Counting the bodies: Estimating the numbers and spatial variation of Australian reptiles, birds and mammals killed by two invasive mesopredators

Authors: Alyson M Stobo-Wilson, Brett P Murphy, Sarah M Legge, Hernan Caceres-Escobar, David G Chapple, Heather M Crawford, Stuart J Dawson, Chris R Dickman, Tim S Doherty, Patricia A Fleming, Stephen T Garnett, Matthew Gentle, Thomas M Newsome, Russell Palmer, Matthew W Rees, Euan G Ritchie, James Speed, John-Michael Stuart, Andrés F Suarez-Castro, Eilysh Thompson, Ayesha Tulloch, Jeff M Turpin, and John CZ Woinarski

Published in: Diversity and Distributions

Abstract

Aim

Introduced predators negatively impact biodiversity globally, with insular fauna often most severely affected. Here, we assess spatial variation in the number of terrestrial vertebrates (excluding amphibians) killed by two mammalian mesopredators introduced to Australia, the red fox (Vulpes vulpes) and feral cat (Felis catus). We aim to identify prey groups that suffer especially high rates of predation, and regions where losses to foxes and/or cats are most substantial.

Location

Australia.

Methods

We draw information on the spatial variation in tallies of reptiles, birds and mammals killed by cats in Australia from published studies. We derive tallies for fox predation by

  1. modelling continental-scale spatial variation in fox density,
  2. modelling spatial variation in the frequency of occurrence of prey groups in fox diet,
  3. analysing the number of prey individuals within dietary samples and
  4. discounting animals taken as carrion.

We derive point estimates of the numbers of individuals killed annually by foxes and by cats and map spatial variation in these tallies.

Results

Foxes kill more reptiles, birds and mammals (peaking at 1071 km−2 year−1) than cats (55 km−2 year−1) across most of the unmodified temperate and forested areas of mainland Australia, reflecting the generally higher density of foxes than cats in these environments. However, across most of the continent — mainly the arid central and tropical northern regions (and on most Australian islands) — cats kill more animals than foxes. We estimate that foxes and cats together kill 697 million reptiles annually in Australia, 510 million birds and 1435 million mammals.

Main conclusions

This continental-scale analysis demonstrates that predation by two introduced species takes a substantial and ongoing toll on Australian reptiles, birds and mammals. Continuing population declines and potential extinctions of some of these species threatens to further compound Australia’s poor contemporary conservation record.

Stobo‐Wilson AM, Murphy BP, Legge SM, Caceres‐Escobar H, Chapple DG, Crawford HM, Dawson SJ, Dickman CR, Doherty TS, Fleming PA, Garnett ST, Gentle M, Newsome TM, Palmer R, Rees MW, Ritchie EG, Speed J, Stuart J, Suarez‐Castro AF, Thompson E, Tulloch A, Turpin JM, Woinarski JCZ (2022) Counting the bodies: Estimating the numbers and spatial variation of Australian reptiles, birds and mammals killed by two invasive mesopredators. Diversity and Distributions PDF DOI

The Conversation: ‘The sad reality is many don’t survive’ – how floods affect wildlife, and how you can help them

A koala joey was found drenched and trembling near the edge of the Brisbane River. It was one of the lucky animals to be rescued from the severe floodwaters. Image credit: WWF Australia

By Euan Ritchie (Deakin University) and Chris J Jolly (Macquarie University).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

For over two decades, bull sharks have called a Brisbane golf course home after, it’s believed, a flood washed them into the course’s lake in 1996. Now, after severe floods connected their landlocked home back to the river system, these sharks have gone missing, perhaps attempting to seek larger water bodies.

This bizarre tale is one of many accounts illustrating how Australia’s wildlife respond to flooding. But the sad reality is many don’t survive. Those that do may find their homes destroyed or, like those bull sharks and others, find themselves displaced far from their original homes or suitable habitat.

The RSPCA and other wildlife care organisations have received hundreds of calls to help rescue and care for stranded animals. But the true toll on wildlife will remain unknown, in part because we know surprisingly little about the impacts of floods on wildlife.

Still, as many animals have amazing abilities to survive fire, so too do many possess the means to survive or even profit from floods. After all, Australia’s wildlife has evolved over millions of years to survive in this land of extremes.

How wildlife responds to floods

Floods rapidly turn land habitats into underwater habitats, allowing aquatic animals to venture into places you wouldn’t expect. Flooding during northern Australia’s annual wet season, for example, sees crocodiles occasionally turn up in people’s backyard pools.

Land-dwelling animals typically don’t fare as well in floods. Some may be able to detect imminent inundation and head for higher, drier ground. Others simply don’t have the ability or opportunity to take evasive action in time. This can include animals with dependent young in burrows, such as wombats, platypus and echidnas.

The extent to which flooding affects animals will depend on their ability to sense what’s coming and how they’re able to respond. Unlike humans who must learn to swim, most animals are born with the ability.

Echidnas, for example, have been known to cover large areas of open water, but fast flowing, powerful floods pose a very different proposition.

Animals that can fly – such as many insects, bats and birds – may be able to escape. But their success will also partly depend on the scale and severity of weather systems causing floods.

Many birds, for example, couldn’t get away from the heavy rain and seek shelter, ending up waterlogged. If birds are exhausted and can’t fly, they may suffer from exposure and also be more vulnerable to predators, such as feral cats and foxes.

During floods, age old predator-prey relationships, forged through evolution, can break down. Animals are more focused on self preservation, rather than their next meal. This can result in strange, ceasefire congregations.

For example, a venomous eastern brown snake was filmed being an unintentional life raft for frogs and mice. Likewise, many snakes, lizards and frogs are expert climbers, and will seek safety in trees – with or without company.

Some spiders have ingenious ways of finding safety, including spinning balloon-like webs to initiate wind-driven lift-off: destination dry land. This is what happened when Victoria’s Gippsland region flooded last year.

One of the challenges of extreme events is it can make food hard to find. Some animals – including microbats, pygmy possums, and many reptiles – may reduce their energy requirements by essentially going to “sleep” for extended periods, commonly referred to as torpor. This includes echidnas and Antechinus (insect-eating marsupials), in response to bushfire.

Might they do the same during floods? We really don’t know, and it largely depends on an animal’s physiology. In general, invertebrates, frogs, fish and reptiles are far better at dealing with reduced access to food than birds and mammals.

What happens when floods recede?

Flooding may provide a bounty for some species. Some predators such as cats, foxes, and birds of prey, may have access to exhausted prey with fewer places to hide. These same predators may scavenge the windfall of dead animals.

Fish, waterbirds, turtles and other aquatic or semi-aquatic life may benefit from an influx of nutrients, increasing foraging opportunities and even stimulating breeding events.

Other wildlife may face harsher realities. Some may become trapped far from their homes. Those that attempt to return home will have to run the gauntlet of different habitats, roads, cats, dogs and foxes, and other threats.

Even if they make it home, will their habitats be the same or destroyed? Fast and large volumes of water can destroy vegetation and other habitat structures (soils, rock piles) in minutes, but they may take many years or decades to return, if ever.

Floodwaters can also carry extremely high levels of pollution, leading to further tragic events such as fish kills and the poisoning of animals throughout food chains.

How can you help?

Seeing wildlife in distress is confronting, and many of us may feel compelled to want to rescue animals in floodwaters. However, great caution is required.

Wading into floodwaters can put yourself at significant risk. Currents can be swift. Water can carry submerged and dangerous obstacles, as well as chemicals, sewage and pathogens. And distressed animals may panic when approached, putting them and yourself at further risk.

For example, adult male eastern grey kangaroos regularly exceed 70 kilograms with long, razor sharp claws and toe nails, and powerful arms and legs. They’ve been known to deftly use these tools to drown hostile farm dogs in dams and other water bodies.

So unless you’re a trained wildlife expert or animal carer, we don’t recommend you try to save animals yourself. There is more advice online, such as here and here.

If you’d like to support the care and recovery of wildlife following the floods, a number of organisations are taking donations, including WWF Australia, WIRES and the RSPCA.

What does the future hold?

While many Australian wildlife species are well adapted to dealing with periodic natural disasters, including floods, we and wildlife will face even more intense events in the future under climate change. Cutting greenhouse gas emissions can lessen this impact.

For common, widespread species such as kangaroos, the loss of individuals to infrequent, albeit severe, events is tragic but overall doesn’t pose a great problem. But if floods, fires and other extreme events become more regular, we could see some populations or species at increased risk of local or even total extinction.

This highlights how Earth’s two existential crises – climate change and biodiversity loss – are inextricably linked. We must combat them swiftly and substantially, together, if we’re to avoid a bleak future.

360info: The koala in the coal mine

Indigenous rangers programs are win-win solutions to the problems of species conservation and loss of culture. Image credit: Parks Australia

Originally published under Creative Commons by 360info

With the scrutiny on climate change, the collapse of Australian ecosystems has received scant attention. But saving them is entirely possible.

Australia’s iconic koala, listed as endangered in the Australian regions of Queensland, New South Wales and the Australian Capital Territory in 2022, is unfortunately far from alone.

Since European colonisation of Australia, roughly 230 years ago, at least 39 native mammal species have been driven to extinction. The Australian continent, with its extraordinary and largely unique (endemic) plants and animals, now has more than 1,900 threatened species and ecological communities.

Ecosystems from the tropics to Antarctica, including the Great Barrier Reef, are showing signs of collapse.

Ecologists and conservation biologists have been documenting and warning of the widespread demise of nature for decades. Then in 2019 an intergovernmental body confirmed what many had been pointing out: we are in the midst of Earth’s sixth mass extinction event.

Using the fossil record as a reference for ‘normal’ rates of extinction, we are now seeing rates of extinction tens, hundreds or thousands of times higher than expected.

It’s a crisis no less catastrophic than climate change, but one that garners far less attention.

Far too few recognise the need to combat climate change, environmental destruction, and extinction in an integrated way.

Addressing climate change has rightly received considerable global attention. But climate change is one dimension — albeit a big one — of the environmental and extinction crisis we face.

Without a substantial increase in investment in conservation, habitat destruction and modification, invasive species, pollution, and disease will continue to be key threats. If we hope to turn things around, we need stronger, not weaker environmental legislation. And ultimately, if environmental decline is to stop, we will need to confront the main driver of these issues: consumption and living unsustainably.

Climate change, extinction, and environmental health are inextricably linked.

Protecting forests, either on land or underwater, helps to capture and store carbon thereby helping to fight climate change. It also provides homes for countless species. Restoring whale populations can increase the productivity of oceans, as what whales leave behind after their meals helps to fertilise microscopic phytoplankton, which themselves capture carbon and drive foodchains.

Restoring or protecting nature via returning species to landscapes, often known as ‘rewilding’, is seen as a key ingredient in fighting climate change and extinction.

Everything is linked, and needs to be managed as though it is.

Another key ingredient for change is investment. The more countries invest in conservation, the better their conservation outcomes will be. Money is needed for establishing conservation reserves, and just as importantly, managing them. It also costs money to monitor species’ populations and the diversity of plants, animals, fungi and other organisms within them.

By area, most land and sea is not under conservation protection, and many threatened species occur on private land. Conservation initiatives spanning public and private land would better protect them.

Investing in people to carry out conservation would have far reaching benefits. For example, Indigenous Protected Areas and Indigenous Ranger programs help to conserve native plants and animals, reduce invasive animal populations, manage fire, and maintain connections with culture and Country. Likewise, undertaking pest animal control, revegetation, species reintroductions and other conservation-focussed actions, can create jobs in cities and regional towns.

