Arian Wallach | University of Technology Sydney (original) (raw)

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Terrestrial mammals are experiencing a massive collapse in their population sizes and geographica... more Terrestrial mammals are experiencing a massive collapse in their population sizes and geographical ranges around the world, but many of the drivers, patterns and consequences of this decline remain poorly understood. Here we provide an analysis showing that bushmeat hunting for mostly food and medicinal products is driving a global crisis whereby 301 terrestrial mammal species are threatened with extinction. Nearly all of these threatened species occur in developing countries where major coexisting threats include deforestation, agricultural expansion, human encroachment and competition with livestock. The unrelenting decline of mammals suggests many vital ecological and socioeconomic services that these species provide will be lost, potentially changing ecosystems irrevocably. We discuss options and current obstacles to achieving effective conservation, alongside consequences of failure to stem such anthropogenic mammalian extirpation. We propose a multi-pronged conservation strategy to help save threatened mammals from immediate extinction and avoid a collapse of food security for hundreds of millions of people.

Trophy hunting has occupied a prominent position in recent scholarly literature and popular media... more Trophy hunting has occupied a prominent position in recent scholarly literature and popular media. In the scientific conservation literature, researchers are generally supportive of or sympathetic to its usage as a source of monetary support for conservation. Although authors at times acknowledge that trophy hunting faces strong opposition from many members of the public, often for unspecified reasons associated with ethics, neither the nature nor the implications of these ethical concerns have been substantively addressed. We identify the central act of wildlife " trophy " taking as a potential source of ethical discomfort and public opposition. We highlight that trophy hunting entails a hunter paying a fee to kill an animal and claim its body or body parts as a trophy of conquest. Situating this practice in a Western cultural narrative of chauvinism, colonialism, and anthropocentrism, we argue trophy hunting is morally inappropriate. We suggest alternative strategies for conservation and community development should be explored and decisively ruled out as viable sources of support before the conservation community endorses trophy hunting. If wildlife conservation is broadly and inescapably dependent on the institution of trophy hunting, conservationists should accept the practice only with a due appreciation of tragedy, and proper remorse. K E Y W O R D S

A significant proportion of Earth’s wildlife has been erased, not from the world, but from our co... more A significant proportion of Earth’s wildlife has been erased, not from the world, but from our collective depiction of nature. Even the most noticeable animals, terrestrial herbivorous megafauna weighing 100–4,000 kg, have been made nominally invisible. Wildlife outside native ranges are conspicuously missing from conservation data sets, distribution maps, population estimates, and conservation statuses. They are to be found, instead on invasive species lists. Introduced megafauna are a wonder of the Anthropocene hidden in plain sight.

Large predators are declining worldwide primarily due to hunting and persecution by humans, drive... more Large predators are declining worldwide primarily due to hunting and persecution by humans, driven in large part by the livestock industry. Some ranchers are transitioning to "predator-friendly" farming by adopting nonlethal predator deterrents. On very large rangeland properties, such as the vast stations of the Australian arid zone, ending lethal control may in itself reduce livestock losses by enabling the predator's social structure to stabilize. The dingo (Canis dingo), Australia's apex predator, is commonly subjected to eradication campaigns to protect livestock. We analyzed causes of cattle (Bos taurus) deaths on Evelyn Downs, a 2,300-km 2 predator-friendly station in central Australia, for 2 years after dingo protection was established. Husbandry-related challenges, associated with deteriorating environmental conditions, were the leading causes of deaths of cattle. Predation by dingoes was minor and declined as the indices of dingo abundance stabilized and social stability increased. Shifting from killing predators to improving husbandry standards is likely to improve livestock survival and welfare.

