Authors: David R Daversa, Ryan F Hechinger, Elizabeth Madin, Andy Fenton, Anthony I Dell, Euan G Ritchie, Jason Rohr, Volker HW Rudolf, and Kevin D Lafferty
Published in:Proceedings of the Royal Society B: Biological Sciences
Research on the ‘ecology of fear’ posits that defensive prey responses to avoid predation can cause non-lethal effects across ecological scales. Parasites also elicit defensive responses in hosts with associated non-lethal effects, which raises the longstanding, yet unresolved question of how non-lethal effects of parasites compare with those of predators.
We developed a framework for systematically answering this question for all types of predator–prey and host–parasite systems. Our framework reveals likely differences in non-lethal effects not only between predators and parasites, but also between different types of predators and parasites.
Trait responses should be strongest towards predators, parasitoids and parasitic castrators, but more numerous and perhaps more frequent for parasites than for predators. In a case study of larval amphibians, whose trait responses to both predators and parasites have been relatively well studied, existing data indicate that individuals generally respond more strongly and proactively to short-term predation risks than to parasitism.
Apart from studies using amphibians, there have been few direct comparisons of responses to predation and parasitism, and none have incorporated responses to micropredators, parasitoids or parasitic castrators, or examined their long-term consequences.
Addressing these and other data gaps highlighted by our framework can advance the field towards understanding how non-lethal effects impact prey/host population dynamics and shape food webs that contain multiple predator and parasite species.
Daversa DR, Hechinger RF, Madin E, Fenton A, Dell AI, Ritchie EG, Rohr J, Rudolf VHW, Lafferty KD (2021) Broadening the ecology of fear: non-lethal effects arise from diverse responses to predation and parasitism. Proceedings of the Royal Society B: Biological Sciences PDFDOI
Authors: E A Moallemi, F J de Haan, M Hadjikakou, S Khatami, S Malekpour, A Smajgl, M Stafford Smith, A Voinov, R Bandari, P Lamichhane, K K Miller, E Nicholson, W Novalia, E G Ritchie, A M Rojas, M A Shaikh, K Szetey, and B A Bryan
Published in:Earth’s Future
The achievement of global sustainability agendas, such as the Sustainable Development Goals, relies on transformational change across society, economy, and environment that are co‐created in a transdisciplinary exercise by all stakeholders. Within this context, environmental and societal change is increasingly understood and represented via participatory modeling for genuine engagement with multiple collaborators in the modeling process. Despite the diversity of participatory modeling methods to promote engagement and co‐creation, it remains uncertain what the extent and modes of participation are in different contexts, and how to select the suitable methods to use in a given situation.
Based on a review of available methods and specification of potential contextual requirements, we propose a unifying framework to guide how collaborators of different backgrounds can work together and evaluate the suitability of participatory modeling methods for co‐creating sustainability pathways.
The evaluation of method suitability promises the integration of concepts and approaches necessary to address the complexities of problems at hand while ensuring robust methodologies based on well‐tested evidence and negotiated among participants. Using two illustrative case studies, we demonstrate how to explore and evaluate the choice of methods for participatory modeling in varying contexts.
The insights gained can inform creative participatory approaches to pathway development through tailored combinations of methods that best serve the specific sustainability context of particular case studies.
Moallemi EA, de Haan FJ, Hadjikakou M, Khatami S, Malekpour S, Smajgl A, Smith MS, Voinov A, Bandari R, Lamichhane P, Miller KK, Nicholson E, Novalia W, Ritchie EG, Rojas AM, Shaikh MA, Szetey K, Bryan BA (2021) Evaluating Participatory Modeling Methods for Co‐creating Pathways to Sustainability. Earth’s FuturePDFDOI
By Don Driscoll (Deakin University), April Reside (The University of Queensland), Brendan Wintle (University of Melbourne), Euan Ritchie (Deakin University), and Martine Maron (The University of Queensland).
And the findings aren’t news to many other Australians, who have watched wildlife and iconic places such as Kakadu and Kosciuszko national parks, and the Great Barrier Reef, decline at rates that have only accelerated since the act was introduced in 1999. Even globally recognisable wildlife, such as the platypus, now face a future that’s far from certain.
For example, the original distribution of the endangered southern black-throated finch of southern and central Queensland has shrunk to less than 10% due to land clearing and habitat degradation. Yet, further clearing was approved for coal mines, housing developments and sugar cane farms.
The centre piece of Samuel’s report are proposed new National Environmental Standards. These would provide clear grounds for drawing a line in the sand on environmental damage.
Legal, rigorous enforcement of these standards could turn around Australia’s centuries-long record of destroying its natural heritage, and curb Australia’s appalling extinction rate — while also providing clarity and certainty for business.
Vital features of the standards Samuel recommends include:
avoiding impacts on the critical habitat of threatened species
avoiding impacts that could reduce the abundance of threatened species with already small and declining populations
no net reduction in the population size of critically endangered and endangered species
cumulative impacts must be explicitly considered for threatened species and communities
offsets can only be used as a last resort, not as a routine part of business like they are at the moment.
Under the proposed National Environmental Standards, any new developments would need to be in places where environmental damage is avoided from the outset, with offsets only available if they’re ecologically feasible and effective.
2. Greater government accountability
The federal environment minister can make decisions with little requirement to publicly justify them.
In 2014, then environment minister Greg Hunt controversially approved an exemption to the EPBC Act for Western Australia’s shark cull. This was despite evidence the cull wouldn’t make people safer, would harm threatened species and would degrade marine ecosystems. Hunt could shirk the evidence, deny the impacts and make a politically expedient decision, with no mechanisms in place to call him to account.