It’s estimated it would cost around A$1.7 billion a year to bring all the species on Australia’s threatened list back to health. Australia currently spends around A$120 million a year on targeted threatened species conservation and recovery. Recently, it committed A$10 million (or $100,000 each) to 100 species deemed a priority, of the more than 1,800 species on the threatened list.

Despite its immense social, cultural, economic and environmental value, Australian governments and society seemingly don’t see the environment as a priority investment. The question we must confront, is why?

Beyond spatial overlap: harnessing new technologies to resolve the complexities of predator–prey interactions

Authors: Justin P Suraci, Justine A Smith, Simon Chamaillé-Jammes, Kaitlyn M Gaynor, Menna Jones, Barney Luttbeg, Euan G Ritchie, Michael J Sheriff, and Andrew Sih

Published in: Oikos

Abstract

Predation risk, the probability that a prey animal will be killed by a predator, is fundamental to theoretical and applied ecology. Predation risk varies with animal behavior and environmental conditions, yet attempts to understand predation risk in natural systems often ignore important ecological and environmental complexities, relying instead on proxies for actual risk such as predator–prey spatial overlap.

Here we detail the ecological and environmental complexities driving disconnects between three stages of the predation sequence that are often assumed to be tightly linked: spatial overlap, encounters and prey capture. Our review highlights several major sources of variability in natural predator–prey systems that lead to the decoupling of spatial overlap estimates from actual encounter rates (e.g. temporal activity patterns, predator and prey movement capacity, resource limitations) and that affect the probability of prey capture given encounter (e.g. predator hunger levels, temporal, topographic and other environmental influences on capture success). Emerging technologies and statistical methods are facilitating a transition to a more spatiotemporally detailed, mechanistic understanding of predator–prey interactions, allowing for the concurrent examination of multiple stages of the predation sequence in mobile, free-ranging animals.

We describe crucial applications of this new understanding to fundamental and applied ecology, highlighting opportunities to better integrate ecological contingencies into dynamic predator–prey models and to harness a mechanistic understanding of predator–prey interactions to improve targeting and effectiveness of conservation interventions.

Suraci JP, Smith JA, Chamaillé‐Jammes S, Gaynor KM, Jones M, Luttbeg B, Ritchie EG, Sheriff MJ, Sih A (2022) Beyond spatial overlap: harnessing new technologies to resolve the complexities of predator–prey interactions. Oikos PDF DOI

Australia’s biodiversity crisis and opportunity

Author: Euan G Ritchie

Published in: Science (Letters)

Australia is failing to meet its international obligations to conserve its unique native biodiversity and ecosystems. Most of Australia’s plants and animals are found nowhere else on Earth, but since colonization about 230 years ago, at least 100 endemic species have been driven to extinction, and 17 ecosystems spanning the continent are now showing signs of collapse. Many more species face the same grim fate, with more than 1900 species and ecological communities currently listed as of conservation concern under Australia’s centerpiece environmental legislation, the Environment Protection and Biodiversity Conservation Act 1999. Numerous reports demonstrate that Australia is simply not doing enough to address key threats to biodiversity, including land clearing and urbanization, invasive species, altered fire regimes, pollution, disease, and climate change. Despite being a member of the G20, Australian federal and state government environmental spending is well short of what’s required to reverse the nation’s biodiversity extinction trajectory.

A stark example of this failure is the newly announced priority threatened species list. Just 100 threatened species — fewer than 6% of the country’s listed threatened species — are earmarked for conservation attention and AUS $10 million of new funding, equating to about $100,000 per species. Of Australia’s Critically Endangered or Endangered species, only 2 of 25 frog species (8%), 7 of 53 invertebrate species (13.2%), and 28 of 776 plant species (3.6%) make the priority list.

Stronger environmental laws, combined with a substantial increase in investment in environmental and conservation spending, will not only benefit Australia’s biodiversity but also undoubtedly deliver substantial social, cultural, and economic benefits. The international community is moving to implement a new post-2020 global biodiversity framework, and heads of state recently met at the United Nations Climate Change Conference to chart a course to avert the climate change crisis deepening. Australia must be a leader of change, not a laggard.

Ritchie EG (2022) Australia’s biodiversity crisis and opportunity. Science PDF DOI

Twenty important research questions in microbial exposure and social equity

Authors: Jake M Robinson, Nicole Redvers, Araceli Camargo, Christina A Bosch, Martin F Breed, Lisa A Brenner, Megan A Carney, Ashvini Chauhan, Mauna Dasari, Leslie G Dietz, Michael Friedman, Laura Grieneisen, Andrew J Hoisington, Patrick F Horve, Ally Hunter, Sierra Jech, Anna Jorgensen, Christopher A Lowry, Ioana Man, Gwynne Mhuireach, Edauri Navarro-Pérez, Euan G Ritchie, Justin D Stewart, Harry Watkins, Philip Weinstein, Suzanne L Ishaq

Published in: mSystems (American Society for Microbiology)

Abstract

Social and political policy, human activities, and environmental change affect the ways in which microbial communities assemble and interact with people. These factors determine how different social groups are exposed to beneficial and/or harmful microorganisms, meaning microbial exposure has an important socioecological justice context. Therefore, greater consideration of microbial exposure and social equity in research, planning, and policy is imperative.

Here, we identify 20 research questions considered fundamentally important to promoting equitable exposure to beneficial microorganisms, along with safeguarding resilient societies and ecosystems. The 20 research questions we identified span seven broad themes, including the following:

  1. sociocultural interactions;
  2. Indigenous community health and well-being;
  3. humans, urban ecosystems, and environmental processes;
  4. human psychology and mental health;
  5. microbiomes and infectious diseases;
  6. human health and food security; and
  7. microbiome-related planning, policy, and outreach.

Our goal was to summarize this growing field and to stimulate impactful research avenues while providing focus for funders and policymakers.

Robinson JM, Redvers N, Camargo A, Bosch CA, Breed MF, Brenner LA, Carney MA, Chauhan A, Dasari M, Dietz LG, Friedman M, Grieneisen L, Hoisington AJ, Horve PF, Hunter A, Jech S, Jorgensen A, Lowry CA, Man I, Mhuireach G, Navarro-Pérez E, Ritchie EG, Stewart JD, Watkins H, Weinstein P, Ishaq SL (2022) Twenty Important Research Questions in Microbial Exposure and Social Equity. mSystems PDF DOI 

Creating testable questions in practical conservation: a process and 100 questions

Authors: William J Sutherland, Jake M Robinson, David C Aldridge, Tim Alamenciak, Matthew Armes, Nina Baranduin, Andrew J Bladon, Martin F Breed, Nicki Dyas, Chris S Elphick, Richard A Griffiths, Jonny Hughes, Beccy Middleton, Nick A Littlewood, Roger Mitchell, William H Morgan, Roy Mosley, Silviu O Petrovan, Kit Prendergast, Euan G Ritchie, Hugh Raven, Rebecca K Smith, Sarah H Watts, and Ann Thornton

Published in: Conservation Evidence

Summary

It is now clear that the routine embedding of experiments into conservation practice is essential for creating reasonably comprehensive evidence of the effectiveness of actions. However, an important barrier is the stage of identifying testable questions that are both useful but also realistic to carry out without a major research project. We identified approaches for generating such suitable questions. A team of 24 participants crowdsourced suggestions, resulting in a list of a hundred possible tests of actions.

Sutherland WJ, Robinson JM, Aldridge DC, Alamenciak T, Armes M, Baranduin N, Bladon AJ, Breed MF, Dyas N, Elphick CS, Griffiths RA, Hughes J, Middleton B, Littlewood NA, Mitchell R, Morgan WH, Mosley R, Petrovan SO, Prendergast K, Ritchie EG, Raven H, Smith RK, Watts SH & Thornton A (2022) EDITORIAL Creating testable questions in practical conservation: a process and 100 questions. Conservation Evidence PDF DOI

The Conversation: Ever wondered who would win in a fight between a dingo and a wolf? An expert explains

Image credit: Wes Mountain via The Conversation

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Imagine two of the world’s most iconic canids – a dingo and a wolf – head to head in a fight. Who would win?

Before we examine the combatants in more detail, we need to answer an important question first, which wolf and which dingo? Taxonomy – the way we describe, name and classify Earth’s biodiversity – remains contentious for both animals.

Dingoes are recognised as a species in their own right by some, but not others. And, dingoes are quite different in their size and appearance, depending on whether they live in Australia’s alpine and forested areas, deserts, or tropical regions.

As for wolves, there are North American (“Grey”), Mexican, Eurasian, Himalayan, Asiatic, Indian and Tibetan, Red, African golden, Ethiopian and even “ghost wolves” – yes, ghost wolves! Ghost wolves are species we can recognise from the past using genetic information, but they no longer survive and no fossils are known to exist.

And then there are “wolves” that aren’t wolves at all: the fox-like maned wolf in South America, and the gargantuan, now-extinct dire wolf.

For the purposes of this battle, let’s assume it’s between a grey wolf and an alpine dingo.

Why do dogs, dingoes and wolves fight?

For wild canids, fights occur for many reasons, within and between species when they overlap. Wolves and dingoes fight for mates, to attain dominance within packs, and to establish and maintain their territories.

So, let’s get to know each opponent a little better.

Dingoes and wolves are both social and intelligent species, capable of complex behaviours and problem solving.

Grey wolves are what we call hyper-carnivores, feeding predominantly on other animals, in many cases large prey such as deer, elk, moose and bison.

Dingoes are omnivores with a broad, varied diet. They eat everything from fruits, to invertebrates, to small and large vertebrates – think lizards, birds, wombats, wallabies, possums, kangaroos, and feral animals like goats and deer. Dingoes will also scavenge food and carcasses.

Prior to European invasion, dingoes likely occupied all of mainland Australia.

Aside from humans, it’s thought the grey wolf was once the world’s most widespread mammal, where it, and its subspecies, occurred across much of Europe, Asia, and North and Central America. But, like with dingoes, humans have caused substantial population and range decline of wolves.

The battle: terrain is crucial

The terrain of the arena for our combatants would be crucial. Dingoes and wolves are capable of moving at great speeds, sustained for long periods of time, especially in open country. Both can reach top speeds in the range of 50-60 kilometres per hour!

However, dingoes arguably have the advantage in tight spots, in terms of their much smaller size, greater agility and flexibility, and climbing abilities. Dingoes typically weigh between 15 and 20 kilograms, while grey wolves are usually in the range of 30-65kg, and up to around 80kg for some males.

Dingoes have been recorded vertically jumping 2 metres and climbing fences, making them quite cat-like in many respects. So, if the battle occurs among many obstacles and on steep terrain, this will give dingoes an edge.

But if the fight is in the open, the much heavier, taller, and longer wolves will be too much for dingoes. They also pack a heavier bite quotient (bite force relative to body mass) of 136 as compared to the dingo’s 108.

Having said that, wolves are much taller than dingoes, around 65-80 centimetres and 45-60cm at their shoulders, respectively. So it’s possible a wily dingo could dash under the legs of a tall wolf and launch an attack on the vulnerable underbelly.

What about pack vs pack?

The final factor to consider is whether the fight is simply one dingo vs one wolf. Both can occur as individuals or in packs.

Dingoes are typically found alone, in pairs or in small packs of a few individuals, but occasionally can be found in much larger, less socially cohesive groups of ten or more when food resources are plentiful.

