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Publications

Free as a drone: ecologists can add UAVs to their toolbox

Authors: Blake M Allan, Daniel Ierodiaconou, Dale G Nimmo, Mathew Herbert, Euan G Ritchie

Published in: Frontiers in Ecology and the Environment, volume 13, issue 7 (September 2015)

UAVs are at the cutting edge of ecological research. Image credit: Dr Alexandre Schimel
UAVs are at the cutting edge of ecological research technology. Image credit: Dr Alexandre Schimel

Abstract

Unmanned aerial vehicles (UAVs) are at the cutting edge of technology being applied in ecological research.

As UAV technology continues to rapidly develop, Vincent et al. (Front Ecol Environ 2015; 13[2]: 74–75) noted that the potential research applications of UAVs are stymied by legislative regulations imposed by government bodies. However, US laws are being revised to reflect differences between UAV and manned aircraft, and new Federal Aviation Administration (FAA) policies in the US will greatly assist ecologists who seek to use UAVs in their research. New FAA policy grants a Certificate of Waiver or Authorization (COA) for UAV applications by registered operators who meet their new criteria (WebTable 1; FAA 2015). This is a breakthrough, given that previous policy required a “Certificate of Authorization” for individual UAV flights. Ecologists, once becoming certified operators, now have an automatic “Certificate of Authorization” for undertaking most UAV operations relevant to conducting science. As a result of the change in policy, UAV laws in the US now more closely resemble the unambiguous and less restrictive UAV laws in Australia (WebTable 1), where Google and Amazon chose to site their drone delivery testing facilities.

Regardless of legislative change, there are ways to incorporate UAVs into research that can avoid some of the issues outlined by Vincent et al. If universities do not want to become registered operators, they can collaborate with industry partners who are registered. We are currently using such an approach in our ecological research. We believe this provides the best starting point for academic institutions to use UAVs for research purposes, without the need for in-house logistical support or expertise to meet legislative requirements.

While few universities have UAV Operators Certificate (UOC) approval in Australia (http://bit.ly/1cNbY6T), 25 academic institutions in the US — as of July 2015 — hold a COA (http://1.usa.gov/1CDy5W3). Thus, if Vincent et al. worked with a registered industry partner who already had a COA, they could work as close as two nautical miles from the airstrip they describe without the requirement to hold their own COA.

To conduct research within two nautical miles of a registered airstrip still requires a COA, and with good reason. A registered airstrip is marked on official aviation maps for all aircraft, and can be used for emergency landings. The last thing that a pilot in distress needs is to mistake a small UAV in close proximity for a large airplane in the distance. After all, UAV operators typically do not monitor aviation radio frequencies to inform pilots otherwise. It is important for the broader research community to recognize that UAVs are not toys; they are certified aircraft used for commercial purposes, and can pose a serious threat to both people and property when used irresponsibly.

Finally, proposed changes to UAV laws in Australia could relax the requirement of a UOC for remote-piloted aircraft under 2 kg (CASA 2014). As ecologists already undertaking research with UAVs under 2 kg, we are excited about the possibilities that such changes could foster.

Continued positive changes in UAV-relevant legislation globally — together with industry partnerships — should promote the rapid uptake of UAVs as important tools in conducting ecological field-based studies.

Allan BM, Ierodiaconou D, Nimmo DG, Herbert M Ritchie EG (2015) Free as a drone: ecologists can add UAVs to their toolbox. Frontiers in Ecology and the Environment, 13: 354–355. PDF DOI 

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Publications Research

Draft national targets for feral cat management: Towards the effective control of feral cats in Australia – targets with teeth

Authors: John CZ Woinarski, Keith Morris and Euan G Ritchie

Published in: Tracey J, Lane C, Fleming P, Dickman C, Quinn J, Buckmaster, T, McMahon S (ed) (2015) 2015 National Feral Cat Management Workshop Proceedings.

Summary

Feral cats have been present in Australia since soon after European settlement. They are now numerous and pervasive across the continent, and occur on many islands. Although they have been recognised as a Key Threatening Process to Australian biodiversity under the EPBC Act since 1999, and there has been a Threat Abatement Plan for them in place since 2008, there has to date been little progress towards their effective management.

The challenges to effective control of feral cats in Australia are formidable. The geographic scale of concern is immense; many potential control mechanisms (such as trapping and shooting) typically have only superficial, transient and localised benefits; design of effective baits has only recently progressed substantially; there may be significant non-target impacts (including for threatened species such as quolls) from such toxic baits; baiting programs may need to be sustained for many years, and in many places need to also consider integration with control of foxes; reduction in cat numbers may have unwanted consequences (increases in other pest species, such as rabbits or introduced rodents); control programs will be expensive; and there will be some community concern about cat control.

However, progress towards the effective control of feral cats will achieve marked biodiversity benefits. Such control is likely to be substantially more efficient and cost-effective, and produce more enduring outcomes, than alternative conservation approaches based on intensive management for individual threatened species.
Here, we propose short-term (one year) targets towards the effective control of feral cats in Australia. These targets are set within a broader contextual and long-term (ca. 20 years) objective: No further extinctions of Australian wildlife, and pronounced recovery (and return to the wild) of at least 40 currently threatened animal species.

The targets recommended here are designed strategically to help establish a robust foundation for the decadal-scale campaign likely to be required to achieve enduring success. This should not be taken to indicate that significant progress can be achieved, if at all, only at glacial speed. Rather, explicit and dramatic short-term targets set now are required to overcome inertia, to recognise that this is a problem that should be confronted, to demonstrate that successful outcomes are possible, and because the continuing existence of some threatened species requires immediate action.

