Category Archives: Publications

After the catastrophe: a blueprint for a conservation response to large-scale ecological disaster

Authors: Chris Dickman, Don Driscoll, Stephen Garnett, David Keith, Sarah Legge, David Lindenmayer, Martine Maron, April Reside, Euan Ritchie, James Watson, Brendan Wintle, and John Woinarski

The wildfires that afflicted Australia in the summer of 2019-2020 was ecological disaster at enormous scale, and without comparable precedent. With escalating global climate change, such large-scale ecological catastrophes are likely to become more widespread and frequent. Here, we describe a blueprint for conservation responses to these wildfires, to document the challenge and attempted solutions to this particular event and as a potential template for dealing with comparable future events.

The purpose of this report, published as part of the Threatened Species Recovery Hub, is to frame a comprehensive set of linked responses to large-scale impacts for conservation across immediate to longer time frames, in order to best achieve the recovery of affected species, ecosystems and ecological health.

Dickman C, Driscoll D, Garnett S, Keith D, Legge S, Lindenmayer D, Maron M, Reside A, Ritchie EG, Watson J, Wintle B, Woinarski J (2020) After the catastrophe: a blueprint for a conservation response to large-scale ecological disaster. Threatened Species Recovery Hub PDF LINK

Predator responses to fire: A global systematic review and meta‐analysis

Authors: William L Geary, Tim S Doherty, Dale G Nimmo, Ayesha I T Tulloch, and Euan G Ritchie

Published in: Journal of Animal Ecology

Abstract

Knowledge of how disturbances such as fire shape habitat structure and composition, and affect animal interactions, is fundamental to ecology and ecosystem management. Predators also exert strong effects on ecological communities, through top‐down regulation of prey and competitors, which can result in trophic cascades. Despite their ubiquity, ecological importance and potential to interact with fire, our general understanding of how predators respond to fire remains poor, hampering ecosystem management.

To address this important knowledge gap, we conducted a systematic review and meta‐analysis of the effects of fire on terrestrial, vertebrate predators worldwide. We found 160 studies spanning 1978–2018. There were 36 studies with sufficient information for meta‐analysis, from which we extracted 96 effect sizes (Hedge’s g) for 67 predator species relating to changes in abundance indices, occupancy or resource selection in burned and unburned areas, or before and after fire.

Studies spanned geographic locations, taxonomic families, and study designs, but most were located in North America and Oceania (59% and 24%, respectively), and largely focussed on felids (24%) and canids (25%). Half (50%) of the studies reported responses to wildfire, and nearly one third concerned prescribed (management) fires.

There were no clear, general responses of predators to fire, nor relationships with geographic area, biome or life history traits (e.g. body mass, hunting strategy and diet). Responses varied considerably between species. Analysis of species for which at least three effect sizes had been reported in the literature revealed that red foxes (Vulpes vulpes) mostly responded positively to fire (e.g. higher abundance in burned compared to unburned areas) and eastern racers (Coluber constrictor) negatively, with variances overlapping zero only slightly for both species.

Our systematic review and meta‐analysis revealed strong variation in predator responses to fire, and major geographic and taxonomic knowledge gaps. Varied responses of predator species to fire likely depend on ecosystem context. Consistent reporting of ongoing monitoring and management experiments is required to improve understanding of the mechanisms driving predator responses to fire, and any broader effects (e.g. trophic interactions). The divergent responses of species in our study suggest that adaptive, context‐specific management of predator‐fire relationships is required.

Geary WL, Doherty TS, Nimmo DG, Tulloch AIT, Ritchie EG (2019) Predator responses to fire: A global systematic review and meta‐analysis. Journal of Animal Ecology PDF DOI 

Digging up the dirt: quantifying the effects on soil of a translocated ecosystem engineer

Authors: Lauren M Halstead, Duncan R Sutherland, Leonie E Valentine, Anthony R Rendall, Amy L Coetsee, and Euan G Ritchie

Published in: Austral Ecology

Abstract

Digging mammals are often considered ecosystem engineers, as they affect important properties of soils and in turn nutrient exchange, vegetation dynamics and habitat quality. Returning such species, and their functions, to areas from where they have been extirpated could help restore degraded landscapes and is increasingly being trialled as a conservation tool.

