Category Archives: Publications

Taxonomic status of the Australian dingo: the case for Canis dingo Meyer, 1793

Authors: Bradley P Smith, Kylie M Cairns, Justin W Adams, Thomas M Newsome, Melanie Fillios, Eloïse C Déaux, William C H Parr, Mike Letnic, Lily M Van Eeden, Robert G Appleby, Corey J A Bradshaw, Peter Savolainen, Euan G Ritchie, Dale G Nimmo, Clare Archer-Lean, Aaron C Greenville, Christopher R Dickman, Lyn Watson, Katherine E Moseby, Tim S Doherty, Arian D Wallach, Damian S Morrant, and Mathew S Crowther

Published in: Zootaxa

Abstract

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.

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 PDF DOI

The Conversation: Feral cat cull: why the two million target is on scientifically shaky ground

The government’s target to kill 2 million feral cats sounds impressive, but lacks scientific rigour. Image credit Daniel Parks via Flickr

By Tim Doherty (Deakin University), Dale Nimmo (Charles Sturt University), Don Driscoll (Deakin University), Euan Ritchie (Deakin University), and Ricky Spencer (Western Sydney University).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The Australian government’s target of killing two million feral cats by 2020 attracted significant public interest and media attention when it was unveiled in 2015.

But in our new research, published today in Conservation Letters, we explain why it has a shaky scientific foundation.

The target was developed for the Threatened Species Strategy. At the time of its launch in 2015, there was no reliable estimate of the size of Australia’s feral cat population. Figures of between five million and 18 million were quoted, but their origin is murky: it’s possible they came from a single estimate of feral cat density in Victoria, extrapolated across the continent.

A recent review estimated a much smaller population size — probably varying from two million to six million, depending on environmental conditions. Using this estimate, the proportion of Australia’s cat population to be killed under the government’s target is now likely in the range 32–95%, rather than 11–40% based on the original population estimate.

Targets for the removal of pest animals should consider how they will affect an animal’s current and future population size. But because a scientific justification for the two million target was never provided, it is unclear whether or how the revised estimate would alter the target.

Hitting the target, missing the point

For cat control to have a lasting effect on feral populations, it needs to be intense, sustained, and carried out over large areas. This is because cats can rapidly reproduce and re-invade areas. To benefit threatened species, cat control also needs to be undertaken in areas that contain — or could potentially contain — native species that are threatened by cats.

Research commissioned by the government conservatively estimated that around 211,500 feral cats were killed in 12 months in 2015–16 (ranging between around 135,500 and 287,600). This estimate was used to report that the first-year target to kill 150,000 cats was met with room to spare.

The benefit to threatened species of achieving this target is unclear, because we don’t know if the control efforts had a measurable effect on cat populations; whether they took place in areas that would benefit threatened species; or how (or if) the target and related activities contributed to the estimated 211,500 cat deaths.

Around 75% of the killed cats were attributed to shooting by farmers and hunters. It is questionable whether such approaches could keep pace with high rates of population growth and re-invasion from surrounding areas.

These and other issues were known before the target was set, leading experts to recommend that an overall cat culling target should not be set.

Shifting focus

The focus on killing cats risks distracting attention from other threats to native wildlife. These threats include habitat loss, which has been largely overlooked in the Threatened Species Strategy.

Habitat loss is politically sensitive because its main driver is the clearing of land to make way for economic activities such as agriculture, urban development, and mining. The strategy mentions feral cats more than 70 times, but habitat loss is mentioned just twice and land clearing not at all. Australia has one of the world’s worst rates of land clearing, which has recently increased in some regions. For instance, clearing of native vegetation in New South Wales rose by 800% between 2013 and 2016.

A focus on feral cats is warranted, but not at the expense of tackling other conservation threats too. A comprehensive, integrated approach towards threatened species conservation is essential.

Any upside?

Despite its questionable scientific basis, it is possible that the ambitious nature of the two million target has raised the public profile of feral cats as a conservation issue. However, to our knowledge, there has been no attempt to measure the effectiveness of the target in raising awareness or changing attitudes, and so this remains a hypothetical proposition.

The Threatened Species Strategy has other targets that are more closely linked to conservation outcomes, such as the eradication of cats from five particular islands and the establishment of ten new fenced cat-free exclosures. Achieving these targets will make a small contribution to the culling target, but have a comparatively large benefit for some threatened species.

Australia’s target to kill two million feral cats is a highly visible symbol of a broader campaign, but the success of policies aimed at reducing the impacts of feral cats should focus squarely on the recovery of native species.

Conservation or politics? Australia’s target to kill two million cats

Authors: Tim S Doherty, Don A Driscoll, Dale G Nimmo, Euan G Ritchie and Ricky‐John Spencer

Published in: Conservation Letters

Abstract

The Australian Government’s five‐year Threatened Species Strategy contains four priority action areas and associated targets.

Here, we argue that the well‐publicised target to cull two million feral cats has a weak scientific basis because:

  1. reliable estimates of Australia’s cat population size did not exist when the target was set;
  2. it is extremely difficult to measure progress (numbers of cats killed) in an accurate, reliable way; and, most importantly,
  3. the cull target is not explicitly linked to direct conservation outcomes (e.g., measured increases in threatened species populations).

These limitations mean that the cull target fails to meet what would be considered best practice for pest management. The focus on killing cats runs the risk of distracting attention away from other threats to biodiversity, most prominent of which is widespread, ongoing habitat loss, which has been largely overlooked in the Threatened Species Strategy.

The culling target is a highly visible symbol of a broader campaign around feral cat research and management in Australia, rather than a direct indicator of conservation action and success. We are concerned that progress toward the 2 million target could be misinterpreted as progress toward conserving threatened species, when the link between the two is not clear.