Woinarski JCZ, Morris K, Ritchie EG (2015) Draft national targets for feral cat management: Towards the effective control of feral cats in Australia – targets with teeth in Tracey J, Lane C, Fleming P, Dickman C, Quinn J, Buckmaster, T, McMahon S (ed) (2015) 2015 National Feral Cat Management Workshop Proceedings, Canberra, 21-22 April 2015. PestSmart Toolkit publication, Invasive Animals Cooperative Research Centre, Canberra, Australia. PDF LINK

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Publications Research

Incorporating anthropogenic effects into trophic ecology: predator–prey interactions in a human-dominated landscape

Authors: Ine Dorresteijn, Jannik Schultner, Dale G Nimmo, Joern Fischer, Jan Hanspach, Tobias Kuemmerle, Laura Kehoe and Euan G Ritchie

Published in: Proceedings of the Royal Society B, volume 282 (September 2015)

Apex predators perform important functions that regulate ecosystems world- wide. However, little is known about how ecosystem regulation by predators is influenced by human activities. In particular, how important are top-down effects of predators relative to direct and indirect human-mediated bottom-up and top-down processes?

Combining data on species’ occurrence from camera traps and hunting records, we aimed to quantify the relative effects of top-down and bottom-up processes in shaping predator and prey distributions in a human-dominated landscape in Transylvania, Romania. By global standards this system is diverse, including apex predators (brown bear and wolf), mesopredators (red fox) and large herbivores (roe and red deer). Humans and free-ranging dogs represent additional predators in the system.

Using structural equation modelling, we found that apex predators suppress lower trophic levels, especially herbivores. However, direct and indirect top- down effects of humans affected the ecosystem more strongly, influencing species at all trophic levels.

Our study highlights the need to explicitly embed humans and their influences within trophic cascade theory. This will greatly expand our understanding of species interactions in human-modified landscapes, which compose the majority of the Earth’s terrestrial surface.

Dorresteijn I, Schultner J, Nimmo DG, Fischer J, Hanspach J, Kuemmerle T, Kehoe L, Ritchie EG (2015) Incorporating anthropogenic effects into trophic ecology: predator–prey interactions in a human-dominated landscape, Proceedings of the Royal Society B, 282: 20151602 PDF DOI

 

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Publications Research

Multiple threats, or multiplying the threats? Interactions between invasive predators and other ecological disturbances

Authors: Tim S Doherty, Chris R Dickman, Dale G Nimmo and Euan G Ritchie

Abstract

Invasive species have reshaped the composition of biomes across the globe, and considerable cost is now associated with minimising their ecological, social and economic impacts. Mammalian predators are among the most damaging invaders, having caused numerous species extinctions.

Here, we review evidence of interactions between invasive predators and six key threats that together have strong potential to influence both the impacts of the predators, and their management.

We show that impacts of invasive predators can be classified as either functional or numerical, and that they interact with other threats through both habitat- and community-mediated pathways.

Ecosystem context and invasive predator identity are central in shaping variability in these relationships and their outcomes. Greater recognition of the ecological complexities between major processes that threaten biodiversity, including changing spatial and temporal relationships among species, is required to both advance ecological theory and improve conservation actions and outcomes.

We discuss how novel approaches to conservation management can be used to address interactions between threatening processes and ameliorate invasive predator impacts.

Doherty TS, Dickman CR, Nimmo DG, Ritchie EG (2015) Multiple threats, or multiplying the threats? Interactions between invasive predators and other ecological disturbances, Biological Conservation, 190, 60-68 PDF DOI

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Publications

Data management challenges in analysis and synthesis in the ecosystem sciences

Authors: A Specht,  S Guru, L Houghton, L Keniger, P Driver, EG Ritchie, K Lai, A Treloar

Published in: Science of the Total Environment (online April 2015)

Abstract

Open-data has created an unprecedented opportunity with new challenges for ecosystem scientists. Skills in data management are essential to acquire, manage, publish, access and re-use data. These skills span many disciplines and require trans-disciplinary collaboration.

Science synthesis centres support analysis and synthesis through collaborative ‘Working Groups’ where domain specialists work together to synthesise existing information to provide insight into critical problems. The Australian Centre for Ecological Analysis and Synthesis (ACEAS) served a wide range of stakeholders, from scientists to policy-makers to managers. This paper investigates the level of sophistication in data management in the ecosystem science community through the lens of the ACEAS experience, and identifies the important factors required to enable us to benefit from this new data-world and produce innovative science.

ACEAS promoted the analysis and synthesis of data to solve transdisciplinary questions, and promoted the publication of the synthesised data. To do so, it provided support in many of the key skillsets required. Analysis and synthesis in multi-disciplinary and multi-organisational teams, and publishing data were new for most. Data were difficult to discover and access, and to make ready for analysis, largely due to lack of metadata. Data use and publication were hampered by concerns about data ownership and a desire for data citation. A web portal was created to visualise geospatial datasets to maximise data interpretation. By the end of the experience there was a significant increase in appreciation of the importance of a Data Management Plan.

It is extremely doubtful that the work would have occurred or data delivered without the support of the Synthesis centre, as few of the participants had the necessary networks or skills. It is argued that participation in the Centre provided an important learning opportunity, and has resulted in improved knowledge and understanding of good data management practices.

Specht A,  Guru S, Houghton L,  Keniger L, Driver P,  Ritchie EG, Lai K, Treloar A (2015) Data management challenges in analysis and synthesis in the ecosystem sciences, Science of the Total Environment DOI PDF

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Publications Research

Interspecific and Geographic Variation in the Diets of Sympatric Carnivores: Dingoes/Wild Dogs and Red Foxes in South-Eastern Australia

Authors: Naomi E Davis, David M Forsyth, Barbara Triggs, Charlie Pascoe, Joe Benshemesh, Alan Robley, Jenny Lawrence, Euan G Ritchie, Dale G Nimmo and Lindy F Lumsden.

Abstract

Dingoes/wild dogs (Canis dingo/familiaris) and red foxes (Vulpes vulpes) are widespread carnivores in southern Australia and are controlled to reduce predation on domestic livestock and native fauna.

We used the occurrence of food items in 5875 dingo/wild dog scats and 11,569 fox scats to evaluate interspecific and geographic differences in the diets of these species within nine regions of Victoria, south-eastern Australia.

