A recent survey on the world’s plants found a shocking number have gone extinct – 571 since 1750. And this is likely to be a stark underestimate. Not all plants have been discovered, so it’s likely other plants have gone extinct before researchers know they’re at risk, or even know they exist.
In Australia, the situation is just as dire. The Threatened Species Recovery Hub recently conducted two evaluations that aren’t yet published of extinct plants in Australia. They found 38 have been lost over the last 170 years, such as the Daintree River banana (Musa fitzalanii) and the fringed spider-orchid (Caladenia thysanochila).
But uncertainty about the number of plant extinctions, in addition to the 38 confirmed, is an ongoing concern.
Both studies pointed out the actual number of extinctions is likely to be far more than those recognised in formal lists produced by the Commonwealth and state and territory agencies.
For example, there is still a high rate of discovery of new plant species in Australia. More than 1,600 plants were discovered between 2009 and 2015, and an estimated 10% are still yet to be discovered.
The extinction of Australian plants is considered most likely to have occurred in areas where there has been major loss and degradation of native bushland. This includes significant areas in southern Australia that have been cleared for agriculture and intensive urbanisation around major cities.
Many of these extinct plants would have had very restricted geographic ranges. And botanical collections were limited across many parts of Australia before broad scale land clearing and habitat change.
Why extinction goes undocumented
There is already one well recognised Australian plant extinction, a shrub in Phillip Island (Streblorrhiza speciosa), which was never formally recognised on any Australian threatened species list.
Researchers also note there are Australian plants that are not listed as extinct, but have not been collected for 50 years or more.
While undocumented extinction is an increasing concern, the recent re-assessment of current lists of extinct plants has provided a more positive outcome.
The re-assessment found a number of plants previously considered to be extinct are not actually extinct. This includes plants that have been re-discovered since 1980, and where there has been confusion over plant names. Diel’s wattle (Acacia prismifolia), for instance, was recently rediscovered in Western Australia.
A significant challenge for accurately assessing plant extinction relates to the difficulties in surveying and detecting them in the Australian landscapes.
Many have histories associated with fire or some other disturbance. For example, a number of plants spend a significant part of their time as long-lived seeds – sometimes for decades – in the soil with nothing visible above ground, and with plants only appearing for a few years after a fire.
But by far, the greatest reason for the lack of information is the shortage of field surveys of the rare plants, and the availability of botanists and qualified biologists to survey suitable habitat and accurately identify the plants.
What we’ve learnt
The continuing decline of Australia’s threatened plants suggests more extinctions are likely. But there have been important achievements and lessons learnt in dealing with the main causes of loss of native vegetation.
Our understanding of plant extinction processes – such as habitat loss, habitat degradation, invasive weeds, urbanisation, disease and climate change – is improving. But there is still a significant way to go.
One challenge in dealing with the causes of Australian plant extinction is how to manage introduced diseases.
Two plant diseases in particular are of major concern: Phytophthora dieback, a soil-borne water mould pathogen, and Myrtle rust, which is spread naturally by wind and water.
Both diseases are increasingly recognised as threats, not only because of the impact they are already having on diverse native plant communities and many rare species, but also because of the difficulties in effective control.
Two Australian rainforest tree species Rhodomyrtus psidioides and Rhodamnia rubescens were recently listed as threatened under the NSW legislation because of myrtle rust.
While extinction associated with disease is often rapid, some individual plants may survive for decades in highly degraded landscapes, such as long-lived woody shrubs and trees. These plants will ultimately go extinct, and this is often difficult to communicate to the public.
While individual species will continue to persist for many years in highly disturbed and fragmented landscapes, there is little or no reproduction. And with their populations restricted to extremely small patches of bush, they’re vulnerable to ongoing degradation.
In many such cases there is an “extinction debt”, where it may take decades for extinction to occur, depending on the longevity of the plants involved.
But it’s not all doom and gloom. A recent study found of the 418 threatened Australian plants showing ongoing decline, 83% were assessed as having medium to high potential for bouncing back.
And with long-term investment and research there are good prospects of saving the majority of these plants.
You may have seen news in recent days of the suspected demise of the Victorian grassland earless dragon – now thought to be the first lizard species to be driven to extinction by humans in mainland Australia.