Doherty TS, Driscoll DA, Nimmo DG, Ritchie EG, Spencer R (2019) Conservation or politics? Australia’s target to kill 2 million cats, Conservation Letters PDF DOI

Improving the assessment of food system sustainability

Authors: Michalis Hadjikakou, Euan G Ritchie, Kate E Watermeyer, and Brett A Bryan

Published in: The Lancet – Planetary Health

The global food system is causing unsustainable pressures on the environment, leading to widespread land use change, increased greenhouse gas emissions, disruption of the nitrogen and phosphorus cycles, biodiversity loss, and freshwater depletion and pollution. Environmental pressures are mounting as populations grow and diets change, escalating the need to make food production and consumption more sustainable. Yet, there are limitations in the current analysis of global food system sustainability. We believe there are four main areas that could be improved to make such analysis more comprehensive and insightful. These improvements could have important repercussions on the development of effective evidence-based policy that ultimately promotes production efficiencies and sustainable diets.

One set of opportunities for improvement in the analysis of food system sustainability relates to the robustness of the dietary scenarios that are modelled. First, these scenarios need to be made more plausible. Although assessment of radical shifts in human diets might be useful in highlighting the effects of animal-based versus plant-based foods, we question the benefit of emphasising the most extreme of scenarios (ie, a complete switch from omnivore to vegetarian or vegan diets), when the foreseeable global trend is heading strongly in the opposite direction. In addition, analyses of these extreme diet substitution scenarios tend to focus on greenhouse gas emissions, but in such scenarios, trade-offs between sustainability indicators are highly likely—aptly highlighted by the increased use of water in scenarios that model shifts from grass-fed livestock towards water-intensive crops. We argue that it is more insightful to model ambitious yet achievable, context-specific reductions in animal products, overconsumption (particularly of discretionary foods), and food waste, in line with those recently recommended by the EAT-Lancet Commission on sustainable food systems for overall planetary health.

Secondly, more granular and dynamic analyses are needed. Estimates of environmental effects underpinning global food system analyses are typically based on life cycle assessment, an environmental accounting framework that captures effects from farm-to-fork. While the rigour and comprehensiveness of available life cycle assessment data and associated meta-analyses are improving and encompassing important trade-offs between sustainability objectives,5 significant shortcomings remain, notably in terms of low commodity-level detail and the use of global averages to infer region-specific or nation-specific environmental intensities (defined in life cycle assessments as the impact per functional unit of production). In addition, most life cycle assessments are static, and therefore do not represent system feedbacks that incorporate changes in demand because of production efficiency enhancements, or marginal changes in environmental effects involved in large-scale dietary shifts—such as when animal-based products are completely eliminated. The quantification of these dynamics and their system-wide environmental impacts is an opportunity to greatly improve sustainability assessments of different food products and proposed substitutions.

Thirdly, protein sources beyond conventional livestock need greater consideration. In many parts of the world, alternative animal protein sources such as abundant native species that are better adapted to local conditions (eg, kangaroo in Australia and deer in the northern hemisphere) can contribute to human nutrition, with such sourcing having considerably lower environmental effects than farming of conventional livestock. Many countries are also host to introduced feral animal populations that could serve as alternative protein sources—for example, Australia has substantial feral deer, goat, rabbit, pig, horse, and camel populations. Partly replacing existing mainstream protein sources with wild harvests of these alternative sources could achieve co-benefits for the environment (eg, through reducing emissions, land degradation, and the effects on native biodiversity), and improve human health, since game meat is typically leaner than lamb and beef. Conventional analyses also fail to account for other transformative shifts in animal-sourced protein, such as those towards laboratory-grown meat, insect-derived protein, and feeding animals on ecological leftovers such as food waste or grass from pastures. Including potential shifts to novel low-impact protein sources would ensure more comprehensive modelling of the associated environmental effects.

Finally, analyses should better quantify the diverse effects of food production on biodiversity and ecosystems. Food production contributes considerably to species extinction, which has detrimental effects on many ecosystems and plant and animal communities that are essential for supporting human life. Yet, there is an overreliance on proxy indicators such as land use when assessing terrestrial food systems. Previous research has highlighted how the extent of agricultural land area is not a good proxy for biodiversity impact, because of differences in production intensity and heterogeneity in biodiversity values. This limited analysis also extends to marine and freshwater food production. Stock depletion, bycatch, and habitat modification or loss, resulting from intensive aquaculture and fishing practices such as trawling, have substantial effects on the biodiversity of coastal and oceanic ecosystems. However, although some studies have considered the environmental intensities of aggregate categories such as farmed fish and crustaceans, the effect of fishing on wild stocks is typically not encompassed in life cycle assessments, despite appropriate data being available. Integration of a more diverse range of biodiversity indicators into the assessment of food system sustainability would allow for more meaningful analyses.

Taking advantage of the opportunities outlined here could facilitate a more complete understanding of the environmental effects of food production and consumption. Embracing these advances is a key prerequisite for developing effective policy recommendations. Our recommendations aim to foster a more comprehensive and nuanced debate on sustainable diets and the food system within the context of global environmental limits.

We declare no competing interests. We thank D Driscoll and BG Ridoutt for their insightful comments on the manuscript.

Hadjikakou M, Ritchie EG, Watermeyer KE, Bryan BA (2019) Improving the assessment of food system sustainability. The Lancet – Planetary Health PDF DOI

Feral horse impacts on threatened plants and animals in sub-alpine and montane environments in Victoria, Australia

Authors: Rebecca C Cherubin, Susanna E Venn, Don A Driscoll, Tim S Doherty, and Euan G Ritchie

Published in: Ecological Management & Restoration

Summary

Feral herbivores are a major driver of biodiversity loss globally and can alter the structure, composition and functioning of ecosystems. The direct impacts of feral herbivores on plant communities are well studied, but the direct and indirect effect they have on wildlife is not well understood.

In Victoria (south‐eastern Australia), a large feral Horse (Equus caballus) population coincides with highly sensitive and nationally endangered Alpine Sphagnum Bogs and Associated Fens communities, and several threatened animal species.