In our recent perspective article, we noted that most (approximately 60 percent) terrestrial larg... more In our recent perspective article, we noted that most (approximately 60 percent) terrestrial large carnivore and large herbivore species are now threatened with extinction, and we offered a 13-point declaration designed to promote and guide actions to save these iconic mammalian megafauna (Ripple et al. 2016). Some may worry that a focus on saving megafauna might undermine efforts to conserve biodiversity more broadly. We believe that all dimensions of biodiversity are important and that efforts to conserve megafauna are not in themselves sufficient to halt the dispiriting trends of species and population losses in recent decades. From 1970 to 2012, a recent global analysis showed a 58 percent overall decline in vertebrate population abundance (WWF 2016). Bold and varied approaches are necessary to conserve what remains of Earth’s biodiversity, and our declaration in no way disputes the value of specific conservation initiatives targeting other taxa. Indeed, the evidence is clear that without massively scaling up conservation efforts for all species, we will fail to achieve internationally agreed-upon targets for biodiversity (Tittensor et al. 2014).

1. Trophic cascade theory predicts that apex predators structure ecosystems by regulating mesopre... more 1. Trophic cascade theory predicts that apex predators structure ecosystems by regulating mesopredator and herbivore abundance and behaviour. Studies on trophic cascades have typically focused on short linear chains of species interactions. A framework that integrates more realistic and complex interactions is needed to make broader predictions on ecosystem structuring.

2. Network analysis is used to study food webs and other types of species interaction networks. These often comprise large numbers of species but rarely account for multiple interaction types and strengths. Here, we develop an intermediate complexity theoretical framework that allows specification of multiple interaction types and strengths for the study of trophic cascades. This ecological network is designed to suit data typically derived from field-based studies. The trophic cascade network contains fewer nodes than food webs, but provides semi-weighted directional links that enable different types of interactions to be included in a single model.

3. We use this trophic cascade network model to explore how an apex predator shapes ecosystem structure in an Australian arid ecosystem. We compared two networks that contrasted in the dominance of an apex predator, the dingo (Canis dingo), using published results ranking the direction and strength of key interactions. Nodes and links interacted dynamically to shape these networks. We examined how changes to an apex predator population affect ecosystem structure through their direct and indirect influences on different components of this ecological community.

4. Under strong apex predator influence, the network structure was denser and more complex, even and top-down driven; and dingo predation and soil commensalism formed denser interactive modules. Under weak apex predator influence (e.g. reflecting predator control), the resulting network structure was frayed, with mesopreda-tor predation and grazing forming modules.

5. Our study demonstrates that networks of intermediate complexity can provide a powerful tool for elucidating potential ecosystem-wide effects of apex predators and predicting the consequences of management interventions such as predator control. Integrating trophic cascades, with their array of complex interactions, with the three-dimensional structure of ecological networks, has the potential to reveal 'ecological architecture' that neither captures on its own.

From the late Pleistocene to the Holocene and now the so-called Anthropocene, humans have been dr... more From the late Pleistocene to the Holocene and now the so-called Anthropocene, humans have been driving an ongoing series of species declines and extinctions. Large-bodied mammals are typically at a higher risk of extinction than smaller ones. However, in some circumstances, terrestrial megafauna populations have been able to recover some of their lost numbers because of strong conservation and political commitment, as well as human cultural changes. Indeed, many would be in considerably worse predicaments in the absence of conservation action. Nevertheless,
most mammalian megafauna face dramatic range contractions and population declines.

In Australia, dingoes are widely regarded as enemies of livestock, and accordingly livestock prod... more In Australia, dingoes are widely regarded as enemies of livestock, and accordingly livestock producers commonly attempt to reduce or eradicate them by lethal control. This can have two forms of perverse outcomes: lethal control often does not succeed in reducing dingo populations and can even result in increased attacks on livestock; and the environmental benefits provided by dingoes, some of which are valuable to livestock production, are lost. We describe these outcomes and suggest mechanisms by which tolerance of dingoes could provide benefits to livestock enterprises, at the same time widening the scope of ecological restoration, and humane treatment of wildlife in Australia.

