My research investigates the ecological role of large predators on biodiversity and functioning of novel ecosystems. My fieldwork is mainly conducted across the Australian arid zone, where I am researching the influence of dingoes on biodiversity and native-non-native coexistence.
My research has challenged established paradigms on the cause and treatment of biodiversity decline in Australia, by showing that protecting dingoes enables species to thrive in modern ecosystems, and that lethal control of introduced species is both unnecessary and counterproductive.
My work on predators featured in the journals Nature and Science, and together with a collaborative research team has been awarded the 2013 Eureka Prize for Environmental Research.
I co-founded the Dingo for Biodiversity Project, an initiative that brings scientists and landholders together to transition to predator-friendly practices. The project has helped establish three large-scale dingo recovery programs in collaboration with the indigenous custodians and pastoral landowners.
During 2012-2014 I co-managed Evelyn Downs, a predator-friendly cattle station in northern SA. In 2014 I was awarded a Churchill Fellowship and travelled to Israel, India, southern Africa and North America to investigate the ecological effects of losing and recovering the Earth's largest predators. Since 2015 I have been based at the UTS Centre for Compassionate Conservation.
Can supervise: YES
Trophic cascades: large predators and their role as top-down regulators of ecosystems
Novel ecosystems: Evolutionary and ecological drivers that enable coexistence between native and non native species
Social stability: The influence of predator sociality and behavior on their ecological functioning
Biotic globalization: Conservation values of species outside their historic range
Compassionate conservation: promoting coexistence with wildlife in conservation and farming
Batavia, C, Nelson, MP, Darimont, CT, Paquet, PC, Ripple, WJ & Wallach, AD 2019, 'The elephant (head) in the room: A critical look at trophy hunting', Conservation Letters, vol. 12, no. 1.View/Download from: Publisher's site
© 2018 The Authors. Conservation Letters published by Wiley Periodicals, Inc. 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.
Smith, BP, Cairns, KM, Adams, JW, Newsome, TM, Fillios, M, Déaux, EC, Parr, WCH, Letnic, M, van Eeden, LM, Appleby, RG, Bradshaw, CJA, Savolainen, P, Ritchie, EG, Nimmo, DG, Archer-Lean, C, Greenville, AC, Dickman, CR, Watson, L, Moseby, KE, Doherty, TS, Wallach, AD, Morrant, DS & Crowther, MS 2019, 'Taxonomic status of the Australian dingo: The case for Canis dingo Meyer, 1793', Zootaxa, vol. 4564, no. 1, p. 173.View/Download from: Publisher's site
Copyright © 2019 Magnolia Press. The taxonomic status and systematic nomenclature of the Australian dingo remain contentious, resulting in decades of inconsistent applications in the scientific literature and in policy. Prompted by a recent publication calling for dingoes to be considered taxonomically as domestic dogs (Jackson et al. 2017, Zootaxa 4317, 201-224), we review the issues of the taxonomy applied to canids, and summarise the main differences between dingoes and other canids. We conclude that (1) the Australian dingo is a geographically isolated (allopatric) species from all other Canis, and is genetically, phenotypically, ecologically, and behaviourally distinct; and (2) the dingo appears largely devoid of many of the signs of domestication, including surviving largely as a wild animal in Australia for millennia. The case of defining dingo taxonomy provides a quintessential example of the disagreements between species concepts (e.g., biological, phylogenetic, ecological, morphological). Applying the biological species concept sensu stricto to the dingo as suggested by Jackson et al. (2017) and consistently across the Canidae would lead to an aggregation of all Canis populations, implying for example that dogs and wolves are the same species. Such an aggregation would have substantial implications for taxonomic clarity, biological research, and wildlife conservation. Any changes to the current nomen of the dingo (currently Canis dingo Meyer, 1793), must therefore offer a strong, evidence-based argument in favour of it being recognised as a subspecies of Canis lupus Linnaeus, 1758, or as Canis familiaris Linnaeus, 1758, and a successful application to the International Commission for Zoological Nomenclature - neither of which can be adequately supported. Although there are many species concepts, the sum of the evidence presented in this paper affirms the classification of the dingo as a distinct taxon, namely Canis dingo.