We assessed the impact of feral horses on this ecological community and the Alpine Water Skink (Eulamprus kosciuskoi) and the Broad‐toothed Rat (Mastacomys fuscus) at 20 sites with varying levels of horse disturbance. We used scat counts to determine an index of feral horse abundance and quantified impacts associated with their presence in the landscape. Active searches were used for Alpine Water Skink and scat and runway surveys for Broad‐toothed Rat. We also measured the vegetation structure and the abundance of different vegetation types (life forms).

Our results suggest that feral horses are associated with vegetation types and characteristics that negatively influence the presence or abundance of Alpine Water Skink and Broad‐toothed Rat. Sites with high horse activity had more low‐growing forbs, and the abundance of Alpine Water Skink was negatively related to this vegetation type. Grasses, sedges, rushes and shrubs were also less dense and lower in height in high horse activity sites, and Broad‐toothed Rat was less likely to be present in areas with these habitat attributes.

We recommend that feral horses are controlled to protect these threatened vertebrate species and their Sphagnum bog habitat.

Cherubin RC, Venn SE, Driscoll DA, Doherty TS, Ritchie EG (2019) Feral horse impacts on threatened plants and animals in sub-alpine and montane environments in Victoria, Australia. Ecological Management & Restoration PDF DOI

Impacts of feral horses in the Australian Alps and evidence-based solutions

Authors: Don A Driscoll, Graeme L Worboys, Hugh Allan, Sam C Banks, Nicholas J Beeton, Rebecca C Cherubin, Tim S Doherty, C Max Finlayson, Ken Green, Renée Hartley, Geoffrey Hope, Chris N Johnson, Mark Lintermans, Brendan Mackey, David J Paull, Jamie Pittock, Luciana L Porfirio, Euan G Ritchie, Chloe F Sato, Ben C Scheele, Deirdre A Slattery, Susanna Venn, David Watson, Maggie Watson, and Richard M Williams

Published in: Ecological Management & Restoration

Summary

New evidence of impacts by feral horses in Australia’s alpine parks systems confirms they endanger threatened species and extensively damage critically endangered bog communities that could take millennia to recover. These impacts are not confounded by effects of deer and accumulate over time, even when only a small number of feral horses (∼100) are present.

With protected areas representing only a small proportion of the area of the Australian states of New South Wales (9.3%) and Victoria (17%), allowing feral horses to degrade reserves is not a reasonable management compromise, is contrary to the purpose of the protected area system and conflicts with international obligations.

Modelling and decades of management experience indicate that trapping alone does not control feral horse numbers. Trapping and fertility control can work in small populations, but not when there are several thousand horses in remote areas. Aerial culling is needed to cost‐effectively and humanely control feral horse populations.

The relatively small amount of suffering feral horses experience during a cull is outweighed by

  1. avoiding suffering and death of horses from starvation and thirst,
  2. avoiding the suffering of native animals displaced by horses, and
  3. avoiding the ethical concerns of driving threatened species towards extinction.

Objections to aerial culling on welfare and cultural grounds are contradicted by evidence.

Improving knowledge in the general community about what is at stake is long overdue because without this knowledge, small groups with vested interests and unfounded claims have been able to dominate debate and dictate management actions.

As a result of ineffective management, horse populations are now expanding and causing well‐documented damage to Australia’s alpine parks, placing at risk almost $10M spent on restoration after livestock grazing ended. The costs of horse control and restoration escalate the longer large horse populations remain in the alpine parks.

It is crucial that feral horse numbers are rapidly reduced to levels where ecosystems begin to recover. Aerial culling is needed as part of the toolbox to achieve that reduction.

Driscoll DA, Worboys GL, Allan H, Banks SC, Beeton NJ, Cherubin RC, Doherty TS, Finlayson CM, Green K, Hartley R, Hope G, Johnson CN, Lintermans M, Mackey B, Paull DJ, Pittock J, Porfirio LL, Ritchie EG, Sato CF, Scheele BC, Slattery DA, Venn S, Watson D, Watson M, Williams RM (2019) Impacts of feral horses in the Australian Alps and evidence-based solutions. Ecological Management & Restoration PDF DOI 

Animal movements in fire-prone landscapes

Authors: Dale G Nimmo, Sarah Avitabile, Sam C Banks, Rebecca Bliege Bird, Kate Callister, Michael F Clarke, Chris R Dickman, Tim S Doherty, Don A Driscoll, Aaron C Greenville, Angie Haslem, Luke T Kelly, Sally A Kenny, José J Lahoz‐Monfort, Connie Lee, Steven Leonard, Harry Moore, Thomas M Newsome, Catherine L Parr, Euan G Ritchie, Kathryn Schneider, James M Turner, Simon Watson, Martin Westbrooke, Mike Wouters, Matthew White, and Andrew F Bennett.

Published in: Biological Reviews

Abstract

Movement is a trait of fundamental importance in ecosystems subject to frequent disturbances, such as fire‐prone ecosystems. Despite this, the role of movement in facilitating responses to fire has received little attention.

Herein, we consider how animal movement interacts with fire history to shape species distributions. We consider how fire affects movement between habitat patches of differing fire histories that occur across a range of spatial and temporal scales, from daily foraging bouts to infrequent dispersal events, and annual migrations.

We review animal movements in response to the immediate and abrupt impacts of fire, and the longer‐term successional changes that fires set in train.

We discuss how the novel threats of altered fire regimes, landscape fragmentation, and invasive species result in suboptimal movements that drive populations downwards.

We then outline the types of data needed to study animal movements in relation to fire and novel threats, to hasten the integration of movement ecology and fire ecology.

We conclude by outlining a research agenda for the integration of movement ecology and fire ecology by identifying key research questions that emerge from our synthesis of animal movements in fire‐prone ecosystems.