Studies examining the effects of digging mammals have largely been from arid and semi‐arid environments, with little known about their impacts and importance in mesic systems. To address this knowledge gap, we investigated the ecological role of a recently introduced population of eastern barred bandicoots (Perameles gunnii) on Churchill Island, Victoria, south‐eastern Australia, from which all digging mammals have been lost.

We quantified the annual rate of soil turnover by estimating the number of foraging pits bandicoots created in 100‐m² plots over a 24‐hour period. Foraging pit counts could not be completed in each season, and the overall turnover estimate assumes that autumn/winter months represent turnover rates for the entire year; however, this is likely to fluctuate between seasons. Ten fresh and ten old pits were compared to paired undug control sites to quantify the effect soil disturbance had on soil hydrophobicity, moisture content and soil strength. Plots contained between zero and 64 new foraging pits each day. We estimated that an individual eastern barred bandicoot digs ~487 (95% CI = 416–526) small foraging pits per night, displacing ~13.15 kg (95% CI = 11.2–14.2 kg) of soil, equating to ~400 kg (95% CI = 341–431 kg) of soil in a winter month. Foraging pits were associated with decreased soil compaction and increased soil moisture along the foraging pit profile.

Eastern barred bandicoots likely play an important role in ecosystems through their effects on soil, which adds to an increasing body of knowledge suggesting restoration of ecosystems, via the return of ecosystem engineers and their functions, holds much promise for conserving biodiversity and ecological function.

Halstead LM, Sutherland DR, Valentine LE, Rendall AR, Coetsee AL, Ritchie EG (2019) Digging up the dirt: Quantifying the effects on soil of a translocated ecosystem engineer. Austral Ecology PDF DOI

Constraints on vertebrate range size predict extinction risk

Authors: Thomas M Newsome, Christopher Wolf, Dale G Nimmo, R Keller Kopf, Euan G Ritchie, Felisa A Smith, and William J Ripple

Published in: Global Ecology and Biogeography

Abstract

Aim: The only factor in the fossil record that consistently buffers against extinction risk is large geographical range. We ask whether extant vertebrate species with the smallest geographical range for their body size have a higher extinction risk, and thus whether the lower bound of the modern range–body size relationship could serve as an effective conservation prioritization tool.

Location: Global in scope.

Time period: Modern.

Major taxa studied: Six classes of vertebrates.

Methods: We compiled a database of geographical range, body size and extinction risk for six vertebrate classes (n = 26,076). We characterized the shape of the relationship between geographical range and body size for each class, using 90% and 10% quantile regression to describe the upper and lower bounds, respectively. We then evaluated the degree of extinction vulnerability of species at the lower bound of the regression using generalized linear mixed models. All analyses accounted for phylogenetic dependence between related species.

Results: The relationships between species ranges and body sizes were generally positive at both the upper and the lower bounds, and segmented (nonlinear) relationships were common. Despite this variability, species near the lower boundary of the relationship were more often in higher extinction risk categories, and this remained true when the role of range size in the International Union for Conservation of Nature Red Listing criteria was accounted for.

Main conclusions: Variability in the upper and lower bounds of the range–body size relationship suggests that some classes of vertebrates exhibit combinations of ranges and body sizes that might not reflect historical patterns. Nonetheless, the range–body size relationship remains a reliable and useful predictor of extinction risk, more so than range size does alone. The range–body size relationship could therefore be used to track the trajectories of species towards or away from an extinction threshold and allow the tracking of how different human activities alter the range–body size relationship.