Ripple, WJ, Wolf, C, Newsome, TM, Betts, MG, Ceballos, G, Courchamp, F, Hayward, MW, Van Valkenburgh, B, Wallach, AD & Worm, B 2019, 'Are we eating the world's megafauna to extinction?', Conservation Letters.View/Download from: Publisher's site
© 2019 The Authors. Conservation Letters published by Wiley Periodicals, Inc. Many of the world's vertebrates have experienced large population and geographic range declines due to anthropogenic threats that put them at risk of extinction. The largest vertebrates, defined as megafauna, are especially vulnerable. We analyzed how human activities are impacting the conservation status of megafauna within six classes: mammals, ray-finned fish, cartilaginous fish, amphibians, birds, and reptiles. We identified a total of 362 extant megafauna species. We found that 70% of megafauna species with sufficient information are decreasing and 59% are threatened with extinction. Surprisingly, direct harvesting of megafauna for human consumption of meat or body parts is the largest individual threat to each of the classes examined, and a threat for 98% (159/162) of threatened species with threat data available. Therefore, minimizing the direct killing of the world's largest vertebrates is a priority conservation strategy that might save many of these iconic species and the functions and services they provide.
Lynn, WS, Santiago-Ávila, F, Lindenmayer, J, Hadidian, J, Wallach, A & King, BJ 2019, 'A moral panic over cats.', Conservation biology : the journal of the Society for Conservation Biology, vol. 33, no. 4, pp. 769-776.View/Download from: UTS OPUS or Publisher's site
Some conservationists believe that free-ranging cats pose an enormous risk to biodiversity and public health and therefore should be eliminated from the landscape by any means necessary. They further claim that those who question the science or ethics behind their arguments are science deniers (merchants of doubt) seeking to mislead the public. As much as we share a commitment to conservation of biodiversity and wild nature, we believe these ideas are wrong and fuel an unwarranted moral panic over cats. Those who question the ecological or epidemiological status of cats are not science deniers, and it is a false analogy to compare them with corporate and right-wing special interests that perpetrate disinformation campaigns over issues, such as smoking and climate change. There are good conservation and public-health reasons and evidence to be skeptical that free-ranging cats constitute a disaster for biodiversity and human health in all circumstances. Further, there are significant and largely unaddressed ethical and policy issues (e.g., the ethics and efficacy of lethal management) relative to how people ought to value and coexist with cats and native wildlife. Society is better served by a collaborative approach to produce better scientific and ethical knowledge about free-ranging cats.
Large herbivorous mammals, already greatly reduced by the late-Pleistocene extinctions, continue to be threatened with decline. However, many herbivorous megafauna (body mass ≥ 100 kg) have populations outside their native ranges. We evaluate the distribution, diversity and threat status of introduced terrestrial megafauna worldwide and their contribution towards lost Pleistocene species richness. Of 76 megafauna species, 22 (∼29%) have introduced populations; of these eleven (50%) are threatened or extinct in their native ranges. Introductions have increased megafauna species richness by between 10% (Africa) and 100% (Australia). Furthermore, between 15% (Asia) and 67% (Australia) of extinct species richness, from the late Pleistocene to today, have been numerically replaced by introduced megafauna. Much remains unknown about the ecology of introduced herbivores, but evidence suggests that these populations are rewilding modern ecosystems. We propose that attitudes towards introduced megafauna should allow for broader research and management goals.
Article impact statement: Incorporating introduced populations into the moral universe of conservation shows the Anthropocene is astoundingly rich in megafauna.
Wallach, AD, Bekoff, M, Batavia, C, Nelson, MP & Ramp, D 2018, 'Summoning compassion to address the challenges of conservation.', Conservation Biology, vol. 32, no. 6, pp. 1255-1265.View/Download from: UTS OPUS or Publisher's site
Conservation practice is informed by science, but also reflects ethical beliefs about how we ought to value and interact with the Earth's biota. As human activities continue to drive extinctions and diminish critical life-sustaining ecosystem processes, achieving conservation goals becomes increasingly urgent. In our determination to react decisively, conservation challenges can be handled without due deliberation, particularly when wildlife individuals are sacrificed "for the greater good" of wildlife collectives (populations, species, ecosystems). With growing recognition of the widespread sentience and sapience of many nonhuman animals, standard conservation practices that categorically prioritize collectives without due consideration for the wellbeing of individuals are ethically untenable. Here we highlight three overarching ethical orientations characterizing current and historical practices in conservation that suppress compassion: instrumentalism, collectivism, and nativism. We illustrate how establishing a commitment to compassion could re-orient conservation in more ethically expansive directions, which incorporate recognition of the intrinsic value of wildlife, the sentience of nonhuman animals, and the values of novel ecosystems, introduced species and their members. A compassionate conservation approach allays practices that intentionally and unnecessarily harm wildlife individuals, while aligning with critical conservation goals. Although the urgency of achieving effective outcomes for solving major conservation problems may enhance the appeal of quick and harsh measures, the costs are too high. Continuing to justify moral indifference when causing the suffering of wildlife individuals, particularly those who possess sophisticated capacities for emotion, consciousness, and sociality, risks estranging conservation practice from prevailing, and appropriate, social values. As conservationists and compassionate beings, we must demonstrate concern for bo...