The nine regions encompass a wide variety of ecosystems. Diet overlap between dingoes/wild dogs and foxes varied among regions, from low to near complete overlap. The diet of foxes was broader than dingoes/wild dogs in all but three regions, with the former usually containing more insects, reptiles and plant material. By contrast, dingoes/wild dogs more regularly consumed larger mammals, supporting the hypothesis that niche partitioning occurs on the basis of mammalian prey size.

The key mammalian food items for dingoes/wild dogs across all regions were black wallaby (Wallabia bicolor), brushtail possum species (Trichosurus spp.), common wombat (Vombatus ursinus), sambar deer (Rusa unicolor), cattle (Bos taurus) and European rabbit (Oryctolagus cuniculus). The key mammalian food items for foxes across all regions were European rabbit, sheep (Ovis aries) and house mouse (Mus musculus).

Foxes consumed 6.1 times the number of individuals of threatened Critical Weight Range native mammal species than did dingoes/wild dogs. The occurrence of intraguild predation was asymmetrical; dingoes/wild dogs consumed greater biomass of the smaller fox.

The substantial geographic variation in diet indicates that dingoes/wild dogs and foxes alter their diet in accordance with changing food availability.

We provide checklists of taxa recorded in the diets of dingoes/wild dogs and foxes as a resource for managers and researchers wishing to understand the potential impacts of policy and management decisions on dingoes/wild dogs, foxes and the food resources they interact with.

Davis NE, Forsyth DM, Triggs B, Pascoe C, Benshemesh J, Davis NE, Forsyth DM, Triggs B, Pascoe C, Benshemesh J, Robley A, Lawrence J, Nimmo DG, Ritchie EG, Lumsden LF (2015) Interspecific and Geographic Variation in the Diets of Sympatric Carnivores: Dingoes/Wild Dogs and Red Foxes in South-Eastern Australia. PLoS ONE 10(3): e0120975. PDF DOI

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Publications Research

Stemming the tide: progress towards resolving the causes of decline and implementing management responses for the disappearing mammal fauna of northern Australia

Authors: Mark R Ziembicki, John C Z Woinarski, Jonathan K Webb, Eric Vanderduys, Katherine Tuft, James Smith, Euan G Ritchie, Terry B Reardon, Ian J Radford, Noel Preece, Justin Perry, Brett P Murphy, Hugh McGregor, Sarah Legge, Lily Leahy, Michael J Lawes, John Kanowski, Chris N Johnson, Alex James, Anthony D Griffiths, Graeme Gillespie, Anke S K Frank, Alaric Fisher and Andrew A Burbidge.

Abstract

Recent studies at some sites in northern Australia have reported severe and rapid decline of some native mammal species, notwithstanding an environmental context (small human population size, limited habitat loss, substantial reservation extent) that should provide relative conservation security.

All of the more speciose taxonomic groups of mammals in northern Australia have some species for which the conservation status has been assessed as threatened, with 53% of dasyurid, 46% of macropod and potoroid, 33% of bandicoot and bilby, 33% of possum, 31% of rodent, and 24% of bat species being assessed as extinct, threatened or near-threatened.

This paper reviews disparate recent and ongoing studies that provide information on population trends across a broader geographic scope than the previously reported sites, and provides some information on the conservation status and trends for mammal groups (bats, larger macropods) not well sampled in previous monitoring studies. It describes some diverse approaches of studies seeking to document conservation status and trends, and of the factors that may be contributing to observed patterns of decline.

The studies reported provide some compelling evidence that predation by feral cats is implicated in the observed decline, with those impacts likely to be exacerbated by prevailing fire regimes (frequent, extensive and intense fire), by reduction in ground vegetation cover due to livestock and, in some areas, by ‘control’ of dingoes. However the impacts of dingoes may be complex, and are not yet well resolved in this area.

The relative impacts of these individual factors vary spatially (with most severe impacts in lower rainfall and less topographically rugged areas) and between different mammal species, with some species responding idiosyncratically: the most notable example is the rapid decline of the northern quoll Dasyurus hallucatus due to poisoning by the introduced cane toad Rhinella marina, which continues to spread extensively across northern Australia. The impact of disease, if any, remains unresolved.

Recovery of the native mammal fauna may be impossible in some areas. However, there are now examples of rapid recovery following threat management. Priority conservation actions include: enhanced biosecurity for important islands, establishment of a network of substantial predator exclosures, intensive fire management (aimed at increasing the extent of longer-unburnt habitat and in delivering fine scale patch burning), reduction in feral stock in conservation reserves, and acquisition for conservation purposes of some pastoral lands in areas that are significant for mammal conservation.

Ziembicki MR, Woinarski JCZ, Webb JK, Vanderduys E, Tuft K, Smith J, Ritchie EG, Reardon TB, Radford IJ, Preece N, Perry JP, Murphy BP, McGregor H, Legge S, Leahy L, Lawes MJ, Kanowski J, Johnson CN, James A, Griffiths AD, Gillespie G, Frank ASK, Fisher A, Burbidge AA (2015) Stemming the tide: progress towards resolving the causes of decline and implementing management responses for the disappearing mammal fauna of northern Australia, Therya 2015 6(1) 169-225 PDF DOI

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Publications

Resolving the value of the dingo in ecological restoration

Authors: Thomas M Newsome, Guy-Anthony Ballard, Mathew S Crowther, Justin A Dellinger, Peter J S Fleming, Alistair S Glen, Aaron C Greenville, Chris N Johnson, Mike Letnic, Katherine E Moseby, Dale G Nimmo, Michael Paul Nelson, John L Read, William J Ripple, Euan G Ritchie, Carolyn R Shores, Arian D Wallach, Aaron J Wirsing and Christopher R Dickman.

Abstract

There is global interest in restoring populations of apex predators, both to conserve them and to harness their ecological services.