Newsome TM, Wolf C, Nimmo DG, Kopf RK, Ritchie EG, Smith FA, Ripple WJ (2019) Constraints on vertebrate range size predict extinction risk, Global Ecology and Biogeography PDF DOI

Topographic ruggedness and rainfall mediate geographic range contraction of a threatened marsupial predator

Authors: Harry A Moore, Judy A Dunlop, Leonie E Valentine, John C Z Woinarski, Euan G Ritchie, David M Watson, and Dale G Nimmo

Published in: Diversity and Distributions

Abstract

Aim: Species range contractions are increasingly common globally. The niche reduction hypothesis posits that geographic range contractions are often patterned across space owing to heterogeneity in threat impacts and tolerance. We applied the niche reduction hypothesis to the decline of a threatened marsupial predator across northern Australia, the northern quoll (Dasyurus hallucatus).

Location: Northern Australia.

Methods: We assembled a database containing 3,178 historic and contemporary records for northern quolls across the extent of their distribution dating between 1778 and 2019. Based on these records, we estimated changes in the geographic range of the northern quoll using α‐hulls across four main populations. We then examined how range contractions related to factors likely to mediate the exposure, susceptibility, or tolerance of northern quolls to threats.

Result: The extent of range contractions showed an east–west gradient, most likely reflecting the timing of spread of introduced cane toads (Rhinella marina). There were clear changes in environmental characteristics within the contemporary compared to the historic geographic range, with the most substantial occurring in populations that have suffered the greatest range contractions. The contemporary range is comprised of higher quality habitats (measured using environmental niche models), characterized by higher topographical ruggedness and annual rainfall, and reduced distance to water, compared to the historic range.

Main conclusions: Changes to range and niche likely reflect the capacity of complex habitats to ameliorate threats (namely predation and altered fire regimes), and access to resources that increase threat tolerance. This study highlights the multivariate nature of ecological refuges and the importance of high‐quality habitats for the persistence of species exposed to multiple threats. Our methods provide a useful framework which can be applied across taxa in providing valuable insight to management.

Moore HA, Dunlop JA, Valentine LE, Woinarski JCZ, Ritchie EG, Watson DM, Nimmo DG (2019) Topographic ruggedness and rainfall mediate geographic range contraction of a threatened marsupial predator. Diversity and Distributions PDF DOI

Life in linear habitats: the movement ecology of an endangered mammal in a peri‐urban landscape

Authors: Sarah J Maclagan, Terry Coates, Bronwyn A Hradsky, Ryan Butryn, and Euan G Ritchie

Published in: Animal Conservation

Abstract

Animal movement can be significantly altered in human‐dominated landscapes such as urban and peri‐urban areas, where habitat is often fragmented and/or linear. Knowledge regarding how wildlife respond to anthropogenic change is vital for informing conservation efforts in such landscapes, including the design of nature reserves and wildlife corridors.

To better understand how threatened species persist and behave within human‐dominated landscapes, we examined the home range and space use of the nationally endangered southern brown bandicoot Isoodon obesulus obesulus in peri‐urban Melbourne, Australia’s second‐largest city. Specifically, we examined whether:

  • bandicoots were confined to linear strips of remnant vegetation or also made use of the broader highly modified landscape matrix;
  • the configuration of the linear vegetated strips affected home range shape; and
  • home range area differed between bandicoots living in linear strips and those in larger remnant habitat patches.

We found that:

  • 71% of adult males and 33% of adult females used the matrix, but non‐dispersing juveniles were entirely confined to the linear strips; males also travelled greater distances into the matrix (away from the vegetated strips) than females;
  • bandicoots had longer home ranges in narrower strips and males had longer home ranges than females; and
  • home range area for both sexes was smaller in linear strips than has been recorded in other studies in larger remnant habitats.

Our study highlights the importance of retaining narrow, fragmented and modified vegetation to accommodate threatened biodiversity within human‐dominated landscapes, but suggests the surrounding matrix may also offer important resources for adaptable species, such as bandicoots.