Samuel’s report states the minister can make decisions that aren’t consistent with the National Environmental Standards — but only as a “rare exception”. He says these exceptions must be “demonstrably justified in the public interest”, and this justification must be published.
We think this epitomises democracy. Ministers can make decisions, but they must be open to public and robust scrutiny and explain how their decisions might affect environments and species.
Improved accountability will be one of the many benefits of Samuel’s proposed independent Environment Assurance Commissioner, which would be backed up by an Office of Compliance and Enforcement. Samuel says these must be free from political interference.
These are absolutely critical aspects of the reforms. Standards that aren’t audited or enforced are as worthless as an unfunded recovery plan.
Engaging experts is key to achieving Samuel’s long-overdue proposed reforms. He calls for the immediate creation of expert committees on sustainable development, Indigenous participation, conservation science, heritage, and water resources. This will help support the best available data collection to underpin important decisions.
Ultimately, though, much more investment in building ecological knowledge is required.
Australia has more than 1,900 listed threatened species and ecological communities, and most don’t even have active recovery plans. Ecologists will need to collect, analyse and interpret new, up-to-date data to make biodiversity conservation laws operational for most threatened species.
Samuel recommends Regional Recovery Plans be adequately funded to help develop some knowledge. But we suggest substantial new environmental capacity is needed, including new ecological research positions, increased environmental monitoring infrastructure, and appropriate funding of recovery plans, to ensure enough knowledge supports decision making.
Cherry picking recommendations condemns our species
Samuel’s report has provided a path forward that could make a substantial difference to Australia’s shocking track record of biodiversity conservation and land stewardship.
But Environment Minister Sussan Ley’s response so far suggests the Morrison government plans to cherry pick from Samuel’s recommendations, and rush through changes without appropriate safeguards.
If the changes we outlined above aren’t implemented as a package, our precious natural heritage will continue to decline.
Australia’s Threatened Species Strategy — a five-year plan for protecting our imperilled species and ecosystems — fizzled to an end last year. A new 10-year plan is being developed to take its place, likely from March.
Now, more than ever, Australia’s remarkable species and environments need strong and effective policies to strengthen their protection and boost their recovery.
So as we settle into the new year, let’s reflect on what’s worked and what must urgently be improved upon, to turn around Australia’s extinction crisis.
How effective was the first Threatened Species Strategy?
The Threatened Species Strategy is a key guiding document for biodiversity conservation at the national level. It identifies 70 priority species for conservation, made up of 20 birds, 20 mammals and 30 plants, such as the plains-wanderer, malleefowl, eastern quoll, greater bilby, black grevillea and Kakadu hibiscus.
These were considered among the most urgent in need of assistance of the more than 1,800 threatened species in Australia.
The strategy also identifies targets such as numbers of feral cats to be culled, and partnerships across industry, academia and government key to making the strategy successful.
The original strategy (2015-20) was eagerly welcomed for putting the national spotlight on threatened species conservation. It has certainly helped raise awareness of its priority species.
However, there’s little evidence the strategy has had a significant impact on threatened species conservation to date.
The midterm report in 2019 found only 35% of the priority species (14 in total) had improving trajectories compared to before the strategy (pre-2015). This number included six species — such as the brush-tailed rabbit-rat and western ringtail possum — that were still declining, but just at a slower rate.
On average, the trends of threatened mammal and bird populations across Australia are not increasing.
Other targets, such as killing two million feral cats by 2020, were not explicitly linked to measurable conservation outcomes, such as an increase in populations of threatened native animals. Because of this, it’s difficult to judge their success.
Other important threats to native Australian species include pollution, feral herbivores (such as horses and goats), very frequent or hot bushfires and weeds. Buffel grass was recently identified as a major emerging threat to Australia’s biodiversity, with the risk being as high as the threat posed by cats and foxes.
Five vital improvements
We made a submission to the Morrison government when the Threatened Species Strategy was under review. Below, we detail our key recommendations.
1. A holistic and evidence-based approach encompassing the full range of threats
2. Formal prioritisation of focal species, threats and actions
The previous strategy focused heavily on a small subset of the more than 1,800 threatened species and ecosystems in Australia. It mostly disregarded frog, reptile, fish and invertebrate species also threatened with extinction.
To reduce bias towards primarily “charismatic” species, the federal government should use an evidence-based prioritisation approach, known as “decision science”, like they do in New South Wales, New Zealand and Canada. This would ensure funds are spent on the most feasible and beneficial recovery efforts.
3. Targets linked to clear and measurable conservation outcomes
Some targets in the first Threatened Species Strategy were difficult to measure, not explicitly linked to conservation outcomes, or weak. Targets need to be more specific.
For example, a target to “improve the trajectory” of threatened species could be achieved if extinction is occurring at a slightly slower rate. Alternatively, a target to “improve the conservation status” of a species is achieved if new assessments rate it as “vulnerable” rather than “endangered”.
4. Significant financial investment from government
The first strategy featured a call for co-investment from industry. But this failed to attract much private sector interest, meaning many important projects aimed at conserving species did not proceed.
5. Government leadership, coordination and policy alignment
Authors: Ninon FV Meyer, Niko Balkenhol, Trishna Dutta, Maarten Hofman, Jean‐Yves Meyer, Euan G Ritchie, Charlotte Alley, Chad Beranek, Cassandra K Bugir, Alex Callen, Simon Clulow, Michael V Cove, Kaya Klop‐Toker, Omar R Lopez, Michael Mahony, Robert Scanlon, Sandeep Sharma, Elen Shute, Rose Upton, Emy Guilbault, Andrea S Griffin, Edwin Hernández Pérez, Lachlan G Howell, John‐Paul King, Dean Lenga, Patrick O Donoghue, and Matt W Hayward
Published in:Conservation Biology
Combining native and non‐native species to evaluate biodiversity is overly simplistic and may undermine the conservation of ecosystems.