Faith in, and tolerance for, killing for conservation is waning. Despite this, killing still mono... more Faith in, and tolerance for, killing for conservation is waning. Despite this, killing still monopolizes conservation. Visions of restoring ecological communities to ancestral config- urations are fantasies that continue to harm millions of animals globally each year. Rather than paralyzing action, compassion can help restrain impulsive decisions that cause harm and provide a guiding framework that enables innovation in conservation.

Novel assemblages of native and introduced species characterize a growing proportion of ecosystem... more Novel assemblages of native and introduced species characterize a growing proportion of ecosystems worldwide. Some introduced species have contributed to extinctions, even extinction waves, spurring widespread efforts to eradicate or control them. We propose that trophic cascade theory offers insights into why introduced species sometimes become harmful, but in other cases stably coexist with natives and offer net benefits. Large predators commonly limit populations of potentially irruptive prey and mesopredators, both native and introduced. This top-down force influences a wide range of ecosystem processes that often enhance biodiversity. We argue that many species, regardless of their origin or priors, are allies for the retention and restoration of biodiversity in top-down regulated ecosystems.

There is global interest in restoring populations of apex predators, both to conserve them and to... more There is global interest in restoring populations of apex predators, both to conserve them and to harness their ecological services. In Australia, reintroduction of dingoes (Canis dingo) has been proposed to help restore degraded rangelands. This proposal is based on theories and the results of studies suggesting that dingoes can suppress populations of prey (especially medium- and large-sized herbivores) and invasive predators such as red foxes (Vulpes vulpes) and feral cats (Felis catus) that prey on threatened native species. However, the idea of dingo reintroduction has met opposition, especially from scientists who query the dingo’s positive effects for some species or in some environments. Here, we ask ‘what is a feasible experimental design for assessing the role of dingoes in ecological restoration?’ We outline and propose a dingo reintroduction experiment — one that draws upon the existing dingo-proof fence—and identify an area suitable for this (Sturt National Park, western New South Wales). Although challenging, this initiative would test whether dingoes can help restore Australia’s rangeland biodiversity, and potentially provide proof-of-concept for apex predator reintroductions globally.

Large ‘apex’ predators influence ecosystems in profound ways, by limiting the density of their pr... more Large ‘apex’ predators influence ecosystems in profound ways, by limiting the density of their prey and controlling smaller ‘mesopredators’. The loss of apex predators from much of their range has lead to a global outbreak of mesopredators, a process known as ‘mesopredator release’ that increases predation pressure and diminishes biodiversity. While the classifica- tions apex- and meso-predator are fundamental to current ecological thinking, their definition has remained ambiguous. Trophic cascades theory has shown the importance of predation as a limit to population size for a variety of taxa (top–down control). The largest of predators however are unlikely to be limited in this fashion, and their densities are commonly assumed to be determined by the availability of their prey (bottom–up control). However, bottom–up regulation of apex predators is contradicted by many studies, particularly of non-hunted populations. We offer an alternative view that apex predators are distinguishable by a capacity to limit their own population densities (self-regulation). We tested this idea using a set of life-history traits that could contribute to self-regulation in the Carnivora, and found that an upper limit body mass of 34 kg (corresponding with an average mass of 13–16 kg) marks a transition between extrinsically- and self- regulated carnivores. Small carnivores share fast reproductive rates and development and higher densities. Large carnivores share slow reproductive rates and development, extended parental care, sparsely populated territories, and a propensity towards infanticide, reproductive suppression, alloparental care and cooperative hunting. We discuss how the expression of traits that contribute to self-regulation (e.g. reproductive suppression) depends on social stability, and highlight the importance of studying predator–prey dynamics in the absence of predator persecution. Self-regulation in large carnivores may ensure that the largest and the fiercest do not overexploit their resources.

