large animals have significant impacts on the environment.
The loss of large mammals could lead to long-lasting ecological changes, including overpopulation of prey, higher disease risks and the loss of benefits for humans, the researchers said. The scientists found that 57 species of even-toed ungulates (such as hippopotamus, wild yak, camel, marsh deer) larger than 10 kilograms are threatened by hunting.
Smaller mammals play crucial roles in dispersing seeds, pollinating plants and controlling insects. The largest group of mammals under 1 kilogram (about 2 pounds) threatened by hunting is comprised of 27 species of bats.
Ripple has led international collaborations to analyze the status and ecological effects of large animals. Co-authors on this project include researchers at Oregon State University, Stanford University, the University of California Santa Barbara and universities in Gabon, the U.K., Sweden, South Africa, Brazil and Australia.
Editor: Photos of some of the animals mentioned in this story are available on Flickr:
- Clouded leopard, https://flic.kr/p/MwEGqt
- Giant ground pangolin, https://flic.kr/p/MwEsuc
- Mountain gorilla, https://flic.kr/p/MwEmyp
- Collared brown lemur, https://flic.kr/p/LzeDQ7
- Aye-aye, https://flic.kr/p/LzhSu8
About the OSU College of Forestry: For a century, the College of Forestry has been a world class center of teaching, learning and research. It offers graduate and undergraduate degree programs in sustaining ecosystems, managing forests and manufacturing wood products; conducts basic and applied research on the nature and use of forests; and operates 14,000 acres of college forests.
Chris Watson, a colleague from my time in Alice Springs, recently reviewed our book “The Red Kangaroo in Central Australia; an early account by A.E. Newsome“.
Below is a copy of the review and links to the original webpages.
“Desert lands have an appealing starkness and simplicity. The very grain of the countryside is exposed to all. Ancient mountain ranges plunge and rear from the plains. Rocks and boulders lie tumbled at their feet. Dry watercourses break through mountain gorges to meander and die in the desert. Stunted trees stand mutely enduring the heat.
Biological survival in such a land is not simple.” – p.15-16
It is just such a land, however, which is home to the Red Kangaroo Osphranter rufus; the largest extant marsupial on Earth and Australia’s largest terrestrial mammal. The Red Kangaroo is an Australian icon that ranks with Uluru and the Sydney Opera House for international recognition. The Red Kangaroo in Central Australia presents the gathered thoughts and findings on the species, from the early work of one of the great minds of Australian ecology.
Alan Newsome’s work was already familiar to me when I gained employment as an environmental consultant in Alice Springs in 2011. As it happens, Alan’s son, Thomas Newsome, was working at the firm which took me on, and I’d learn that he is a gifted ecologist in his own right. I’d been living in Central Australia for several years at that time and, being interested in the ecology of Central Australian fauna, Alan Newsome’s name was a regular feature on my reading list. Though I only worked with Thomas for a short time, my excitement at the publication of The Red Kangaroo in Central Australia comes, not only from my own affinity for the country and animals that it describes, but from an appreciation of his standing, and his father’s, in the Australian ecological community.
Alan began studying the Red Kangaroo in 1957 and it’s important to appreciate how rudimentary our understanding of the animal’s ecology was at that time. Alan was the first to discover many of the behavioural and physiological adaptations that have allowed the species to live so successfully in a landscape with such famously extreme and irregular conditions. Working on the beautiful plains to the north of the MacDonnell Range, Alan methodically uncovered the mysteries of the Red Kangaroo’s life. His book takes us through the challenges the kangaroo must overcome to survive in this country in chapters dealing with the landforms, climate and vegetation; distribution and abundance; reproduction (some of Alan’s most astonishing discoveries relate to the reproductive biology of the Red Kangaroo and these breakthroughs, and the methods by which they were revealed, are presented in considerable detail); food and water; sociology and a final chapter titled Ecomythology.
In addition to the main body of text there is an enlightening foreword by famed marsupial biologist Hugh Tyndale-Biscoe and a preface by Thomas Newsome in his role as co-author and editor. [Alan Newsome passed away in 2007. This book is the edited result of a mostly complete manuscript which Thomas discovered among Alan’s effects in 2010.]
In the intervening decades since Alan Newsome’s field work, another generation of ecologists has built on his findings and we understand the Red Kangaroo’s biology well. But perhaps the great story presented by The Red Kangaroo in Central Australia, and a thread running through the entire book, is Alan’s determination to also come to grips with the Aranda* understanding of kangaroo ecology.
Like few other outback zoologists since Baldwin Spencer and F. J. Gillen, Newsome allows room for Indigenous Ecological Knowledge (IEK) to be interpreted scientifically and considered alongside his own findings. The culmination of the book is in the final chapter titled Ecomythology in which Alan sets out the close alignment of his own hard-won knowledge with the traditional knowledge of his Aranda colleagues. The world has turned now and it is routine for IEK to be incorporated into scientific research and reporting, but we see the foundations of this practice in Alan’s work at a time when such considerations were by no means commonplace.
In addition to the book’s value as an important work of science and history, it is a beautiful piece of writing. As the brief excerpt I’ve used reveals, Alan’s was an engaging writing style, as stripped-back and plain as the desert landscapes he describes. As an avowed desert-lover myself, Alan’s deep affection for the country in which he spent so much of his career, is instantly relatable from the way he writes about it. He also had that all-too-rare talent for rendering scientific writing enjoyable for the reader, without sacrificing any of its rigour. The ease of his style is such that The Red Kangaroo in Central Australia reads more like a story than a scientific treatise at times. This is testament to his ability to render deep scholarship comprehensible to the lay-reader rather than any “dumbing down” or skimping on detail.
Ultimately, The Red Kangaroo in Central Australia will appeal to an audience far beyond the ranks of biologists. It includes almost as much history and anthropology as it does ecology. It’s difficult to avoid drawing comparisons with the writings of other prominent Centralian researchers like T.G.H. Strehlow, with whom Alan discussed his work at some length, and the correspondence of the aforementioned Spencer and Gillen.
As well as being a peerless account of animal ecology and scientific investigation in the desert, it is a postcard from Central Australia and the ecological adventures of a young scientist on a personal journey of discovery. There is no doubt that The Red Kangaroo in Central Australia will continue to inspire and inform future generations of Australian ecologists for a very long time to come.
*Also spelled Arrernte and Arunta, these are the Aboriginal Australians who are the traditional custodians of the lands surrounding Alice Springs and much of the MacDonnell Ranges in Central Australia.
Thanks Chris for the kind review.