Meyer NFV, Balkenhol N, Dutta T, Hofman M, Meyer J, Ritchie EG, Alley C, Beranek C, Bugir CK, Callen A, Clulow S, Cove MV, Klop‐Toker K, Lopez OR, Mahony M, Scanlon R, Sharma S, Shute E, Upton R, Guilbault E, Griffin AS, Hernández Pérez E, Howell LG, King J, Lenga D, O Donoghue P, Hayward MW (2020) Beyond species counts for assessing, valuing, and conserving biodiversity: response to Wallach et al. 2019. Conservation BiologyPDFDOI
Authors: Sarah J Maclagan, Terry Coates, Austin O’Malley, and Euan G Ritchie
Published in:Austral Ecology
Understanding how fundamental aspects of species’ ecology, such as diet, are affected in human‐dominated landscapes is vital for informing management and conserving biodiversity – particularly where species influence important ecosystem functions. Digging, mycophagous (‘fungus‐eating’) mammals play various such roles, including the dispersal of hypogeal (‘truffle‐like’) fungi.
The endangered, mycophagous southern brown bandicoot (Isoodon obesulus obesulus: Peramelidae) persists in a peri‐urban landscape south‐east of Melbourne, Australia, where it occupies both ‘novel’ habitats (linear strips of vegetation along roadsides, drains and railway lines) and ‘remnant’ habitats (larger blocks of native vegetation) within dedicated conservation areas. It remains unknown how bandicoot diet, including the diversity of hypogeal fungi, varies between these habitat types, yet this could have important conservation implications.
Our study aimed to (i) compare the diet of I. o. obesulus at novel and remnant sites; and (ii) attain knowledge of hypogeal fungal diversity in these different contexts. We collected 133 bandicoot scats over 23 months and examined both broad diet composition and diversity of fungi consumed.
Bandicoot diet differed between site types; in particular, ants were more prominent in scats from remnant sites, while millipedes and seeds were more prominent in scats from novel sites. All scats contained fungal spores, with hypogeal taxa comprising at least 35 of the 78 ‘morphotypes’ found at novel sites and 28 of the 59 detected at remnant sites. Fewer samples were collected at remnant sites, but they appeared to contain a greater richness of hypogeal fungi per scat. We did not detect any differences in fungal composition between site types. However, our sampling effort was insufficient to estimate true morphotype richness at either site type.
Our study highlights the adaptable generalist diet of the southern brown bandicoot, as well as the likely under‐appreciated diversity of hypogeal fungi that can occur in highly modified, novel ecosystems.
Maclagan SJ, Coates T, O’Malley A, Ritchie EG (2020) Dietary variation of an endangered mycophagous mammal in novel and remnant habitats in a peri‐urban landscape. Austral EcologyPDFDOI
Mammals are extraordinarily successful animals, occupying Earth’s skies, seas and land, but many species also face significant threats and uncertain futures.
In this 35-minute presentation, I share stories about dingoes, bandicoots, tree kangaroos, bears and other mammals, highlighting their ecological and cultural importance, and how science is aiding their conservation.
Authors: William L Geary, Michael Bode, Tim S Doherty, Elizabeth A Fulton, Dale G Nimmo, Ayesha I T Tulloch, Vivitskaia J D Tulloch, and Euan G Ritchie
Published in:Nature Ecology & Evolution
Applied ecology has traditionally approached management problems through a simplified, single-species lens. Repeated failures of single-species management have led us to a new paradigm — managing at the ecosystem level. Ecosystem management involves a complex array of interacting organisms, processes and scientific disciplines. Accounting for interactions, feedback loops and dependencies between ecosystem components is therefore fundamental to understanding and managing ecosystems.
We provide an overview of the main types of ecosystem models and their uses, and discuss challenges related to modelling complex ecological systems. Existing modelling approaches typically attempt to do one or more of the following: describe and disentangle ecosystem components and interactions; make predictions about future ecosystem states; and inform decision making by comparing alternative strategies and identifying important uncertainties.
Modelling ecosystems is challenging, particularly when balancing the desire to represent many components of an ecosystem with the limitations of available data and the modelling objective. Explicitly considering different forms of uncertainty is therefore a primary concern.
We provide some recommended strategies (such as ensemble ecosystem models and multi-model approaches) to aid the explicit consideration of uncertainty while also meeting the challenges of modelling ecosystems.
Geary WL, Bode M, Doherty TS, Fulton EA, Nimmo DG, Tulloch AIT, Tulloch VJD, Ritchie EG (2020) A guide to ecosystem models and their environmental applications. Nature Ecology & EvolutionPDFDOI
Ecologists and conservation experts in government, industry and universities are routinely constrained in communicating scientific evidence on threatened species, mining, logging and other threats to the environment, our new research has found.
Our study, just published, shows how important scientific information about environmental threats often does not reach the public or decision-makers, including government ministers.
In some cases, scientists self-censor information for fear of damaging their careers, losing funding or being misrepresented in the media. In others, senior managers or ministers’ officers prevented researchers from speaking truthfully on scientific matters.
This information blackout, termed “science suppression”, can hide environmentally damaging practices and policies from public scrutiny. The practice is detrimental to both nature and democracy.