In Australia, reintroduction of dingoes (Canis dingo) has been proposed to help restore degraded rangelands. This proposal is based on theories and the results of studies suggesting that dingoes can suppress populations of prey (especially medium- and large-sized herbivores) and invasive predators such as red foxes (Vulpes vulpes) and feral cats (Felis catus) that prey on threatened native species. However, the idea of dingo reintroduction has met opposition, especially from scientists who query the dingo’s positive effects for some species or in some environments.

Here, we ask ‘what is a feasible experimental design for assessing the role of dingoes in ecological restoration?’ We outline and propose a dingo reintroduction experiment — one that draws upon the existing dingo-proof fence—and identify an area suitable for this (Sturt National Park, western New South Wales).

Although challenging, this initiative would test whether dingoes can help restore Australia’s rangeland biodiversity, and potentially provide proof-of-concept for apex predator reintroductions globally.

Newsome TM, Ballard G, Crowther MS, Glen AS, Dellinger JA, Fleming PJS, Greenville AC, Johnson CN, Letnic M, Moseby KE, Nimmo DG, Nelson MP, Read JL, Ripple WJ, Ritchie EG, Shores CR, Wallach AD, Wirsing AJ, Dickman CR (2015) Resolving the value of the dingo in ecological restoration, Restoration Ecology PDF DOI

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Media Publications

The conversation: Mourn our lost mammals, while helping the survivors battle back

he thylacine is just one of Australia’s mammals to disappear since European settlement. Image credit: Wikimedia Commons
The thylacine is just one of Australia’s mammals to disappear since European settlement. Image credit: Baker, EJ Keller, via Wikimedia Commons.

By Dale Nimmo, Deakin University, Euan Ritchie, Deakin University and Thomas Newsome, University of Sydney.

“There was a plague of them and one night I got approximately 300 which had been poisoned in the garden during night. This went on for two or three years.”

Take a second and have a guess what animal species this quote might be referring to. Here’s a hint, the quote is from western Victoria, Australia, during the 1800s.

What did you guess? A house mouse, or another introduced species like a rabbit?

In fact, the quote refers to a native mammal species, the eastern quoll. A species that was “one of the commonest animals” in southeastern Australia, a species that would plague, is now officially extinct on the mainland. It has been more than 50 years since a confirmed sighting.

Australia has the worst rate of mammal extinctions in the world. More than a third have become extinct since European settlement​, or are currently threatened with extinction. But what about the survivors? And what can we do to prevent further losses?

A lost world

Few Australians would appreciate just how much our native mammal communities have changed since European arrival more than 200 years ago. Early quotes from books and newspaper articles like the one above, painstakingly collated by researchers, offer some insight.

Early explorers made similar notes about abundant mammals because their dogs were “completely distracted by the numbers of wallabies, paddymelons and kangaroo rats that bounded off on all sides”.

Their poor horses would struggle through the sandy soils that were “full of Wallabi holes”.

Such quotes describe an Australian landscape rich in native wildlife. A landscape that, owing to the decline and extinction of so many mammal species, has radically changed.

The abundant mammals that distracted the dog and made life difficult for the horse probably refer to species long gone. According to researchers, the burrowing bettong, which is now extinct on mainland Australia, was probably the “kangaroo rat” responsible for those pesky holes.

The “paddymelons” and wallabies are probably the eastern hare and/or bridled nailtail wallabies; the former now extinct, the latter now restricted to a few pockets across eastern Australia.

On the bright side

Even with the sad loss of so many native mammals, Australia retains a suite of truly fascinating species, many of which occur right among us.

In Melbourne’s suburb of Cranbourne, populations of southern brown bandicoots persist, fossicking in people’s gardens and dining from dog’s bowls by night.

Species of flying fox survive in our inner cities and darken the dusk sky as they leave their colony for their nightly foraging.

In most major capitals, some possum species are so common as to be an annoyance to many as they bound over roofs and devour prized roses.

Less raucous but arguably more striking sugar gliders and striped possums occupy urban parks, while a range of species of pygmy possums and hopping mice live on in our parks and reserves.

A diverse array of kangaroo species still bound through rural landscapes, sharing paddocks with wombats, echidnas, dingoes and koalas. Platypuses fish for yabbies in farm dams nearby.

Australia is still blessed with spectacular and globally unique mammals. But we can do better.

Where to next for Australia’s mammals?

As part of the federal government’s National Environmental Science Programme, approximately A$30 million is being devoted to a Threatened Species Recovery Hub.

Australia’s native mammals will undoubtedly be a focus of the hub, as many species are on the brink of extinction.

However, one thing our history of mammal extinctions has taught us is that complacency is our worst enemy. Common species go extinct, and can do so rapidly.

It’s not just about conserving threatened species. The decline of eastern quolls, and many other similarly rapid declines of common species, tell of the need to be vigilant.

On the other hand, species that are regionally extinct should not be forgotten when assessing how our conservation dollar is best spent. This is particularly true for species that perform important functional roles that benefit other species (or entire ecosystems), such as native predators. Just as complacency is to be avoided, an aversion to taking calculated risks and trying new approaches in conservation also jeopardises our species’ chances of survival. We urgently need to go further and be bold if our landscapes are to be restored.

The revival of apex predators across Europe, species such as wolves, bears and lynx, demonstrates that biodiversity change is not a one way street. Indeed, few would have predicted a predator renaissance in Europe 50 years ago. Yet, European society has deemed that predators are important to conserve and they are actively restoring them.

There are emerging signs that Australians are up to the task too.

The western quoll, a species that once occurred in every mainland state (now restricted to southwestern Western Australia), has been reintroduced to the Flinders Ranges, and is reproducing.

There is growing support for ambitious projects such as the reintroduction of Tasmanian Devils onto mainland Australia, both for their own conservation and to help control invasive predators, such as red foxes and feral cats. The eastern quoll also persists in Tasmania and so their reintroduction to mainland Australia remains a possibility.

Even dingoes are being recognised for considerable conservation values, and at times, their economic benefits.

Organisations are being assembled to specifically promote and support the recovery of many of our iconic apex predators.

