In this podcast with Pete Smissen for Aussie English, I talk about a wide range of topics including:
- how I became a wildlife ecologist
- why large predators died out in Australia
- how Australia’s past and present ecology differs
- the impact of feral species in Australia including cats, foxes, and rabbits
- why bushfires are so bad for Australia wildlife
- the Australian wildlife extinction crisis
- and more!
By Euan Ritchie, (Deakin University), Amy Coetsee (University of Melbourne), Anthony Rendall (Deakin University), Duncan Sutherland (University of Melbourne), and Leonie Valentine (University of Western Australia).
On Churchill Island, southeast of Melbourne, small cone-shaped, shallow holes (digs) puncture the grass. They’re widespread, and reveal moist soil below the surface. A soil heap at the entrance of a dig is a sign it was made recently.
Older digs are filled with leaves, grass, spiders, beetles and other invertebrates. They are made by hungry eastern barred bandicoots – small, roughly rabbit-sized digging marsupials – looking for a juicy worm or grub.
It turns out these bandicoot digs are far from just environmental curiosities – they can improve the properties and health of soils, and even reduce fire risk.
But eastern barred bandicoots are under threat from introduced predators like foxes and cats. In fact, they’re considered extinct in the wild on mainland Australia, so conservation biologists are releasing them on fox-free islands to help establish new populations and ensure the species is conserved long-term.
Our recent research on Churchill Island put a number on just how much the eastern barred bandicoot digs – and the results were staggering, showing how important they are for the ecosystem. But more on that later.
Why you should dig marsupial diggers
Digging mammals – such as bettongs, potoroos, bilbies and bandicoots – were once abundant and widespread across Australia, turning over large amounts of soil every night with their strong front legs as they dig for food or create burrows for shelter.
Their digs improve soil health, increase soil moisture and nutrient content, and decrease soil compaction and erosion. Digs also provide habitat for invertebrates and improve seed germination.
What’s more, by digging fuel loads (dry, flammable vegetation, such as leaves) into the soil, they can help bring down the risk of fire.
Rather than leaves and other plant matter accumulating on the soil surface and drying out, this material is turned over faster, entering the soil when the badicoots dig, which speeds up its decay. Research from 2016 showed there’s less plant material covering the soil surface when digging mammals are about. Without diggers, models show fire spread and flame height are bigger.
In fact, all their functions are so important ecologists have dubbed these mighty diggers “ecosystem engineers”.
Losing diggers leads to poorer soil health
Of Australia’s 29 digging mammals, 23 are between 100 grams and 5 kilograms. Most are at risk of cat and fox predation, and many of these are officially listed as threatened species by the International Union for Conservation of Nature.
Since European settlement, six of Australia’s digging mammals have gone extinct, including the lesser bilby, desert rat kangaroo and pig-footed bandicoots. Many others have suffered marked population declines and extensive range contraction through habitat destruction and the introduction of foxes and cats.
Soils that were once soft textured, easy to crumble, rich and fertile are now often compact, repel water and nutrient poor, impeding seed germination and plant growth. Fuel loads are also likely to be much higher now than in the past, as less organic matter is dug into the soil.
To date, most research on digging mammals has focused on arid environments, with much less known about how digging influences wetter (mesic) environments. But our recently published study on eastern barred bandicoots provides new insights.
Just how much do bandicoots dig anyway?
In 2015, 20 mainland eastern barred bandicoots were released onto Churchill Island in Victoria’s Westernport Bay.
On mainland Australia, fox predation has driven this species to near extinction, and it’s classified as extinct in the wild. All Victoria’s islands are beyond the historic range of eastern barred bandicoots, but fox-free islands could be how we recover them.
Introducing bandicoots on Churchill Island presented the perfect opportunity to quantify how they influence soil properties when digging for food.
To do this we recorded the number of digs bandicoots made each night and measured the volume of soil they displaced through digging. We also compared soil moisture and compaction within the digs, versus un-dug soil – and we didn’t expect what we found.
In one night on Churchill Island, one bandicoot can make 41 digs an hour. That’s nearly 500 digs a night, equating to around 13 kilograms of soil being turned over every night, or 4.8 tonnes a year. That’s almost as much as the average weight of a male African elephant.
So, an astonishing amount of soil is being turned over, especially considering these bandicoots typically weigh around 750 grams.
If you multiply this by the number of bandicoots on Churchill Island (up from 20 in 2015 to around 130 at the time of our study in 2017), there’s a staggering 1,690 kilos of soil being dug up every night. That’s some major earthworks!
However, we should note our study was conducted during the wetter months, when soils are typically easier to dig.
In summer, as soil becomes harder and drier on Churchill Island, digging may become more difficult. And bandicoots, being great generalists, feed more on surface invertebrates like beetles and crickets, resulting in fewer digs. So we expect in summer that soil is less disturbed.
Bandicoots might help agriculture too
All this digging was found to boost soil health on Churchill Island. This means eastern barred bandicoots may not only play an important role in ecosystem health and regeneration, but also potentially in agriculture by assisting pasture growth and condition, reducing topsoil runoff, and mitigating the effects of trampling and soil compaction from livestock.
The benefits bandicoot digs have across agricultural land is of particular importance now that eastern barred bandicoots have also been released on Phillip Island and French Island, and are expected to extensively use pasture for foraging.
These island releases could not just help to ensure eastern barred bandicoots avoid extinction, but also promote productive agricultural land for farmers.
So, given the important ecological roles ecosystem engineers like bandicoots perform, it’s also important we try to reestablish their wild populations on the mainland and outside of fenced sanctuaries so we can all benefit from their digging, not just on islands.
By Marissa Parrott (University of Melbourne), Dale Nimmo (Charles Sturt University) and Euan Ritchie (Deakin University).
