Tag Archives: biodiversity

Invasive predators and global biodiversity loss

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

Published in: Proceedings of the National Academy of Sciences


Invasive species threaten biodiversity globally, and invasive mammalian predators are particularly damaging, having contributed to considerable species decline and extinction. We provide a global meta-analysis of these impacts and reveal their full extent.

Invasive predators are implicated in 87 bird, 45 mammal, and 10 reptile species extinctions — 58% of these groups’ contemporary extinctions worldwide. These figures are likely underestimated because 23 critically endangered species that we assessed are classed as “possibly extinct.”

Invasive mammalian predators endanger a further 596 species at risk of extinction, with cats, rodents, dogs, and pigs threatening the most species overall.

Species most at risk from predators have high evolutionary distinctiveness and inhabit insular environments. Invasive mammalian predators are therefore important drivers of irreversible loss of phylogenetic diversity worldwide.

That most impacted species are insular indicates that management of invasive predators on islands should be a global conservation priority. Understanding and mitigating the impact of invasive mammalian predators is essential for reducing the rate of global biodiversity loss.

Doherty TS, Glen AS, Nimmo DG, Ritchie EG, Dickman CR (2016) Invasive predators and global biodiversity loss. Proceedings of the National Academy of Sciences PDF DOI


The Conversation: Nature is neglected in this election campaign – at its and our own peril

By Don Driscoll and Euan Ritchie (Deakin University).

The electioneering has begun. In a campaign set to be dominated by economic issues, the Coalition and Labor are locking horns over who can best manage our finances, protect jobs and make housing more affordable. The Greens predictably decry the major parties, including their cavalier climate-change policies.

These are important issues, but are they highest priority on the political agenda? An arguably even greater issue exists that nobody is seriously championing, but which impacts all of us, socially, environmentally and economically.

Our natural heritage – the plants, animals and other organisms that help define Australia’s identity – are in dire straits. Yet this biodiversity crisis is barely mentioned in political discourse, nor is it foremost in the public consciousness.

Everlastings in the Australian Alps. But will they be? Image credit: John O'Neill via Wikimedia Commons

Everlastings in the Australian Alps. But will they be? Image credit: John O’Neill via Wikimedia Commons

The world economy is losing €50 billion (A$73 billion) a year through lost ecosystem services. It is predicted to lose €14 trillion per year by 2050 without action now. With potentially 7% of global economic product at stake by mid-century, nature conservation must surely be on the agenda in this election.

Actions needed to conserve our natural heritage, and reap substantial rewards, will challenge some of our most cherished ideas about social and economic policy. This demands reforms to reverse creeping losses to our democratic process.

Looking at the major parties’ platforms, it is clear that nature is not on the agenda. Labor lists 23 positive policies, none of which deals directly with conserving Australia’s plants and animals. The Liberal-National Party has done slightly better, claiming to believe in preserving Australia’s natural beauty and environment for future generations. However, its federal platform, released last year, shows no evidence of this belief.

Public concern has also shifted away from nature issues and towards other concerns like terrorism, as well as traditional areas of focus such as health care and the economy. This shift can be seen in some surprising places, such as the major grassroots lobby group GetUp – of its ten current campaigns only one, the Great Barrier Reef program, is directly about conserving wildlife diversity.

Environmental riches, but for how long?

The value of biodiversity to humans is well established (for example, see here, here, and here). Biodiversity reduces stress, crime and disease. It also provides new economic opportunities and many other benefits, from climate control, to flood defence, to the many benefits delivered by birds.

These are just the tip of the iceberg, but like the polar ice they are at risk of disappearing through our neglect.

Despite biodiversity’s immense value, Australia’s natural heritage is not assured. Good news stories exist,
but as a succession of government State of the Environment reports over recent decades has shown, our natural heritage continues to be squandered.

The reports cite population growth, economic growth and climate change as key drivers of decline. Land clearing and invasive species also lead to biodiversity loss. All must be addressed to reverse the alarming trajectory of our wildlife.

These threats to our natural heritage should be high on the political agenda. But despite recent extinctions, caused in no small part by a failure to act quickly on conservation advice, bureaucrats and politicians have failed to rise to the challenge. Australia’s plants, animals and other wildlife continue to be swept aside with an enthusiasm and abandon reminiscent of the 19th-century pioneers.