Supporting off‐reserve conservation of biodiversity in novel ecosystems is increasingly pertinent in our rapidly urbanizing world.

Maclagan SJ, Coates T, Hradsky BA, Butryn R, Ritchie EG (2019) Life in linear habitats: the movement ecology of an endangered mammal in a peri‐urban landscape. Animal Conservation PDF DOI

Restricted‐area culls and red fox abundance: Are effects a matter of time and place?

Authors: Jim‐Lino Kämmerle, Euan G Ritchie, and Ilse Storch

Published in: Conservation Science and Practice

Abstract

Predators are often culled to benefit prey, but in many cases this conservation goal is not achieved or results remain unknown.

The red fox (Vulpes vulpes) is a predator of global significance, and an invasive species in some regions. Red fox culls intended to benefit prey are often restricted to small areas, and effectiveness is rarely sufficiently evaluated.

Given the economic, ecological, social, and welfare issues associated with lethal predator control, there is a strong need to assess the effects of spatiotemporal variation in culling intensity on red fox abundance.

We surveyed red fox populations in fragmented forests of south‐western Germany and related indices of local fox abundance to culling data, predicted landscape‐scale fox abundance, and other covariates. We tested whether restricted‐area culling was associated with local reductions in fox abundance, and examined how this relationship changed over time.

Local fox abundance was temporarily reduced in spring, following winter culls. However, the effect was minor and fox populations had compensated for the reductions at the latest by autumn. Restricted‐area culling therefore likely failed to sustain effects on fox abundance throughout the period most relevant for conservation (i.e., the reproductive period of the target prey species).

To be effective as a conservation tool, culling will therefore require explicit spatiotemporal coordination matching the biology of predators and target prey.

Kämmerle J, Ritchie EG, Storch I (2019) Restricted‐area culls and red fox abundance: Are effects a matter of time and place? Conservation Science and Practice PDF DOI

Science communication in a post‐truth world: promises and pitfalls

Authors: R Keller Kopf, Dale G Nimmo, Euan G Ritchie, and Jen K Martin

Published in: Frontiers in Ecology and the Environment

The mass decline of biodiversity in this post-truth era means that reliable and influential conservation science communication is more important than ever.

In this era, truths and lies are increasingly difficult to distinguish, posing a major challenge to science communication. As a result, conservation scientists and managers are grappling with new ways of countering misinformation and sharing factual information.

Facebook, Twitter, YouTube, Instagram, blogs, online news outlets, webcomics, and satirical articles all provide communication opportunities, but we still have a poor understanding of which of these are most effective, and when and where to best communicate science…

Kopf RK, Nimmo DG, Ritchie EG, Martin JK (2019) Science communication in a post-truth world: promises and pitfalls. Frontiers in Ecology and the Environment PDF DOI

The Conversation: Academia can help humans and large carnivores coexist

In Romania, wolves live in the same landscapes as shepherds. Image credit: Vlada Cech via Shutterstock.

By Euan Ritchie (Deakin University), Abi Vanak (University of KwaZulu-Natal), Benjamin Scheele (Australian National University), Laurentiu Rozylowicz, and Tibor Hartel

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

Bears, wolves, lions and other top predators have a long history of conflict with people – they can threaten our safety and kill livestock.

In our recent study, published in Conservation Biology, we outline how conventional conservation approaches are unlikely to lead to effective coexistence between humans and large carnivores in human-dominated landscapes.

This wicked problem encompasses public safety, agriculture, conservation, animal welfare, and more. Each facet is commonly managed by a different institution working in isolation – often failing to reflect the reality of our highly connected world.

Academia can help foster better institutional arrangements, especially in places like Romania, India and Brazil, where there are substantial populations of people and large carnivores in shared spaces.

In Romania, for instance, bears and wolves live in the same places used by shepherds and their livestock. Guardian dogs typically help protect livestock from being attacked.