Australians have helped raise millions of dollars to support Australia’s imperilled wildlife, such as to set up triage centres and evacuate threatened species like eastern bristlebirds and Macquarie perch.
But beyond the vital role of providing financial support, here are a few simple things individuals can do – and avoid – to help our native wildlife recover.
Animals need fresh water, but not from a bottle
Photos of well-meaning people offering water from bottles to animals, especially thirsty koalas, often go viral online. But this is not a safe way to help koalas.
Animals must be allowed to drink water themselves, rather than us pouring water into their mouths. Animals, such as koalas, can’t drink quickly and poured water can fill their lungs, leading to potentially fatal aspiration pneumonia.
Still, providing safe, fresh drinking water is one crucial and practical way we can help them as summer grinds on.
This is particularly important since recent storms have washed ash, sediment and chemicals from burnt infrastructure into waterways, contaminating many catchments.
Water should be stationed at ground level, in a shaded location safe from predators, and in trees for birds and tree-dwelling species like possums, gliders and koalas. Check out DIY guides for building drinking fountains, or “watering pods”, for wildlife.
Sticks and rocks should be placed in the water to allow small species, such as reptiles, to climb out if they fall in. Water must be checked and changed regularly to ensure hygiene and avoid the spread of disease. And pets must be kept away from these locations (especially cats).
What to do if you spot injured wildlife by the road
Authorities are searching the fire grounds for injured animals, and the public is reminded to avoid these areas until they’re confirmed as safe to enter.
But if you happen upon an injured survivor, what should you do?
First of all, call government agencies or trained wildlife rescuers, who can assist any injured wildlife.
Many animals may be in pain and frightened and some, including kangaroos, koalas and wombats, are potentially dangerous if approached. In urgent cases, such as when an animal is in obvious distress or has clear injuries, some animals can be carefully caught and wrapped in a towel, then placed in a well-ventilated, dark and secure box for quiet transport to wildlife veterinary hospitals for care.
Sadly, many animals are hit by cars during fires when they’re disoriented and panicked, and so it’s important to slow down in such areas.
You can also check animals found by roads for injuries and surviving young in pouches, and call authorities to assist. But always be careful of traffic when attending to animals on roadsides, and help other drivers be aware of you by putting hazard lights on and wearing bright clothes.
Don’t feed native wildlife, especially not peanut butter mixes
But feeding wildlife without expert advice and legal approval can do more harm than good.
Feeding inappropriate foods like processed foods, over-feeding, providing unhygienic foods or food stations, and attracting predators to food stations, can all be fatal for native wildlife.
Even some foods suggested online, such as bait balls (peanut butter mixes), can cause gastrointestinal issues for wildlife, potentially killing them. Similar issues can arise if wildlife are given some types of hay, vegetables, seeds, and fruits.
Supplementary feeding isn’t advised unless habitat and sources of food have been completely destroyed, and is only appropriate as a short-term emergency intervention until natural resources recover.
Somewhere to run and hide
In some cases, fire may mean native animals are more prone to predators killing and eating them. And, depending on the habitat, it may take months or even years for plants and animals’ homes to recover sufficiently to provide safety once again.
However, new approaches – such as building artificial shelters out of fencing wire and shade cloth – may help to buy species time, keeping small mammals, reptiles and other potential prey safe from hungry mouths. This could occur both on private and public land.
Show wildlife the money
Caring for wildlife after fires, whether they’re injured or have lost their homes, is a marathon, not a sprint. And given the scale of these fires, our wild neighbours need our increased support.
Some wildife species, such as bristlebirds, corroboree frogs, and mountain pygmy-possums, are being pushed to the brink of extinction and may need long-term captive breeding and release programs, or investment in active management of wild populations (such as the newly constructed feral predator-free area for Kangaroo Island dunnarts).
We can all help to make a difference and protect our remarkable and unique wildlife that so desperately needs our help.
Authors: Chris Dickman, Don Driscoll, Stephen Garnett, David Keith, Sarah Legge, David Lindenmayer, Martine Maron, April Reside, Euan Ritchie, James Watson, Brendan Wintle, and John Woinarski
The wildfires that afflicted Australia in the summer of 2019-2020 was ecological disaster at enormous scale, and without comparable precedent. With escalating global climate change, such large-scale ecological catastrophes are likely to become more widespread and frequent. Here, we describe a blueprint for conservation responses to these wildfires, to document the challenge and attempted solutions to this particular event and as a potential template for dealing with comparable future events.
The purpose of this report, published as part of the Threatened Species Recovery Hub, is to frame a comprehensive set of linked responses to large-scale impacts for conservation across immediate to longer time frames, in order to best achieve the recovery of affected species, ecosystems and ecological health.
Dickman C, Driscoll D, Garnett S, Keith D, Legge S, Lindenmayer D, Maron M, Reside A, Ritchie EG, Watson J, Wintle B, Woinarski J (2020) After the catastrophe: a blueprint for a conservation response to large-scale ecological disaster. Threatened Species Recovery Hub PDF LINK
By Euan Ritchie (Deakin University), Ayesha Tulloch (University of Sydney), Dale Nimmo (Charles Sturt University), Tim Doherty (Deakin University) and William Geary (Deakin University).
2019 might well be remembered as the year the world caught fire. Some 2.9 million hectares of eastern Australia have been incinerated in the past few months, an area roughly the same size as Belgium. Fires in the Amazon, the Arctic, and California captured global attention.
As climate change continues, large, intense, and severe fires will become more common. But what does this mean for the animals living in fire-prone environments?
Our new research, published recently in the Journal of Animal Ecology, looked at studies from around the world to identify how predators respond to fire.
We found some species seem to benefit from fires, others appear to be vulnerable, and some seem indifferent. In a changing climate, it’s urgent we understand how fires affect predators – and hence potentially their prey –in order to keep ecosystems healthy.