Code of silence
Our online survey ran from October 25, 2018, to February 11, 2019. Through advertising and other means, we targeted Australian ecologists, conservation scientists, conservation policy makers and environmental consultants. This included academics, government employees and scientists working for industry such as consultants and non-government organisations.
Some 220 people responded to the survey, comprising:
88 working in universities
79 working in local, state or federal government
47 working in industry, such as environmental consulting and environmental NGOs
6 who could not be classified.
In a series of multiple-choice and open-ended questions, we asked respondents about the prevalence and consequences of suppressing science communication.
About half (52%) of government respondents, 38% from industry and 9% from universities had been prohibited from communicating scientific information.
Communications via traditional (40%) and social (25%) media were most commonly prohibited across all workplaces. There were also instances of internal communications (15%), conference presentations (11%) and journal papers (5%) being prohibited.
‘Ministers are not receiving full information’
Some 75% of respondents reported having refrained from making a contribution to public discussion when given the opportunity – most commonly in traditional media or social media. A small number of respondents self-censored conference presentations (9%) and peer-reviewed papers (7%).
Factors constraining commentary from government respondents included senior management (82%), workplace policy (72%), a minister’s office (63%) and middle management (62%).
Fear of barriers to advancement (49%) and concern about media misrepresentation (49%) also discouraged public communication by government respondents.
Almost 60% of government respondents and 36% of industry respondents reported unduly modified internal communications.
One government respondent said:
Due to ‘risk management’ in the public sector […] ministers are not receiving full information and advice and/or this is being ‘massaged’ by advisors (sic).
University respondents, more than other workplaces, avoided public commentary out of fear of how they would be represented by the media (76%), fear of being drawn beyond their expertise (73%), stress (55%), fear that funding might be affected (53%) and uncertainty about their area of expertise (52%).
One university respondent said:
I proposed an article in The Conversation about the impacts of mining […] The uni I worked at didn’t like the idea as they received funding from (the mining company).
Critical conservation issues suppressed
Information suppression was most common on the issue of threatened species. Around half of industry and government respondents, and 28% of university respondents, said their commentary on the topic was constrained.
Government respondents also reported being constrained in commenting on logging and climate change.
One government respondent said:
We are often forbidden (from) talking about the true impacts of, say, a threatening process […] especially if the government is doing little to mitigate the threat […] In this way the public often remains ‘in the dark’ about the true state and trends of many species.
University respondents were most commonly constrained in talking about feral animals. A university respondent said:
By being blocked from reporting on the dodgy dealings of my university with regards to my research and its outcomes I feel like I’m not doing my job properly. The university actively avoids any mention of my study species or project due to vested financial interests in some key habitat.
Industry respondents, more than those from other sectors, were constrained in commenting on the impacts of mining, urban development and native vegetation clearing. One industry respondent said:
A project […] clearly had unacceptable impacts on a critically endangered species […] the approvals process ignored these impacts […] Not being able to speak out meant that no one in the process was willing or able to advocate for conservation or make the public aware of the problem.
The system is broken
Of those respondents who had communicated information publicly, 42% had been harassed or criticised for doing so. Of those, 83% believed the harassers were motivated by political or economic interests.
Some 77 respondents answered a question on whether they had suffered personal consequences as a result of suppressing information. Of these, 18% said they had suffered mental health effects. And 21% reported increased job insecurity, damage to their career, job loss, or had left the field.
One respondent said:
I declared the (action) unsafe to proceed. I was overruled and properties and assets were impacted. I was told to be silent or never have a job again.
As a consultant working for companies that damage the environment, you have to believe you are having a positive impact, but after years of observing how broken the system is, not being legally able to speak out becomes harder to deal with.
Change is needed
We acknowledge that we receive grants involving contracts that restrict our academic freedom. And some of us self-censor to avoid risks to grants from government, resulting in personal moral conflict and a less informed public. When starting this research project, one of our colleagues declined to contribute for fear of losing funding and risking employment.
But Australia faces many complex and demanding environmental problems. It’s essential that scientists are free to communicate their knowledge on these issues.
Public servant codes of conduct should be revised to allow government scientists to speak freely about their research in both a public and private capacity. And government scientists and other staff should report to new, independent state and federal environment authorities, to minimise political and industry interference.
A free flow of information ensures government policy is backed by the best science. Conservation dollars would be more wisely invested, costly mistakes avoided and interventions more effectively targeted.
Authors: Don A Driscoll, Georgia E Garrard, Alexander M Kusmanoff, Stephen Dovers, Martine Maron, Noel Preece, Robert L Pressey, and Euan G Ritchie
Published in:Conservation Letters
Suppressing expert knowledge can hide environmentally damaging practices and policies from public scrutiny.
We surveyed ecologists and conservation scientists from universities, government, and industry across Australia to understand the prevalence and consequences of suppressing science communication.
Government (34%) and industry (30%) respondents reported higher rates of undue interference by employers than did university respondents (5%). Internal communications (29%) and media (28%) were curtailed most, followed by journal articles (11%), and presentations (12%). When university and industry researchers avoided public commentary, this was mainly for fear of media misrepresentation, while government employees were most often constrained by senior management and workplace policy. One third of respondents reported personal suffering related to suppression, including job losses and deteriorating mental health.
Substantial reforms are needed, including to codes of practice, and governance of environmental assessments and research, so that scientific advice can be reported openly, in a timely manner and free from interference.
Driscoll DA, Garrard GE, Kusmanoff AM, Dovers S, Maron M, Preece N, Pressey RL, Ritchie EG (2020) Consequences of information suppression in ecological and conservation sciences. Conservation LettersPDFDOI
Humans have long been inspired and transfixed by the Moon, and as we’re discovering, moonlight can also change the behaviour of Australian wildlife.