Similarly, Australia’s own dingo occurs across agricultural and pastoral regions, with sentiments ranging from protected native species to disliked pest.

Why institutions fail carnivore-human relationships

From bears in Romania to dingoes in Australia, large carnivores are found in an array of places. This means they regularly affect the interests of a range of institutions, from agriculture to forestry.

But the current arrangements are poorly suited to facilitate a peaceful coexistence between humans and large carnivores.

Typically, institutions focus on a small subset of concerns. Forestry and agricultural sectors, for instance, may not feel responsible for large carnivore conservation because they are primarily interested in timber and agricultural production.

On the other hand, institutions for transport, energy and border security might be indifferent towards large carnivores. But they can negatively affect these animals if they put up barriers restricting predator movement and inappropriately handle roadkill.

These compartmentalised, and often conflicting, institutions are poorly suited to helping wildlife, especially when large carnivores, such as leopards, wolves and bears, live in human-dominated regions.

A role for academia

Academia has solutions to offer.

Most environment-related professionals, like foresters, wildlife managers and conservation biologists, are trained in a range of academic institutions. Unfortunately, they are often taught narrowly within their sector or discipline.

However, all these future professionals passing through the same institutions provides a great opportunity for a broad change in how we approach difficult conservation challenges and conflict with wildlife.

There are at least three ways in which academia could help address the challenges of human and large carnivore coexistence:

1. Break down the silos

Academic institutions need to create special centres to better support teaching and research across different disciplines.

Conservation – and, on a broader level, how humans should relate to the natural world – cannot be siloed away in wildlife management courses.

2. Broaden the view

We need to actively foster a broader perspective that does not see large carnivores as an “enemy”, while still safeguarding human life. This is a complex and multifaceted challenge.

By working across disciplines, universities have the chance to actively foster this broader perspective. This may seem like a nebulous point, but the collapse of species around the world has highlighted how ineffective our current approach to conservation is. We need to move beyond tinkering around the edges of our extinction crisis.

Conservation policy is already equipped to address individual targets such as regulating carnivore populations and legally protecting species. It is the larger aim of changing norms, challenging values and ensuring all these various institutions are pulling in the same direction that we need to tackle – a tactic called the “leverage points approach”.

3. Work outside the academy

Academia could support existing collaborations. When people with shared interests come together to pool knowledge and address a particular issue, we call it a community of practice. Academia can contribute to these communities by offering the skills and expertise of its graduates, but also broader social and industry connections (where required), knowledge sharing, collaborative research, education and technological innovation.

We need big carnivores and they need us

Large carnivores are critical for the health of ecosystems globally, and we need to provide them with enough space and tolerance to survive.

The ongoing controversy regarding the management of the dingo, Australia’s largest land-based predator (aside from humans), provides a perfect test case for this new approach to managing human-wildlife conflict.

If we can achieve more harmonious relations with the world’s top predators, many of the myriad other species that coexist with them are also likely to benefit from both better habitat management and conservation and the important ecological effects large carnivores can have, such as keeping herbivore and smaller predator numbers in check. This can be a positive step towards addressing Earth’s mass extinction crisis.

The authors would like to thank John Linnell, Senior Research Scientist at the Norwegian Institute for Nature Research, for his contribution to this article.
The Conversation

Threat webs: reframing the co-occurrence and interactions of threats to biodiversity

Authors: William L Geary, Dale G Nimmo, Tim S Doherty, Euan G Ritchie, and Ayesha IT Tulloch

Published in: Journal of Applied Ecology

Abstract

Interactions between threatening processes and their effects on biodiversity are a major focus of ecological research and management. Threat interactions arise when threats or their effects co‐occur spatially and temporally.

Whether the associations between threats are coincidental or causally linked is poorly understood, but has fundamental impacts on how, when and where threats should be managed. We propose that examining threat co‐occurrence, supplemented by experiments and triangulation of evidence, can help identify when and where threats interact causally, informing pressing biodiversity management goals.