Predators: the good and the bad
Large predators, like wolves and lions, often play important roles in ecosystems, regulating food webs by reducing the numbers or changing the behaviour of herbivores and smaller predators. Many large predators are in dire straits within their native range, while introduced predators, such as feral cats and red foxes, have spread to new regions, where they have devastated native wildlife .
Fires can offer new opportunities as well as problems to predators. Some predators take advantage of charred, more open landscapes to hunt vulnerable prey; others rely on thick vegetation to launch an ambush.
But until now, we have not known which predators are drawn to fire, which are repelled by it, and which don’t care either way. Synthesising information on how different kinds of predators (for example, large or small, pursuit or ambush) respond to fire is vital for both the conservation of top predators and to help protect native prey from introduced predators.
Some like it hot
Our research reviewed studies from around the world to identify how different vertebrate predators (birds, mammals and reptiles) respond to fire in different ecosystems.
We found 160 studies on the response of 188 predator species to fire, including wolves, coyotes, foxes, cats, hawks, owls, goannas and snakes, amongst others. The studies came from 20 different countries, although most were from North America or Australia, and focused on canine and feline species.
Some predators seem to like fire: they are more abundant, or spend more time in, recently burnt areas than areas that escape fire. Our review found red foxes (Vulpes vulpes) mostly responded positively to fire and become more active in burned areas.
Raptors have even been observed in Northern Australia carrying burning sticks, helping to spread fire and targeting prey as they flee the fire.
For other predators, fire is bad news. Following Californian wildfires, numbers of eastern racer snakes fell in burnt areas. Likewise, lions avoid recently burned areas, because they rely on dense vegetation from which to ambush prey.
The authors of the papers we reviewed thought food availability, vegetation cover, and competition with other predators were the most important things affecting species’ responses to fire.
But perhaps more surprising was that most species, including bobcats and the striped skunk, appeared largely unaffected by fire. Of the affected species, some (such as spotted owls) responded differently to fire in different places.
Overall, we found it is difficult to predict how a predator species will respond to fire.
We still have a lot to learn
Our results show while many predators appear to adapt to the changes that fires bring about, some species are impacted by fire, both negatively and positively. The problem is that, with a few exceptions, we will struggle to know how a given fire will affect a predator species without local knowledge. This means environmental managers need to monitor the local outcomes of fire management, such as fuel reduction burns.
There may be situations in which predator management needs to be coupled with fire management to help prevent native wildlife becoming fox food after fire. There has even been trials to see if artificial shelters can help protect native wildlife from introduced predators after fire.
Getting our knowledge base right
One thing that has hampered our research is the lack of contextual information in many studies. No two fires are the same – they differ in size, intensity, severity, and season – but these details are often absent. The literature is also biased towards dog-like and cat species, and there are few studies on the response of predators to fire in Africa, Asia, and South America.
It is important to note that some predator responses to fire may be overlooked due to the way experiments were carried out, or because monitoring happened too long after the fire.
Unifying how fire, predator numbers and environmental features are recorded would help future studies predict how predators might react to different types of fires in various situations.
As wildfires become more frequent and severe under climate change, understanding how fire intensity and frequency shapes predator populations and their prey will be critical for effective and informed ecosystem management and conservation.
By Don Driscoll (Deakin University), David M Watson (Charles Sturt University), and Euan Ritchie (Deakin University).
Feral horse numbers have more than doubled in the past five years in the Australian Alps, according to results just released from the Australian Alps Feral Horse Aerial Survey. In one of the three survey blocks, North Kosciuszko, feral horse numbers have risen from an estimated 3,255 in 2014 to 15,687 in 2019, a near five-fold increase.
Scientists warned the government that very high numbers of horses would be the inevitable consequence of its inaction over horse management.
More than just allowing numbers to increase, the NSW parliament legislated to protect feral horses within Kosciuszko National Park, effectively prioritising the preservation of horse populations over native alpine species and environmental values, where they are in conflict.
This was despite the strong advice from scientists, and amid substantial controversy around the origins and timing of the bill.
A potentially fatal feral horse problem
High feral horse numbers forced the closure of the popular Blue Waterholes campground in November, after substantial risks and several injuries to visitors were reported. Freedom of information requests were needed to bring to light crashes between cars and feral horses in Kosciuszko.
Despite the NSW government trying to keep this information from reaching the public, several incidents of feral horses being struck by vehicles have now been reported.
The community group Reclaim Kosci has warned it is only a matter of time before someone is killed in a collision with a feral horse unless numbers are drastically and rapidly reduced.
Besides impacts on people, the lack of effective feral horse policy in NSW has now set the stage for another mass animal welfare disaster.
With an estimated 25,318 feral horses distributed across the surveyed area (more than 7,400 square kilometres) of the Australian Alps, many thousands of horses will face starvation when the region next burns. This is predictable, inevitable and tragically also completely avoidable had effective feral horse control been implemented.
The prolonged drought hitting Australia has worsened the impacts of horses in the high country. Plants already struggling to survive are being trampled and grazed, and areas around standing water resemble feedlots.
These impacts will worsen over summer, both for the national park and the horses themselves, with herds suffering in the heat and struggling to survive. Horses starved to death along the snowy river in Kosciuszko in 2018.
Now many more animals are at risk of this fate because scientifically-supported solutions have been dismissed by NSW deputy premier John Barilaro.
Natural wildlife threatened
Evidence presented at the Kosciuszko Science Conference and research published earlier this year showed how a broad range of Alpine species and ecosystems were being affected by feral horses. These effects will now be more intense and occur across more of Australia’s ecologically sensitive and biodiverse alpine environments.
For example, the native broad toothed rat depends on dense vegetation along watercourses. With feral horses eating out or trampling plants along streams, these delightful, rotund fur-balls may lose their homes, and hence be more exposed to the elements and predators.