Why the lack of action?

Nature is missing in action from the political agenda for many reasons. Here are two key ones: questionable political donations and processes, and the gagging of the public service, government and university scientists. Both issues go to the heart of our democracy.

Australia has some of the weakest electoral laws concerning political donations and spending. Time lags between receiving donations and declaring them means that appropriate scrutiny of policy motivations, particularly at election times, is uncommon. This is concerning, because links between political favours for donors, while hard to prove, are frequently noted.

These correlations are not surprising. Corporate political activities are typically not gestures of goodwill, but a widely accepted corporate strategy aimed at securing better outcomes. Because many companies depend on using land for activities such as digging up resources and clearing native vegetation, the success of their political donations can often be reflected in damage to nature.

Equally concerning is the deafening silence from people who really know how damaging government policies can be for the environment. Inconvenient truths might challenge government policies. So public servants, including government scientists, are prohibited from speaking, or tweeting. Governments will go to extremes more often seen in the pages of crime thrillers to track down and punish whistle-blowers.

Governments attempting to silence academics hit the spotlight over cattle grazing trials in Victorian national parks. A senior Victorian public servant reportedly threatened to withdraw further funding from the University of Melbourne if the university did not agree to oversee the government’s grazing trial, despite the trial being widely regarded as flawed and unnecessary. Faced with this type of pressure, many university scientists simply avoid public debate for fear of damaging their job prospects or government funding.

In this climate of silence, major biodiversity issues and damaging government policies aren’t appropriately aired. The public don’t hear about it and so can’t make informed decisions at the polling booth. Consequently, government and public service barriers to honest media coverage undermine an informed democracy.

Valuing and preserving nature are critical for our well-being and prosperity, but species continue disappearing at alarming rates to causes we could better manage.

There are things that can be done, at a political level, to help stop this erosion of Australia’s natural heritage before it’s too late. In addition to adequately funding conservation, we should reform political funding rules. We should also encourage, even legally require, honest and open disclosure of how government policy impacts our environment.

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

The Conversation


Effects of the fire regime on mammal occurrence after wildfire: site effects vs landscape context in fire-prone forests

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

Published in: Forest Ecology and Management, volume 363 (March 2016)


Wildfires have major impacts on ecosystems globally. Fire regimes (including fire frequency, intensity, season and type of fire) influence the status of species by altering habitat suitability at the site scale, and by creating heterogeneity at the landscape scale.

The relative effects of site and landscape-scale fire attributes on animal species are rarely examined together. Such knowledge is important, given that fire regimes are sensitive to changing land management practices; and that fires are predicted to become larger and more frequent in some regions as a result of climate change.

Here, we tested the relative influence of elements of the fire regime (fire severity, fire history) at the site-scale, and the landscape context (extent of surrounding unburnt forest, fire heterogeneity) on the occurrence of native terrestrial mammals after severe wildfire in south-eastern Australia.

We conducted surveys by using automatically triggered, infrared cameras at 80 sites in fire-prone eucalypt forests, 2–3 years post-wildfire. Thirteen native mammal species were recorded, eight of which were detected with sufficient frequency for analysis.

Most species were widespread (35–90% of sites) and recorded in all fire severity classes. Fire effects at the site-level were more influential than landscape context effects arising from heterogeneity in the fire regime (e.g. extent of surrounding unburnt forest). Fire severity was the most influential of the fire-regime elements investigated, but it affected different species in different ways.

This study highlights three main points relevant to conservation of terrestrial mammals after wildfire. First, spatial variation in fire severity associated with wildfire (ranging from unburned to severely burned stands) is an important contributor to the post-fire status of species. Second, post-fire environmental conditions are significant: here, rapid regeneration of vegetation following drought-breaking rains greatly influenced the suitability of post-fire habitats. Third, it is valuable to consider the effects of the fire regime at multiple scales, including both the site (forest stand) and its landscape context.

Insights from short-term surveys, such as this, will be enhanced by complementary longitudinal studies, especially where they encompass environmental variation through the post-fire succession.