Wolves, on the other hand, are often found in groups of between five and ten, but much larger packs of 20 or more can also occur.

I spoke to Lyn Watson, who runs the Dingo Discovery and Research Centre. She says dingoes are “flight, rather than fight, canids”. This is wise behaviour, as dingoes are small in number and size and can’t rely on a large pack, like wolves sometimes can, to substitute them should they become injured in a fight.

She goes on to say that from her 30 years of observations, female dingoes are particularly deadly.

While dingoes are small, bonded pairs will fight in a coordinated way. Males fight in traditional neck and throat grabs, or “elbow”, but their bonded other has a completely different mode – and it’s deadly.

The female will stay at the periphery then dart into the soft parts of the combatant that is threatening her mate. She aims to maim – and does so, targeting the most “sensitive” of areas, enough said!

So if it’s pack vs pack, wolves will be far too strong. But if a single wolf was unlucky enough to come across a pack of dingoes, the tide could turn strongly in favour of dingoes.

Learning to live together

Even though wolves and dingoes fight in the wild, despite common perceptions, they generally pose a very small risk to people, especially if we adhere to advice such as not feeding them.

Domestic and feral dogs pose a far greater risk to us. It’s estimated that around the world, dogs bite and injure tens of millions of people annually. In the US alone, it’s thought around 4.5 million people are bitten by dogs each year.

Of course, in reality wolves and dingoes will never fight each other in the wild. The greatest threat they both face is the ongoing destruction of their habitats and widespread direct persecution from humans (trapping, poisoning, shooting, and exclusion from areas), often aimed at protecting livestock.

Like other apex predators, dingoes and wolves have critical roles in our ecosystems and, in many cases, have deep cultural significance for Indigenous people. We must find more ethical and sustainable ways to share our world.

This article is part of the “Who would win?” series, where wildlife experts dream up hypothetical battles between predators (all in the name of science).
The Conversation

Compounding and complementary carnivores: Australian bird species eaten by the introduced European red fox Vulpes vulpes and domestic cat Felis catus

Authors: John C Z Woinarski, Alyson M Stobo-Wilson, Heather M Crawford, Stuart J Dawson, Chris R Dickman, Tim S Doherty, Patricia A Fleming, Stephen T Garnett, Matthew N Gentle, Sarah M Legge, Thomas M Newsome, Russell Palmer, Matthew W Rees, Euan G Ritchie, James Speed, John-Michael Stuart , Eilysh Thompson, Jeff Turpin and Brett P Murphy

Published in: Bird Conservation International

Abstract

Two introduced carnivores, the European red fox Vulpes vulpes and domestic cat Felis catus, have had extensive impacts on Australian biodiversity. In this study, we collate information on consumption of Australian birds by the fox, paralleling a recent study reporting on birds consumed by cats.

We found records of consumption by foxes on 128 native bird species (18% of the non-vagrant bird fauna and 25% of those species within the fox’s range), a smaller tally than for cats (343 species, including 297 within the fox’s Australian range, a subset of that of the cat). Most (81%) bird species eaten by foxes are also eaten by cats, suggesting that predation impacts are compounded.

As with consumption by cats, birds that nest or forage on the ground are most likely to be consumed by foxes. However, there is also some partitioning, with records of consumption by foxes but not cats for 25 bird species, indicating that impacts of the two predators may also be complementary. Bird species ≥3.4 kg were more likely to be eaten by foxes, and those <3.4 kg by cats.

Our compilation provides an inventory and describes characteristics of Australian bird species known to be consumed by foxes, but we acknowledge that records of predation do not imply population-level impacts. Nonetheless, there is sufficient information from other studies to demonstrate that fox predation has significant impacts on the population viability of some Australian birds, especially larger birds, and those that nest or forage on the ground.

Woinarski JCZ, Stobo-Wilson AM, Crawford HM, Dawson SJ, Dickman CR, Doherty TS, Fleming PA, Garnett ST, Gentle MN, Legge SM, Newsome TM, Palmer R, Rees MW, Ritchie EG, Speed J, Stuart JM, Thompson E, Turpin J, Murphy BP (2021) Compounding and complementary carnivores: Australian bird species eaten by the introduced European red fox Vulpes vulpes and domestic cat Felis catus. Bird Conservation International PDF DOI 

The Conversation: Destroying vegetation along fences and roads could worsen our extinction crisis — yet the NSW government just allowed it

By Euan Ritchie (Deakin University), Ben Moore (Western Sydney University), Jen Martin (The University of Melbourne), Mark Hall (Western Sydney University), Megan C Evans (UNSW), and Ross Crates (Australian National University).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

What do koalas, barking owls, greater gliders, southern rainbow skinks, native bees, and regent honeyeaters all have in common? Like many native species, they can all be found in vegetation along fences and roadsides outside formal conservation areas.

They may be relatively small, but these patches and strips conserve critical remnant habitat and have disproportionate conservation value worldwide. They represent the last vestiges of once-expansive tracts of woodland and forests, long lost to the chainsaw or plough.

And yet, the NSW government last week made it legal for rural landholders to clear vegetation on their properties, up to 25 metres from their property boundaries, without approval. This radical measure is proposed to protect people and properties from fires, despite the lack of such an explicit recommendation from federal and state-based inquiries into the devastating 2019-20 bushfires.

This is poor environmental policy that lacks apparent consideration or justification of its potentially substantial ecological costs. It also gravely undermines the NSW government’s recent announcement of a plan for “zero extinction” within the state’s national parks, as the success of protected reserves for conservation is greatly enhanced by connection with surrounding “off-reserve” habitat.

Small breaks in habitat can have big impacts

A 25m firebreak might sound innocuous, but when multiplied by the length of property boundaries in NSW, the scale of potential clearing and impacts is alarming, and could run into the hundreds of thousands of kilometres.

Some plants, animals and fungi live in these strips of vegetation permanently. Others use them to travel between larger habitat patches. And for migratory species, the vegetation provides crucial refuelling stops on long distance journeys.

For example, the roadside area in Victoria’s Strathbogie Ranges shown below is home to nine species of tree-dwelling native mammals: two species of brushtail possums, three species of gliders (including threatened greater gliders), common ringtail possums, koalas, brush-tailed phascogales, and agile antenchinus (small marsupials).

Many of these species depend on tree hollows that can take a hundred years to form. If destroyed, they are effectively irreplaceable.

Creating breaks in largely continuous vegetation, or further fragmenting already disjointed vegetation, will not only directly destroy habitat, but can severely lower the quality of adjoining habitat.

This is because firebreaks of 25m (or 50m where neighbouring landholders both clear) could prevent the movement and dispersal of many plant and animal species, including critical pollinators such as native bees.

An entire suite of woodland birds, including the critically endangered regent honeyeater, are threatened because they depend on thin strips of vegetation communities that often occur inside fence-lines on private land.

For instance, scientific monitoring has shown five pairs of regent honeyeaters (50% of all birds located so far this season) are nesting or foraging within 25m of a single fence-line in the upper Hunter Valley. This highlights just how big an impact the loss of one small, private location could have on a species already on the brink of extinction.

But it’s not just regent honeyeaters. The management plan for the vulnerable glossy black cockatoo makes specific recommendation that vegetation corridors be maintained, as they’re essential for the cockatoos to travel between suitable large patches.

Native bee conservation also relies on the protection of remnant habitat adjoining fields. Continued removal of habitat on private land will hinder chances of conserving these species.

Disastrous clearing laws

The new clearing code does have some regulations in place, albeit meagre. For example, on the Rural Fire Service website, it says the code allows “clearing only in identified areas, such as areas which are zoned as Rural, and which are considered bush fire prone”. And according to the RFS boundary clearing tool landowners aren’t allowed to clear vegetation near watercourses (riparian vegetation).

Even before introducing this new code, NSW’s clearing laws were an environmental disaster. In 2019, The NSW Audit Office found:

clearing of native vegetation on rural land is not effectively regulated [and] action is rarely taken against landholders who unlawfully clear native vegetation.

The data back this up. In 2019, over 54,500 hectares were cleared in NSW. Of this, 74% was “unexplained”, which means the clearing was either lawful (but didn’t require state government approval), unlawful or not fully compliant with approvals.

Landholders need to show they’ve complied with clearing laws only after they’ve already cleared the land. But this is too late for wildlife, including plant species, many of which are threatened.

Landholders follow self-assessable codes, but problems with these policies have been identified time and time again — they cumulatively allow a huge amount of clearing, and compliance and enforcement are ineffective.

We also know, thanks to various case studies, the policy of “offsetting” environmental damage by improving biodiversity elsewhere doesn’t work.

So, could the federal environment and biodiversity protection law step in if habitat clearing gets out of hand? Probably not. The problem is these 25m strips are unlikely to be referred in the first place, or be considered a “significant impact” to trigger the federal law.

The code should be amended

Nobody disputes the need to keep people and their assets safe against the risks of fire. The code should be amended to ensure clearing is only permitted where a genuinely clear and measurable fire risk reduction is demonstrated.

Granting permission to clear considerable amounts of native vegetation, hundreds if not thousands of metres away from homes and key infrastructure in large properties is hard to reconcile, and it seems that no attempt has been made to properly justify this legislation.

We should expect that a comprehensive assessment of the likely impacts of a significant change like this would inform public debate prior to decisions being made. But to our knowledge, no one has analysed, or at least revealed, how much land this rule change will affect, nor exactly what vegetation types and wildlife will likely be most affected.

A potentially devastating environmental precedent is being set, if other regions of Australia were to follow suit. The environment and Australians deserve better.
The Conversation

A brief history of the northern quoll (Dasyurus hallucatus): a systematic review

Authors: Harry A Moore, Judy A Dunlop, Chris J Jolly, Ella Kelly, John C Z Woinarski, Euan G Ritchie, Scott Burnett, Stephen van Leeuwen, Leonie E Valentine, Mitchell A Cowan, and Dale G Nimmo.

Published in: Australian Mammalogy

Abstract

In response to Australia’s current extinction crisis, substantial research efforts have been targeted towards some of the most imperilled species. One such species is the northern quoll (Dasyurus hallucatus), a marsupial predator that has recently suffered substantial declines in range and is now listed as Endangered.

We conducted a systematic review of all literature relevant to the conservation and ecology of northern quolls. We reviewed 143 studies, including research articles, government and industry reports, theses, and books, and quantified research effort in terms of topic, location, and publication period. We then summarised research relevant to northern quoll taxonomy, genetics, distribution, habitat associations, diet, reproduction, movement, threats, management, and Indigenous knowledge. Research effort was higher between 2011 and 2020 than the previous four decades combined.

Northern quolls in the Northern Territory were the most studied, followed by the Pilbara, the Kimberley, and Queensland populations. Most studies focused on northern quoll distribution and habitat, management, and threats – primarily cane toads, predation, and fire.

We conclude with a non-exhaustive list of ten future research directions. If pursued, these future research directions should provide information critical to managing and conserving northern quolls.