Using case studies, we demonstrate how co‐occurring and interacting threats can be visualised as networks (threat webs) and how this could guide conservation interventions at local, regional and global scales.

Synthesis and applications. Recognising that threats co‐occur and interact as networks, and are potentially driven by multiple agents (e.g. other threats, shared environmental drivers), helps us understand their dynamics and impacts on ecosystems. This greater understanding can help facilitate more targeted, efficient and effective environmental management.

Geary WL, Nimmo DG, Doherty TS, Ritchie EG, Tulloch AIT (2019) Threat webs: reframing the co‐occurrence and interactions of threats to biodiversity. Journal of Applied Ecology PDF DOI

The Conversation: We must rip up our environmental laws to address the extinction crisis

The Christmas Island pipistrelle (Pipistrellus murrayi) became extinct in 2009. Image credit Lindy Lumsden

By Don Driscoll, Deakin University; Desley Whisson, Deakin University; Euan Ritchie, Deakin University; Mike Weston, Deakin University; Raylene Cooke, Deakin University, and Tim Doherty, Deakin University.

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

Humans are causing the Earth’s sixth mass extinction event, with an estimated one million species at risk of extinction.

Addressing this crisis requires transformative change, including more effective environmental law and implementation.

Improved legislation is one of five main levers for realising change identified in the recent United Nation’s global biodiversity report and the key lesson arising from the Senate’s interim report into Australia’s faunal extinction crisis.

The Senate’s interim report, based on 420 submissions and five hearings, shows Australia is a world leader in causing species extinctions, in part because Australia’s systems for conserving our natural heritage are grossly inadequate.

To allow the continued erosion of this continent’s spectacular and remarkable array of globally unique plants and animals is a travesty of the highest order.

Inadequate protections

One of the problems is species may decline from common to extinct quite rapidly – faster than the time it takes species to be listed as threatened under the federal Environment Protection and Biodiversity Conservation (EPBC) Act.

The Christmas Island forest skink was formally listed as a threatened species only four months before the last individual died in captivity, but 15 years after the decline was first reported.

Extinction of the forest skink, Bramble Cay melomys and Christmas Island pipistrelle between 2009 and 2014 may have been averted if the risk was formally recognised in a more timely manner and effective conservation actions, such as captive breeding programs, were implemented.

Currently, if a species is not listed, it is not a “matter of national environmental significance” and federal agency staff generally have no legal basis for acting to protect it.

The black-throated finch has been listed as threatened on the EPBC Act for 14 years and during this time 600,000 ha of potential finch habitat has been destroyed. Worse still, five large coal mines, including the Carmichael Coal Mine, have been given approval (pending environmental conditions being met in Queensland) to clear more than 29,000 ha of black-throated finch habitat in one of its final strongholds, the Galilee Basin.

Coal mining will drive these finches into the critically endangered threat category, pushing them perilously close to extinction, and all with federal government approval.

The controversial Toondah Harbour development in Brisbane is another example of how ministerial discretion can allow disastrous environmental outcomes. The project plans to build 3,600 apartments on wetlands that provide habitat for migratory waterbirds, including the critically endangered eastern curlew.

Despite being described as “clearly unacceptable” by the federal environment department and knocking it back twice, the minister allowed a third submission to proceed for further assessment.

It was reported this decision was made in the context of legal threats and donations from the developer in question. If true, this context would make it very difficult to make impartial decisions that protect biodiversity, as environmental law intends.

Increasing ministerial discretion was a key result of 2007 amendments to the EPBC act, which meant recovery plans were no longer required for threatened species.

The amendment allowed the minister to develop “conservation advices” instead of recovery plans. This amendment downgraded protections for threatened species because a minister can legally make decisions that are inconsistent with conservation advice, but not a recovery plan.

New environmental legislation

Based on these examples and many others that demonstrate the failings of current laws, the interim report concludes that we should rip up the EPBC act and develop stronger and more effective environmental legislation.

