Category Archives: Publications

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 

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