Nimmo DG, Avitabile S, Banks SC, Bliege Bird R, Callister K, Clarke MF, Dickman CR, Doherty TS, Driscoll DA, Greenville AC, Haslem A, Kelly LT, Kenny SA, Lahoz-Monfort JJ, Lee C, Leonard S, Moore H, Newsome TM, Parr CL, Ritchie EG, Schneider K, Turner JM, Watson S, Westbrooke M, Wouters M, White M, Bennett AF (2018) Animal movements in fire-prone landscapes. Biological Reviews PDF DOI

The secret life of possums: data loggers reveal the movement ecology of an arboreal mammal

Authors: Blake M Allan, Dale G Nimmo, John P Y Arnould, Jennifer K Martin, and Euan G Ritchie

Published in: Journal of Mammalogy

Abstract

Understanding animal movement patterns is fundamental to ecology, as it allows inference about species’ habitat preferences and their niches. Such knowledge also underpins our ability to predict how animals may respond to environmental change, including habitat loss and modification. Data-logging devices such as GPS trackers and accelerometers are rapidly becoming cheaper and smaller, allowing movement at fine scales to be recorded on a broad range of animal species.

We examined movement patterns of an arboreal mammal (bobuck, Trichosurus cunninghami) in a highly fragmented forest ecosystem.

The GPS data showed males travelled greater distances than females in linear roadside strip habitats, but not in forest fragments. The accelerometer data showed that both sexes exhibited higher activity levels in roadside habitats compared to forest fragments. By coupling GPS and accelerometer data, we uncovered for this species an ecological pattern similar to other mammals: that male bobucks had higher activity levels than females for a given distance travelled.

Our findings also suggest that habitat fragmentation changes the amount and type of activity bobucks perform while moving, and that linear forest strips could be considered “energetically challenging” habitats, which informs how we should manage the spatial distribution of key supplementary resources for this species such as nest sites and minimum fragment sizes.

Allan BM, Nimmo DG, Arnould JPY, Martin JK, Ritchie EG (2018) The secret life of possums: data loggers reveal the movement ecology of an arboreal mammal. Journal of Mammalogy PDF DOI

Diversity in Australia’s tropical savannas: An integrative taxonomic revision of agamid lizards from the genera Amphibolurus and Lophognathus (Lacertilia: Agamidae)

Authors: Jane Melville, Euan G Ritchie, Stephanie N J Chapple, Richard E Glor And James A Schulte II

Published in: Memoirs of Museum Victoria, volume 77

Abstract

The taxonomy of many of Australia’s agamid lizard genera remains unresolved because morphological characters have proved to be unreliable across numerous lineages. We undertook a morphological study and integrated this with a recent genetic study to resolve long-standing taxonomic problems in three genera of large-bodied Australian agamid lizards: Amphibolurus, Gowidon and Lophognathus. We had broad geographic sampling across genera, including all currently recognised species and subspecies.

Using an integrative taxonomic approach, incorporating mitochondrial (ND2) and nuclear (RAG1) genetic data, and our morphological review, we found that both generic and species-level taxonomic revisions were required. We revise generic designations, creating one new genus (Tropicagama gen. nov.) and confirming the validity of Gowidon, giving a total of four genera. In addition, we describe a new species (Lophognathus horneri sp. nov.) and reclassify two other species.

Our results provide a significant step forward in the taxonomy of some of Australia’s most iconic and well-known lizards and provide a clearer understanding of biogeographic patterns across Australia’s monsoonal and arid landscapes.

Melville J, Ritchie EG, Chapple SNJ, Glor RE Schulte II JA (2018) Diversity in Australia’s tropical savannas: An integrative taxonomic revision of agamid lizards from the genera Amphibolurus and Lophognathus (Lacertilia: Agamidae). Memoirs of Museum Victoria PDF DOI

Towards meaningful monitoring: A case study of a threatened rodent

Authors: Hayley M Geyle, Gurutzeta Guillera‐Arroita, Hugh F Davies, Ronald S C Firth, Brett P Murphy, Dale G Nimmo, Euan G Ritchie, John C Z Woinarski, and Emily Nicholson

Published in: Austral Ecology

Abstract

Detecting trends in species’ distribution and abundance are essential for conserving threatened species, and depend upon effective monitoring programmes. Despite this, monitoring programmes are often designed without explicit consideration of their ability to deliver the information required by managers, such as their power to detect population changes.

Here, we demonstrate the use of existing data to support the design of monitoring programmes aimed at detecting declines in species occupancy. We used single‐season occupancy models and baseline data to gain information on variables affecting the occupancy and detectability of the threatened brush‐tailed rabbit‐rat Conilurus penicillatus (Gould 1842) on the Tiwi Islands, Australia. This information was then used to estimate the survey effort required to achieve sufficient power to detect changes in occupancy of different magnitudes.

We found that occupancy varied spatially, driven primarily by habitat (canopy height and cover, distance to water) and fire history across the landscape. Detectability varied strongly among seasons, and was three times higher in the late dry season (July–September), compared to the early dry season (April–June). Evaluation of three monitoring scenarios showed that conducting surveys at times when detectability is highest can lead to a substantial improvement in our ability to detect declines, thus reducing the survey effort and costs.

Our study highlights the need for careful consideration of survey design related to the ecology of a species, as it can lead to substantial cost savings and improved insight into species population change via monitoring.

Geyle HM, Guillera-Arroita G, Davies HF, Firth RSC, Murphy BP, Nimmo DG, Ritchie EG, Woinarski JCZ, Nicholson E (2018) Towards meaningful monitoring: A case study of a threatened rodent. Austral Ecology, PDF DOI

Continental patterns in the diet of a top predator: Australia’s dingo

Authors: Tim S Doherty, Naomi E Davis, Chris R Dickman, David M Forsyth, Mike Letnic, Dale G Nimmo, Russell Palmer, Euan G Ritchie, Joe Benshemesh, Glenn Edwards, Jenny Lawrence, Lindy Lumsden, Charlie Pascoe, Andy Sharp, Danielle Stokeld, Cecilia Myers, Georgeanna Story, Paul Story, Barbara Triggs, Mark Venosta, Mike Wysong, and Thomas M Newsome

Published in: Mammal Review

Abstract

Conserving large carnivores is controversial because they can threaten wildlife, human safety, and livestock production. Since large carnivores often have large ranges, effective management requires knowledge of how their ecology and functional roles vary biogeographically.