Wallach, AD, Lundgren, E, Yanco, E & Ramp, D 2018, 'Is the prickly pear a 'Tzabar'? Diversity and conservation of Israel's migrant species', Israel Journal of Ecology and Evolution, vol. 63, pp. 9-22.View/Download from: UTS OPUS
Ripple, WJ, Chapron, G, López-Bao, JV, Durant, SM, MacDonald, DW, Lindsey, PA, Bennett, EL, Beschta, RL, Bruskotter, JT, Campos-Arceiz, A, Corlett, RT, Darimont, CT, Dickman, AJ, Dirzo, R, Dublin, HT, Estes, JA, Everatt, KT, Galetti, M, Goswami, VR, Hayward, MW, Hedges, S, Hoffmann, M, Hunter, LTB, Kerley, GIH, Letnic, M, Levi, T, Maisels, F, Morrison, JC, Nelson, MP, Newsome, TM, Painter, L, Pringle, RM, Sandom, CJ, Terborgh, J, Treves, A, Van Valkenburgh, B, Vucetich, JA, Wirsing, AJ, Wallach, AD, Wolf, C, Woodroffe, R, Young, H & Zhang, L 2017, 'Conserving the world's megafauna and biodiversity: The fierce urgency of now', Bioscience, vol. 67, no. 3, pp. 197-200.View/Download from: UTS OPUS or Publisher's site
Wallach, AD, Dekker, AH, Lurgi, M, Montoya, JM, Fordham, DA & Ritchie, EG 2017, 'Trophic cascades in 3D: network analysis reveals how apex predators structure ecosystems', Methods in Ecology and Evolution, vol. 8, no. 1, pp. 135-142.View/Download from: UTS OPUS or Publisher's site
The role of apex predators as ecosystem regulators is now firmly embedded in ecological theory, suggesting that the world is green and biologically diverse in large part because predators suppress herbivore densities (Hairston, Smith & Slobodkin 1960; Estes et al. 2011; Ripple et al. 2014). Studies from across the globe show that apex predators limit the abundance and modify the behaviour of their prey and smaller mesopredators, suppressing grazing and predation pressure, and enhancing biodiversity and productivity (Ritchie & Johnson 2009; Ritchie et al. 2012). This top-down forcing cascades throughout ecosystems influencing a broad range of processes, both biotic and abiotic, including species abundances and richness, animal behaviour, disease dynamics, carbon sequestration and stream morphology (Estes et al. 2011; Ripple et al. 2014; Atwood et al. 2015). The rise and fall of apex predators not only affects the composition of species within ecological communities therefore, but also ecosystem functioning (Estes et al. 2011; Ripple et al. 2014; Standish et al. 2014). For example, wolves (Canis lupus) provide critical resource subsidies to scavenging species during warm months, thus enhancing their resilience to shortening winters due to global warming (Wilmers & Getz 2005). Similarly, dingoes (C. dingo) stabilize herbivore prey densities by dampening their population responses to rainfall in arid environments, thereby enabling plant biomass to accumulate during brief wet seasons (Letnic & Crowther 2013).
Wallach, A, Ramp, D & O'Neill, AJ 2017, 'Cattle mortality on a predator-friendly station in central Australia', Journal of Mammalogy, vol. 98, no. 1, pp. 45-52.View/Download from: UTS OPUS or Publisher's site
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-km2 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.
