Category Archives: Publications

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

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.