It is time for the public, governments and non-government organisations to capitalise on this momentum and support audacious projects that seek to rewild Australia and restore its natural glory.

Let us hope that a future not so far away will see our landscapes reinvigorated by a resurgent mammal fauna.

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

The Conversation

 

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Publications

The effects of topographic variation and the fire regime on coarse woody debris: Insights from a large wildfire

Fire shapes the composition of ecosystems through its effects on vegetation structure. Fire is integral to the dynamics of coarse woody debris - logs and dead trees - as it both consumes existing debris and generates new material through its influence on tree death and collapse. Image credit: Edgar Vonk via Flickr
Fire shapes the composition of ecosystems through its effects on vegetation structure. Fire is integral to the dynamics of coarse woody debris — logs and dead trees — as it both consumes existing debris and generates new material through its influence on tree death and collapse. Image credit: Edgar Vonk via Flickr

Authors: Michelle Bassett, Evelyn K Chia, Steve W J Leonard, Dale G Nimmo Greg J Holland, Euan G Ritchie, Michael F Clarke and Andrew F Bennett

Published in: Forest Ecology and Management, volume 340 (March 2015)

Abstract

Coarse woody debris (CWD) is a common structural component of terrestrial ecosystems, and provides important habitat for biota.

Fires modify the distribution of CWD, both spatially and temporally. Changes in fire regimes, such as those arising from prescribed burning and changing climatic conditions, make it critical to understand the response of this resource to fire.

We created a conceptual model of the effects of fire on logs and dead trees in topographically diverse forests in which trees often survive severe fire. We then surveyed paired sites, in a damp gully and adjacent drier slope, ~3.5 years after a large wildfire in south-eastern Australia.

Sites were stratified by fire severity (unburnt, understorey burnt and severely burnt), and fire history (burnt ≤3 years or ≥20 years prior to the wildfire).

Both components of the fire regime influenced CWD availability in gullies. Severe wildfire and fire history ≤3 years reduced the volume of small logs (10–30 cm diameter) in gullies, while severe wildfire increased the number of large dead trees in gullies. CWD on slopes was not affected by fire severity or history at ~3.5 years post-fire.

Log volumes on slopes may recover more quickly after wildfire through rapid collapse of branches and trees. Gullies generally supported more logs than slopes, but longer inter-fire intervals in gullies may allow fuel loads to accumulate and lead to comparatively larger fire impacts.

Given that fire severity and fire interval are predicted to change in many fire-prone ecosystems in coming decades, this study highlights the importance of understanding the interacting effects of multiple components of the fire regime with landscape structure. In particular, variation in fire interval and fire severity in relation to topographic position will influence the pattern of accumulation of coarse woody debris across the landscape, and therefore the structure and quality of habitats for biota.

Bassett M, Chia EK, Leonard SWJ, Nimmo DG, Holland GJ, Ritchie EG, Clarke MF, Bennett AF (2015) The effects of topographic variation and the fire regime on coarse woody debris: Insights from a large wildfire, Forest Ecology and Management, 340, 126–134 PDF DOI

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Publications

A comment on the influence of dingoes on the Australian sheep flock

Authors: David Forsyth, Andrew Woolnough, Dale Nimmo, Euan Ritchie, Malcolm Kennedy, Anthony Pople and Ian Watson

Published in: Australian Veterinary Journal, volume 92, number 12 (December 2014)

Allen and West recently proposed that dingoes (Canis dingo, including hybrids with feral dogs C. lupus familiaris) are a critical causal factor in the decline of Australia’s sheep (Ovis aries) flock and implied that dingoes would cause the rangeland sheep industry to disappear within 30−40 years.

We agree that dingo predation can reduce the profitability of affected sheep properties and has important negative social effect on rural communities, and that exclusion fences and a range of lethal control methods are options for reducing those negative effects.

However, we argue that the importance of dingoes as a cause of the decline in Australia’s sheep flock has been overstated.

Forsyth D, Woolnough AP, Nimmo D, Ritchie EG, Kennedy M, Pople A, Watson I (2014) A comment on the influence of dingoes on the Australian sheep flock. Australian Veterinary Journal, 92: 461–462. PDF DOI

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Publications Research

Does fire influence the landscape-scale distribution of an invasive mesopredator?

Authors: Catherine J Payne, Euan G Ritchie, Luke T Kelly and Dale G Nimmo.

Abstract

Predation and fire shape the structure and function of ecosystems globally. However, studies exploring interactions between these two processes are rare, especially at large spatial scales. This knowledge gap is significant not only for ecological theory, but also in an applied context, because it limits the ability of landscape managers to predict the outcomes of manipulating fire and predators.

We examined the influence of fire on the occurrence of an introduced and widespread mesopredator, the red fox (Vulpes vulpes), in semi-arid Australia. We used two extensive and complimentary datasets collected at two spatial scales.

We examined the influence of fire on the distribution of introduced red foxes in semi-arid Australia. Image credit Area51Bel [CC-BY-SA 3.0] via Wikimedia Commons.
We examined the influence of fire on the distribution of introduced red foxes in semi-arid Australia. Image credit Area51Bel [CC-BY-SA 3.0] via Wikimedia Commons.
At the landscape-scale, we surveyed red foxes using sand-plots within 28 study landscapes — which incorporated variation in the diversity and proportional extent of fire-age classes — located across a 104 000 km² study area. At the site-scale, we surveyed red foxes using camera traps at 108 sites stratified along a century-long post-fire chronosequence (0–105 years) within a 6630 km² study area.

Red foxes were widespread both at the landscape and site-scale. Fire did not influence fox distribution at either spatial scale, nor did other environmental variables that we measured.
Our results show that red foxes exploit a broad range of environmental conditions within semi-arid Australia.

The presence of red foxes throughout much of the landscape is likely to have significant implications for native fauna, particularly in recently burnt habitats where reduced cover may increase prey species’ predation risk.