Johnson, CN & Wallach, AD 2016, 'The virtuous circle: predator-friendly farming andecological restoration in Australia', RESTORATION ECOLOGY, vol. 24, no. 6, pp. 821-826.View/Download from: UTS OPUS or Publisher's site
Ripple, WJ, Abernethy, K, Betts, MG, Chapron, G, Dirzo, R, Galetti, M, Levi, T, Lindsey, PA, Macdonald, DW, Machovina, B, Newsome, TM, Peres, CA, Wallach, AD & Wolf, C 2016, 'Bushmeat hunting and extinction risk to the world's mammals', Royal Society Open Science, vol. 3, no. 10, pp. 1-16.View/Download from: UTS OPUS or Publisher's site
© 2016 The Authors. 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 socio-economic 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 multipronged conservation strategy to help save threatened mammals from immediate extinction and avoid a collapse of food security for hundreds of millions of people.
Ripple, WJ, Chapron, G, López-Bao, JV, Durant, SM, Macdonald, DW, Lindsey, PA, Bennett, EL, Beschta, RL, Bruskotter, JT, Campos-Arceiz, A, Corlett, RT, Darimont, CT, Dickman, AJ, Dirzo, R, Dublin, HT, Estes, JA, Everatt, KT, Galetti, M, Goswami, VR, Hayward, MW, Hedges, S, Hoffmann, M, Hunter, LTB, Kerley, GIH, Letnic, M, Levi, T, Maisels, F, Morrison, JC, Nelson, MP, Newsome, TM, Painter, L, Pringle, RM, Sandom, CJ, Terborgh, J, Treves, A, Van Valkenburgh, B, Vucetich, JA, Wirsing, AJ, Wallach, AD, Wolf, C, Woodroffe, R, Young, H & Zhang, L 2016, 'Saving the World's Terrestrial Megafauna', Bioscience, vol. 66, no. 10, pp. 807-812.View/Download from: UTS OPUS or Publisher's site
Wallach, AD, Bekoff, M, Nelson, MP & Ramp, D 2015, 'Promoting predators and compassionate conservation', Conservation Biology, vol. 29, no. 5, pp. 1481-1484.View/Download from: UTS OPUS or Publisher's site
Newsome, TM, Ballard, G-A, Crowther, MS, Dellinger, JA, Fleming, PJS, Glen, AS, Greenville, AC, Johnson, CN, Letnic, M, Moseby, KE, Nimmo, DG, Nelson, MP, Read, JL, Ripple, WJ, Ritchie, EG, Shores, CR, Wallach, AD, Wirsing, AJ & Dickman, CR 2015, 'Resolving the value of the dingo in ecological restoration', RESTORATION ECOLOGY, vol. 23, no. 3, pp. 201-208.View/Download from: UTS OPUS or Publisher's site
Wallach, AD, Ripple, WJ & Carroll, SP 2015, 'Novel trophic cascades: apex predators enable coexistence', TRENDS IN ECOLOGY & EVOLUTION, vol. 30, no. 3, pp. 146-153.View/Download from: UTS OPUS or Publisher's site
Johnson, CN, Crowther, MS, Dickman, CR, Letnic, MI, Newsome, TM, Nimmo, DG, Ritchie, EG & Wallach, AD 2014, 'Experiments in no-impact control of dingoes: comment on Allen et al. 2013', FRONTIERS IN ZOOLOGY, vol. 11.View/Download from: UTS OPUS or Publisher's site
Ripple, WJ, Estes, JA, Beschta, RL, Wilmers, CC, Ritchie, EG, Hebblewhite, M, Berger, J, Elmhagen, B, Letnic, M, Nelson, MP, Schmitz, OJ, Smith, DW, Wallach, AD & Wirsing, AJ 2014, 'Status and ecological effects of the world's largest carnivores.', Science, vol. 343, no. 6167, pp. 1-11.View/Download from: UTS OPUS or Publisher's site
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.