We examine continental‐scale patterns in the diet of the dingo – Australia’s largest terrestrial mammalian predator. We describe and quantify how dingo dietary composition and diversity vary with environmental productivity and across five bioclimatic zones: arid, semi‐arid, tropical, sub‐tropical, and temperate.

Based on 73 published and unpublished data sets from throughout the continent, we used multivariate linear modelling to assess regional trends in the occurrence of nine food groups (arthropods, birds, reptiles, European rabbits Oryctolagus cuniculus, medium‐sized (25–125 kg) and large (169–825 kg) exotic ungulates (including livestock), and other small (<0.5 kg) medium‐sized (0.5–6.9 kg) and large (≥7 kg) mammals) in dingo diets. We also assessed regional patterns in the dietary occurrence of livestock and the relationship between dietary occurrence of rabbits and small, medium‐sized and large mammals.

Dingoes eat at least 229 vertebrate species (66% mammals, 22% birds, 11% reptiles, and 1% other taxa). Dietary composition varied across bioclimatic zones, with dingo diets in the arid and semi‐arid zones (low‐productivity sites) having the highest occurrence of arthropods, reptiles, birds, and rabbits. Medium‐sized mammals occurred most frequently in temperate and sub‐tropical zone diets (high‐productivity sites), large mammals least in the arid and sub‐tropical zones, and livestock most in the arid and tropical zones. The frequency of rabbits in diets was negatively correlated with that of medium‐sized, but not small or large mammals.

Dingoes have a flexible and generalist diet that differs among bioclimatic zones and with environmental productivity in Australia. Future research should focus on examining how dingo diets are affected by local prey availability and human‐induced changes to prey communities.

Doherty TS, Davis NE, Dickman CR, Forsyth DM, Letnic M, Nimmo DG, Palmer R, Ritchie EG, Benshemesh J, Edwards G, Lawrence J, Lumsden L, Pascoe C, Sharp A, Stokeld D, Myers C, Story G, Story P, Triggs B, et al. (2018) Continental patterns in the diet of a top predator: Australia’s dingo, Mammal Review, PDF DOI

Species definitions shape policy

Authors: Euan G Ritchie, Bradley P Smith, Lily M van Eeden, and Dale G Nimmo

Published in: Science, volume 361, issue 6,409 (September 2018)

The names we assign to organisms, and why, have important ramifications for our understanding of Earth’s diversity and, more practically, how it is managed. For example, wolves, coyotes, domestic dogs, and other canids are often considered distinct (1), but their members can, and frequently do, interbreed (2). Differing concepts of species—which might take into account morphology, ecology, behaviour, genetics, or evolutionary history (3) —could describe canids as very few or many species, depending on which concepts are used and how strictly they are applied. Which definition scientists adopt can have political and ecological consequences.

The dingo (Canis dingo) has traditionally been considered native in Australia, given evidence of its presence before the year 1400 (4) and indications that it has lived in Australia for at least 5,000 years (5). This designation meant that Western Australia had to have a management strategy in place for the dingo, along with other native fauna. However, a recent paper (6) argues that dingoes are in fact C. familiaris because they don’t satisfy zoological nomenclature protocols nor sufficiently differ genetically or morphologically from other canids, including domestic dogs.

The Western Australian government cited this work in justifying its recent decision to declare the dingo a non-native species under the state’s Biodiversity Conservation Act (BCA) (7). The new order removesthe government requirement to manage the species. As a result, dingoes can now be killed anywhere in the state without a BCA license. A potential increase in lethal control of dingoes could have dire consequences for Australia’s ecosystems. The dingo is Australia’s largest terrestrial top predator (adults typically weigh 15 to 20 kg (8)), it fulfils a crucial ecological role, and it has strong cultural significance for Australia’s Indigenous people (8).

Taxonomy serves a critical purpose for cataloguing and conserving biodiversity, but different interpretations and applications of species concepts can affect management decisions. Policy-makers may use the interpretations that justify their preferred values, such as prioritizing livestock more than biodiversity protection. It is therefore imperative that scientists carefully engage in the policy decision-making process. Scientists must work with policy-makers to convey the multiple dimensions and values that can affect species delineation and make clear the potential consequences of applying such classifications.

  1.  J.Clutton-Brocketal.,Bull.Br.Mus.Nat.Hist.Zool. 29,117 (1976).
  2. Z.Fanetal.,Gen.Res.26,163(2016).
  3. F.E.Zachos, Mammal Rev.10.1111/mam.12121(2018).
  4. Department of the Environment and Energy, Australian Government, “Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)” (1999); http://www.environment.gov.au/epbc
  5. K.M.Cairns, A.N.Wilton, Genetica 144,553(2016).
  6. S.M.Jackson et al., Zootaxa 4317,201(2017).
  7. M.Bamford, “Dingoes to remain classified as non-native wild dogs under reform to Western Australian law,” ABC News (2018); http://www.abc.net.au/news/2018-08-28/dingoes-will-no-longer-be-native-animals-in-western-australia/10172448
  8. M.Letnic et al., Biol.Rev. 87,390(2012).

Ritchie EG, Smith BP, van Eeden LM, Nimmo DG (2018) Species definitions shape policy, Science PDF DOI

Expanding the role of targets in conservation policy

Authors: Tim S Doherty, Lucie M Bland Brett A Bryan, Timothy Neale, Emily Nicholson, Euan G Ritchie, and Don A Driscoll

Published in: Trends in Ecology & Evolution

Conservation targets perform beneficial auxiliary functions that are rarely acknowledged, including raising awareness, building partnerships, promoting investment, and developing new knowledge. Building on these auxiliary functions could enable more rapid progress towards current targets and inform the design of future targets.