Payne CJ, Ritchie EG, Kelly LT, Nimmo DG (2014) Does Fire Influence the Landscape-Scale Distribution of an Invasive Mesopredator? PLoS ONE 9(10): e107862 PDF DOI 

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Publications

Ecological connectivity or Barrier Fence? Critical choices on the agricultural margins of Western Australia

Authors: Keith Bradby, James A Fitzsimons, Andrew Del Marco, Don A Driscoll, Euan G Ritchie, Jenny Lau, Corey JA Bradshaw and Richard J Hobbs.

Published in: Ecological management and restoration

Abstract

Western Australia’s State Barrier Fence represents a continuation of colonial era attitudes that considered kangaroos, emus and dingoes as vermin.

Recent plans to upgrade and extend the Barrier Fence have shown little regard for ecological impacts or statutory environmental assessment processes.

EmusAtBarreirFence
Emus are known to travel up to 1000 kilometres between seasons. This is what happens when their migration is impeded by the West Australian State Barrier Fence. Image credit : Graeme Chapman.

Bradby K, Fitzsimons JA, Del Marco A, Driscoll DA, Ritchie EG, Lau J, Bradshaw CJA Hobbs RJ (2014) Ecological connectivity or Barrier Fence? Critical choices on the agricultural margins of Western Australia. Ecological management and restoration PDF DOI

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Publications Research

Towards a cohesive, holistic view of top predation: a definition, synthesis and perspective

Authors: Fabrizio Sergio, Oswald J Schmitz, Charles J Krebs, Robert D Holt, Michael R Heithaus, Aaron J Wirsing, William J Ripple, Euan G Ritchie, David Ainley, Daniel Oro, Yadvendradev Jhala, Fernando Hiraldo and Erkki Korpimäki.

Abstract

Research on the ecology of top predators — upper trophic level consumers that are relatively free from predation once they reach adult size — has provided regular contributions to general ecology and is a rapidly expanding and increasingly experimental, multidisciplinary and technological endeavour.

Yet, an exponentially expanding literature coupled with rapid disintegration into specialized, disconnected subfields for study (e.g. vertebrate predators versus invertebrate predators, community ecology versus biological control, etc.) increasingly means that we are losing a coherent, integrated understating of the role and importance of these species in ecosystems.

This process of canalization is likely to hinder sharing of scientific discovery and continued progress, especially as there is a growing need to understand the generality of the top–down forcing, as demonstrated for some members of this group.

Here, we propose ways to facilitate synthesis by promoting changes in mentality and awareness among specialists through increased debate and collaboration, conceptual reviews and a series of exemplary case studies.

The strategy will rely on the collective contribution by all scientists in the field and will strive to consolidate and formalise top-order predation as a holistic, cohesive, cross-taxonomical field of research studying the ecology, evolution and behaviour of apex predators and their capability to exert top–down forcing on lower trophic levels.

Sergio F, Schmitz OJ, Krebs CJ, Holt RD, Heithaus MR, Wirsing AJ, Ripple WJ, Ritchie EG, Ainley D, Oro D, Jhala Y, Hiraldo F, Korpimäki E (2014) Towards a cohesive, holistic view of top predation: a definition, synthesis and perspective. Oikos DOI PDF

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The influence of non-climate predictors at local and landscape resolutions depends on the autecology of the species

Authors: Donna B Harris, Stephen D Gregory, Barry W Brook, Euan G Ritchie, David B Croft, Graeme Coulson and Damien A Fordham.

Abstract

Species distribution models have come under criticism for being too simplistic for making robust future forecasts, partly because they assume that climate is the main determinant of geographical range at large spatial extents and coarse resolutions, with non-climate predictors being important only at finer scales.

We suggest that this paradigm might be obscured by species movement patterns.

To explore this we used contrasting kangaroo (family Macropodidae) case studies: two species with relatively small, stable home ranges (Macropus giganteus and M. robustus) and three species with more extensive, adaptive ranging behaviour (M. antilopinus, M. fuliginosus and M. rufus).

We suggest that Image credit blah
We used two contrasting kangaroo case studiess. Image credit: Nick Talbot / Department of Environment and Primary Industries via Flickr [CC BY-NC 2.0]
We predicted that non-climate predictors will be most influential to model fit and predictive performance at local spatial resolution for the former species and at landscape resolution for the latter species.

We compared residuals autocovariate – boosted regression tree (RAC-BRT) model statistics with and without species-specific non-climate predictors (habitat, soil, fire, water and topography), at local- and landscape-level spatial resolutions (5 and 50 km).

As predicted, the influence of non-climate predictors on model fit and predictive performance (compared with climate-only models) was greater at 50 compared with 5 km resolution for M. rufus and M. fuliginosus and the opposite trend was observed for M. giganteus.T he results for M. robustus and M. antilopinus were inconclusive. Also notable was the difference in inter-scale importance of climate predictors in the presence of non-climate predictors.

In conclusion, differences in autecology, particularly relating to space use, may contribute to the importance of non-climate predictors at a given scale, not model scale per se. Further exploration of this concept across a range of species is encouraged and findings may contribute to more effective conservation and management of species at ecologically meaningful scales.

Harris DB, Gregory SD, Brook BW, Ritchie EG, Croft DB, Coulson G, Fordham DA (2014) The influence of non-climate predictors at local and landscape resolutions depends on the autecology of the species. Austral Ecology PDF DOI

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Experiments in no-impact control of dingoes: comment on Allen et al. 2013

Authors: Christopher N Johnson, Mathew S Crowther, Chris R Dickman, Michael I Letnic, Thomas M Newsome, Dale G Nimmo, Euan G Ritchie and Arian D Wallach.

Abstract

There has been much recent debate in Australia over whether lethal control of dingoes incurs environmental costs, particularly by allowing increase of populations of mesopredators such as red foxes and feral cats.

Allen et al. (2013) claim to show in their recent study that suppression of dingo activity by poison baiting does not lead to mesopredator release, because mesopredators are also suppressed by poisoning.

We show that this claim is not supported by the data and analysis reported in Allen et al.’s paper.