Right now, feral horses are reducing the habitat for these animals, causing already threatened populations to become smaller and more fragmented. As these small populations blink into extinction we can expect widespread losses across the national park.
Corroboree frogs will now be under enormous pressure. We already know feral horses destroy the wetlands these iconic yellow-striped black frogs depend on for breeding. This destruction will likely now impact many more swamps, reducing breeding success and reducing options for reintroduction of this critically endangered frog.
Another species, the Stocky Galaxias, teeters on the brink of extinction. This small native fish now only lives in a 3km stretch of stream in Kosciuszko National Park. Feral horses trample the river banks and rip out vegetation that causes silt to accumulate in the stream.
This is disastrous for the fish, which breed beneath boulders in the stream. If silt fills up the gaps beneath boulders, there is no place for the fish to lay eggs.
The high numbers of feral horses in Kosciuszko mean this process of stream destruction will likely worsen, potentially hastening the demise of this species unique to Kosciuszko National Park.
New management plan needed
Hope for change now rests with the new feral horse management plan being developed by the recently established Kosciuszko National Park Wild Horse Community Advisory Panel and the Wild Horse Scientific Advisory Panel. The community panel has expressed interest in working with the scientific panel, and such collaboration will be essential for making progress.
These committees will need to consider all options for resolving this human safety, animal welfare, and ecological crisis. Although trapping is crueller and many times more expensive than aerial culling, if the trapping effort is substantially ramped up across the park, it could potentially limit population growth and reduce horse numbers.
Aerial culling, despite being the most cost-effective and humane method to lower the horse population size and reduce impacts, is misrepresented by the pro-brumby lobby and sections of the media as cruel, and hence has been deemed unacceptable. These costs, and animal welfare and political trade-offs, must be carefully considered by the committees.
The scientific committee said the draft plan for action will be open for comment in February 2020 to meet NSW environment minister Matt Kean’s deadline for a final plan by May 1, 2020. This rapid timeframe is absolutely essential, as the increase of feral horses in the Alpine National Park will not abate any time soon without urgent and substantial control measures.
Authors: William L Geary, Tim S Doherty, Dale G Nimmo, Ayesha I T Tulloch, and Euan G Ritchie
Published in: Journal of Animal Ecology
Knowledge of how disturbances such as fire shape habitat structure and composition, and affect animal interactions, is fundamental to ecology and ecosystem management. Predators also exert strong effects on ecological communities, through top‐down regulation of prey and competitors, which can result in trophic cascades. Despite their ubiquity, ecological importance and potential to interact with fire, our general understanding of how predators respond to fire remains poor, hampering ecosystem management.
To address this important knowledge gap, we conducted a systematic review and meta‐analysis of the effects of fire on terrestrial, vertebrate predators worldwide. We found 160 studies spanning 1978–2018. There were 36 studies with sufficient information for meta‐analysis, from which we extracted 96 effect sizes (Hedge’s g) for 67 predator species relating to changes in abundance indices, occupancy or resource selection in burned and unburned areas, or before and after fire.
Studies spanned geographic locations, taxonomic families, and study designs, but most were located in North America and Oceania (59% and 24%, respectively), and largely focussed on felids (24%) and canids (25%). Half (50%) of the studies reported responses to wildfire, and nearly one third concerned prescribed (management) fires.
There were no clear, general responses of predators to fire, nor relationships with geographic area, biome or life history traits (e.g. body mass, hunting strategy and diet). Responses varied considerably between species. Analysis of species for which at least three effect sizes had been reported in the literature revealed that red foxes (Vulpes vulpes) mostly responded positively to fire (e.g. higher abundance in burned compared to unburned areas) and eastern racers (Coluber constrictor) negatively, with variances overlapping zero only slightly for both species.
Our systematic review and meta‐analysis revealed strong variation in predator responses to fire, and major geographic and taxonomic knowledge gaps. Varied responses of predator species to fire likely depend on ecosystem context. Consistent reporting of ongoing monitoring and management experiments is required to improve understanding of the mechanisms driving predator responses to fire, and any broader effects (e.g. trophic interactions). The divergent responses of species in our study suggest that adaptive, context‐specific management of predator‐fire relationships is required.
Authors: Lauren M Halstead, Duncan R Sutherland, Leonie E Valentine, Anthony R Rendall, Amy L Coetsee, and Euan G Ritchie
Published in: Austral Ecology
Digging mammals are often considered ecosystem engineers, as they affect important properties of soils and in turn nutrient exchange, vegetation dynamics and habitat quality. Returning such species, and their functions, to areas from where they have been extirpated could help restore degraded landscapes and is increasingly being trialled as a conservation tool.
Studies examining the effects of digging mammals have largely been from arid and semi‐arid environments, with little known about their impacts and importance in mesic systems. To address this knowledge gap, we investigated the ecological role of a recently introduced population of eastern barred bandicoots (Perameles gunnii) on Churchill Island, Victoria, south‐eastern Australia, from which all digging mammals have been lost.
We quantified the annual rate of soil turnover by estimating the number of foraging pits bandicoots created in 100‐m² plots over a 24‐hour period. Foraging pit counts could not be completed in each season, and the overall turnover estimate assumes that autumn/winter months represent turnover rates for the entire year; however, this is likely to fluctuate between seasons. Ten fresh and ten old pits were compared to paired undug control sites to quantify the effect soil disturbance had on soil hydrophobicity, moisture content and soil strength. Plots contained between zero and 64 new foraging pits each day. We estimated that an individual eastern barred bandicoot digs ~487 (95% CI = 416–526) small foraging pits per night, displacing ~13.15 kg (95% CI = 11.2–14.2 kg) of soil, equating to ~400 kg (95% CI = 341–431 kg) of soil in a winter month. Foraging pits were associated with decreased soil compaction and increased soil moisture along the foraging pit profile.