Predators can have dramatic and lethal effects on individual prey, but they can also have subtle ... more Predators can have dramatic and lethal effects on individual prey, but they can also have subtle yet powerful effects on non-prey species via webs of indirect interactions. Top predators may, for example, suppress the activity of smaller predators and in turn provide a net benefit for the prey of the smaller predators; they can also reduce the impacts of herbivores and thus indirectly alter vegetation dynamics. Species that have such pervasive effects on their communities, and the broader ecosystems to which they belong, are termed strongly interactive. Here, we begin by reviewing the kinds of effects that theoretically can be engendered by the presence of strongly interactive carnivores, and then present examples of such species among the native reptiles, birds and mammals of Australia. The examples include elapid snakes, varanid (monitor) lizards, day-active raptors and owls, dasyurid marsupials and the dingo. The dingo, in particular, has been shown in many studies to suppress the activity of smaller mesopredators and herbivores and to have broadly beneficial effects on biodiversity and ecosystem function. Using the dingo as a case study, we propose that this important but persecuted species should be maintained in areas where it still occurs and that immediate consideration should be given to reintroducing it to areas from which it has been banished. We conclude that strongly interactive carnivores are key components of many ecosystems and should be retained where they still occur and reintroduced, where possible, elsewhere.

There has been much recent debate in Australia over whether lethal control of dingoes incurs envi... more There has been much recent debate in Australia over whether lethal control of dingoes incurs environmental costs, particularly by allowing increase of populations of mesopredators such as red foxes and feral cats. Allen et al. (2013) claim to show in their recent study that suppression of dingo activity by poison baiting does not lead to mesopredator release, because mesopredators are also suppressed by poisoning. We show that this claim is not supported by the data and analysis reported in Allen et al.’s paper.

Science, 2014

Large carnivores face serious threats and are experiencing massive declines in their populations ... more Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around the world. We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest mammalian carnivores on Earth. Consistent with theory, empirical studies increasingly show that large carnivores have substantial effects on the structure and function of diverse ecosystems. Significant cascading trophic interactions, mediated by their prey or sympatric mesopredators, arise when some of these carnivores are extirpated from or repatriated to ecosystems. Unexpected effects of trophic cascades on various taxa and processes include changes to bird, mammal, invertebrate, and herpetofauna abundance or richness; subsidies to scavengers; altered disease dynamics; carbon sequestration; modified stream morphology; and crop damage. Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately determine the fate of Earth’s largest carnivores and all that depends upon them, including humans.

Ecology Letters, 2010

Invasive species are regarded as one of the top five drivers of the global extinction crisis. In ... more Invasive species are regarded as one of the top five drivers of the global extinction crisis. In response, extreme measures have been applied in an attempt to control or eradicate invasives, with little success overall. We tested the idea that state shifts to invasive dominance are symptomatic of losses in ecosystem resilience, due to the suppression of apex predators. This concept was investigated in Australia where the high rate of mammalian extinctions is largely attributed to the destructive influence of invasive species. Intensive pest control is widely applied across the continent, simultaneously eliminating Australia’s apex predator, the dingo (Canis lupus dingo). We show that predator management accounts for shifts between two main ecosystem states. Lethal control fractures dingo social structure and leads to bottom-up driven increases in invasive mesopredators and herbivores. Where control is relaxed, dingoes re-establish top–down regulation of ecosystems, allowing for the recovery of biodiversity and productivity.Invasive species are regarded as one of the top five drivers of the global extinction crisis. In response, extreme measures have been applied in an attempt to control or eradicate invasives, with little success overall. We tested the idea that state shifts to invasive dominance are symptomatic of losses in ecosystem resilience, due to the suppression of apex predators. This concept was investigated in Australia where the high rate of mammalian extinctions is largely attributed to the destructive influence of invasive species. Intensive pest control is widely applied across the continent, simultaneously eliminating Australia’s apex predator, the dingo (Canis lupus dingo). We show that predator management accounts for shifts between two main ecosystem states. Lethal control fractures dingo social structure and leads to bottom-up driven increases in invasive mesopredators and herbivores. Where control is relaxed, dingoes re-establish top–down regulation of ecosystems, allowing for the recovery of biodiversity and productivity.