Dingo-poison-1080
The management of dingoes is a highly conflicted and frequently emotional issue in rural Australia. Image by Peripitus [CC-BY-SA-3.0] via Wikimedia Commons. Skull and Crossbones icon by Jens Tärning [CC-BY-SA-2.0] via the Noun Project.
Johnson CN, Crowther MS, Dickman CR, Letnic MI, Newsome TM, Nimmo DG, Ritchie EG, Wallach AD (2014) Experiments in no-impact control of dingoes: comment on Allen et al. 2013. Frontiers in Zoology 11:17 PDF DOI

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Published: Differing impact of a major biogeographic barrier on genetic structure in two large kangaroos from the monsoon tropics of Northern Australia

Authors: Mark D B Eldridge, Sally Potter, Christopher N Johnson and Euan G Ritchie

Abstract

Tropical savannas cover 20–30% of the world’s land surface and exhibit high levels of regional endemism, but the evolutionary histories of their biota remain poorly studied.

The most extensive and unmodified tropical savannas occur in Northern Australia, and recent studies suggest this region supports high levels of previously undetected genetic diversity.

Macropus robustus, Image credit: David Cook Wildlife Photography[CC BY-NC 2.0] via Flickr
Macropus robustus, Image credit: David Cook Wildlife Photography[CC BY-NC 2.0] via Flickr
To examine the importance of barriers to gene flow and the environmental history of Northern Australia in influencing patterns of diversity, we investigated the phylogeography of two closely related, large, vagile macropodid marsupials, the antilopine wallaroo (Macropus antilopinus; n=78), and the common wallaroo (Macropus robustus; n=21). Both species are widespread across the tropical savannas of Australia except across the Carpentarian Barrier (CB) where there is a break in the distribution of M. antilopinus.

We determined sequence variation in the hypervariable Domain I of the mitochondrial DNA control region and genotyped individuals at 12 polymorphic microsatellite loci to assess the historical and contemporary influence of the CB on these species. Surprisingly, we detected only limited differentiation between the disjunct Northern Territory and Queensland M. antilopinus populations. In contrast, the continuously distributed M. robustus was highly divergent across the CB.

Although unexpected, these contrasting responses appear related to minor differences in species biology. Our results suggest that vicariance may not explain well the phylogeographic patterns in Australia’s dynamic monsoonal environments. This is because Quaternary envi- ronmental changes in this region have been complex, and diverse individual species’ biologies have resulted in less predictable and idiosyncratic responses.

Eldridge MDB, Potter S, Johnson CN, Ritchie EG (2014) Differing impact of a major biogeographic barrier on genetic structure in two large kangaroos from the monsoon tropics of Northern Australia, Ecology and Evolution PDF DOI

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Herald Sun: Predators such as sharks essential for world’s health

Sharks are critical to keeping environments in balance. Image credit: Terry Goss [CC-BY-SA-3.0] via Wikimedia Commons
Sharks are critical to keeping environments in balance. Image credit: Terry Goss [CC-BY-SA-3.0] via Wikimedia Commons
We have good reason to fear sharks and lions.

None of us wants to be an animal’s next meal.

And a number of recent fatal shark attacks in Western Australia have intensified the issue of human-predator conflict.

In response, the WA Government has introduced a shark cull to create “safe zones” for beachgoers – with the first killing on the weekend.

Thousands of people, including surfers, have since rallied against the move.

So what are the broader consequences of losing sharks and other large predators?

Landmark research in the international journal Science this month reviewed the conservation status and ecological roles of the world’s 31 largest carnivores.

Our study suggests that we should be greatly concerned about the ongoing loss of predators.

We studied lions, tigers, African wild dogs, leopards, cheetahs, wolves, lynx, otters, bears, hyenas and dingoes. The study spans all continents except Antarctica.

Alarmingly, roughly 75 per cent of all predators are declining and headed towards extinction.

So unless genuine and urgent efforts are made to conserve these animals, many of them could be gone for ever.

What happens when predators decline or, worse, disappear? In short, wherever we looked, we saw major environmental problems.

Research on Australia’s top predator, the dingo, tells a compelling story.

Over much of the continent, this native predator is shot and poisoned to protect livestock.

But science has now shown that by killing dingoes we make life easier for introduced foxes, cats, goats and pigs, as well as native kangaroos.

This has many impacts: most importantly the net loss of our native animals.

And in many cases, we actually lose more stock after killing dingoes. More sophisticated solutions to managing dingoes are available, like the use of livestock guardian dogs.

Globally, when top predators are lost, the number of mammals grazing on vegetation goes up, causing soil erosion, lower carbon sequestration and loss of habitat for native animals. Predators can also prevent the spread of disease.

In Africa, we are also seeing children forgoing an education to stay home and help their families protect crops from raids by rising numbers of Olive baboons, once kept in check by leopards and lions.

So what about sharks?

Like other top predators, they are critical to keeping environments in balance.

When large sharks are culled, numbers of rays and smaller fish species increase dramatically. Because these smaller species feed on commercially valuable fish, the economic impacts can be huge.

If endangered and legally protected species such as great white sharks are targeted and killed under government orders, we are surely within our rights to request a full cost-benefit analysis.

We need to make sure millions of taxpayer-funded dollars are not being wasted or even making things worse.

Persecuting sharks is not the answer. The management of any wildlife should be based on sound scientific evidence, not political rhetoric.

Clearly, predators have far-reaching ecological, economic and social benefits that are grossly underappreciated.

There is no doubt predators pose challenges, such as wolves attacking livestock and sharks attacking humans. But education and new management practices offer alternatives to culling.

When sharks were culled in Hawaii there was no long-term benefit because shark attacks occurred immediately after.

This is because many species of shark are migratory – some travelling thousands of kilometres. This means killing sharks in a local area only is doomed to fail.

Public education programs about sharks and installing shark exclusion nets is more sensible.

It is telling that many recent victims of shark attacks have come out to protest against the planned shark cull in WA.

Clearly, many people, including those most deeply affected, want smarter solutions to coexisting.