Doherty TS, Bland LM, Bryan BA, Neale T, Nicholson E, Ritchie EG, Driscoll DA (2018) Expanding the Role of Targets in Conservation Policy, Trends in Ecology & Evolution, PDF DOI 

Carnivore conservation needs evidence-based livestock protection

Authors: Lily M van Eeden, Ann Eklund, Jennifer R B Miller, José Vicente López-Bao, Guillaume Chapron, Mikael R Cejtin, Mathew S Crowther, Christopher R Dickman, Jens Frank, Miha Krofel, David W Macdonald, Jeannine McManus, Tara K Meyer, Arthur D Middleton, Thomas M Newsome, William J Ripple, Euan G Ritchie, Oswald J Schmitz, Kelly J Stoner, Mahdieh Tourani, Adrian Treves

Published in: PloS Biology

Abstract

Carnivore predation on livestock often leads people to retaliate. Persecution by humans has contributed strongly to global endangerment of carnivores. Preventing livestock losses would help to achieve three goals common to many human societies: preserve nature, protect animal welfare, and safeguard human livelihoods.

Between 2016 and 2018, four independent reviews evaluated >40 years of research on lethal and nonlethal interventions for reducing predation on livestock. From 114 studies, we find a striking conclusion: scarce quantitative comparisons of interventions and scarce comparisons against experimental controls preclude strong inference about the effectiveness of methods.

For wise investment of public resources in protecting livestock and carnivores, evidence of effectiveness should be a prerequisite to policy making or large-scale funding of any method or, at a minimum, should be measured during implementation.

An appropriate evidence base is needed, and we recommend a coalition of scientists and managers be formed to establish and encourage use of consistent standards in future experimental evaluations.

van Eeden LM, Eklund A, Miller JRB, López-Bao JV, Chapron G, Cejtin MR, Crowther MS, Dickman CR, Frank J, Krofel M, Macdonald DW, McManus J, Meyer TK, Middleton AD, Newsome TM, Ripple WJ, Ritchie EG, Schmitz OJ, Stoner KJ, Tourani M, Treveset A (2018) Carnivore conservation needs evidence-based livestock protection, PLOS Biology PDF DOI 

The Conversation: A numbers game: killing rabbits to conserve native mammals

Controlling rabbit populations has a key role in conserving Australia’s native plants and animals

By Euan Ritchie (Deakin University), Damien Fordham (University of Adelaide), and Miguel Lurgi, (Centre national de la recherche scientifique)

This article was originally published on The Conversation. Read the original article.

Invasive species have a devastating effect on biodiversity. In Australia, introduced red foxes and feral cats have been implicated in the majority of the extinctions of the native mammal fauna, which has been decimated since European arrival.

But there’s a herbivore that also causes eco-catastrophe. Rabbits both compete with native animals for food and shelter and act as easy prey for abundant populations of cats and foxes. By over-grazing vegetation and reducing habitat complexity, they make hunting easier for introduced predators.

Food webs are complex. Because of this, once an invasive species is embedded in a food web, simply eradicating them without considering the potential knock-on effects to other species they interact with, could cause unintended and undesirable consequences. We modelled different rates of rabbit population reduction to assess what level of control might be best for aiding the conservation of native mammals and not causing negative outcomes.

Rabbit numbers boom and crash

Rabbits, famously, reproduce rapidly and can cope with a relatively high predation rate. This can cause “hyper-predation”, where rabbit-inflated cat and fox populations indirectly increase the predation pressure on native mammals. This is especially so when rabbit populations intermittently crash due to, for example, extreme environmental events (like severe and prolonged droughts) or disease. This causes predators to switch their diet and eat more native mammals.

This logically suggests that reducing rabbit numbers might thus help reduce cat and fox populations, by removing their abundant prey. Collectively this should benefit native plants and animals, including many threatened mammal species. However, ecosystem and pest management is a complex game.

When controlling rabbits we need to look beyond one or two species. We should consider the potential consequences for the entire ecological community, which ultimately depend on how changes in one species percolate through the network of ecological interactions between them.

Our new research, recently published in the Journal of Applied Ecology, set out to examine these questions in more detail. We consider other key players in Australia’s arid regions, such as kangaroos and dingoes, when looking at the effects of rabbit control on small native mammals. Our aim was to provide a better understanding of how changes in rabbit populations might affect other species via the food web.

We developed a multi-species ecological network model to describe and quantify how changing rabbit abundance can affect species on different feeding levels. In addition to rabbits, small native mammals, and mesopredators (cats and foxes), our model also considers apex predators (dingo) and large herbivores (kangaroo) as part of the Australian arid food web. This model allowed us to examine changes in predator-prey interactions (including potential prey switching and hyper-predation) and how these could affect the survival of native prey through time.

We found that removing rabbits at rates between 30-40% appeared to benefit small mammals. This is approximately the rate at which rabbits are currently managed in Australia using biocontrol agents (introduced diseases).

Rabbit control in Australia typically involves a “press and pulse” approach. Rabbit populations are suppressed via biocontrol (press) and periods of warren destruction and poisoning (pulse). Finding that reducing rabbit populations by around 40% seems most beneficial to small mammals is important, as it informs how and when we combine these strategies.

The 40% rate corresponds well with the disease-induced (press) mortality rate in rabbit populations due to rabbit haemorrhagic disease and myxomatosis. These are the primary biocontrol agents used in arid Australia to control rabbit populations.

Our study supports rabbit-reduction strategies that involve sustained “press” control, that kill a moderate portion of a rabbit population, with less frequent removal at higher proportions of the population.

To effectively manage invasive species, it’s important to focus on entire communities. Targeting single species might not be enough – every animal exists within a complex web of interactions.

There has been much focus by the current government on controlling feral cats, as a way to conserve many of Australia’s unique and threatened mammal species.

However, more focus could be devoted to protecting habitat cover and complexity, by reducing the land clearing and over-grazing that makes hunting easier. We can also manage rabbits sensibly to reduce competition for resources, and indirectly control cats and foxes.
The Conversation

Eradicating abundant invasive prey could cause unexpected and varied biodiversity outcomes: The importance of multispecies interactions

Authors: Miguel Lurgi, Euan G Ritchie, and Damien A Fordham

Published in: Journal of Applied Ecology

Abstract

Abundant and widely distributed invasive prey can negatively affect co‐occurring native species by competing for food and/or shelter, removing vegetation cover and reducing habitat complexity (changing predation risk), and by sustaining elevated abundances of invasive mesopredators. However, information regarding the community and trophic consequences of controlling invasive prey and their temporal dynamics remain poorly understood.