Moore HA, Dunlop JA, Jolly CJ, Kelly E, Woinarski JCZ, Ritchie EG, Burnett S, van Leeuwen S, Valentine LE, Cowan MA, Nimmo DG (2021) A brief history of the northern quoll (Dasyurus hallucatus): a systematic review. Australian Mammalogy PDF DOI

Sharing meals: Predation on Australian mammals by the introduced European red fox compounds and complements predation by feral cats

Authors: Alyson M Stobo-Wilson, Brett P Murphy, Heather M Crawford, Stuart J Dawson, Chris R Dickman, Tim S Doherty, Patricia A Fleming, Matthew N Gentle, Sarah M Legge, Thomas M Newsome, Russell Palmer, Matthew W Rees, Euan G Ritchie, James Speed, John-Michael Stuart, Eilysh Thompson, Jeff Turpin, and John C Z Woinarski

Published in: Biological Conservation

Abstract

Two introduced carnivores, the European red fox Vulpes vulpes and domestic cat Felis catus, have had, and continue to have, major impacts on wildlife, particularly mammals, across Australia. Based mainly on the contents of almost 50,000 fox dietary samples, we provide the first comprehensive inventory of Australian mammal species known to be consumed by foxes, and compare this with a similar assessment for cats.

We recorded consumption by foxes of 114 species of Australian land mammal (40% of extant species), fewer than consumed by cats (173 species). Foxes are known to consume 42 threatened mammal species (50% of Australia’s threatened land mammals and 66% of those within the fox’s Australian range). Reflecting the importance of mammals in their diet, foxes are known to consume a far higher proportion of Australian mammal species (40%) than of Australian birds (24%) and reptiles (16%).

Both foxes and cats were most likely to consume medium-sized mammals, with the likelihood of predation by foxes peaking for mammals of ca. 280 g and by cats at ca. 130 g. For non-flying mammals, threatened species had a higher relative likelihood of predation by foxes than non-threatened species. Using trait-based modelling, we estimate that many now-extinct Australian mammal species had very high likelihoods of predation by foxes and cats, although we note that for some of these species, extinction likely pre-dated the arrival of foxes. These two predators continue to have compounding and complementary impacts on Australian mammals. Targeted and integrated management of foxes and cats is required to help maintain and recover the Australian mammal fauna.

Stobo-Wilson AM, Murphy BP, Crawford HM, Dawson SJ, Dickman CR, Doherty TS, Fleming PA, Gentle MN, Legge SM, Newsome TM, Palmer R, Rees MW, Ritchie EG, Speed J, Stuart J-M, Thompson E, Turpin J, Woinarski JCZ (2021) Sharing meals: Predation on Australian mammals by the introduced European red fox compounds and complements predation by feral cats. Biological Conservation PDF DOI

Reptiles as food: predation of Australian reptiles by introduced red foxes compounds and complements predation by cats

Authors: Alyson M Stobo-Wilson, Brett P Murphy, Sarah M Legge, David G Chapple, Heather M Crawford, Stuart J Dawson, Chris R Dickman, Tim S Doherty, Patricia A Fleming, Matthew Gentle, Thomas M Newsome, Russell Palmer, Matthew W Rees, Euan G Ritchie, James Speed, John-Michael Stuart, Eilysh Thompson, Jeff Turpin, and and John C Z Woinarski

Published in: Wildlife Research

Abstract

Context: Invasive species are a major cause of biodiversity loss across much of the world, and a key threat to Australia’s diverse reptile fauna. There has been no previous comprehensive analysis of the potential impact of the introduced European red fox, Vulpes vulpes, on Australian reptiles.

Aims: We seek to provide an inventory of all Australian reptile species known to be consumed by the fox, and identify characteristics of squamate species associated with such predation. We also compare these tallies and characteristics with reptile species known to be consumed by the domestic cat, Felis catus, to examine whether predation by these two introduced species is compounded (i.e. affecting much the same set of species) or complementary (affecting different groups of species).

Methods: We collated records of Australian reptiles consumed by foxes in Australia, with most records deriving from fox dietary studies (tallying >35 000 samples). We modelled presence or absence of fox predation records against a set of biological and other traits, and population trends, for squamate species.

Key results: In total, 108 reptile species (~11% of Australia’s terrestrial reptile fauna) have been recorded as consumed by foxes, fewer than that reported for cats (263 species). Eighty-six species have been reported to be eaten by both predators. More Australian turtle species have been reported as consumed by foxes than by cats, including many that suffer high levels of predation on egg clutches. Twenty threatened reptile species have been reported as consumed by foxes, and 15 by cats. Squamate species consumed by foxes are more likely to be undergoing population decline than those not known to be consumed by foxes. The likelihood of predation by foxes increased with squamate species’ adult body mass, in contrast to the relationship for predation by cats, which peaked at ~217 g. Foxes, but not cats, were also less likely to consume venomous snakes.

Conclusions: The two introduced, and now widespread, predators have both compounding and complementary impacts on the Australian reptile fauna.

Implications: Enhanced and integrated management of the two introduced predators is likely to provide substantial conservation benefits to much of the Australian reptile fauna.

Stobo-Wilson AM, Murphy BP, Legge SM, Chapple DG, Crawford HM, Dawson SJ, Dickman CR, Doherty TS, Fleming PA, Gentle M, Newsome TM, Palmer R, Rees MW, Ritchie EG, Speed J, Stuart J-M, Thompson E, Turpin J, Woinarski JCZ (2021) Reptiles as food: predation of Australian reptiles by introduced red foxes compounds and complements predation by cats. Wildlife Research PDF DOI

The Conversation: Australia’s threatened species plan has failed on several counts. Without change, more extinctions are assured

By Euan Ritchie (Deakin University) and Ayesha Tulloch (University of Sydney).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia is globally renowned for its abysmal conservation record – in roughly 230 years we’ve overseen the extinction of more mammal species than any other nation. The federal government’s Threatened Species Strategy was meant to address this confronting situation.

The final report on the five-year strategy has just been published. In it, Threatened Species Commissioner Dr Sally Box acknowledges while the plan had some important wins, it fell short in several areas, writing:

…there is much more work to do to ensure our native plants and animals thrive into the future, and this will require an ongoing collective effort.

Clearly, Australia must urgently chart a course towards better environmental and biodiversity outcomes. That means reflecting honestly on our successes and failures so far.

How did the strategy perform?

The strategy, announced in 2015, set 13 targets linked to three focus areas:

  • feral cat management
  • improving the population trajectories of 20 mammal, 21 bird and 30 plant species
  • improving practices to recover threatened species populations.

Given the scale of the problem, five years was never enough time to turn things around. Indeed, as the chart below shows, the report card indicates five “red lights” (targets not met) and three “orange lights” (targets only partially met). It gave just five “green lights” for targets met.

Summary of the Threatened Species Strategy’s targets and outcomes. Department of Agriculture, Water and the Environment

Falling short on feral cats

Feral cats were arguably the most prominent focus of the strategy, despite other threats requiring as much or more attention, such as habitat destruction via land clearing.

However, the strategy did help start a national conversation about the damage cats wreak on wildlife and ecosystems, and how this can be better managed.

In the five years to the end of 2020, an estimated 1.5 million feral cats were killed under the strategy – 500,000 short of the 2 million goal. But this estimate is uncertain due to a lack of systematic data collection. In particular, the number of cats culled by farmers, amateur hunters and shooters is under-reported. And more broadly, information is scattered across local councils, non-government conservation agencies and other sources.

Australia’s feral cat population fluctuates according to rainfall, which determines the availability of prey – numbering between 2.1 million and 6.3 million. Limited investment in monitoring makes it impossible to know whether the average of 300,000 cats killed each year over the past five years will be enough for native wildlife to recover.

The government also failed in its goal to eradicate cats from five islands, only achieving this on Dirk Hartog Island off Western Australia. Importantly, that effort began in 2014, before the strategy was launched. And it was primarily funded by the WA government and an industry offset scheme, so the federal government can’t really claim this success.

On a positive note, ten mainland areas excluding feral cats have been established or are nearly complete. Such areas are a vital lifeline for some wildlife species and can enable native species reintroductions in the future.

Priority species: how did we do?

The strategy met its target of ensuring recovery actions were underway for at least 50 threatened plant species and 60 ecological communities. It also made good headway into storing all Australia’s 1,400 threatened plant species in seed banks. This is good news.

The bad news is that, even with recovery actions, the population trajectories of most priority species failed to improve. For the 24 out of about 70 priority species where population numbers were deemed to have “improved” over five years, about 30% simply got worse at a slower rate than in the decade prior. This can hardly be deemed a success.

What’s more, the populations of at least eight priority species, including the eastern barred bandicoot, eastern bettong, Gilbert’s potoroo, mala, woylie, numbat and helmeted honeyeater, were increasing before the strategy began – and five of these deteriorated under the strategy.

The finding that more priority species recovery efforts failed than succeeded means either:

  • the wrong actions were implemented
  • the right actions were implemented but insufficient effort and funding were dedicated to recovery
  • the trajectories of the species selected for action simply couldn’t be improved in a 5-year window.

All these problems are alarming but can be rectified. For example, the government’s new Threatened Species Strategy, released in May, contains a more evidence-based process for determining priority species.

For some species, it’s unclear whether success can be attributed to the strategy. Some species with improved trajectories, such as the helmeted honeyeater, would likely have improved regardless, thanks to many years of community and other organisation’s conservation efforts before the strategy began.

What must change

According to the report, habitat loss is a key threat to more than half the 71 priority species in the strategy. But the strategy does not directly address habitat loss or climate change, saying other government policies are addressing those threats.

We believe habitat loss and climate change must be addressed immediately.

Of the priority bird species threatened by land clearing and fragmentation, the trajectory of most – including the swift parrot and malleefowl – did not improve under the five years of the strategy. For several, such as the Australasian bittern and regent honeyeater, the trajectory worsened.

Preventing and reversing habitat loss will take years of dedicated restoration, stronger legislation and enforcement. It also requires community engagement, because much threatened species habitat is on private properties.

Effective conservation also requires raising public awareness of the dire predicament of Australia’s 1,900-plus threatened species and ecological communities. But successive governments have sought to sugarcoat our failings over many decades.

Bushfires and other extreme events hampered the strategy’s recovery efforts. But climate change means such events are likely to worsen. The risks of failure should form part of conservation planning – and of course, Australia requires an effective plan for emissions reduction.

The strategy helped increase awareness of the plight our unique species face. Dedicated community groups had already spent years volunteering to monitor and recover populations, and the strategy helped fund some of these actions.

However, proper investment in conservation – such as actions to reduce threats, and establish and maintain protected areas – is urgently needed. The strategy is merely one step on the long and challenging road to conserving Australia’s precious species and ecosystems.
The Conversation

The Conversation: Australia’s threatened species plan sends in the ambulances but ignores glaring dangers

By Euan Ritchie (Deakin University), Ayesha Tulloch (University of Sydney) and Don Driscoll (Deakin University).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Australia is unquestionably in the midst of an extinction crisis. Some 34 native mammal species have been driven to extinction since European invasion, and threatened species and ecological communities now number more than 1,900.

On Friday, federal environment minister Sussan Ley released Australia’s second Threatened Species Strategy – a roadmap for combating threats to native plants, animals and ecological communities.

The ten-year plan builds on the first strategy launched in 2015, and contains welcome changes. But there remain serious questions about how the plan will be funded and implemented – and quite possibly undermined by other federal government policies.

In essence, the strategy sends a few extra ambulances to the bottom of the cliff, rather than installing a fence at the top to stop species tumbling over.

First, the good news

It would be useful when assessing the new strategy to know how the previous one measured up. Unfortunately, federal environment officials have not yet released the last report card for that strategy, which makes it hard to identify what worked and what didn’t.

Nonetheless, the second strategy differs from the first in important ways.