This includes establishing an independent Environmental Protection Agency to ensure enforcement of environmental laws, and, in a forward-looking addition by the Greens senators, an independent National Environmental Commission to monitor effectiveness of environmental legislation and propose improvements.

Australia needs a well-resourced, independent umpire for the environment, with powers to investigate environmental concerns and scrutinise government policy, akin to New Zealand’s Parliamentary Commissioner for the Environment. While Australia’s Threatened Species Commissioner is an excellent champion for the environment, this role provides no ability to question government actions regarding environmental protection and nature conservation.

Although replacing the EPBC act with new legislation may seem like a radical step to some (but not all), the interim Senate report, and the global UN report, have independently concluded major reform is essential. We are not in a moment of time when tweaking the current system will do the trick.

Changing Australia’s environmental legislation is a relatively minor update compared with the fundamental social and economic changes recommended by the UN report.

Such changes are already recommended by scientific societies like the Ecological Society of Australia, non-government organisations like Birdlife Australia and the Australian Conservation Foundation, and are demanded by a growing section of society. New, fit-for-purpose legislation must be enforceable, apolitical and responsive.

Opinion polls show that the level of environmental concern is higher in Australia than in other countries , while 29% of ABC Vote Compass respondents ranked the environment as the most important issue, up from 9% in 2016.

This groundswell of environmental concern has spawned mass protest movements like Extinction Rebellion. Young Australians also have shown their concern. In March 2019, thousands of school students took part in 50 rallies across the country to protest against “the destruction of our future”.

Decisions about what and how much we buy, what we eat, how much we travel and by what means, and family size, all contribute to our environmental footprints, and are the fundamental instigators of the biodiversity crisis.

However, we must also look to our political leaders to support effective change. The simplest and most powerful action you can take to reverse the extinction crisis is to vote for a party with policies best aligned with credible scientific advice on how we can get out of this mess.
The Conversation

Mainstreaming human and large carnivore coexistence through institutional collaboration

Authors: Tibor Hartel, Ben C Scheele, Abi Tamim Vanak, Laurențiu Rozylowicz, John D C Linnell, and Euan G Ritchie

Published in: Conservation Biology

Abstract

Achieving human‐large carnivore coexistence in Human Dominated Landscapes (HDL) is a key challenge for societies globally. This challenge cannot be adequately met with the current sectoral approaches of HDL governance and an academic sector largely dominated by disciplinary silos.

In this essay, we urge academia (universities and other research institutions and organisations) to take a more active role in embracing societal challenges around large carnivore conservation in HDL. Drawing on key lessons from populated regions of Europe, Asia and South America with significant densities of large carnivores, we illustrate how academia can help facilitate cross‐sectoral cooperation for mainstreaming human large carnivore coexistence.

We propose three ways for academia to engage with human‐large carnivore coexistence in HDL.

First, academia should better embrace the principles and methods of sustainability sciences and create institutional spaces for the implementation of transdisciplinary curricula and projects.

Second, researchers should reflect on the research approaches (i.e. disciplinary, interdisciplinary or transdisciplinary) they apply, and how their outcomes could aid leveraging institutional transformations for mainstreaming human‐large carnivore coexistence.

Third, researchers should engage with various institutions and stakeholder groups for creating novel institutional structures which can respond to the multiple challenges of HDL management, as well as human‐large carnivore coexistence.

Success in mainstreaming human‐large carnivore coexistence in HDL will rest on our collective ability to think and act cooperatively. Such a conservation achievement, if realized, stands to have far-reaching benefits for people and biodiversity alike.