That suspicion arose on the basis of a newly published study in Royal Society Open Science by our research team, in which we discovered that the grassland earless dragons of southeastern Australia are not a single species, but four distinct ones: one that lives around Canberra, two in New South Wales, and one restricted to the Melbourne region.
The most recent confident sighting of the Melbourne species was 50 years ago, in 1969 – hence the fears that the Victorian species has already succumbed.
But despite this worrying news, we’re not leaving this lizard for dead just yet. Conservationists are now combing remaining grassland around Melbourne in a search for survivors.
Although no lizard species have previously been declared extinct on the Australian mainland, the grassland earless dragons (Tympanocryptis) of southeastern Australia have long been the subject of conservation concern. Even before being split into four separate species, they were already officially listed as endangered.
The Victorian grassland earless dragon (Tympanocryptis pinguicolla) is known only to occur in the native grasslands around Melbourne. A review of historical collections at Museums Victoria show that it was found at several locations including Sunbury, Maribyrnong River (then called “Saltwater River”), and as far west as the Geelong area until the late 1960s.
Although there is little information available about the ecology of this species, it was described by Lucas and Frost in 1894 as:
Inhabiting stony plains and retreating into small holes, like those of the ‘Trap-door Spider,’ in the ground when alarmed […] Often met with under loose basalt boulders.
The last confirmed sighting was near Geelong in July 1969.
First mainland extinction?
Globally, 31 reptiles have been listed as extinct or extinct in the wild, according to the IUCN Red List, the global authority on the status of species. Two skinks and one gecko species have been declared extinct in the wild on Christmas Island, a remote Australian territory in the Indian Ocean. But until now there have been no recorded reptile extinctions on the Australian mainland.
Yet it is too early to give up on the Australian grassland earless dragon. Zoos Victoria researchers have completed a mapping analysis of potential grassland habitats. But this doesn’t give us enough information to say whether or not any grassland earless dragons remain.
There are several factors that leave open the possibility that the Victorian grassland earless dragon is still clinging to survival. There are some remaining habitat areas that have not yet been surveyed, and this species is small, secretive and hard to find. We urgently need more surveys to try and find any remaining populations.
If these lizards are not yet extinct, their protection will clearly become an urgent conservation priority. But it is hard to develop a conservation program without knowing where the target species actually lives, or indeed whether it is still alive at all.
Zoos Victoria is now leading a campaign, alongside expert ecologists and local communities, to try and confirm the presence or absence of the Victorian grassland earless dragon. This involves various methods, including habitat mapping, camera trapping, and active searching. The team is also working to identify unsurveyed areas that might potentially be home to these elusive lizards.
Last year the team deployed a series of small pitfall traps at two locations in Little River. Unfortunately, no earless dragons were detected during the survey and few lizards of any species were caught, despite the fact that these locations seemed to offer appropriate food and habitat.
The team is not giving up yet and is committed to continuing the search, with Zoos Victoria researchers having identified sites with suitable habitat both within and outside of the historical distribution, which they aim to survey intensively over the coming years. Meanwhile, reptile keepers at Zoos Victoria are developing husbandry techniques to help look after the grassland earless dragon species from Canberra and NSW.
The conservation challenge has got harder, because where previously we were tasked with looking after one species, we now have to safeguard at least three – and hopefully four!
This article is based on a blog post that originally appeared here. It was coauthored by Adam Lee and Deon Gilbert of Zoos Victoria.
Don Driscoll, Deakin University; Desley Whisson, Deakin University; Euan Ritchie, Deakin University; Mike Weston, Deakin University; Raylene Cooke, Deakin University, and Tim Doherty, Deakin University
Addressing this crisis requires transformative change, including more effective environmental law and implementation.
Improved legislation is one of five main levers for realising change identified in the recent United Nation’s global biodiversity report and the key lesson arising from the Senate’s interim report into Australia’s faunal extinction crisis.
The Senate’s interim report, based on 420 submissions and five hearings, shows Australia is a world leader in causing species extinctions, in part because Australia’s systems for conserving our natural heritage are grossly inadequate.
To allow the continued erosion of this continent’s spectacular and remarkable array of globally unique plants and animals is a travesty of the highest order.
One of the problems is species may decline from common to extinct quite rapidly – faster than the time it takes species to be listed as threatened under the federal Environment Protection and Biodiversity Conservation (EPBC) Act.
The Christmas Island forest skink was formally listed as a threatened species only four months before the last individual died in captivity, but 15 years after the decline was first reported.