Animal Biodiversity and Conservation, 2009

"The introduction of alien mesopredators and herbivores has been implicated as the main driver of... more "The introduction of alien mesopredators and herbivores has been implicated as the main driver of mammalian extinction in Australia. Recent studiessuggest that the devastating effects of invasive species are mitigated by top–order predators. The survivalof many threatened species may therefore depend on the presence and ecological functioning of large pre-dators. Australia’s top predator, the dingo (Canis lupus dingo), has been intensively persecuted across the continent and it is extremely rare to find dingo populations that are not being subjected to lethal control. We
predicted that the presence of threatened species point out places where dingo populations are relativelyintact, and that their absence may indicate that dingoes are either rare or socially fractured. A comparisonof a site which harbors a threatened marsupial, the kowari (Dasyuroides byrnei), and a neighboring sitewhere the kowari is absent, offers support for this suggested pattern."

PLoS ONE, 2009

Population control of socially complex species may have profound ecological implications that rem... more Population control of socially complex species may have profound ecological implications that remain largely invisible if only their abundance is considered. Here we discuss the effects of control on a socially complex top-order predator, the dingo (Canis lupus dingo). Since European occupation of Australia, dingoes have been controlled over much of the continent. Our aim was to investigate the effects of control on their abundance and social stability. We hypothesized that dingo abundance and social stability are not linearly related, and proposed a theoretical model in which dingo populations may fluctuate between three main states: (A) below carrying capacity and socially fractured, (B) above carrying capacity and socially fractured, or (C) at carrying capacity and socially stable. We predicted that lethal control would drive dingoes into the unstable states A or B, and that relaxation of control would allow recovery towards C. We tested our predictions by surveying relative abundance (track density) and indicators of social stability (scent-marking and howling) at seven sites in the arid zone subject to differing degrees of control. We also monitored changes in dingo abundance and social stability following relaxation and intensification of control. Sites where dingoes had been controlled within the previous two years were characterized by low scent-marking activity, but abundance was similar at sites with and without control. Signs of social stability steadily increased the longer an area was allowed to recover from control, but change in abundance did not follow a consistent path. Comparison of abundance and stability among all sites and years demonstrated that control severely fractures social groups, but that the effect of control on abundance was neither consistent nor predictable. Management decisions involving large social predators must therefore consider social stability to ensure their conservation and ecological functioning.

Biological Conservation, 2009

In a recent Review article in Biological Conservation Fensham and Fairfax (2008) concluded that l... more In a recent Review article in Biological Conservation Fensham and Fairfax (2008) concluded that land degradation and biodiversity loss are associated with the proliferation of artiﬁcial waterpoints in arid environments. They highlighted the conservation value of water remote areas as refuges from high grazing pressure,and proposed that water point closure over large areas mayachieve grazing relief. We believe that research conducted so farhas not demonstrated beneﬁts to water point closure, and thatovergrazing and land degradation are merely symptoms of anothervariable that has been overlooked. The spread of artiﬁcial waterpoints is directly linked with intensive control of Australia’s top predator, the dingo (Canis lupus dingo).

Science, 2014

Ecology Letters, 2010

Animal Biodiversity and Conservation, 2009

PLoS ONE, 2009

Biological Conservation, 2009

Humans have fundamentally transformed the planet to such an extent that many agree that we have e... more Humans have fundamentally transformed the planet to such an extent that many agree that we have entered a new geological epoch – the ‘Anthropocene’. Much about how we think about this period is dominated by the stark recognition that this epoch is identifiable as a sixth mass extinction. One distinguishing feature of this period is the vast movement of species across the globe. This ‘biotic globalisation’ is considered a major threat, and much effort is directed towards saving biodiversity by controlling non-native species. However, emerging evidence urges caution, and highlights a fundamentally di erent approach. Embracing our modern ecologies can signi cantly promote biodiversity, locally and globally.