The first strategy was criticised for its heavy focus on feral cats. Other problems which are just as (and often more) threatening to vulnerable species were not given the same attention. These include altered fire regimes, land clearing and other invasive species such as weeds and rabbits. Importantly, the new strategy recognises a greater number of key threats to wildlife and their habitats.

It also expands the number of actions for threatened species recovery from four to eight. Such actions may include tackling weeds and diseases, relocating species and identifying climate refuges.

The first strategy was rightly questioned for a somewhat myopic focus on 20 mammal, 20 bird and 30 plant species. It also lacked a transparent and evidence-based process for determining how a species was selected as a priority.

The new strategy could expand the types of species targeted for conservation to include fish, amphibian, reptile and invertebrate species. Also, the process for prioritising species for action promises to be more rigorous – assessed against six principles supported by science and existing conservation frameworks.

Significantly, priority places in need of conservation will likewise be assessed through a formal process. This is welcome if it ultimately protects habitats and broader ecosystems, an essential element of avoiding species extinctions.

But challenges remain

The strategy talks of improving species trajectories, but it’s unclear what would constitute success in this regard.

If a threatened species’ population numbers were declining at a slower rate due to an intervention, would that intervention be deemed a success? Will successful actions be attributed to the strategy (and, by association, the federal government), even if they were entirely funded by philanthropic or community efforts?

Scientists have gone to great lengths to improve our knowledge about trends in threatened bird, mammal and plant species for which monitoring programs exist. However data for threatened species remains deficient, due to funding cuts for monitoring and associated infrastructure.

This means measuring progress on the strategy will be difficult, because we simply don’t have enough reliable data. And the strategy does not appear to remedy this situation with funding.

The strategy makes references to six important principles to guide decisions on which species are to be prioritised for assistance. These include how close a species is to extinction, a species’ ‘uniqueness’, the likelihood an intervention will work and whether the species is culturally significant. But these principles should not be applied in isolation from each other.

For example, it may be more cost efficient to save species with both a high chance of extinction and relatively cheap and effective interventions. But the most unique species may not be the cheapest to save, and the most endangered species may not be the species of greatest importance to one sector of the community.

So prioritisation may require trade-offs between different principles. There is no magic “one size fits all” solution, but excellent scientific guidance exists on how to keep this process objective, transparent and, most of all, repeatable.

The strategy acknowledges major drivers of biodiversity decline and extinction, including climate change, habitat destruction and pollution. However, nowhere is there an explicit declaration that to conserve or recover our species and environments we must tackle the underlying causes of these drivers.

The strategy also fails to acknowledge the key role legislation plays in reining in – or enabling – threats such as land clearing. An independent review earlier this year confirmed federal environment laws are failing abysmally. But fundamental recommendations stemming from the review, such as independent oversight and adequate resourcing, are not included in the strategy.

A better deal for nature

To be effective, the strategy must chart a path to effective environmental law reform.

And saving our threatened species and ecosystems shouldn’t be seen as a cost, but rather a savvy investment.

Increased and targeted funding for on-ground actions, such as weed and pest animal control, species re-introductions, and Indigenous ranger programs, could generate many thousands of jobs. Such measures would also boost local economies and support industries such as tourism.

A 2019 study found Australia’s listed threatened species could be recovered for about A$1.7 billion a year.

The Morrison government recently announced it would spend A$7 billion setting up a military space division to better protect satellites from attack.

What’s our best defence for an uncertain future? We argue it’s ensuring Earth’s life support systems, including its remarkable species and landscapes, are also protected.
The Conversation

Diet of the introduced red fox Vulpes vulpes in Australia: analysis of temporal and spatial patterns

Authors: Patricia A Fleming, Heather M Crawford, Alyson M Stobo-Wilson, Stuart J Dawson, Christopher R Dickman, Shannon J Dundas, Matthew N Gentle, Thomas M Newsome, Julie O’Connor, Russell Palmer, Joanna Riley, Euan G Ritchie, James Speed, Glen Saunders, John-Michael D Stuart, Eilysh Thompson, Je! M Turpin, John C Z Woinarski

Published in: Mammal Review

The red fox Vulpes vulpes is one of the world’s most widespread carnivores. A key to its success has been its broad, opportunistic diet. The fox was introduced to Australia about 150 years ago, and within 30 years of its introduction was already recognised as a threat to livestock and native wildlife.

We reviewed 85 fox diet studies (totalling 31693 samples) from throughout the species’ geographic range within Australia. Mammals were a major component of fox diet, being present in 70 ± 19% of samples across n = 160 locations. Invertebrates (38 ± 26% n = 130) and plant material (26 ± 25% n = 123) were also both staple foods and often the dominant food category recorded. Birds (13 ± 11% n = 137) and reptiles (10 ± 15% n = 132) were also commonly reported, while frogs were scarcely represented (1.6 ± 3.6% n = 111) in fox diet studies.

Biogeographical differences reveal factors that likely determine prey availability. Diet composition varied with ecosystem, level of vegetation clearing and condition, and climate zone.

Sample type (i.e. stomach versus scat samples) also significantly influenced reporting of diet composition. Livestock and frogs were underrepresented in records based on analysis of scats, whereas small mammals (native rodents, dasyurid marsupials, and bats) were more likely to be recorded in studies of scats than in studies of stomach contents.

Diet varied seasonally, reflecting activity patterns of prey species and food availability. This synthesis also captures temporal shifts in fox diet over 70 years (1951–2020), as foxes have switched to consuming more native species in the wake of successful broadscale biological control of the invasive European rabbit Oryctolagus cuniculus.

Diet analyses, such as those summarised in this review, capture the evidence required to motivate for greater control of foxes in Australia. This synthesis also highlights the importance of integrated pest species management to meet biodiversity conservation outcomes.

Fleming PA, Crawford HM, Stobo‐Wilson AM, Dawson SJ, Dickman CR, Dundas SJ, Gentle MN, Newsome TM, O’Connor J, Palmer R, Riley J, Ritchie EG, Speed J, Saunders G, Stuart JD, Thompson E, Turpin JM, Woinarski JCZ (2021) Diet of the introduced red fox Vulpes vulpes in Australia: analysis of temporal and spatial patterns. Mammal Review PDF DOI

Fire and its interactions with other drivers shape a distinctive, semi-arid ‘mallee’ ecosystem

Authors: Michael F Clarke, Luke T Kelly, Sarah C Avitabile, Joe Benshemesh, Kate E Callister, Don A Driscoll, Peter Ewin, Katherine Giljohann, Angie Haslem, Sally A Kenny, Steve Leonard, Euan G Ritchie, Dale G Nimmo, Natasha Schedvin, Kathryn Schneider, Simon J Watson, Martin Westbrooke, Matt White, Michael A Wouters, and Andrew F Bennett

Published in: Frontiers in Ecology and Evolution

Abstract

Fire shapes ecosystems globally, including semi-arid ecosystems. In Australia, semi-arid ‘mallee’ ecosystems occur primarily across the southern part of the continent, forming an interface between the arid interior and temperate south. Mallee vegetation is characterized by short, multi-stemmed eucalypts that grow from a basal lignotuber. Fire shapes the structure and functioning of mallee ecosystems.

Using the Murray Mallee region in south-eastern Australia as a case study, we examine the characteristics and role of fire, the consequences for biota, and the interaction of fire with other drivers.

Wildfires in mallee ecosystems typically are large (1000s ha), burn with high severity, commonly cause top-kill of eucalypts, and create coarse-grained mosaics at a regional scale. Wildfires can occur in late spring and summer in both dry and wet years. Recovery of plant and animal communities is predictable and slow, with regeneration of eucalypts and many habitat components extending over decades. Time since the last fire strongly influences the distribution and abundance of many species and the structure of plant and animal communities.

Animal species display a discrete set of generalized responses to time since fire. Systematic field studies and modeling are beginning to reveal how spatial variation in fire regimes (‘pyrodiversity’) at different scales shapes biodiversity. Pyrodiversity includes variation in the extent of post-fire habitats, the diversity of post-fire age-classes and their configuration.

At regional scales, a desirable mix of fire histories for biodiversity conservation includes a combination of early, mid and late post-fire age-classes, weighted toward later seral stages that provide critical habitat for threatened species. Biodiversity is also influenced by interactions between fire and other drivers, including land clearing, rainfall, herbivory and predation.

Extensive clearing for agriculture has altered the nature and impact of fire, and facilitated invasion by pest species that modify fuels, fire regimes and post-fire recovery.

Given the natural and anthropogenic drivers of fire and the consequences of their interactions, we highlight opportunities for conserving mallee ecosystems. These include learning from and fostering Indigenous knowledge of fire, implementing actions that consider synergies between fire and other processes, and strategic monitoring of fire, biodiversity and other drivers to guide place-based, adaptive management under climate change.

Clarke MF, Kelly LT, Avitabile SC, Benshemesh J, Callister KE, Driscoll DA, Ewin P, Giljohann K, Haslem A, Kenny SA, Leonard S, Ritchie EG, Nimmo DG, Schedvin N, Schneider K, Watson SJ, Westbrooke M, White M, Wouters MA, Bennett AF (2021) Fire and its interactions with other drivers shape a distinctive, semi-arid ‘mallee’ ecosystem, Frontiers in Ecology and Evolution PDF DOI

Assessing the benefits of integrated introduced predator management for recovery of native predators

Authors: Tim S Jessop, Ben Holmes, Arvel Sendjojo, Mary O Thorpe, and Euan G Ritchie

Published in: Restoration Ecology

Abstract

Increasingly threatened species and their habitats require multiple successful management actions to ensure persistence. Introduced predator exclusion and suppression programs are key conservation actions used to retain or restore Australian ecosystems. Nevertheless, few direct comparisons are made to ascertain the individual and combined efficacy of multiple introduced predator conservation actions to benefit biodiversity. When colocated, both management actions could generate additive conservation benefits that greatly assist the recovery or persistence of threatened native species.

Varanid lizards are key functional components in Australian predator guilds and could benefit, via ecological release, when introduced predator management actions are successful. Here we tested the effects of a colocated predator-exclusion fence and lethal fox baiting on varanid site occupancy in a semiarid protected area.

Varanid site occupancy was higher at sites inside (Ψ = 0.90 ± 0.26) compared to sites outside (Ψ = 0.61 ± 0.28) the introduced predator-proof fenced enclosure. There was only weak evidence of increased varanid site occupancy at fox baited sites (Ψ = 0.037 ± 0.024) compared to nonfox baited (Ψ = 0.00) sites.

Overall, colocated introduced predator management actions achieved some additive benefits via possible spillover fencing effects for native mesopredator populations. However, most potential benefits to varanid populations outside of the predator-proof fenced enclosure were absent due to unsuccessful lethal-baiting effects on fox populations. The predator-proof fenced enclosure nevertheless provides important habitat refugia for future source populations for reintroduction once adjacent protected areas become suitable.

Jessop TS, Holmes B, Sendjojo A, Thorpe MO, Ritchie EG (2021) Assessing the benefits of integrated introduced predator management for recovery of native predators. Restoration Ecology PDF DOI

A rocky heart in a spinifex sea: occurrence of an endangered marsupial predator is multiscale dependent in naturally fragmented landscapes

Authors: Harry A Moore, Damian R Michael, Euan G Ritchie, Judy A Dunlop, Leonie E Valentine, Richard J Hobbs, and Dale G Nimmo

Published in: Landscape Ecology

Abstract

Context

Research on the impacts of anthropogenic habitat fragmentation has dominated landscape ecology for decades, yet our understanding of what drives species’ distributions in naturally fragmented landscapes remains limited.