Extinction of the forest skink, Bramble Cay melomys and Christmas Island pipistrelle between 2009 and 2014 may have been averted if the risk was formally recognised in a more timely manner and effective conservation actions, such as captive breeding programs, were implemented.
Currently, if a species is not listed, it is not a “matter of national environmental significance” and federal agency staff generally have no legal basis for acting to protect it.
The black-throated finch has been listed as threatened on the EPBC Act for 14 years and during this time 600,000 ha of potential finch habitat has been destroyed. Worse still, five large coal mines, including the Carmichael Coal Mine, have been given approval (pending environmental conditions being met in Queensland) to clear more than 29,000 ha of black-throated finch habitat in one of its final strongholds, the Galilee Basin.
The controversial Toondah Harbour development in Brisbane is another example of how ministerial discretion can allow disastrous environmental outcomes. The project plans to build 3,600 apartments on wetlands that provide habitat for migratory waterbirds, including the critically endangered eastern curlew.
Despite being described as “clearly unacceptable” by the federal environment department and knocking it back twice, the minister allowed a third submission to proceed for further assessment.
It was reported this decision was made in the context of legal threats and donations from the developer in question. If true, this context would make it very difficult to make impartial decisions that protect biodiversity, as environmental law intends.
Increasing ministerial discretion was a key result of 2007 amendments to the EPBC act, which meant recovery plans were no longer required for threatened species.
The amendment allowed the minister to develop “conservation advices” instead of recovery plans. This amendment downgraded protections for threatened species because a minister can legally make decisions that are inconsistent with conservation advice, but not a recovery plan.
New environmental legislation
Based on these examples and many others that demonstrate the failings of current laws, the interim report concludes that we should rip up the EPBC act and develop stronger and more effective environmental legislation.
This includes establishing an independent Environmental Protection Agency to ensure enforcement of environmental laws, and, in a forward-looking addition by the Greens senators, an independent National Environmental Commission to monitor effectiveness of environmental legislation and propose improvements.
Australia needs a well-resourced, independent umpire for the environment, with powers to investigate environmental concerns and scrutinise government policy, akin to New Zealand’s Parliamentary Commissioner for the Environment. While Australia’s Threatened Species Commissioner is an excellent champion for the environment, this role provides no ability to question government actions regarding environmental protection and nature conservation.
Although replacing the EPBC act with new legislation may seem like a radical step to some (but not all), the interim Senate report, and the global UN report, have independently concluded major reform is essential. We are not in a moment of time when tweaking the current system will do the trick.
Changing Australia’s environmental legislation is a relatively minor update compared with the fundamental social and economic changes recommended by the UN report.
Such changes are already recommended by scientific societies like the Ecological Society of Australia, non-government organisations like Birdlife Australia and the Australian Conservation Foundation, and are demanded by a growing section of society. New, fit-for-purpose legislation must be enforceable, apolitical and responsive.
Opinion polls show that the level of environmental concern is higher in Australia than in other countries , while 29% of ABC Vote Compass respondents ranked the environment as the most important issue, up from 9% in 2016.
This groundswell of environmental concern has spawned mass protest movements like Extinction Rebellion. Young Australians also have shown their concern. In March 2019, thousands of school students took part in 50 rallies across the country to protest against “the destruction of our future”.
Decisions about what and how much we buy, what we eat, how much we travel and by what means, and family size, all contribute to our environmental footprints, and are the fundamental instigators of the biodiversity crisis.
However, we must also look to our political leaders to support effective change. The simplest and most powerful action you can take to reverse the extinction crisis is to vote for a party with policies best aligned with credible scientific advice on how we can get out of this mess.
Don Driscoll, Professor in Terrestrial Ecology, Deakin University; Desley Whisson, Lecturer in Wildlife and Conservation Biology, School of Life and Environmental Sciences, Deakin University; Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University; Mike Weston, Associate Professor, Deakin University; Raylene Cooke, Associate Professor, Deakin University, and Tim Doherty, Alfred Deakin Post-doctoral Research Fellow, Deakin University
This week many people across the world stopped and stared as extreme headlines announced that one eighth of the world’s species – more than a million – are threatened with extinction.
According to the UN report from the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES) which brought this situation to public attention, this startling number is a consequence of five direct causes: changes in land and sea use; direct exploitation of organisms; climate change; pollution; and invasion of alien species.