We used multispecies ecological network models to simulate the consequences of changing European rabbit Oryctolagus cuniculus abundance in an arid mammalian community. We quantified how changes in the dominant prey (rabbits) affected multiple trophic levels, examining changes in predator–prey interactions through time and how they affected native prey persistence.

Our results suggest that removal of rabbits can benefit native biodiversity immediately at removal rates between 30% and 40%. However, beyond these levels, densities of small native mammals will decline in the short term. The processes underpinning these declines are: (a) increased competition for resources (vegetation) with kangaroos Macropus spp., whose numbers increase due to their release from competition with rabbits and (b) increased predation (prey switching) by feral cats Felis catus. Both effects are mediated by dingoes Canis dingo, a native apex predator.

Importantly, native mammal abundance recovers after a time delay, which is prolonged when high rates of rabbit control are applied. This is likely due to a reduction in hyperpredation by invasive feral cats and red foxes Vulpes vulpes following rabbit removal.

Continued eradication of rabbits in arid Australia will benefit native species due to a decrease in apparent competition for resources and by alleviating hyperpredation from invasive mesopredators. Furthermore, ecosystem‐level conservation benefits of reducing invasive prey abundance are as important as direct control of invasive mesopredators.

Synthesis and applications: Multispecies ecological network models provide wildlife managers with tools to better understand and predict the complex effects of species removal and control on both intact and modified ecosystems. Our results show that management of the Australian arid zone can benefit from controlling invasive prey as well as invasive predators. However, invasive species control can cause unexpected outcomes on native biodiversity. This extends to other systems where dominant prey may play fundamental roles in ecosystem structure and function.

Lurgi M, Ritchie EG, Fordham DA (2018) Eradicating abundant invasive prey could cause unexpected and varied biodiversity outcomes: The importance of multispecies interactions, Journal of Applied Ecology, PDF DOI 

Evaluating the efficacy of predator removal in a conflict-prone world

Authors: Robert J Lennox, Austin J Gallagher, Euan G Ritchie, and Steven J Cooke

Published in: Biological Conservation, volume 224 (August 2018)

Abstract

Predators shape ecosystem structure and function through their direct and indirect effects on prey, which permeate through ecological communities. Predators are often perceived as competitors or threats to human values or well-being. This conflict has persisted for centuries, often resulting in predator removal (i.e. killing) via targeted culling, trapping, poisoning, and/or public hunts. Predator removal persists as a management strategy but requires scientific evaluation to assess the impacts of these actions, and to develop a way forward in a world where human-predator conflict may intensify due to predator reintroduction and rewilding, alongside an expanding human population.

We reviewed literature investigating predator removal and focused on identifying instances of successes and failures. We found that predator removal was generally intended to protect domestic animals from depredation, to preserve prey species, or to mitigate risks of direct human conflict, corresponding to being conducted in farmland, wild land, or urban areas. Because of the different motivations for predator removal, there was no consistent definition of what success entailed so we developed one with which to assess studies we reviewed. Research tended to be retrospective and correlative and there were few controlled experimental approaches that evaluated whether predator removal met our definition of success, making formal meta-analysis impossible. Predator removal appeared to only be effective for the short-term, failing in the absence of sustained predator suppression. This means predator removal was typically an ineffective and costly approach to conflicts between humans and predators.

Management must consider the role of the predator within the ecosystem and the potential consequences of removal on competitors and prey. Simulations or models can be generated to predict responses prior to removing predators. We also suggest that alternatives to predator removal be further developed and researched.

Ultimately, humans must coexist with predators and learning how best to do so may resolve many conflicts.

Lennox RJ, Gallagher AJ, Ritchie EG, Cooke SJ (2018) Evaluating the efficacy of predator removal in a conflict-prone world, Biological Conservation, PDF DOI

Crowdfunded campaigns are conserving the Earth’s environment

Crowdfunded campaigns to save the orange-bellied parrot are a rare ray of hope. Image credit: Fatih Sam

By Eduardo Gallo-Cajiao (University of Queensland), Carla Archibald (University of Queensland), Euan Ritchie (Deakin University), Rachel Friedman (University of Queensland), Richard Fuller (The University of Queensland), Rochelle Steven (University of Queensland), and Tiffany Morrison (James Cook University)

This article was originally published on The Conversation. Read the original article, including reader comments.

If not for the public’s generosity, the iconic Statue of Liberty might not have the solid and impressive footing she does today. In the late 1800s, government funds for the monument were exhausted. Yet through a fundraising campaign, the New York World newspaper garnered support from over 160,000 residents to cover the pedestal costs.

Just as large monuments need solid bases to ensure their long-term existence, so too does the environment. In the case of nature conservation, it requires money to support diverse research projects, on-ground activities, and outreach aimed at protecting and managing species and habitats.

While the health of the environment continues to decline globally, in most regions government funding falls short of what is required to stem the losses. Crowdfunding plays an important and under-appreciated role for biodiversity conservation.

Our new research presents a global analysis of how crowdfunding, still a relatively novel and minor financial mechanism in the conservation community, is contributing to conservation around the world.

Show me the money. What’s being funded and why?

Crowdfunding offers a powerful mechanism for mobilising resources for conservation across borders. We recorded 577 conservation-oriented projects (from 72 crowdfunding platforms), which have raised around US$4.8 million since 2009. The people leading these projects were based in 38 countries, but projects took place across 80 countries.

This pattern has important implications for conservation, because there is often a mismatch between high-priority areas for global conservation and countries with the greatest financial and technical capacity. For instance, we discovered that a third of the projects were delivered in different countries to where their proponents were based. The USA, UK and Australia were the countries with the highest outflow of projects (“project exporters”). Indonesia, South Africa, Costa Rica and Mexico had the highest inflow (“project importers”).