A collection of recently published research has illuminated how certain behaviours of animals – including potoroos, wallabies and quolls – change with variation in ambient light, phases of the Moon and cloud cover.
One study found small mammals were more active on cloudy nights. Another found variation in moonlight led to differing amounts of species captured in non-lethal traps. And a study on willie wagtails found males just love singing on a full moon.
These findings are interesting from a natural history perspective. But they’ll also help ecologists and conservation scientists better locate and study nocturnal animals, and learn how artificial light pollution is likely changing where animals can live and how they behave.
Moonlit predator-prey games of hide and seek
Most of Australia’s mammals are nocturnal, and some smaller species are thought to use the cover of darkness to avoid the attention of hungry predators. However, there’s much we don’t know about such relationships, especially because it can be difficult to study these interactions in the wild.
In the relatively diverse mammal community at Mt Rothwell, Victoria, we examined how variation in ambient light affected species’ activity, and how this might influence species interactions. Mt Rothwell is a fenced conservation reserve free of feral cats and foxes, and with minimal light pollution.
Over two years, we surveyed the responses of predator and prey species to different light levels from full, half and new moon phases.
Just as we predicted, we found that while there does appear to be relationships between cloud cover, Moon phase and mammal activity, these interactions depend on the sizes and types of mammals involved.
Both predators and prey generally increased their activity in darker conditions.
Smaller, prey species increased their activity when cloud cover was higher, and predators increased their activity during the half and new moon phases.
This suggests their deadly game of hide and seek might intensify on darker nights. And prey might have to trade off foraging time to reduce their chances of becoming the evening meal.
What happens in the wild?
It’s important to acknowledge that studies in sanctuaries such as Mt Rothwell might not always reflect well what goes on in the wild, including in areas where introduced predators, such as feral cats and red foxes, are found.
Another recent study, this time of small mammals in the wilds of Victoria’s Mallee region, sheds further light on the situation. The authors tested if variation in weather and Moon phase affected the numbers of five small mammal species – Bolam’s mouse, common dunnart, house mouse, southern ningaui, and western pygmy possum – captured in pitfall traps.
Pitfall traps are long fences small animals can’t climb over or through, so follow along the side until they fall into a bucket dug in the ground. Ecologists typically use these traps to capture and measure animals and then return them to the wild, unharmed.
At more than 260 sites and over more than 50,000 trap nights, they found wind speed, temperature and moonlight influenced which species were caught and in what numbers.
For example, captures of a small native rodent, Bolam’s mouse, and carnivorous marsupial, southern ningaui, decreased with more moonlight, whereas captures of pygmy possums were higher with more moonlight.
Moonlight songbird serenades
Research from last month has shown even species normally active by day may change their behaviour and activity by night.
It’s not uncommon to hear bird song by night, including the quintessentially Aussie warbling of magpies. Using bioacoustic recorders and song detection software, these researchers show the willie wagtail – another of Australia’s most recogisable and loved birds – is also a nighttime singer, particularly during the breeding season.
While both male and female wagtails sing by day, it is the males that are most vocal by night. And it seems the males aren’t afraid of a little stage-lighting either, singing more with increasing moonlight, with performances peaking during full moons.
This work provides insight into the importance and potential role of nocturnal song for birds, such as mate attraction or territory defence, and helps us to better understand these behaviours more generally.
Moonlight affects wildlife conservation
These studies, and others, can help inform wildlife conservation, as practically speaking, ecological surveys must consider the relative brightness of nights during which work occurred.
Depending on when and where we venture out to collect information about species, and what methods we use (camera traps, spotlighting, and non-lethal trapping) we might have higher or lower chances of detecting certain species. And this might affect our insights into species and ecosystems, and how we manage them.
Pipistrelle bats, for example, will be roughly half as active around well-lit bridges than unlit bridges. They’ll also keep further away from well-lit bridges, and fly faster when near them.
This means artificial light might reduce the amount and connectivity of habitat available to some bat species in urban areas. This, in turn could affect their populations.
Research is underway around the world, examining the conservation significance of such issues in more detail, but it’s another timely reminder of the profound ways in which we influence the environments we share with other species.
The authors acknowledge Yvette Pauligk, who contributed to our published work at Mt Rothwell, and that the traditional custodians of this land are the Wathaurong people of the Kulin nation.
Authors: Matthew J Selinske, Georgia E Garrard, Emily A Gregg, Alexander M Kusmanoff, Lindall R Kidd, Meghan T Cullen, Michelle Cooper, William L Geary, Melissa A Hatty, Fern Hames, Sarah Kneebone, Emily M McLeod, Euan G Ritchie, Zoe E Squires, Janelle Thomas, Madelaine A W Willcock, Sera Blair, and Sarah A Bekessy
Published in: Conservation Science and Practice
The conservation profession is increasingly seeking effective ways to reduce societal impact on biodiversity, including through targeted behavior change interventions. Multiple conservation behavior change programs exist, but there is also great uncertainty regarding which behaviors are most strategic to target.
Behavioral prioritization is a tool that has been used effectively to support behavior change decision‐making in other environmental disciplines and more recently for a small sub‐set of biodiversity behavior change challenges.
Here, we use behavioral prioritization to identify individual behaviors that could be modified to achieve biodiversity benefits in the state of Victoria, Australia. We use an adapted nominal group technique method to identify potential biodiversity behaviors and, for each behavior, estimate the corresponding plasticity (or capacity for change) and positive impact on biodiversity outcomes.