Eastern barred bandicoots likely play an important role in ecosystems through their effects on soil, which adds to an increasing body of knowledge suggesting restoration of ecosystems, via the return of ecosystem engineers and their functions, holds much promise for conserving biodiversity and ecological function.
Authors: Thomas M Newsome, Christopher Wolf, Dale G Nimmo, R Keller Kopf, Euan G Ritchie, Felisa A Smith, and William J Ripple
Published in: Global Ecology and Biogeography
Aim: The only factor in the fossil record that consistently buffers against extinction risk is large geographical range. We ask whether extant vertebrate species with the smallest geographical range for their body size have a higher extinction risk, and thus whether the lower bound of the modern range–body size relationship could serve as an effective conservation prioritization tool.
Location: Global in scope.
Time period: Modern.
Major taxa studied: Six classes of vertebrates.
Methods: We compiled a database of geographical range, body size and extinction risk for six vertebrate classes (n = 26,076). We characterized the shape of the relationship between geographical range and body size for each class, using 90% and 10% quantile regression to describe the upper and lower bounds, respectively. We then evaluated the degree of extinction vulnerability of species at the lower bound of the regression using generalized linear mixed models. All analyses accounted for phylogenetic dependence between related species.
Results: The relationships between species ranges and body sizes were generally positive at both the upper and the lower bounds, and segmented (nonlinear) relationships were common. Despite this variability, species near the lower boundary of the relationship were more often in higher extinction risk categories, and this remained true when the role of range size in the International Union for Conservation of Nature Red Listing criteria was accounted for.
Main conclusions: Variability in the upper and lower bounds of the range–body size relationship suggests that some classes of vertebrates exhibit combinations of ranges and body sizes that might not reflect historical patterns. Nonetheless, the range–body size relationship remains a reliable and useful predictor of extinction risk, more so than range size does alone. The range–body size relationship could therefore be used to track the trajectories of species towards or away from an extinction threshold and allow the tracking of how different human activities alter the range–body size relationship.
Authors: Harry A Moore, Judy A Dunlop, Leonie E Valentine, John C Z Woinarski, Euan G Ritchie, David M Watson, and Dale G Nimmo
Published in: Diversity and Distributions
Aim: Species range contractions are increasingly common globally. The niche reduction hypothesis posits that geographic range contractions are often patterned across space owing to heterogeneity in threat impacts and tolerance. We applied the niche reduction hypothesis to the decline of a threatened marsupial predator across northern Australia, the northern quoll (Dasyurus hallucatus).
Location: Northern Australia.
Methods: We assembled a database containing 3,178 historic and contemporary records for northern quolls across the extent of their distribution dating between 1778 and 2019. Based on these records, we estimated changes in the geographic range of the northern quoll using α‐hulls across four main populations. We then examined how range contractions related to factors likely to mediate the exposure, susceptibility, or tolerance of northern quolls to threats.
Result: The extent of range contractions showed an east–west gradient, most likely reflecting the timing of spread of introduced cane toads (Rhinella marina). There were clear changes in environmental characteristics within the contemporary compared to the historic geographic range, with the most substantial occurring in populations that have suffered the greatest range contractions. The contemporary range is comprised of higher quality habitats (measured using environmental niche models), characterized by higher topographical ruggedness and annual rainfall, and reduced distance to water, compared to the historic range.
Main conclusions: Changes to range and niche likely reflect the capacity of complex habitats to ameliorate threats (namely predation and altered fire regimes), and access to resources that increase threat tolerance. This study highlights the multivariate nature of ecological refuges and the importance of high‐quality habitats for the persistence of species exposed to multiple threats. Our methods provide a useful framework which can be applied across taxa in providing valuable insight to management.
Moore HA, Dunlop JA, Valentine LE, Woinarski JCZ, Ritchie EG, Watson DM, Nimmo DG (2019) Topographic ruggedness and rainfall mediate geographic range contraction of a threatened marsupial predator. Diversity and Distributions PDF DOI
Authors: Sarah J Maclagan, Terry Coates, Bronwyn A Hradsky, Ryan Butryn, and Euan G Ritchie
Published in: Animal Conservation
Animal movement can be significantly altered in human‐dominated landscapes such as urban and peri‐urban areas, where habitat is often fragmented and/or linear. Knowledge regarding how wildlife respond to anthropogenic change is vital for informing conservation efforts in such landscapes, including the design of nature reserves and wildlife corridors.
To better understand how threatened species persist and behave within human‐dominated landscapes, we examined the home range and space use of the nationally endangered southern brown bandicoot Isoodon obesulus obesulus in peri‐urban Melbourne, Australia’s second‐largest city. Specifically, we examined whether:
- bandicoots were confined to linear strips of remnant vegetation or also made use of the broader highly modified landscape matrix;
- the configuration of the linear vegetated strips affected home range shape; and
- home range area differed between bandicoots living in linear strips and those in larger remnant habitat patches.
We found that:
- 71% of adult males and 33% of adult females used the matrix, but non‐dispersing juveniles were entirely confined to the linear strips; males also travelled greater distances into the matrix (away from the vegetated strips) than females;
- bandicoots had longer home ranges in narrower strips and males had longer home ranges than females; and
- home range area for both sexes was smaller in linear strips than has been recorded in other studies in larger remnant habitats.
Our study highlights the importance of retaining narrow, fragmented and modified vegetation to accommodate threatened biodiversity within human‐dominated landscapes, but suggests the surrounding matrix may also offer important resources for adaptable species, such as bandicoots.
Supporting off‐reserve conservation of biodiversity in novel ecosystems is increasingly pertinent in our rapidly urbanizing world.
Authors: Jim‐Lino Kämmerle, Euan G Ritchie, and Ilse Storch
Published in: Conservation Science and Practice
Predators are often culled to benefit prey, but in many cases this conservation goal is not achieved or results remain unknown.