Chia EK, Bassett M, Leonard SWJ, Hollanda GJ, Ritchie EG , Clarke MF, Bennett AF (2016) Effects of the fire regime on mammal occurrence after wildfire: Site effects vs landscape context in fire-prone forests, Forest Ecology and Management PDF DOI

Fire severity and fire-induced landscape heterogeneity affect arboreal mammals in fire-prone forests

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

Published in: Ecoshere, volume 6, issue 10 (October 2015)


We examined the role of topography, fire history and fire sensitivity on the occurrence of arboreal mammals 2 to 3 years after wildfire in temperate Eucalypt forests. Image credit: Elizabeth Donoghue via Flickr.


In fire-prone regions, wildfire influences spatial and temporal patterns of landscape heterogeneity. The likely impacts of climate change on the frequency and intensity of wildfire highlights the importance of understanding how fire-induced heterogeneity may affect different components of the biota.

Here, we examine the influence of wildfire, as an agent of landscape heterogeneity, on the distribution of arboreal mammals in fire-prone forests in south-eastern Australia.

First, we used a stratified design to examine the role of topography, and the relative influence of fire severity and fire history, on the occurrence of arboreal mammals 2–3 years after wildfire. Second, we investigated the influence of landscape context on the occurrence of arboreal mammals at severely burnt sites. Forested gullies supported a higher abundance of arboreal mammals than slopes.

Fire severity was the strongest influence, with abundance lower at severely burnt than unburnt sites. The occurrence of mammals at severely burned sites was influenced by landscape context: abundance increased with increasing amount of unburnt and understorey-only burnt forest within a one kilometre radius.

These results support the hypothesis that unburnt forest and moist gullies can serve as refuges for fauna in the post-fire environment and assist recolonization of severely burned forest. They highlight the importance of spatial heterogeneity created by wildfire and the need to incorporate spatial aspects of fire regimes (e.g. creation and protection of refuges) for fire management in fire-prone landscapes.

Chia EK, Bassett M, Nimmo DG, Leonard SWJ, Ritchie EG, Clarke MF, Bennett AF (2015) Fire severity and fire-induced landscape heterogeneity affect arboreal mammals in fire-prone forests, Ecosphere, 6:10 PDF DOI

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

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


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

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

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

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

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

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

Science Network Western Australia: Thousands predicted to die along state barrier fence

The south-west of WA is a global biodiversity hotspot. The state barrier fence has had a questionable impact on controlling pest species and extending it would likely cause more harm than good.

Read more, including reader comments, on the Science Network Western Australia website.

Published: Continental-scale governance failure will hasten loss of Australia’s biodiversity

Authors: Euan G Ritchie, Corey JA Bradshaw, Chris R Dickman, Richard Hobbs, Christopher N Johnson, Emma L Johnston, William F Laurence, David Lindenmayer, Michael A McCarthy, Dale G Nimmo, Hugh H Possingham, Robert L Pressey, David M Watson and John Woinarski


Conserving biodiversity against a global backdrop of rapid environmental change poses one of the biggest and most important challenges to society. For this reason, systems of nature reserves have never been more important.

Protected areas are under threat in many parts of the world (Mascia and Pailler 2011), but the weakening of protected areas in a rich, developed country with a global reputation for conservation leadership (Harrison 2006) is particularly alarming (Ritchie 2013). Consequently, we are concerned about the recent spate of substantial policy, legislative and management changes being made by three of six Australian state governments for exploitative uses of national parks — actions that could affect much of Australia and have significant negative effects on biodiversity.

In recent decades, the Australian state and federal governments have collectively built a system of terrestrial and marine conservation reserves that aspires to be comprehensive and adequate, and to form the cornerstone of biodiversity conservation. The resulting national reserve system is imperfect, but goes some way toward protecting Australia’s unique species and ecosystems (Taylor et al. 2011). That system is now being systematically undermined, even while continental-scale biodiversity losses are underway.

Ritchie EG, Bradshaw CJA, Dickman CR, Hobbs R, Johnson CN, Johnston EL, Laurence WF, Lindenmayer D, McCarthy MA, Nimmo DG, Possingham HH, Pressey RL, Watson DM, Woinarski J (2013) Continental-scale governance failure will hasten loss of Australia’s biodiversity, Conservation Biology, 27(6) 1133–1135 PDF DOI