Hartel T, Scheele BC, Vanak AT, Rozylowicz L, Linnell JDC, Ritchie EG (2019) Mainstreaming human and large carnivore coexistence through institutional collaboration. Conservation Biology PDF DOI

Persistence through tough times: fixed and shifting refuges in threatened species conservation

Authors: April E Reside, Natalie J Briscoe, Chris R Dickman, Aaron C Greenville, Bronwyn A Hradsky, Salit Kark, Michael R Kearney, Alex S Kutt, Dale G Nimmo, Chris R Pavey, John L Read, Euan G Ritchie, David Roshier, Anja Skroblin, Zoe Stone, Matt West, and Diana O Fisher

Published in: Biodiversity and Conservation

Abstract

It may be possible to avert threatened species declines by protecting refuges that promote species persistence during times of stress. To do this, we need to know where refuges are located, and when and which management actions are required to preserve, enhance or replicate them.

Here we use a niche-based perspective to characterise refuges that are either fixed or shifting in location over ecological time scales (hours to centuries). We synthesise current knowledge of the role of fixed and shifting refuges, using threatened species examples where possible, and examine their relationships with stressors including drought, fire, introduced species, disease, and their interactions.

Refuges often provide greater cover, water, food availability or protection from predators than other areas within the same landscapes. In many cases, landscape features provide refuge, but refuges can also arise through dynamic and shifting species interactions (e.g., mesopredator suppression). Elucidating the mechanisms by which species benefit from refuges can help guide the creation of new or artificial refuges. Importantly, we also need to recognise when refuges alone are insufficient to halt the decline of species, and where more intensive conservation intervention may be required.

We argue that understanding the role of ecological refuges is an important part of strategies to stem further global biodiversity loss.

Reside AE, Briscoe NJ, Dickman CR, Greenville AC, Hradsky BA, Kark S, Kearney MR, Kutt AS, Nimmo DG, Pavey CR, Read JL, Ritchie EG, Roshier D, Skroblin A, Stone Z, West M, Fisher DO (2019) Persistence through tough times: fixed and shifting refuges in threatened species conservation. Biodiversity and Conservation PDF DOI

The truth about cats and dogs: assessment of apex- and mesopredator diets improves with reduced observer uncertainty

Authors: Michael L Wysong, Ayesha IT Tulloch, Leonie E Valentine, Richard J Hobbs, Keith Morris, and Euan G Ritchie

Published in: Jornal of Mammalogy

Abstract

Dietary (scat) analysis is a key tool for assessing the potential effects of predators on prey and for comparing resource use between predators, information that is crucial for effective wildlife management. However, misidentification of the species from which scats originate could result in inaccurate conclusions regarding predator–prey interactions and their consequences for ecosystems, which may ultimately compromise conservation and management actions.

To address this issue, we developed a framework for decision-making in the face of uncertain scat species origin by incorporating field, laboratory, and molecular identification techniques.

We used the framework to examine the diets of two predators, a native apex predator (dingo, Canis lupus dingo) and an invasive mesopredator (feral cat, Felis catus), from 696 field-collected scats in the arid zone of Australia.

We examined how uncertainty regarding scat species origin changed perceptions of the nature of the relationship between coexisting predators and their prey.

The extent of dietary overlap between dingoes and cats varied with the method used to identify scat species origin. Dietary overlap assessed by laboratory identifications was twice as high as when uncertainty in scat species origin was resolved through our decision framework.

If uncertainty in scat species origin is not resolved in dietary studies, practitioners and decision-makers relying on this information run the risk of making misinformed conclusions regarding the ecological function of predators (including potential impacts on threatened species), which could have perverse outcomes if the wrong predators are targeted for management.

With uncertainty in scat species origin resolved through our decision framework, a low level of dietary overlap between the two predators was demonstrated, and medium-sized mammals most threatened with extinction were shown to be more at risk of impact from feral cat than from dingo depredations.

Wysong ML, Tulloch AIT, Valentine LE, Hobbs RJ, Morris K, Ritchie EG (2019) The truth about cats and dogs: assessment of apex- and mesopredator diets improves with reduced observer uncertainty. Journal of Mammalogy PDF DOI

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