The red fox (Vulpes vulpes) is a predator of global significance, and an invasive species in some regions. Red fox culls intended to benefit prey are often restricted to small areas, and effectiveness is rarely sufficiently evaluated.
Given the economic, ecological, social, and welfare issues associated with lethal predator control, there is a strong need to assess the effects of spatiotemporal variation in culling intensity on red fox abundance.
We surveyed red fox populations in fragmented forests of south‐western Germany and related indices of local fox abundance to culling data, predicted landscape‐scale fox abundance, and other covariates. We tested whether restricted‐area culling was associated with local reductions in fox abundance, and examined how this relationship changed over time.
Local fox abundance was temporarily reduced in spring, following winter culls. However, the effect was minor and fox populations had compensated for the reductions at the latest by autumn. Restricted‐area culling therefore likely failed to sustain effects on fox abundance throughout the period most relevant for conservation (i.e., the reproductive period of the target prey species).
To be effective as a conservation tool, culling will therefore require explicit spatiotemporal coordination matching the biology of predators and target prey.
Authors: R Keller Kopf, Dale G Nimmo, Euan G Ritchie, and Jen K Martin
Published in: Frontiers in Ecology and the Environment
The mass decline of biodiversity in this post-truth era means that reliable and influential conservation science communication is more important than ever.
In this era, truths and lies are increasingly difficult to distinguish, posing a major challenge to science communication. As a result, conservation scientists and managers are grappling with new ways of countering misinformation and sharing factual information.
Facebook, Twitter, YouTube, Instagram, blogs, online news outlets, webcomics, and satirical articles all provide communication opportunities, but we still have a poor understanding of which of these are most effective, and when and where to best communicate science…
By Euan Ritchie (Deakin University), Abi Vanak (University of KwaZulu-Natal), Benjamin Scheele (Australian National University), Laurentiu Rozylowicz, and Tibor Hartel
Bears, wolves, lions and other top predators have a long history of conflict with people – they can threaten our safety and kill livestock.
In our recent study, published in Conservation Biology, we outline how conventional conservation approaches are unlikely to lead to effective coexistence between humans and large carnivores in human-dominated landscapes.
This wicked problem encompasses public safety, agriculture, conservation, animal welfare, and more. Each facet is commonly managed by a different institution working in isolation – often failing to reflect the reality of our highly connected world.
Academia can help foster better institutional arrangements, especially in places like Romania, India and Brazil, where there are substantial populations of people and large carnivores in shared spaces.
Similarly, Australia’s own dingo occurs across agricultural and pastoral regions, with sentiments ranging from protected native species to disliked pest.
Why institutions fail carnivore-human relationships
From bears in Romania to dingoes in Australia, large carnivores are found in an array of places. This means they regularly affect the interests of a range of institutions, from agriculture to forestry.
But the current arrangements are poorly suited to facilitate a peaceful coexistence between humans and large carnivores.
Typically, institutions focus on a small subset of concerns. Forestry and agricultural sectors, for instance, may not feel responsible for large carnivore conservation because they are primarily interested in timber and agricultural production.
On the other hand, institutions for transport, energy and border security might be indifferent towards large carnivores. But they can negatively affect these animals if they put up barriers restricting predator movement and inappropriately handle roadkill.
These compartmentalised, and often conflicting, institutions are poorly suited to helping wildlife, especially when large carnivores, such as leopards, wolves and bears, live in human-dominated regions.
A role for academia
Academia has solutions to offer.
Most environment-related professionals, like foresters, wildlife managers and conservation biologists, are trained in a range of academic institutions. Unfortunately, they are often taught narrowly within their sector or discipline.
However, all these future professionals passing through the same institutions provides a great opportunity for a broad change in how we approach difficult conservation challenges and conflict with wildlife.
There are at least three ways in which academia could help address the challenges of human and large carnivore coexistence:
1. Break down the silos
Academic institutions need to create special centres to better support teaching and research across different disciplines.
Conservation – and, on a broader level, how humans should relate to the natural world – cannot be siloed away in wildlife management courses.
2. Broaden the view
We need to actively foster a broader perspective that does not see large carnivores as an “enemy”, while still safeguarding human life. This is a complex and multifaceted challenge.
By working across disciplines, universities have the chance to actively foster this broader perspective. This may seem like a nebulous point, but the collapse of species around the world has highlighted how ineffective our current approach to conservation is. We need to move beyond tinkering around the edges of our extinction crisis.
Conservation policy is already equipped to address individual targets such as regulating carnivore populations and legally protecting species. It is the larger aim of changing norms, challenging values and ensuring all these various institutions are pulling in the same direction that we need to tackle – a tactic called the “leverage points approach”.
3. Work outside the academy
Academia could support existing collaborations. When people with shared interests come together to pool knowledge and address a particular issue, we call it a community of practice. Academia can contribute to these communities by offering the skills and expertise of its graduates, but also broader social and industry connections (where required), knowledge sharing, collaborative research, education and technological innovation.
We need big carnivores and they need us
The ongoing controversy regarding the management of the dingo, Australia’s largest land-based predator (aside from humans), provides a perfect test case for this new approach to managing human-wildlife conflict.
If we can achieve more harmonious relations with the world’s top predators, many of the myriad other species that coexist with them are also likely to benefit from both better habitat management and conservation and the important ecological effects large carnivores can have, such as keeping herbivore and smaller predator numbers in check. This can be a positive step towards addressing Earth’s mass extinction crisis.
The authors would like to thank John Linnell, Senior Research Scientist at the Norwegian Institute for Nature Research, for his contribution to this article.
By Euan Ritchie, Deakin University.
In Dr Seuss’s The Lorax, his titular character famously said: “I am the Lorax. I speak for the trees. I speak for the trees, for the trees have no tongues.”