Crowdfunding could be supporting conservation work of actors that do not have as much capacity for raising funds.

The people leading projects were primarily from non-governmental organisations (35%) or universities (30%), or were freelancers (26%). Importantly, among non-governmental organisations, we discovered organisations operating at sub-national levels proposed a majority of projects.

Additionally, crowdfunding for conservation is not all about research. While most of the projects we reviewed focused on research (40%), many tackled raising awareness of conservation-related issues (31%) or boots-on-the-ground activities (21%). This expands the sphere of anecdotal evidence and commentary about crowdfunding related to conservation, which has so far revolved around research. For the first time, we’ve systematically unpacked how these funds are being used for additional activities to support conservation.

Crowdfunding can also support innovative projects that traditional funding agencies deem too risky or unconventional. For example, one project supported buying and training two Maremma sheepdogs to protect penguins against predatory foxes in southeastern Australia. (That might sound familiar to those who’ve seen the movie Oddball.)

Such opportunities for innovation can have important consequences for conservation worldwide; crowdfunding could be considered an incubator for novel ideas before widespread dissemination.

More than half of the projects we recorded (around 58%) largely focused on species. These included a disproportionate number of threatened bird and mammal species.

Prominent projects to save orange-bellied parrots or Papua New Guinea’s endangered tree kangaroos are important success stories.

This is not to underplay crowdfunding’s importance for ecosystems – whether land-based (20%), marine (9%) or freshwater (4%). Crowfunding is supporting projects ranging from protection of wilderness areas in remote Tasmania to research informing the conservation of the Californian coast.

Crowdfunding benefits extend beyond dollars and cents

The amount of money for conservation via crowdfunding has so far been relatively modest compared to more traditional conservation finance mechanisms. However, the benefits of crowdfunding extend well beyond dollars and cents. Crowdfunding helps communicate environmental issues and empower researchers and communities.

The figure below shows the reach of a single tweet during the Big Roo Count campaign. It shows how conservation-related messages can spread widely and engage communities via social media.

Crowdfunding is an exciting new tool in the conservation toolbox. But, ultimately, traditional funding sources, like government agencies, still have a major role and duty to invest adequately in environmental protection and nature conservation. Considering the current extinction crisis, governments must avoid further outsourcing of such responsibilities.

The discussion over novel sources and recipients of conservation funding continues. At the same time, transparency and oversight remain critical for managing expectations and overall effectiveness of funding. Crowdfunding contributes one more building block to democratising conservation funding and increasing transparency.

The authors would like to acknowledge the contribution of Edward Game.
The Conversation

Animal recognition and identification with deep convolutional neural networks for automated wildlife monitoring

Authors: Hung Nguyen, Sarah J Maclagan, Tu Dinh Nguyen, Thin Nguyen, Paul Flemons, Kylie Andrews, Euan G Ritchie, and Dinh Phung

Published in: 2017 IEEE International Conference on Data Science and Advanced Analytics

Abstract

Efficient and reliable monitoring of wild animals in their natural habitats is essential to inform conservation and management decisions. Automatic covert cameras or “camera traps” are being an increasingly popular tool for wildlife monitoring due to their effectiveness and reliability in collecting data of wildlife unobtrusively, continuously and in large volume. However, processing such a large volume of images and videos captured from camera traps manually is extremely expensive, time-consuming and also monotonous. This presents a major obstacle to scientists and ecologists to monitor wildlife in an open environment.

Leveraging on recent advances in deep learning techniques in computer vision, we propose in this paper a framework to build automated animal recognition in the wild, aiming at an automated wildlife monitoring system. In particular, we use a single-labeled dataset from Wildlife Spotter project, done by citizen scientists, and the state-of-the-art deep convo- lutional neural network architectures, to train a computational system capable of filtering animal images and identifying species automatically.

Our experimental results achieved an accuracy at 96.6% for the task of detecting images containing animal, and 90.4% for identifying the three most common species among the set of images of wild animals taken in South-central Victoria, Australia, demonstrating the feasibility of building fully automated wildlife observation. This, in turn, can therefore speed up research findings, construct more efficient citizen science- based monitoring systems and subsequent management decisions, having the potential to make significant impacts to the world of ecology and trap camera images analysis.

Nguyen H, Maclagan SJ, Nguyen TD, Nguyen T, Flemons P, Andrews K, Ritchie EG, Phung D (2017) Animal recognition and identification with deep convolutional neural networks for automated wildlife monitoring, 2017 IEEE International Conference on Data Science and Advanced Analytics PDF DOI 

Futurecasting ecological research: the rise of technoecology

Authors: Blake M Allan, Dale G Nimmo, Daniel Ierodiaconou, Jeremy VanDerWal, Lian Pin Koh, and Euan G Ritchie

Published in: Ecosphere, volume 9, issue 5 (May 2018)

Abstract

Increasingly complex research questions and global challenges (e.g., climate change and biodiversity loss) are driving rapid development, refinement, and uses of technology in ecology. This trend is spawning a distinct sub‐discipline, here termed “technoecology.”

We highlight recent ground‐breaking and transformative technological advances for studying species and environments: bio‐batteries, low‐power and long‐range telemetry, the Internet of things, swarm theory, 3D printing, mapping molecular movement, and low‐power computers. These technologies have the potential to revolutionize ecology by providing “next‐generation” ecological data, particularly when integrated with each other, and in doing so could be applied to address a diverse range of requirements (e.g., pest and wildlife management, informing environmental policy and decision making).

Critical to technoecology’s rate of advancement and uptake by ecologists and environmental managers will be fostering increased interdisciplinary collaboration. Ideally, such partnerships will span the conception, implementation, and enhancement phases of ideas, bridging the university, public, and private sectors.

Allan BM, Nimmo DG, Ierodiaconou D, VanDerWal J, Koh LP, Ritchie EG (2018) Futurecasting ecological research: the rise of technoecology, Ecosphere PDF DOI