Objectives

We aimed to

  1. determine whether rocky patches embedded within a ‘matrix’ of fire prone grasslands act as naturally fragmented landscapes for an endangered marsupial predator, the northern quoll (Dasyurus hallucatus), and
  2. reveal the extent to which within-patch, patch, landscape variables, and matrix condition drive the occurrence of northern quolls.

Methods

We deployed remote sensing cameras for a total of 200 nights, at 230 sites spanning rocky and grassland habitats across 6000 km2 of the Pilbara bioregion of Western Australia. We examined the influence of within-patch, patch, landscape variables, and matrix condition on northern quolls using Generalised Linear Mixed Models.

Results

We found strong evidence that northern quoll habitat is naturally fragmented, observing higher occurrence and abundance of quolls in rocky patches than the surrounding grassland matrix. Within rocky patches, quolls were more likely to use patches with higher vegetation cover and den availability (within-patch), lower amounts of edge habitat relative to patch area (patch), and larger amounts of surrounding rocky habitat (landscape). When quolls entered the matrix, they tended to remain in areas with high vegetation cover, close to rocky patches.

Conclusions

Species occurrence in naturally fragmented landscapes is influenced by factors operating at multiple scales. Rocky habitats are naturally fragmented and vital to the conservation of a range of taxa around the world, including the northern quoll.

Moore HA, Michael DR, Ritchie EG, Dunlop JA, Valentine LE, Hobbs RJ, Nimmo DG (2021) A rocky heart in a spinifex sea: occurrence of an endangered marsupial predator is multiscale dependent in naturally fragmented landscapes. Landscape Ecology PDF DOI

The Conversation: ‘Existential threat to our survival’: see the 19 Australian ecosystems already collapsing

By Dana M Bergstrom (University of Wollongong), Euan Ritchie (Deakin University), Lesley Hughes (Macquarie University) and Michael Depledge (University of Exeter).

This article is republished from The Conversation under a Creative Commons license. Read the original article.

In 1992, 1,700 scientists warned that human beings and the natural world were “on a collision course”. Seventeen years later, scientists described planetary boundaries within which humans and other life could have a “safe space to operate”. These are environmental thresholds, such as the amount of carbon dioxide in the atmosphere and changes in land use.

Crossing such boundaries was considered a risk that would cause environmental changes so profound, they genuinely posed an existential threat to humanity.

This grave reality is what our major research paper, published today, confronts.

In what may be the most comprehensive evaluation of the environmental state of play in Australia, we show major and iconic ecosystems are collapsing across the continent and into Antarctica. These systems sustain life, and evidence of their demise shows we’re exceeding planetary boundaries.

We found 19 Australian ecosystems met our criteria to be classified as “collapsing”. This includes the arid interior, savannas and mangroves of northern Australia, the Great Barrier Reef, Shark Bay, southern Australia’s kelp and alpine ash forests, tundra on Macquarie Island, and moss beds in Antarctica.

We define collapse as the state where ecosystems have changed in a substantial, negative way from their original state – such as species or habitat loss, or reduced vegetation or coral cover – and are unlikely to recover.

The good and bad news

Ecosystems consist of living and non-living components, and their interactions. They work like a super-complex engine: when some components are removed or stop working, knock-on consequences can lead to system failure.

Our study is based on measured data and observations, not modelling or predictions for the future. Encouragingly, not all ecosystems we examined have collapsed across their entire range. We still have, for instance, some intact reefs on the Great Barrier Reef, especially in deeper waters. And northern Australia has some of the most intact and least-modified stretches of savanna woodlands on Earth.

Still, collapses are happening, including in regions critical for growing food. This includes the Murray-Darling Basin, which covers around 14% of Australia’s landmass. Its rivers and other freshwater systems support more than 30% of Australia’s food production.

The effects of floods, fires, heatwaves and storms do not stop at farm gates; they’re felt equally in agricultural areas and natural ecosystems. We shouldn’t forget how towns ran out of drinking water during the recent drought.

Drinking water is also at risk when ecosystems collapse in our water catchments. In Victoria, for example, the degradation of giant Mountain Ash forests greatly reduces the amount of water flowing through the Thompson catchment, threatening nearly five million people’s drinking water in Melbourne.

This is a dire wake-up call — not just a warning. Put bluntly, current changes across the continent, and their potential outcomes, pose an existential threat to our survival, and other life we share environments with.

In investigating patterns of collapse, we found most ecosystems experience multiple, concurrent pressures from both global climate change and regional human impacts (such as land clearing). Pressures are often additive and extreme.

Take the last 11 years in Western Australia as an example.

In the summer of 2010 and 2011, a heatwave spanning more than 300,000 square kilometres ravaged both marine and land ecosystems. The extreme heat devastated forests and woodlands, kelp forests, seagrass meadows and coral reefs. This catastrophe was followed by two cyclones.

A record-breaking, marine heatwave in late 2019 dealt a further blow. And another marine heatwave is predicted for this April.

These 19 ecosystems are collapsing: read about each

① Great Barrier Reef

The Great Barrier Reef is the world’s largest coral reef system, extending over 2,300 kilometres. It is home to over 5,000 species of mollusk, 1,500 species of fish, 400 species of coral and around 240 species of birds. It spreads over almost 4,000 individual reefs, 900 continental islands, 300 coral cays and 150 inshore mangrove islands.

In the last 30 years, climate change and many regional pressures have combined to cause ecosystem collapse across the reef, with shallower reefs worse off than deeper reefs. These pressures include five mass coral bleaching events since 1998, marine heatwaves, major tropical cyclones, freshwater floods from extreme high rainfall events, flood sediment and pollution, ocean acidification and crown of thorns starfish outbreaks.

Major feedback loops that compound the pressures are now establishing. From 1985–2017, the reef lost half of all coral cover due to five massive bleaching events, of which two were consecutive (2016, 2017). In 2017, 67% of corals died along a 700km stretch.

The reef provides around A$12 trillion of ecosystem services and over 64,000 jobs. The Australian and Queensland governments have committed billions into reef protection but there are significant challenges to overcome.

Pressures:

  • Temperature
  • Ocean acidification
  • Salinity change
  • Native species interactions
  • Heatwave
  • Flood
  • Storm
  • Habitat change/loss
  • Runoff / pollution
  • Other (dredging, fishing, boat strikes, ship fouling, tourism debris)
② Australian Tropical Savannas

Australia’s tropical savannas sweep across more than 1 million square kilometres of northern Australia, from the western Kimberley region, WA, to the eastern edge of Queensland’s tropical coast. Savanna woodlands and forests have mainly gum trees over an understory of tall grasses and very ancient, poor soils.

These savannas are currently the least altered and unpolluted in the world, but they’re changing fast because of agriculture, mining and the effects of poor management decisions of the past. Land clearing has removed vegetation permanently, reducing food availability for wildlife. Climate change is adding further pressures as rains increase in the wet season, and dry seasons are becoming hotter and last longer.

Add in cat predation, the presence of cane toads, livestock encroachment and increasing bush fire frequency, and it becomes clear why Kakadu National Park is now a hot spot for mammal extinction.

Of particular urgency is the impact of a weed called giant African Gamba grass. It grows up to 4 m in height and produces up to 74,000 seeds per square metre. This adds a huge fuel load for fires, which burn 12 times more intensely than native grass fires, with flames penetrating and killing tree canopy. Gamba grass fires are very expensive to fight, cause loss of livestock and agricultural assets, and diminish the financial viability of the low carbon farming initiative of “savanna burning”.

Damage to the savannas affects the cultural, spiritual and socioeconomic livelihoods of First Nations communities. Loss of ecosystem services, production and pastoral lands is around A$113 million per year.

Pressures:

  • Rainfall changes
  • Temperature
  • Increasing CO2
  • Storm
  • Fire
  • Habitat change/loss/ mining
  • Invasive species
  • Livestock impacts/ harvesting
  • Water extraction
  • Human-lit fire
③ Mangrove Forests, Gulf of Carpentaria

In late 2015, nearly 40 million mangrove trees, representing around one million tons of carbon, died along 1,000 kilometres of the Gulf of Carpentaria. They succumbed to multiple pressures, including extremely high temperatures (39°C for 18 days), prolonged drought conditions, along with feral pigs, scrub fires and invasive weeds.

But most significant was the additive effect of severe El Niño conditions, which effectively pushed the sea away from the coast. This led to a short-term, extreme drop in mean sea level of around 20 centimetres, taking seawater away from mangrove roots.

Two severe tropical cyclones and damaging floods have since hampered its recovery. Continued tidal rafting of dead trunks is curtailing the establishment of seedlings and damaging remaining trees. And the decomposition of dead roots is probably affecting nursery habitat for fish and crustaceans.

The damage is expected to have lasting repercussions on the local economy and livelihoods of the region. The Gulf of Carpentaria fishing industry is worth A$30 million per year. First Nation people and recreational fishers also use the area. Ecosystem services from mangroves are worth around A$250,000 per hectare per year.

Pressures:

  • Rainfall changes- drought
  • Temperature
  • Salinity change
  • Sea level change – extreme lows
  • Heatwave
  • Flood
  • Storm
  • Habitat change/loss – erosion
  • Invasive species
  • Livestock impacts
  • Water extraction
  • Runoff
  • Human-lit fire
  • Other
④ Wet Tropical Rainforest, North Queensland

The wet tropics of North Queensland span around 450 kilometres, with rainforest covering around 1.85 million hectares. The region contains extraordinary diversity, with more than 3,000 plant species and over 60 vertebrate species found nowhere else on Earth. Although tropical rainforests make up only 0.1% of Australia’s landmass, they’re also home to over 50% of its ferns, butterflies and birds, and over 20% of freshwater fish, mammals, orchids, frogs and reptiles.

It’s for this reason and others, such as the significant First Nations cultural values, that the wet tropics are a World Heritage Area.

But they experience a range of pressures, many of which compound each other. These include habitat fragmentation, fringe livestock grazing, increased urbanisation, more frequent and severe fires and invasive plants and animals. Climate change poses perhaps the greatest threat overall.

Many of the region’s plants and animals live in discrete elevation bands: a “Goldilocks” combination of the right habitat and microclimate. As air temperatures increase and extremes in weather worsen, species’ areas of suitable habitat shrink. Some species have already moved to higher elevations and/or experienced striking local population declines. For example, in November 2018, a heatwave killed one-third of all spectacled flying foxes. And two possum species have disappeared from habitat under an altitude of 600 metres.

There have been four major storms or cyclones in 13 years. One event brought up to 2 m of rain, and the storm surge (seawater) inundated coastal rainforest. In 2006, one cyclone killed 35% of the regional cassowary populations, and cars and dogs killed many more as the birds left the destroyed forest.

The wet tropics are visited by around 5 million tourists per year, contributing over A$400 million to the region’s economy. In 2015, the wet tropics were valued at over A$5 billion per year, due to ecosystem services such as carbon sequestration, biodiversity protection, and soil and water resources.