We elicited 27 behaviors that individuals could undertake to benefit or reduce their negative impact on biodiversity. This list was then used to prioritize 10 behaviors as determined by their likely effect(s) on biodiversity, plasticity, and current prevalence in Victoria. We take a first step in outlining a list of behaviors that can direct Victorian decision‐makers toward increasing positive and reducing negative impacts of society on biodiversity, guide motivated individuals to reduce their own biodiversity footprint, and more broadly, develop a behavior change research agenda for behaviors most likely to benefit biodiversity.
Selinske MJ, Garrard GE, Gregg EA, Kusmanoff AM, Kidd LR, Cullen MT, Cooper M, Geary WL, Hatty MA, Hames F, Kneebone S, McLeod EM, Ritchie EG, Squires ZE, Thomas J, Willcock MAW, Blair S, Bekessy SA (2020) Identifying and prioritizing human behaviors that benefit biodiversity. Conservation Science and PracticePDFDOI
Authors: Hayley M Geyle, Michael Stevens, Ryan Duffy, Leanne Greenwood, Dale G Nimmo, Derek Sandow, Ben Thomas, John White, and Euan G Ritchie
Published in:Ecological Solutions and Evidence
Introduced carnivores are often cryptic, making it difficult to quantify their presence in ecosystems, and assess how this varies in relation to management interventions. Survey design should thus seek to improve detectability and maximize statistical power to ensure sound inference regarding carnivore population trends. Roads may facilitate carnivore movements, possibly leading to high detectability. Therefore, targeting roads may improve inferences about carnivore populations.
We assessed our ability to monitor feral cats Felis catus and red foxes Vulpes vulpes on‐ and off‐road, with explicit consideration of the location of monitoring sites on our ability to detect population changes. We also assessed whether there was evidence of spatial or temporal interaction between these species that might influence their road‐use.
Surveys were conducted in a conservation reserve in south‐eastern Australia between 2016 and 2018. At each of 30 sites, we deployed two motion‐sensor cameras, one on‐road, and the other off‐road. Using occupancy models, we estimated cat and fox occupancy and detectability, and conducted a power analysis to assess our ability to detect declines in occupancy under three monitoring regimes (efforts targeted equally on‐ and off‐road, efforts targeted entirely off‐road and efforts targeted entirely on‐road).
On average, on‐road detectability was seven times higher for cats and three times higher for foxes. Targeting survey effort on‐road yielded the greatest power for detecting declines in both species, but our ability to detect smaller declines decreased with decreasing initial occupancy probability. No level of decline was detectable for cats when survey efforts were targeted off‐road, while only large declines (>50%) were detectable for foxes (assuming high initial occupancy probabilities). We found little evidence of spatial or temporal segregation, suggesting limited avoidance or suppression between the two species within this landscape.
Our results suggest that targeting monitoring on roads may be an effective approach for detecting declines in introduced carnivore populations, particularly following management intervention (e.g. lethal control), and in the face of resource limitations. We provide a framework that can help assist land managers to make informed decisions, which balance monitoring efforts and resource constraints with sufficient statistical power to assess management objectives.
Geyle HM, Stevens M, Duffy R, Greenwood L, Nimmo DG, Sandow D, Thomas B, White J, Ritchie EG (2020) Evaluation of camera placement for detection of free‐ranging carnivores; implications for assessing population changes. Ecological Solutions and EvidencePDFDOI
Authors: Grant D Linley, Annette Rypalski, Georgeanna Story, and Euan G Ritchie
Published in:Australian Mammalogy
Information about the ecological functional roles of native predators may help inform the conservation of wildlife and pest management.
If predators show preferences for certain prey, such as invasive species, this could potentially be used as a conservation tool to help restore degraded (e.g. overgrazed) ecosystems via the reintroduction of native predators and suppression of exotic prey (e.g. introduced herbivores).
The diet of spotted-tailed quolls was studied in a fenced reserve in south-eastern Australia where native mammals have been reintroduced, foxes and cats removed, but invasive European rabbits still persist.
A total of 80 scats were collected over 12 months and analysis of macroscopic prey remains was conducted to determine diet.
Rabbits were by far the most commonly consumed prey species by volume (~76%) and frequency (~60%), followed by brushtail possums (~11% for both volume and frequency), and other small and medium-sized native mammals in much smaller amounts. Quoll scat analysis revealed 10 mammal species in total, eight of which were native. Bird, reptile and invertebrate remains were uncommon in quoll scats.
This suggests that spotted-tailed quolls may show a preference for preying on invasive European rabbits in certain contexts, and this could potentially be used as part of quoll reintroductions to aid rabbit population suppression and ecosystem restoration.
Linley GD, Rypalski A, Story G, Ritchie EG (2020) Run rabbit run: spotted-tailed quoll diet reveals invasive prey is top of the menu. Australian MammalogyPDFDOI
Feral and pet cats are responsible for a huge part of Australia’s shameful mammal extinction record. Small and medium-sized ground-dwelling mammals are most susceptible.
But we’ve found one mammal in particular that can outsmart cats and live alongside them: the long-nosed potoroo.
These miniature kangaroo-like marsupials are officially listed as vulnerable. And after the recent devastating fires, extensive swathes of their habitat in southeastern Australia were severely burnt, leaving them more exposed to predators such as foxes and cats. But the true extent of the impact on their numbers remains unclear.
Using motion-sensing camera traps on the wildlife haven of French Island – which is free of foxes, but not cats – we found potoroos may have developed strategies to avoid prowling cats, such as hiding in dense vegetation.