It’s the last, invasive species, that threatens Australian animals and plants more than any other single factor.
Australia’s number one threat
Australia has an estimated 600,000 species of flora and fauna. Of these, about 100 are known to have gone extinct in the last 200 years. Currently, more than 1,770 are listed as threatened or endangered.
While the IPBES report ranks invasive alien species as the fifth most significant cause of global decline, in Australia it is a very different story.
Australia has the highest rate of vertebrate mammal extinction in the world, and invasive species are our number one threat.
Cats and foxes have driven 22 native mammals to extinction across central Australia and a new wave of decline – largely from cats – is taking place across northern Australia. Research has estimated 270 more threatened and endangered vertebrates are being affected by invasive species.
Introduced vertebrates have also driven several bird species on Norfolk Island extinct.
The effects of invasive species are getting worse
Although Australia’s stringent biosecurity measures have dramatically slowed the number of new invasive species arriving, those already here have continued to spread and their cumulative effect is growing.
Recent research highlights that 1,257 of Australia’s threatened and endangered species are directly affected by 207 invasive plants, 57 animals and three pathogens.
These affect our unique biodiversity, as well as the clean water and oxygen we breath – not to mention our cultural values.
When it comes to biodiversity, Australia is globally quite distinct. More than 70% of our species (69% of mammals, 46% of birds and 93% of reptiles) are found nowhere else on earth. A loss to Australia is therefore a loss to the world.
Some of these are ancient species like the Wollemi Pine, may have inhabited Australia for up to 200 million years, well before the dinosaurs.
Wollemi pines are dinosaur trees
But invasive species are found in almost every part of Australia, from our rainforests, to our deserts, our farms, to our cities, our national parks and our rivers.
The cost to Australia
The cost of invasive species in Australia continue to grow with every new assessment.
The most recent estimates found the cost of controlling invasive species and economic losses to farmers in 2011-12 was A$13.6 billion. However this doesn’t include harm to biodiversity and the essential role native species play in our ecosystems, which – based on the conclusions of the IPBES report – is likely to cost at least as much, and probably far more.
Rabbits, goats and camels prevent native desert plant community regeneration; rabbits alone impacting over 100 threatened species. Rye grass on its own costs cereal farmers A$93M a year.
Aquaculture diseases have affected oysters and cost the prawn industry $43M.
From island to savannah
Globally, invasive species have a disproportionately higher effect on offshore islands – and in Australia we have more than 8,000 of these. One of the most notable cases is the case of the yellow crazy ants, which killed 15,000,000 red land crabs on Christmas Island.
Nor are our deserts immune. Most native vertebrate extinctions caused by cats have occurred in our dry inland deserts and savannas, while exotic buffel and gamba grass are creating permanent transformation through changing fire regimes.
Australia’s forests, particularly rainforests, are also under siege on a number of fronts. The battle continues to contain Miconia weed in Australia – the same weed responsible for taking over 70% of Tahiti’s native forests. Chytrid fungus, thought to be present in Australia since 1970, has caused the extinction of at least four frog species and dramatic decline of at least ten others in our sensitive rainforest ecosystems.
Myrtle rust is pushing already threatened native Australian Myrtaceae closer to extinction, notably Gossia gonoclada, and Rhodamnia angustifolia and changing species composition of rainforest understories, and Richmond birdwing butterfly numbers are under threat from an invasive flower known as the Dutchman’s pipe.
Australia’s rivers and lakes are also under increasing domination from invasive species. Some 90% of fish biomass in the Murray Darling Basin are European carp, and tilapia are invading many far north Queensland river systems pushing out native species .
Invasive alien species are not only a serious threat to biodiversity and the economy, but also to human health. The Aedes aegypti mosquito found in parts of Queensland is capable of spreading infectious disease such as dengue, zika, chikungunya and yellow fever.
And it’s not just Queensland that is under threat from diseases spread by invasive mosquitoes, with many researchers and authorities planning for when, not if, the disease carrying Aedes albopictus establishes itself in cooler and southern parts of Australia.
What solutions do we have?
Despite this grim inventory, it’s not all bad news. Australia actually has a long history of effectively managing invasive species.
Targeting viruses as options for controlling rabbits, carp and tilapia; we have successfully suppressed rabbit populations by 70% in this way for 50 years.