Pressures:

  • Climate change
  • Extreme weather and climatic events (heatwaves, floods, cyclones, extended dry seasons)
  • Species interactions (such as snake losing prey due to flooding)
  • Invasive plants and animals
  • Habitat fragmentation and destruction
  • Logging and land clearing
  • Altered fire regimes (more frequent and severe fires)
  • Erosion, sediment runoff and pollution
  • Overgrazing
  • Tourism
  • Urbanisation
  • Chytrid fungus
⑤ Western-central Arid Zones

The arid zone covers around 43% of Australia and is characterised by low lands, generally less than 300 metres in elevation, occasionally punctuated by a few big hills (higher than 1,000 metres). Vegetation ranges from woodlands, shrublands and grasslands to rangelands and desert dunes. There are isolated freshwater systems through the arid zone including waterholes and lakes, underground water, clay pans and springs fed by the Great Artesian Basin.

Widespread pastoral activities over the last 100 years have altered large areas of the arid zone from their pre-European states. Changes include major loss of habitats, reduction in small mammal populations, and livestock trampling of delicate biotic soil crusts (which maintain soil and dune stability and water infiltration).

There are more than 200 weed species. Some were planted for pasture, shade trees or to suppress dust, and dispersed by machinery, vehicles and floods. The most threatening is buffel grass. It has invaded extensive areas, wreaking havoc through degradation, habitat loss and biodiversity decline. Like Gamba grass in the north, in combination with extreme heatwaves, buffel grass has altered fire frequency and intensity. Hot fires now reach well into the tree canopy, killing the trees, as well as shrubs and native grasses.

Introduced feral animals include cattle, goats, camels, foxes, cats and pigs.

The arid zone rangelands are also economically important and contribute approximately A$4.4 billion per year to Australia’s economy through tourism, pastoralism and agriculture combined.

Pressures:

  • Rainfall changes
  • Temperature
  • Heat wave
  • Fire
  • Habitat change/loss
  • Invasive species
  • Livestock
  • Water extraction
⑥ Georgina Gidgee Woodlands, central Australia

Georgina gidgee is a keystone tree, a species that holds an ecosystem together, and dominates low open woodlands. It occurs naturally in small patches (up to 10 hectares) in the arid zone, growing mostly along watercourses and in clay depressions between spinifex grass dunes. Georgina gidgee woodlands are important hot spots for life, acting as refuges for native rodents, small marsupials, red kangaroos and bats. They provide permanent or temporary habitat for more than 80 bird species, and animals such as lizards and ants.

Georgina gidgee woodlands are heading for collapse due to a range of pressures including climate change, fire, overgrazing, wood collection, weeds, feral animals and changes in water flow. For example, harvesting for fence posts in the Brigalow Belt, Queensland, cleared 7.4 million ha of gidgee and associated ecosystems by 1998. What remains still suffers extensive loss through pastoral activities.

As mature trees are relatively long-lived (over 200 years), their recovery is slow. Without significant intervention, this ecosystem will turn into a desert.

The consequences of desertification include loss of shade for cattle, loss of water catchment surface for refilling the artesian basin, and loss of biodiversity and ecosystem function associated with their role in stabilising ancient dunes. Loss of vegetation also increases the number of giant, regional dust storms, which can travel all the way to the major cities in eastern Australia.

Pressures:

  • Rainfall changes
  • Temperature
  • Heat wave
  • Fire
  • Habitat change/loss
  • Invasive species
  • Livestock
  • Water extraction
  • Other
⑦ Ningaloo Reef, northern Western Australia

Ningaloo and adjacent reefs are within the World Heritage listed Ningaloo Coast, and comprise an ecosystem of immense biodiversity, and national and international ecological importance. It’s home to megafauna such as migrating whale sharks and whales, turtles, corals, and economically important habitat for fisheries.

The ecosystem is threatened by rising ocean temperatures, ocean acidification, and increasingly intense and severe weather events such as marine heatwaves and tropical cyclones. Coral bleaching events have been recorded from 1990 to 2019, causing substantial reef-wide death (such as around 80% loss of coral cover of Bundegi Reef).

Fish numbers have also decreased, especially in recreational fishing areas. Pressures from human use and water quality exacerbates these changes. And crown-of-thorns starfish and carnivorous snails hamper their recovery from bleaching.

The impacts of these combined global and local pressures are felt in tourism and commercial fisheries, which are worth around A$1.5 billion per year for the region.

Pressures:

  • Temperature
  • Ocean acidification
  • Sea level change
  • Heat wave
  • Storm
  • Habitat change/loss
  • Livestock harvesting
  • Water extraction
  • Runoff / pollution
⑧ Shark Bay Seagrass Communities, Western Australia

Shark Bay, a World Heritage Area, is the home to one of world’s largest (4,300 square kilometres) and most diverse seagrass meadows. It’s a carbon storage hotspot, holding 350 million tons of carbon.

It supports an extensive food web, and diverse fauna including tiger sharks, and around 10% of the world’s dugongs, manta rays, dolphins, and green and loggerhead turtles. Southern right and humpback whales also use Shark Bay as a migratory staging post.

Over a background of chronic increases in seawater temperatures, Shark Bay experienced an unprecedented marine heatwave in the summer of 2010-11, lasting more than 10 weeks. Meanwhile, flooding from a tropical storm over the Gascoyne River catchment covered the bottom of the bay in up to 10 centimetres of mud. About a quarter of all sea grasses died, with limited recovery since.

This saw major decreases in dugongs (68% decrease), sea snakes (77% decrease). Populations of bottlenose dolphins, pied cormorants and green sea turtles decreased by 35–40%. Another marine heatwave hit in December 2019, and another is predicted for March 2021

The failure of major seagrass recovery has led to the release of millions of tons of carbon dioxide as organic sediments breakdown. The ecosystem collapse caused major disruption to the local commercial fishing industry, when the scallop and crab commercial fishery had to close for five years.

Pressures:

  • Temperature
  • Ocean acidification
  • Heat wave
  • Flood
  • Storm
  • Habitat change/loss
  • Livestock harvesting
  • Other
⑨ Murray Darling River Basin — waterways

The Murray-Darling Basin is Australia’s largest river system with 23 river valleys and over 77,000 kilometres of watercourses. The basin has more than 30,000 wetlands (400 wetlands are considered “high value” in Victoria alone) home to 46 species of native fish and 120 species of water birds. Some wetlands are recognised internationally as globally important.

The overall health of the river system is poor. Since European settlement, the river and tributaries have become highly regulated, with significant water diversion for agriculture and urban uses. These impacts have been exacerbated by increasing temperatures, declining average rainfall and severe droughts, further reducing water flows (by 40% since the mid-1990s).

Salinisation (saltier water), toxic algal blooms, hypoxia (low oxygen), introduced fish species, erosion, bushfire ash and nutrient runoff also contribute to declining water quality. Today, native fish populations are just 10% of pre-European numbers. Some 20 mass fish deaths, including of threatened species, have occurred since the 1960s.

The ecosystem is increasingly non-functional with decreasing freshwater biodiversity, and loss of ecosystem services and cultural values. The 2011 plan to improve the basin set a target to recover water for the environment, diverting it from irrigation. This was estimated to cost A$542 million annually, but the additional water has added A$3–8 billion worth of ecosystem services to the entire basin.

Despite the last drought ending, and rivers are flowing again, troubles are still emerging with recent reports of toxic algal blooms.

Pressures:

  • Rainfall changes
  • Temperature
  • Water level change
  • Heat wave
  • Flood
  • Fire
  • Habitat change/loss
  • Invasive species
  • Livestock/harvesting
  • Water extraction
  • Runoff/pollution
  • Other
⑩ Murray-Darling River Basin — riverine

The Murray Darling Basin covers around 14% of Australia’s land area, comprising low-lying undulating areas, extensive plains and parts of the Great Dividing Range. The basin is Australia’s most important water catchment – forests and wetlands cover over 100 million hectares of floodplains and adjacent riverbank areas. The mighty river red gum is key to the health of these ecosystems that depend on frequent flooding (once every three years) for growth and reproduction.Floodplain and riparian vegetation provide corridors and habitat for millions of animals, including water birds and 46 species of native fish. More than 2 million people live in the basin, and it’s home to 46 First Nations who care for at least 10,000 culturally significant places.

Over the last 200 years, humans have altered much of the basin, including the construction of weirs, irrigation channels, farm dams and municipal water reservoirs. All these changes affect the region’s water, and have significantly deteriorated riparian (bank-side) systems and populations of dependent species such as waterbirds.

Around 40% of the highly diverse ecosystems have been cleared or otherwise modified for logging and agricultural use. In 2008, an investigation of 1,600km of river estimated only 30% of the remaining river red gums were in good condition. Extraction of water for agriculture, including 1.8 million megalitres of groundwater, has increased soil salinity. The region is experiencing chronically raising temperatures, ongoing reductions in rainfall and increasingly long and severe droughts (2003–2009, 2017–2019).

Despite some restoration efforts, ecological collapse of riverine ecosystems continues. As tree deaths are becoming more widespread, forest canopy cover is reducing. Rivers flows and groundwater levels are decreasing, contributing to loss and degradation of habitat. Populations of birds, mammals and fish are shrinking. All these changes have flow-on impacts.

The basin is Australia’s main food bowl; 40% of food worth A$22 billion is produced annually. In addition, tourism contributes some A$8 billion each year. The droughts cut farm profits by 30%.

Pressures:

  • Rainfall changes
  • Temperature
  • Heat wave
  • Fire
  • Habitat change/loss
  • Invasive species
  • Livestock/harvesting
  • Water extraction
⑪ Montane and Sub-alpine Forests, South Australia, New South Wales and the Victorian highlands

Montane alpine ash and subalpine snowgum forests occupy the highest forested areas of the Australian Alps. Alpine ash are giants and can grow over 90 metres tall, although trees over 40m are rare across most of the alps today.

Intense fires kill both snowgums and alpine ash. Climate change is increasing the frequency of fire through droughts, longer snow-free periods, tree stress and dry lightning in storms. This is amplified by positive feedback, where regrowth after prescribed burns or bushfire is much more flammable than long-unburnt forest. From 2000 to 2019, 84% of the entire alpine ash forests in NSW and Victoria were burned, some areas up to three times. Now, 70% of alpine ash are immature trees and over 75% of snow gums are at their most flammable age.These forests are critical to the health of one of Australia’s most important water catchments. They also store large quantities of carbon, and surround high value utility and tourism infrastructure, such as Snowy Mountain power stations and ski resorts.

Increases in wildfire amplified by positive feedbacks place a heavy economic burden on these, as well as a health and safety impact on surrounding human populations.

Pressures:

  • Rainfall changes
  • Temperature
  • Heatwave
  • Storm
  • Fire
  • Habitat change/loss
  • Invasive species
  • Livestock / harvesting
  • Human-lit fire
⑫ Great Southern Reef Kelp Forests, southern Australia

The Great Southern Reef extends along 8,100 kilometres of coast, covering 71,000 square kilometres from Brisbane, around the south coast of Australia and Tasmania, to well north of Perth. It comprises a large number of rocky temperate reefs that support lush kelp forests, dominated by golden kelp and, in colder areas, giant kelp. Kelp supports high levels of biodiversity including other seaweeds, sponges, crustaceans, starfish, abalone, fish and rock-lobsters.

Different combinations of pressures cause kelp forest to degrade and collapse. These include coastal development, pollution, marine heatwaves, ocean acidification, and increased storm severity and frequency. For example, along 100 km of coastline reefs from Perth to Kalbarri, WA, most kelp forests have been lost and replaced with algal turfs. Giant kelp forests are now endangered.