If these long-nosed potoroos can co-exist with one of the world’s most deadly predators, then it’s time we rethink our conservation strategies.
Surviving cats with a deadly game of hide and seek
We conservatively estimated that between five and 14 cats lived in our study area (but it takes only one cat to eradicate a population of native animals).
Although cats were common here, we detected them less often in areas of dense vegetation. By contrast, this was where we found potoroos more often.
Long-nosed potoroos are nocturnal foragers that mainly, but not exclusively, feed in more open habitat before sheltering in dense vegetation during the day. But we found potoroos rarely ventured out of their thick vegetation shelter.
This may be because they’re trading off potentially higher quality foraging habitat in more open areas against higher predation risk. In other words, it appears they’ve effectively learnt to hide from the cats.
Another intriguing result from our study was that although potoroos and feral cats shared more than half of their activity time, the times of peak activity for each species differed.
Cats were active earlier in the night, while potoroo activity peaked three to four hours later. This might be another potoroo strategy to avoid becoming a cat’s evening meal.
Still, completely avoiding cats isn’t possible. Our study site was in the national park on French Island, and it’s likely cats saturate this remnant patch of long-nosed potoroo habitat.
It’s also possible cats may be actively searching for potoroos as prey, and indeed some of our camera images showed cats carrying young long-nosed potoroos in their mouths. These potoroos were more likely killed by these cats, rather than scavenged.
Cats are expert hunters
Cats are exceedingly difficult to manage effectively. They’re adaptable, elusive and have a preference for live prey.
The two most common management practices for feral cats are lethal control and exclusion fencing. Lethal control needs to be intensive and conducted over large areas to benefit threatened species.
“Safe havens” – created through the use of exclusion fencing or predator-free islands – can overcome some of these challenges. But while exclusion fencing is highly effective, it can create other bad outcomes, including an over-abundance of herbivores, leading to excessive grazing of vegetation.
In any case, removing introduced predators might not be really necessary in places native species can co-exist. If long-nosed potoroos have learnt to live with feral cats, we should instead focus on how to maintain their survival strategies.
Why cat eradication isn’t always the best option
It’s clear cats are here to stay, so we shouldn’t simply fall back largely on predator eradication or predator-free havens as the only way to ensure our wildlife have a fighting chance at long-term survival.
But perhaps most important is having predator-savvy insurance populations, such as long-nosed potoroos on French Island. This is incredibly valuable for one day moving them to other areas where predators – native or feral – are present, such as nearby Phillip Island.
In the absence of predators, native wildlife can rapidly lose their ability to recognise predator danger. Programs aimed at eradicating introduced predators where they’re co-existing with native species need to pay careful attention to this.
Authors: Vivianna Miritis, Anthony R Rendall, Tim S Doherty, Amy L Coetsee, and Euan G Ritchie
Published in:Wildlife Research
Feral domestic cats (Felis catus) have contributed to substantial loss of Australian wildlife, particularly small- and medium-sized terrestrial mammals. However, mitigating cat impacts remains challenging.
Understanding the factors that facilitate coexistence between native prey and their alien predators could aid better pest management and conservation actions.
We estimated feral cat density, examined the impact of habitat cover on long-nosed potoroos (Potorous tridactylus tridactylus), and assessed the spatial and temporal interactions between cats and potoroos in the ‘Bluegums’ area of French Island, south-eastern Australia.
Materials and methods
We operated 31 camera stations across Bluegums for 99 consecutive nights in each of winter 2018 and summer 2018/19. We used a spatially explicit capture–recapture model to estimate cat density, and two-species single-season occupancy models to assess spatial co-occurrence of cats and potoroos.
We assessed the influence of vegetation cover and cat activity on potoroo activity by using a dynamic occupancy model. We also used image timestamps to describe and compare the temporal activities of the two species.
Bluegums had a density of 0.77 cats per km² across both seasons, although this is a conservative estimate because of the presence of unidentified cats.
Cats and long-nosed potoroos were detected at 94% and 77% of camera stations, respectively.
Long-nosed potoroo detectability was higher in denser vegetation and this pattern was stronger at sites with high cat activity.
Cats and potoroos overlapped in their temporal activity, but their peak activity times differed.
Feral cat density at Bluegums, French Island, is higher than has been reported for mainland Australian sites, but generally lower than in other islands.
Long-nosed potoroos were positively associated with cats, potentially indicating cats tracking potoroos as prey or other prey species that co-occur with potoroos.
Temporal activity of each species differed, and potoroos sought more complex habitat, highlighting possible mechanisms potoroos may use to reduce their predation risk when co-occurring with cats.
Our study highlighted how predator and prey spatial and temporal interactions, and habitat cover and complexity (ecological refuges), may influence the ability for native prey to coexist with invasive predators.
We encourage more consideration and investigation of these factors, with the aim of facilitating more native species to persist with invasive predators or be reintroduced outside of predator-free sanctuaries, exclosures and island safe havens.
Miritis V, Rendall AR, Doherty TS, Coetsee AL, Ritchie EG (2020) Living with the enemy: a threatened prey species coexisting with feral cats on a fox-free island. Wildlife ResearchPDFDOI
Authors: Grant D Linley, Yvette Pauligk, Courtney Marneweck, and Euan G Ritchie
Published in: Australian Mammology
Moon phase and variation in ambient light conditions can influence predator and prey behaviour. Nocturnal predators locate prey visually, and prey may adjust their activity to minimise their predation risk. Understanding how native mammals in Australia respond to varying phases of the moon and cloud cover (light) enhances knowledge of factors affecting species’ survival and inference regarding ecological and population survey data.