The concept of ‘wilderness’ as a place devoid of humans is a dominant theme in conservation. As a... more The concept of ‘wilderness’ as a place devoid of humans is a dominant theme in conservation. As an ecologist based in Australia, one of the least populated countries, but one that has experienced the highest mammalian extinction rate, I am amazed with India’s rich biodiversity. With a population of over 1.2 billion, projected to surpass China by 2028, in India, humanity is everywhere. Yet it is here where the only population of Asiatic lions persist, where tigers are making a bold comeback and sloth bears are relatively common. Only in India can one say “lions and tiger and bears – oh my!” and mean it.

There’s been a lot of talk about killing feral cats, with the government’s recently announced war... more There’s been a lot of talk about killing feral cats, with the government’s recently announced war on cats setting the goal of killing two million by 2020. But we would like to offer a different idea: let’s embrace cats as part of Australia’s environment. We could even rename them “Australian wildcats”. Let us explain... https://theconversation.com/lets-give-feral-cats-their-citizenship-45165

In a world's first, Australia announced an import ban on lion trophies, which took effect in Marc... more In a world's first, Australia announced an import ban on lion trophies, which took effect in March this year. The announcement came in response to growing public outrage on the practice of breeding of lions for the sole purpose of killing them. But how can killing a threatened species for fun be legal in the first place? The answer to this question lies with South Africa's fundamental model of conservation. South African wildlife are property. They are private property or state property, and highly valuable property. They can be bought, sold and auctioned. And when animals are property, we can do whatever we darn please with them. [Use link to access article online].

Staring out into the streets of Mumbai, I catch a glimpse of two dogs rummaging through a large p... more Staring out into the streets of Mumbai, I catch a glimpse of two dogs rummaging through a large pile of garbage on the street. My taxi driver is winding through the congested and chaotic roads, and I am increasingly nervous that I will miss my flight to Bangalore. This is my first visit to India, and my first sight of completely free-living undomesticated ‘pariah’ dogs. Some call them Indian Native Dogs, or INDogs, considering them an integral part of India’s landscape and ecology, as integral to cities and villages as humans. Not all agree.
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Sitting in the cold of an open jeep, we are waiting for dawn. The thick snow provides some reflec... more Sitting in the cold of an open jeep, we are waiting for dawn. The thick snow provides some reflective light and we strain our eyes, hoping to catch a glimpse of the wolf pack as they return home from their night’s hunt. This family of wolves holds one of the safest territories a large predator could possibly hope for: a minefield in the Golan Heights, near the Israel-Syria border.
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We are celebrating the end of 2014 with the Black Dog Series. The series highlights the science s... more We are celebrating the end of 2014 with the Black Dog Series. The series highlights the science showing the myriad of ecological benefits of Australia's introduced species, and how dingoes help bring out the best in them.

The Black Dog Series contains 12 chapters, each devoted to a species, or group of species, that many consider to be harmful and unwanted: the Australian fox, cat, rabbit, camel, cattle, boar, goat, deer, brumby, toad, weeds, and lastly, dog.

We aim to encourage a more open minded - and open hearted - consideration of the animals and plants that now call Australia home. May 2015 be a kinder space for all species.

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Report of 2015 Churchill Fellowship travel to Israel, India, southern Africa and North America.

Australia is at war... with feral cats. The government announced its Threatened Species Strategy... more Australia is at war... with feral cats.

The government announced its Threatened Species Strategy at the inaugural Threatened Species Summit last month.

The centrepiece is the goal of culling two million feral cats by 2020. On Life Matters we're exploring a contentious idea, that rather than culling feral cats, we should embrace them as part of Australia's environment, even rename them "Australian Wildcats". This argument comes from Dr Arian Wallach, ecologist and founder of the Dingo for Biodiversity Project who expounded it recently in a piece in The Conversation.
http://www.abc.net.au/radionational/programs/lifematters/feral-cats-should-we-let-them-live/6677542

It is time to prick those ears up & listen in for the Foxes! We chat with the Founder of Sydney ... more It is time to prick those ears up & listen in for the Foxes!
We chat with the Founder of Sydney Fox Rescue, Charlie Jackson-Martin & Dr Arian Wallach from the Charles Darwin University's School of Environment about the recent Pest Control Order put out by the NSW Government.