The East Australian Current (thrust into popular culture via the film Finding Nemo) is frequently penetrating southward to Tasmania. This transports warm, nutrient- depleted waters, larvae of a NSW sea urchin and northern species of fish. The sea urchins severely damage the kelp forests, as does overfishing of large lobsters.

On conservatively estimates, the Great Southern Reef kelp forests generate at least A$10 billion per year in economic activity. Economic and social consequences of its decline include the collapse of the rock lobster, abalone and other fisheries, as well as impacts on Indigenous communities and decreases in tourism.

Pressures:

  • Temperature
  • Ocean acidification
  • Native species interactions
  • Heat waves
  • Storms
  • Habitat change/loss
  • Harvesting
  • Runoff/pollution
  • Other
⑬ Mediterranean-type Forests and Woodlands

Forests and woodlands in south-west WA extend over 10,000 square kilometres. They include the northern jarrah forest, tuart forest and woodlands, and banksia woodlands. The woodlands experience a Mediterranean-type climate, with cool, wet winters and dry, hot summers.

Vulnerable parts of these forest ecosystems experienced substantial die-off during an acute drought associated with an extreme heat wave in 2010-2011. But warming and drying of the region has been chronic since the mid-1970s. Impact was locally severe with, for example, up to 60% of Menzies banksia dying in woodlands on the Swan Coastal Plains.

Die-off sites illustrate what can happen when these forests and woodlands don’t have enough water. If die-off occurs at larger scales, forest resources and ecosystem services (such as carbon storage and seed resources) are threatened. Increased fire is also a risk, with associated damage to property and widespread pollution from bushfire smoke, as was recently experienced invFebruary 2021.

Pressures:

  • Rainfall changes
  • Temperature
  • Native species interactions
  • Heatwave
  • Storm
  • Fire
  • Habitat change/loss
⑭ Monaro Tablelands, South Eastern Highlands

The Monaro tablelands of south-east NSW are characterised by mosaics of grassy woodlands, grasslands and forests. These provide important habitat for a range of threatened plants and animal species, including koalas, spotted-tail quolls and dusky wood swallows, as well as 15 other smaller marsupial species, 95 bird species, 14 species of reptiles and more.

Like most other temperate grasslands and grassy woodlands in Australia, the Monaro ecosystems have declined since Indigenous burning regimes were replaced with livestock and feral herbivore grazing, along with clearing, cultivation and non-native plant invasions.

Tragically, since 2005, ribbon gums that once dominated the rolling plains have died in great numbers. This is likely associated with the Millennium drought, ongoing drying conditions and heatwaves, and exacerbated by invertebrate pest outbreaks. More recently, the catastrophic Black Summer bushfires burned extensive areas across the Monaro.

Widespread tree deaths are not only a loss of habitat for mammals, birds, reptiles and invertebrates, but significantly impact the economy through lack of shelter for livestock during the Monaro’s harsh winters and hot summers. The impacts on the landscape’s aesthetic also affects human well-being.

Pressures:

  • Rainfall changes
  • Temperature
  • Native species interactions
  • Heatwave
  • Fire
  • Habitat change/loss
  • Invasive species
  • Livestock/harvesting
⑮ Snowpatch Herbfields, Australian Alps

The snowpatch herbfields, made up of dwarf grasses and alpine herbs, are one of the rarest and most restricted ecosystems in Australia. They occur only on steep, south-east-facing slopes of alpine and high treeless subalpine zones, where snow persists into the spring and summer growing seasons.

Over the past 50 years, climate change has caused warming of almost 1°C, and substantial decrease in snow amount and depth, cover and persistence in the Australian alpine area. Fire has also become a major force with increased frequency, dry lightning storms and extreme fire weather. And feral horses trample vegetation and cause soil erosion. These pressures, and others, are collapsing the snow patch herbfield, replacing them with larger shrubs and grasses or just eroded ground.

The collapse of the snow patch herbfields highlights the plight of the Australian alpine ecosystems in general. The alps are regional economic powerhouses; visitors to the Australian Alps generate over A$1.3 billion and the area employs almost 20,000 people.

Pressures:

  • Rainfall changes
  • Temperature
  • Storm
  • Fire
  • Habitat change/loss
  • Invasive species
  • Human-lit fire
⑯ Mountain Ash Forests, Victorian Central Highlands

The mountain ash ecosystem in the Central Highlands of Victoria supports the world’s tallest flowering plants. It’s among the world’s most carbon-dense forests, supporting an array of threatened forest-dependent species, and generating almost all of the water for the 5 million inhabitants of Melbourne (as well as communities and agriculturalists north of the Great Divide).

The mountain ash ecosystem is under enormous environmental pressure from widespread and recurrent wildfire, coupled with widespread clear-cut logging. Extensive old growth forests once dominated the ecosystem, but now just 1.16% of the ecosystem (1,886 hectares of 170,400 ha) is old growth. The widespread young forest is highly flammable and at extreme risk of reburning at high severity. This is especially due to increased temperatures and greater numbers of days marked as “extreme” on the forest fire danger index.

The collapse will have severe economic and social effects. The value of water from the ecosystem is 25.5 times greater than the value of the timber generated from the same ecosystem. The collapse of the ecosystem also poses an enormous threat for long-term carbon storage, biodiversity conservation and the billion-dollar tourism industry in regional Victoria.

Pressures:

  • Rainfall changes
  • Temperature
  • Fire
  • Habitat change/loss
  • Invasive species
  • Other
⑰ Gondwanan Conifer forests, Tasmania

The Tasmanian Wilderness World Heritage Area covers 15,800 square kilometres. One of its key values is the high concentration of ancient invertebrate animals and plants endemic to Tasmania (often called “palaeoendemics”). An iconic example is the genus Athrotaxis in the conifer family, which is considered one of the oldest surviving plant lineages on Earth — a living fossil.

There are two existing species of Athrotaxis: Pencil pines (Athrotaxis cupressoides) and king billy pines (Athrotaxi selaginoides). Both are very slow growing and can live for more than 1,000 years.

Like other palaeoendemics, Athrotaxis species can’t tolerate frequent or intense fire, and are restricted to fireproof landscapes. Around 30% of the range of king billy pines have been lost in the last 200 years, and half the pencil pines were burnt in the summer of 1960/61 by uncontrolled fires set by graziers to renew grasslands during an intense drought.

Climate change now threatens these and other palaeoendemic species through increased fire activity due to more dry lightning storms and drought. In January 2016, lightning storms ignited numerous fires that destroyed about 1% of the remaining pencil pines. These trees are unlikely to ever return. The loss of palaeo-endemics will profoundly diminish the region’s natural and cultural values.

Securing the survival of palaeoendemics under climate change requires costly management interventions. These include establishing fire breaks, targeted planned burning to reduce fuel surrounding the palaeoendemic refuges and active restoration programs. The Tasmanian Government and the University of Tasmania currently trial these measures.

Pressures:

  • Rainfall changes
  • Temperature
  • Storm
  • Fire
  • Habitat change/loss
  • Invasive species
⑱ Subantarctic Tundra, Macquarie Island

The World Heritage sub-Antarctic Macquarie Island is home to unique alpine tundra. Cushion plants and bryophytes (such as mosses) dominate this treeless ecosystem. This uninhabited island ecosystem is one of the rarest on the planet, occurring on only eight other oceanic, sub-Antarctic islands. It’s home to many invertebrate species, and is the breeding ground of thousands of seabirds and marine mammals.

The ecosystem is rapidly collapsing due to mass die-off of cushion plants. Wind, rain and regional climate patterns all have changed in recent years, due to greenhouse gas increases and loss of ozone. There have also been increases in average wind speed, sunshine hours, and “evapotranspiration” (the sum of evaporation from the land surface plus transpiration from plants). Winter rainfall, cyclones, and a drier atmosphere also appear to have increased.

This has resulted in surface drying and raised surface evaporation of cushions and byrophytes in summer, leading to their death. With plants under such stress, an unknown disease has emerged that has now devastated much of this fragile ecosystem. And this has led to the ecosystem losing World Heritage values.

Pressures:

  • Rainfall changes
  • Temperature
  • Native species interactions
  • Flood
  • Storm
  • Other
⑲ East Antarctica Moss Beds, Windmill Islands (66°S), Vestfold Hills (68°S)

Antarctic vegetation is limited to the small ice-free areas covering less than 0.4% of the continent. Algae, cyanobacterial mats (dense “mats” of microbes), lichens and mosses dominate the flora, and there are no flowering plants. Moss beds only occur in areas where enough moisture is available during the short summer growing season. Some of the most extensive and well-developed vegetation in continental Antarctica support century old moss “forests” near Australia’s Casey Station. These lush, green moss turfs support the majority of invertebrates in the ecosystem.From 2000 to 2013, the species composition in these Antarctic moss beds changed significantly. Moss species that can tolerate drier conditions expanded, while endemic moss, better adapted to frequent pulses of water from melted ice, declined. By 2008, half the mosses that had been green and healthy in 2003 suffered water stress, turning red or grey under drying conditions.This drying is likely due to a combination of climate change and ozone thinning,making it windier and lowering temperatures around coastal East Antarctica in summer. This makes water less available during the growing season, and less water means less moss growth.

Historically, human activity associated with research stations has reduced local moss populations, but drying appears to be more widespread than just in the Casey region. Recovery has been limited, and in the summer of 2019-20, an Antarctic heatwave melted nearby snow banks and glaciers, causing flooding. Some grey mosses greened within a month. However, others that didn’t receive floodwater remained grey, stressed or dead.

Pressures:

  • Rainfall changes
  • Native species interactions
  • Heatwave
  • Storm
  • Habitat change/loss
  • Water extraction
  • Other

What to do about it?

Our brains trust comprises 38 experts from 21 universities, CSIRO and the federal Department of Agriculture Water and Environment. Beyond quantifying and reporting more doom and gloom, we asked the question: what can be done?

We devised a simple but tractable scheme called the 3As:

  • Awareness of what is important
  • Anticipation of what is coming down the line
  • Action to stop the pressures or deal with impacts.

In our paper, we identify positive actions to help protect or restore ecosystems. Many are already happening. In some cases, ecosystems might be better left to recover by themselves, such as coral after a cyclone.

In other cases, active human intervention will be required – for example, placing artificial nesting boxes for Carnaby’s black cockatoos in areas where old trees have been removed.

“Future-ready” actions are also vital. This includes reinstating cultural burning practices, which have multiple values and benefits for Aboriginal communities and can help minimise the risk and strength of bushfires.

It might also include replanting banks along the Murray River with species better suited to warmer conditions.

Some actions may be small and localised, but have substantial positive benefits.

For example, billions of migrating Bogong moths, the main summer food for critically endangered mountain pygmy possums, have not arrived in their typical numbers in Australian alpine regions in recent years. This was further exacerbated by the 2019-20 fires. Brilliantly, Zoos Victoria anticipated this pressure and developed supplementary food — Bogong bikkies.

Other more challenging, global or large-scale actions must address the root cause of environmental threats, such as human population growth and per-capita consumption of environmental resources.

We must rapidly reduce greenhouse gas emissions to net-zero, remove or suppress invasive species such as feral cats and buffel grass, and stop widespread land clearing and other forms of habitat destruction.

Our lives depend on it

The multiple ecosystem collapses we have documented in Australia are a harbinger for environments globally.

The simplicity of the 3As is to show people can do something positive, either at the local level of a landcare group, or at the level of government departments and conservation agencies.

Our lives and those of our children, as well as our economies, societies and cultures, depend on it.

We simply cannot afford any further delay.
The Conversation