With all of this in mind, governments must find and encourage better ways for people and predators to live together. Failure to do so places us all at risk.

This post was originally published in the Herald Sun. Click here to read the original article, including reader comments

HeraldSun350x78

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The Conversation: The world’s top predators are in decline, and it’s hurting us too

Without tigers, our ecosystems will suffer. Image by Sascha Kohlmann [CC-BY-SA 2.0] via Flickr
Without tigers, our ecosystems will suffer. Image credit: Sascha Kohlmann via Flickr
Humans have an innate fear of large predators, and with good reason. Nobody wants to be a shark or a lion’s next meal.

But new research in the journal Science shows that our inability to live with these animals is putting their survival in great danger, and doing untold damage to the environment.

Through modifying the habitats of large predators or killing predators more directly, we are greatly compromising the ecosystems that they help to keep in balance — free of charge. In turn this environmental degradation creates many problems that have severe consequences for humans.

We ain’t lion, this predator stuff is a big deal. Image by Derek Keats via Flickr [CC BY 2.0] via Flickr
We ain’t lion, this predator stuff is a big deal. Image credit: Derek Keats via Flickr

Top dogs (and cats) under threat

For the first time, a team of researchers from the United States, Australia, Italy, and Sweden, and led by Professor Bill Ripple at Oregon State University, have analysed the effects of threats such as habitat loss, human persecution and reduced prey on the world’s 31 largest mammalian carnivores.

The species studied include lions, tigers, African wild dogs, leopards, cheetahs, wolves, lynx, otters, bears, hyenas and dingoes. Together they span all continents except Antarctica.

Alarmingly, more than three quarters of the 31 large carnivores are in decline, and 17 species occupy less than half of their historical distributions. The Red Wolf in the southeastern United States is now found in less than 1% of its historical range, and the Ethiopian Wolf in just 2%.

Hotspots of carnivore decline are southeast Asia, southern and East Africa, and the Amazon, where several large carnivores are declining. And in the developed world there are now few places where large carnivores remain.

In Australia, dingoes help keep introduced predators at bay. Image credit: Ars Electronica [CC BY-NC-ND 2.0] via Flickr
In Australia, dingoes help keep introduced predators at bay. Image credit: Ars Electronica via Flickr
Aside from the intrinsic tragedy of losing any species, what should perhaps concern us even more is that we are only just beginning to understand and appreciate just how important large predators are to maintaining healthy ecosystems, and our dependence on the ecosystem services they deliver.

Ripple effect

Seven carnivore species in particular have been shown to have profound effects on the environment and cause what is known as “trophic cascades”. A trophic cascade is a ripple effect, where one species’ influence spreads through multiple levels of a food web.

Species for which this effect is most well-known are African lions, leopards, Eurasian lynx, cougars, gray wolves, sea otters and dingoes.

It’s hard being a VIP (very important predator). Image credit: Mike Baird [CC BY 2.0] via Flickr
It’s hard being a VIP (very important predator). Image credit: Mike Baird via Flickr
In Australia dingoes greatly reduce kangaroo and red fox numbers, which in turn reduces grazing of vegetation and predation of native animals, helping to conserve and protect biodiversity.

In coastal North America, sea otters keep sea urchin numbers in check, which helps maintain kelp forests and benefits other marine species dependent on this habitat. But in this case otters might also offer a defence against climate change, as healthy kelp forests can grow rapidly and store large amounts of carbon.

And in Africa, a decrease in lions and leopards has coincided with a dramatic increase in Olive Baboons, which threaten farm crops and livestock, and spread intestinal worms. Baboons even impact education, as children have to stay home to defend their farms from raids.

Without lions and leopards, there’s no telling what baboons will do. Image credit: Justin Jensen [CC BY 2.0] via Flickr
Without lions and leopards, there’s no telling what baboons will do. Image credit: Justin Jensen via Flickr
Clearly predators have far-reaching ecological, economic and social benefits that are grossly underappreciated. There is no doubt predators pose challenges too, such as wolves attacking livestock. But education and new management practices offer ways forward. For instance, we could use guardian animals to protect livestock from predators.

Together we call on governments to end policies and management practices that are responsible for the ongoing persecution and loss of predators from our planet. Western Australia’s new shark plan is an example of management that fails to account for the science of big predators. Instead we need an international initiative that aims to conserve large predators and promote their coexistence with people.

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

The Conversation

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Published: Status and ecological effects of the world’s largest carnivores

Authors: William J Ripple, James A Estes, Robert L Beschta, Christopher C Wilmers, Euan G Ritchie, Mark Hebblewhite, Joel Berger, Bodil Elmhagen, Mike Letnic, Michael P Nelson, Oswald J Schmitz, Douglas W Smith, Arian D Wallach and Aaron J Wirsing

Abstract

Large carnivores face serious threats and are experiencing massive declines in their populations and geographic ranges around the world.

We highlight how these threats have affected the conservation status and ecological functioning of the 31 largest mammalian carnivores on Earth.

Consistent with theory, empirical studies increasingly show that large carnivores have substantial effects on the structure and function of diverse ecosystems.

Significant cascading trophic interactions, mediated by their prey or sympatric mesopredators, arise when some of these carnivores are extirpated from or repatriated to ecosystems.

Unexpected effects of trophic cascades on various taxa and processes include changes to bird, mammal, invertebrate, and herpetofauna abundance or richness; subsidies to scavengers; altered disease dynamics; carbon sequestration; modified stream morphology; and crop damage.

Promoting tolerance and coexistence with large carnivores is a crucial societal challenge that will ultimately determine the fate of Earth’s largest carnivores and all that depends upon them, including humans.

Ripple WJ, Estes JA, Beschta RL, Wilmers CC, Ritchie EG, Hebblewhite M, Berger J, Elmhagen B, Letnic M, Nelson MP, Schmitz OJ, Smith DW, Wallach AD, Wirsing AJ (2014) Status and ecological effects of the world’s largest carnivores, Science, 343(6167) DOI