Keysary, A, Eremeeva, ME, Leitner, M, Din, AB, Wikswo, ME, Mumcuoglu, KY, Inbar, M, Wallach, AD, Shanas, U, King, R & Waner, T 2011, 'Spotted Fever Group Rickettsiae in Ticks Collected from Wild Animals in Israel', AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE, vol. 85, no. 5, pp. 919-923.View/Download from: UTS OPUS or Publisher's site
Wallach, AD, Johnson, CN, Ritchie, EG & O'Neill, AJ 2010, 'Predator control promotes invasive dominated ecological states', ECOLOGY LETTERS, vol. 13, no. 8, pp. 1008-1018.View/Download from: Publisher's site
Wallach, AD, Shanas, U & Inbar, M 2010, 'Feeding activity and dietary composition of roe deer at the southern edge of their range', EUROPEAN JOURNAL OF WILDLIFE RESEARCH, vol. 56, no. 1, pp. 1-9.View/Download from: Publisher's site
Wallach, A, Murray, B & O'neill, A 2009, 'Can threatened species survive where the top predator is absent?', Biological Conservation, vol. 142, no. 1, pp. 43-52.View/Download from: UTS OPUS or Publisher's site
Top predators have been described as highly interactive keystone species. Their decline has been linked to secondary extinctions and their increase has been linked to ecological restoration. Several authors have recently argued that the dingo Canis lupus dingo is another example of a top predator that maintains mesopredators and generalist herbivores at low and stable numbers, thereby increasing biodiversity and productivity. Due to the sensitivity of many Australian species to introduced mesopredators and herbivores, the top predator hypothesis predicts that threatened species will not survive where dingoes are rare or absent. However, several threatened species have survived inside the Dingo Barrier Fence (DBF). We present a new view on the survival of the yellow-footed rock-wallaby Petrogale xanthopus xanthopus and the malleefowl Leipoa ocellata inside the DBF where the dingo is considered very rare, or in areas where the dingo is believed to have been eradicated several decades ago. We found that dingoes co-occurred with both threatened species. Dingoes were present at all wallaby colonies surveyed and occurred throughout their range. The most common predator detected in areas inhabited by the wallabies was in fact the dingo, and we found no significant difference between dingo abundance inside compared to outside the DBF. Malleefowl nests were found to be scent marked by dingoes at the three sites that we surveyed, despite these sites being close to human settlement and sheep farms, and in small and fragmented patches of wilderness. These findings provide further evidence for an association between the presence of dingoes and the survival of threatened species, which is in agreement with the top predator hypothesis.
Wallach, AD, Ritchie, EG, Read, J & O'Neill, AJ 2009, 'More than Mere Numbers: The Impact of Lethal Control on the Social Stability of a Top-Order Predator', PLOS ONE, vol. 4, no. 9.View/Download from: Publisher's site
Wallach, AD, Shanas, U, Mumcuoglu, KY & Inbar, M 2008, 'Ectoparasites on reintroduced Roe Deer capreolus capreolus in Israel', Journal of Wildlife Diseases, vol. 44, no. 3, pp. 693-696.View/Download from: Publisher's site
The ectoparasite fauna of reintroduced roe deer (Capreolus capreolus) was surveyed in a Mediterranean forest in Israel. Ectoparasites were collected from four female hand-reared deer during 2004 and 2005. Seasonality, predilection sites of infestation, and the apparent effect of the parasites are presented. This is the first study of roe deer parasites in the East Mediterranean. The ectoparasite fauna included three hippoboscid fly (Lipoptena capreoli, Hippobosca equina, and Hippobosca longipennis ), four tick (Rhipicephalus sanguineus, Rhipicephalus turanicus, Rhipicephalus kohlsi, and Hyalomma marginatum), and one unidentified trombiculid mite species. For most of these ectoparasites, this is the first record on roe deer. All ectoparasite species were documented in Israel prior to the reintroduction program; exotic ectoparasites were not detected. © Wildlife Disease Association 2008.
Wallach, AD, Inbar, M, Scantlebury, M, Speakman, JR & Shanas, U 2007, 'Water requirements as a bottleneck in the reintroduction of European roe deer to the southern edge of its range', CANADIAN JOURNAL OF ZOOLOGY, vol. 85, no. 11, pp. 1182-1192.View/Download from: Publisher's site
Wallach, A, Inbar, M, Lambert, R, Cohen, S & Shanas, U 2007, 'Hand-rearing Roe deer Capreolus capreolus: Practice and research potential', International Zoo Yearbook, vol. 41, no. 1, pp. 183-193.View/Download from: Publisher's site
Four ♀ Roe deer Capreolus capreolus were hand-reared and released into a 10 ha enclosed natural habitat. This paper describes the hand-rearing procedure, nutrition and development, which we compare with other documented cases. We illustrate the handling techniques that enabled us to maintain a close relationship with the hand-reared Roe deer in their adulthood and study them under semi-free-ranging conditions. The benefits of conducting research with hand-reared Roe deer are described, together with possible biases that must be taken into consideration when planning a research programme. The Roe deer were hand-reared in order to conduct a detailed feasibility study for the Roe deer reintroduction programme in Israel, where they have been locally extinct for 100 years. © 2007 The Zoological Society of London.