In the midst of a global extinction crisis, the Lorax’s call to preserve what is precious couldn’t be more apt. The greatest threat to the survival of species globally continues to be habitat destruction and modification.
A potential and local victim of this ongoing environmental catastrophe is a single tree, and a tree I have a deep personal connection with. The tree I refer to is Bulleen’s iconic 300-year-old river red gum (Eucalyptus camaldulensis).
To me, this tree has been a constant in my life. While everything else has changed around me, it has stood there, solid, just as solid as its red gum fibres are known to be.
As a child, I fondly remember looking up at this tree in awe, as we’d often stop at the nearby service station on a hot summer’s day to buy a cold drink or ice-cream on the way to Saturday sport, the nearby Birrarung (Yarra River), or my grandmother’s house.
Bulleen’s majestic river red gum
It’s estimated to be approximately 20 metres in height with a canopy spread of 17 metres. And its trunk measures a whopping two metres across.
The tree is thought to be the oldest remnant of a once substantial red gum forest, and was saved by a local resident when the rest of the area was cleared for the construction of a service station.
It now faces destruction, as it is within the preferred path of construction for Victoria’s North East link.
While the measurements of this tree are impressive, the splendour and value for me is that it has survived for so long and, in more recent times, against tremendous odds.
Surviving against all odds
The Bulleen red gum stands beside one of Melbourne’s busiest roads and the immediate area is covered with concrete and bitumen. The tree’s roots and health have therefore been challenged for a long time, and yet this massive red gum stands, as if in defiance of the modern world and the development that has encircled it.
Since this tree has survived for so long, it undoubtedly holds a special connection with so many: the Wurundjeri-willam people of the Kulin Nation, members of Australia’s famed Heidelberg school of artists who lived and worked in the near vicinty, everyday commuters that have driven or walked by or stopped to admire it, or the war verteran Nevin Phillips who once apparently defended it with his rifle against it being chainsawed.
Further proof of the value of this tree to so many is that it was awarded The National Trust of Australia’s (Victoria) 2019 Victorian Tree of the Year.
Why we must speak for and save old trees
I grew up near this tree and, like the Lorax, I would like to speak for it.
Trees as old as the Bulleen river red gum are now increasingly rare in our world, and beyond their strong personal and cultural values, including in some places as Aboriginal birthing sites, they are tremendously important for other reasons as well.
Perhaps most importantly, under their bark and in their cracks and hollows, they provide homes for many of Australia’s precious but increasingly imperilled native wildlife, including bats, birds, possums and gliders, snakes and lizards, insects and spiders.
These homes are prime wildlife real estate, especially in our big cities, where such large old trees are vanishingly rare but where considerable wildlife, common and threatened, still persists. And yet more could survive with a helping hand from us.
As cities like Melbourne continue to grow around the world, there will be more and more cases where arguments of progress are used to justify the further destruction of what nature remains. But progress shouldn’t come at any cost, and in the case of preserving iconic and valuable trees such as Bulleen’s river red gum, it would seem there’s more than enough reasons to ensure this tree’s life and its many values continue.
Perhaps again the wise sage, the Lorax, says it best. “Unless someone like you cares a whole awful lot, Nothing is going to get better. It’s not.”
Authors: William L Geary, Dale G Nimmo, Tim S Doherty, Euan G Ritchie, and Ayesha IT Tulloch
Published in: Journal of Applied Ecology
Interactions between threatening processes and their effects on biodiversity are a major focus of ecological research and management. Threat interactions arise when threats or their effects co‐occur spatially and temporally.
Whether the associations between threats are coincidental or causally linked is poorly understood, but has fundamental impacts on how, when and where threats should be managed. We propose that examining threat co‐occurrence, supplemented by experiments and triangulation of evidence, can help identify when and where threats interact causally, informing pressing biodiversity management goals.
Using case studies, we demonstrate how co‐occurring and interacting threats can be visualised as networks (threat webs) and how this could guide conservation interventions at local, regional and global scales.
Synthesis and applications. Recognising that threats co‐occur and interact as networks, and are potentially driven by multiple agents (e.g. other threats, shared environmental drivers), helps us understand their dynamics and impacts on ecosystems. This greater understanding can help facilitate more targeted, efficient and effective environmental management.
By Don Driscoll, Deakin University; Desley Whisson, Deakin University; Euan Ritchie, Deakin University; Mike Weston, Deakin University; Raylene Cooke, Deakin University, and Tim Doherty, Deakin University.
Addressing this crisis requires transformative change, including more effective environmental law and implementation.
Improved legislation is one of five main levers for realising change identified in the recent United Nation’s global biodiversity report and the key lesson arising from the Senate’s interim report into Australia’s faunal extinction crisis.
The Senate’s interim report, based on 420 submissions and five hearings, shows Australia is a world leader in causing species extinctions, in part because Australia’s systems for conserving our natural heritage are grossly inadequate.
To allow the continued erosion of this continent’s spectacular and remarkable array of globally unique plants and animals is a travesty of the highest order.
One of the problems is species may decline from common to extinct quite rapidly – faster than the time it takes species to be listed as threatened under the federal Environment Protection and Biodiversity Conservation (EPBC) Act.
The Christmas Island forest skink was formally listed as a threatened species only four months before the last individual died in captivity, but 15 years after the decline was first reported.
Extinction of the forest skink, Bramble Cay melomys and Christmas Island pipistrelle between 2009 and 2014 may have been averted if the risk was formally recognised in a more timely manner and effective conservation actions, such as captive breeding programs, were implemented.
Currently, if a species is not listed, it is not a “matter of national environmental significance” and federal agency staff generally have no legal basis for acting to protect it.
The black-throated finch has been listed as threatened on the EPBC Act for 14 years and during this time 600,000 ha of potential finch habitat has been destroyed. Worse still, five large coal mines, including the Carmichael Coal Mine, have been given approval (pending environmental conditions being met in Queensland) to clear more than 29,000 ha of black-throated finch habitat in one of its final strongholds, the Galilee Basin.