Over a two-year period within a fenced conservation reserve, in south-eastern Australia, with reintroduced native marsupial predator and prey species (eastern barred bandicoot, southern brown bandicoot, long-nosed potoroo, rufous bettong, Tasmanian pademelon, brush-tailed rock-wallaby, red-necked wallaby, eastern quoll, spotted-tailed quoll, and naturally occurring swamp wallaby, common brushtail possum, common ringtail possum), we conducted monthly spotlight surveys during different moon phases (full, half and new moon).
We found an interaction between cloud cover and moon phase, and an interaction of the two depending on the mammal size and class. Increased activity of prey species corresponded with periods of increasing cloud cover. Predators and medium-sized herbivores were more active during times of low illumination.
Our findings suggest that moon phase affects the nocturnal activity of mammal species and that, for prey species, there might be trade-offs between predation risk and foraging. Our findings have implications for: ecological survey design and interpretation of results for mammal populations across moon phases, understanding predator and prey behaviour and interactions in natural and modified (artificial lighting) ecosystems, and potential nocturnal niche partitioning of species.
Linley GD, Pauligk Y, Marneweck C, Ritchie EG (2020) Moon phase and nocturnal activity of native Australian mammals. Australian MammalogyPDFDOI
Authors: Michael L Wysong, Gwenllian D Iacona, Leonie E Valentine, Keith Morris, and Euan G Ritchie
Published in:Wildlife Research
To understand the ecological consequences of predator management, reliable and accurate methods are needed to survey and detect predators and the species with which they interact.
Recently, poison baits have been developed specifically for lethal and broad-scale control of feral cats in Australia. However, the potential non-target effects of these baits on other predators, including native apex predators (dingoes), and, in turn, cascading effects on lower trophic levels (large herbivores), are poorly understood.
We examined the effect that variation in camera trapping-survey design has on detecting dingoes, feral cats and macropodids, and how different habitat types affect species occurrences. We then examined how a feral cat poison baiting event influences the occupancy of these sympatric species.
We deployed 80 remotely triggered camera traps over the 2,410-km² Matuwa Indigenous Protected Area, in the semiarid rangelands of Western Australia, and used single-season site-occupancy models to calculate detection probabilities and occupancy for our target species before and after baiting.
Cameras placed on roads were ~60 times more likely to detect dingoes and feral cats than were off-road cameras, whereas audio lures designed to attract feral cats had only a slight positive effect on detection for all target species.
Habitat was a significant factor affecting the occupancy of dingoes and macropodids, but not feral cats, with both species being positively associated with open woodlands.
Poison baiting to control feral cats did not significantly reduce their occupancy but did so for dingoes, whereas macropodid occupancy increased following baiting and reduced dingo occupancy.
Camera traps on roads greatly increase the detection probabilities for predators, whereas audio lures appear to add little or no value to increasing detection for any of the species we targeted.
Poison baiting of an invasive mesopredator appeared to negatively affect a non-target, native apex predator, and, in turn, may have resulted in increased activity of large herbivores.
Management and monitoring of predators must pay careful attention to survey design, and lethal control of invasive mesopredators should be approached cautiously so as to avoid potential unintended negative ecological consequences (apex-predator suppression and herbivore release).
Wysong ML, Iacona GD, Valentine LE, Morris K, Ritchie EG (2020) On the right track: placement of camera traps on roads improves detection of predators and shows non-target impacts of feral cat baiting. Wildlife ResearchPDFDOI
Authors: Michael L Wysong, Bronwyn A Hradsky, Gwenllian D Iacona, Leonie E Valentine, Keith Morris, and Euan G Ritchie
Published in: Movement Ecology
Where mesopredators co-exist with dominant apex predators, an understanding of the factors that influence their habitat and space use can provide insights that help guide wildlife conservation and pest management actions.
A predator’s habitat use is defined by its home range, which is influenced by its selection or avoidance of habitat features and intra- and inter-specific interactions within the landscape. These are driven by both innate and learned behaviour, operating at different spatial scales.
We examined the seasonal home ranges and habitat selection of actively-managed populations of a native apex predator (dingo Canis dingo) and invasive mesopredator (feral cat Felis catus) in semi-arid Western Australia to better understanding their sympatric landscape use, potential interactions, and to help guide their management.
We used kernel density estimates to characterise the seasonal space use of dingoes and feral cats, investigate inter- and intra-species variation in their home range extent and composition, and examine second-order habitat selection for each predator. Further, we used discrete choice modelling and step selection functions to examine the difference in third-order habitat selection across several habitat features.
The seasonal home ranges of dingoes were on average 19.5 times larger than feral cats. Feral cat seasonal home ranges typically included a larger proportion of grasslands than expected relative to availability in the study site, indicating second-order habitat selection for grasslands.
In their fine-scale movements (third-order habitat selection), both predators selected for roads, hydrological features (seasonal intermittent streams, seasonal lakes and wetlands), and high vegetation cover. Dingoes also selected strongly for open woodlands, whereas feral cats used open woodlands and grasslands in proportion to availability.
Based on these results, and in order to avoid unintended negative ecological consequences (e.g. mesopredator release) that may stem from non-selective predator management, we recommend that feral cat control focuses on techniques such as trapping and shooting that are specific to feral cats in areas where they overlap with apex predators (dingoes), and more general techniques such as poison baiting where they are segregated.
Wysong ML, Hradsky BA, Iacona GD, Valentine LE, Morris K, Ritchie EG (2020) Space use and habitat selection of an invasive mesopredator and sympatric, native apex predator. Movement Ecology PDFDOI