Weeds too are successful targets for weed biological control, with over a 65% success rate controlling more than 25 targets.
The IPBES report calls for “transformative action”. Here too Australia is at the forefront, looking into the potential of gene-technologies to suppress pet hates such as cane toads.
Past and current invasive species programs have been supported by governments and industry. This has provided the type of investment we need for long-term solutions and effective policies.
Australia is better placed now, with effective biosecurity policies and strong biosecurity investment, than many countries. We will continue the battle against invasive species to stem biodiversity and ecosystem loss.
Today the Australian Koala Foundation announced they believe “there are no more than 80,000 koalas in Australia”, making the species “functionally extinct”.
While this number is dramatically lower than the most recent academic estimates, there’s no doubt koala numbers in many places are in steep decline.
It’s hard to say exactly how many koalas are still remaining in Queensland, New South Wales, Victoria, South Australia and the Australian Capital Territory, but they are highly vulnerable to threats including deforestation, disease and the effects of climate change.
Once a koala population falls below a critical point it can no longer produce the next generation, leading to extinction.
What does ‘functionally extinct’ mean?
The term “functionally extinct” can describe a few perilous situations. In one case, it can refer to a species whose population has declined to the point where it can no longer play a significant role in their ecosystem. For example, it has been used to describe dingoes in places where they have become so reduced they have a negligible influence on the species they prey on.
Dingoes are top predators, and therefore can play a significant role in some ecosystems. Our innocuous, leaf-eating koala cannot be considered a top predator.
For millions of years koalas have been a key part of the health of our eucalyptus forests by eating upper leaves, and on the forest floor, their droppings contribute to important nutrient recycling. Their known fossil records date back approximately 30 million years so they may have once been a food source for megafauna carnivores.
Functionally extinct can also describe a population that is no longer viable. For example in Southport, Queensland, native oyster reef beds are functionally extinct because more than 99% of the habitat has been lost and there are no individuals left to reproduce.
Finally, functionally extinct can refer to a small population that, although still breeding, is suffering from inbreeding that can threaten its future viability. We know that at least some koala populations in urban areas are suffering in this way, and genetic studies on the Koala Coast, located 20kms south-east of Brisbane, show that the population is suffering from reduced genetic variation. In South East Queensland, koalas in some areas have experienced catastrophic declines
We also know that koala populations in some inland regions of Queensland and New South Wales are affected by climate extremes such as severe droughts and heatwaves and have declined by as much as 80%.
Exhaustive multi-disciplinary koala research continues apace in an effort to find ways of protecting wild koala populations and ensuring that they remain viable now and into the future. Habitat loss, population dynamics, genetics, disease, diet and climate change are some key areas being studied.
How many koalas are there?
Koala researchers are often asked “how many koalas are in the wild?” It’s a hard question to answer. Koalas are not stationary, are patchily distributed throughout an extremely wide range encompassing urban and rural areas in four states and one territory, and are usually difficult to see.
To determine whether each population of koalas scattered across eastern Australia is functionally extinct would require a gargantuan effort.
In 2016, in an attempt to determine population trends for the koala within the four states, a panel of 15 koala experts used a structured, four-step question format to estimate bioregional population sizes of koalas, and changes in those sizes.
The estimated percentage of koala population loss in Queensland, New South Wales, Victoria and South Australia was 53%, 26%, 14% and 3%, respectively. The estimated total number of koalas for Australia was 329,000 (within a range of 144,000–605,000), with an estimated average decline of 24% over the past three generations and the next three generations.
Since May 2012, koalas have been listed as vulnerable in Queensland, New South Wales and the Australian Capital Territory because populations in these regions have declined significantly or are at risk of doing so.
In the southern states of Victoria and South Australia, koala populations vary widely from abundant to low or locally extinct. Although not currently listed as vulnerable, these koalas are also experiencing a range of serious threats, including low genetic diversity.
To date, the present “vulnerable” listing has not achieved any known positive results for koala populations in Queensland and New South Wales. In fact, recent research invariably shows the opposite.
This is because the key threats to koalas remain, and are mostly increasing. The primary threat is habitat loss. Koala habitat (primarily eucalyptus woodlands and forests) continues to rapidly diminish, and unless it is protected, restored, and expanded, we will indeed see wild koala populations become “functionally extinct”. We know what comes after that.