The controversial Toondah Harbour development in Brisbane is another example of how ministerial discretion can allow disastrous environmental outcomes. The project plans to build 3,600 apartments on wetlands that provide habitat for migratory waterbirds, including the critically endangered eastern curlew.
Despite being described as “clearly unacceptable” by the federal environment department and knocking it back twice, the minister allowed a third submission to proceed for further assessment.
It was reported this decision was made in the context of legal threats and donations from the developer in question. If true, this context would make it very difficult to make impartial decisions that protect biodiversity, as environmental law intends.
Increasing ministerial discretion was a key result of 2007 amendments to the EPBC act, which meant recovery plans were no longer required for threatened species.
The amendment allowed the minister to develop “conservation advices” instead of recovery plans. This amendment downgraded protections for threatened species because a minister can legally make decisions that are inconsistent with conservation advice, but not a recovery plan.
New environmental legislation
Based on these examples and many others that demonstrate the failings of current laws, the interim report concludes that we should rip up the EPBC act and develop stronger and more effective environmental legislation.
This includes establishing an independent Environmental Protection Agency to ensure enforcement of environmental laws, and, in a forward-looking addition by the Greens senators, an independent National Environmental Commission to monitor effectiveness of environmental legislation and propose improvements.
Australia needs a well-resourced, independent umpire for the environment, with powers to investigate environmental concerns and scrutinise government policy, akin to New Zealand’s Parliamentary Commissioner for the Environment. While Australia’s Threatened Species Commissioner is an excellent champion for the environment, this role provides no ability to question government actions regarding environmental protection and nature conservation.
Although replacing the EPBC act with new legislation may seem like a radical step to some (but not all), the interim Senate report, and the global UN report, have independently concluded major reform is essential. We are not in a moment of time when tweaking the current system will do the trick.
Changing Australia’s environmental legislation is a relatively minor update compared with the fundamental social and economic changes recommended by the UN report.
Such changes are already recommended by scientific societies like the Ecological Society of Australia, non-government organisations like Birdlife Australia and the Australian Conservation Foundation, and are demanded by a growing section of society. New, fit-for-purpose legislation must be enforceable, apolitical and responsive.
Opinion polls show that the level of environmental concern is higher in Australia than in other countries , while 29% of ABC Vote Compass respondents ranked the environment as the most important issue, up from 9% in 2016.
This groundswell of environmental concern has spawned mass protest movements like Extinction Rebellion. Young Australians also have shown their concern. In March 2019, thousands of school students took part in 50 rallies across the country to protest against “the destruction of our future”.
Decisions about what and how much we buy, what we eat, how much we travel and by what means, and family size, all contribute to our environmental footprints, and are the fundamental instigators of the biodiversity crisis.
However, we must also look to our political leaders to support effective change. The simplest and most powerful action you can take to reverse the extinction crisis is to vote for a party with policies best aligned with credible scientific advice on how we can get out of this mess.
Authors: Tibor Hartel, Ben C Scheele, Abi Tamim Vanak, Laurențiu Rozylowicz, John D C Linnell, and Euan G Ritchie
Published in: Conservation Biology
Achieving human‐large carnivore coexistence in Human Dominated Landscapes (HDL) is a key challenge for societies globally. This challenge cannot be adequately met with the current sectoral approaches of HDL governance and an academic sector largely dominated by disciplinary silos.
In this essay, we urge academia (universities and other research institutions and organisations) to take a more active role in embracing societal challenges around large carnivore conservation in HDL. Drawing on key lessons from populated regions of Europe, Asia and South America with significant densities of large carnivores, we illustrate how academia can help facilitate cross‐sectoral cooperation for mainstreaming human large carnivore coexistence.
We propose three ways for academia to engage with human‐large carnivore coexistence in HDL.
First, academia should better embrace the principles and methods of sustainability sciences and create institutional spaces for the implementation of transdisciplinary curricula and projects.
Second, researchers should reflect on the research approaches (i.e. disciplinary, interdisciplinary or transdisciplinary) they apply, and how their outcomes could aid leveraging institutional transformations for mainstreaming human‐large carnivore coexistence.
Third, researchers should engage with various institutions and stakeholder groups for creating novel institutional structures which can respond to the multiple challenges of HDL management, as well as human‐large carnivore coexistence.
Success in mainstreaming human‐large carnivore coexistence in HDL will rest on our collective ability to think and act cooperatively. Such a conservation achievement, if realized, stands to have far-reaching benefits for people and biodiversity alike.
We are seeking a PhD student for an exciting, industry-funded project aimed at understanding how fire regimes influence wildlife in semi-arid Victoria. The project is expected to begin in mid-2019.
The project will use new automated methods alongside traditional methods to sample mammal, reptile and amphibian communities across a chronosequence of fire age-classes in each of two major vegetation types (lowan mallee and heathland sands) in the Victorian mallee (Big Desert and Little Desert national parks). The candidate will work closely with machine-learning experts to develop and implement automated data processing methods.
The project is funded and supported via the Victorian Department of Environment, Land, Water and Planning and the Bushfire and Natural Hazards Cooperative Research Centre, and will also involve close collaboration with research partners at La Trobe University.
For more information and to submit an expression of interest, please contact me.
Your expression of interest should include a CV and up to two pages that specifically address the following selection criteria:
- Strong, strong first-class honours degree or equivalent at an Australian university or recognised overseas university.
- Must be able to work independently as well as in a team and show a high level of initiative and collaboration.
- Field experience (ideally in remote locations) in wildlife survey and ecology.
- GIS, statistical (program R) and modelling experience will also be very advantageous.
- Must have a current, manual driver’s license.
Expressions of interest close Tuesday 30 April 2019.