Daily Archives for December 21, 2019

Scientists re-counted Australia’s extinct species, and the result is devastating



The Tasmanian tiger is among the best known of our extinct species, but researchers have now revealed the extent of the crisis.
TASMANIAN MUSEUM AND ART GALLERY

John Woinarski, Charles Darwin University; Brett Murphy, Charles Darwin University; Dale Nimmo, Charles Sturt University; Michael F. Braby, Australian National University; Sarah Legge, Australian National University, and Stephen Garnett, Charles Darwin University

It’s well established that unsustainable human activity is damaging the health of the planet. The way we use Earth threatens our future and that of many animals and plants. Species extinction is an inevitable end point.

It’s important that the loss of Australian nature be quantified accurately. To date, putting an exact figure on the number of extinct species has been challenging. But in the most comprehensive assessment of its kind, our research has confirmed that 100 endemic Australian species living in 1788 are now validly listed as extinct.

Alarmingly, this tally confirms that the number of extinct Australian species is much higher than previously thought.

A southern black-throated finch, which conservationists say is threatened by the Adani coal mine.
ERIC VANDERDUYS/BirdLife Australia

The most precise tally yet

Counts of extinct Australian species vary. The federal government’s list of extinct plants and animals totals 92. However 20 of these are subspecies, five are now known to still exist in Australia and seven survive overseas – reducing the figure to 60.

An RMIT/ABC fact check puts the figure at 46.

The states and territories also hold their own extinction lists, and the International Union for Conservation of Nature keeps a global database, the Red List.

An endangered Manning River turtle.
AUSTRALIAN REPTILE PARK

Our research collated these separate listings. We excluded species that still exist overseas, such as the water tassel-fern. We also excluded some species that, happily, have been rediscovered since being listed as extinct, or which are no longer recognised as valid species (such as the obscure snail Fluvidona dulvertonensis).

We concluded that exactly 100 plant and animal species are validly listed as having become extinct in the 230 years since Europeans colonised Australia:

  • 38 plants, such as the magnificent spider-orchid
  • 1 seaweed species
  • 34 mammals including the thylacine and pig-footed bandicoot
  • 10 invertebrates including a funnel-web spider, beetles and snails
  • 9 birds, such as the paradise parrot
  • 4 frogs, including two species of the bizarre gastric-brooding frog which used its stomach as a womb
  • 3 reptiles including the Christmas Island forest skink
  • 1 fish, the Pedder galaxias.
A 19th century illustration of the Pig-footed bandicoot.
Wikimedia

Our tally includes three species listed as extinct in the wild, with two of these still existing in captivity.

The mammal toll represents 10% of the species present in 1788. This loss rate is far higher than for any other continent over this period.

The 100 extinctions are drawn from formal lists. But many extinctions have not been officially registered. Other species disappeared before their existence was recorded. More have not been seen for decades, and are suspected lost by scientists or Indigenous groups who knew them best. We speculate that the actual tally of extinct Australian species since 1788 is likely to be about ten times greater than we derived from official lists.

And biodiversity loss is more than extinctions alone. Many more Australian species have disappeared from all but a vestige of their former ranges, or persist in populations far smaller than in the past.

The geographical spread of extinctions across Australia. Darker shading represents a higher extinction tally.

Dating the losses

Dating of extinctions is not straightforward. For a few Australian species, such as the Christmas Island forest skink, we know the day the last known individual died. But many species disappeared without us realising at the time.

Our estimation of extinction dates reveals a largely continuous rate of loss – averaging about four species per decade.

Continuing this trend, in the past decade, three Australian species have become extinct – the Christmas Island forest skink, Christmas Island pipistrelle and Bramble Cay melomys – and two others became extinct in the wild.

Cumulative tally of Australian extinctions since 1788.

The extinctions occurred over most of the continent. However 21 occurred only on islands smaller than Tasmania, which comprise less than 0.5% of Australia’s land mass.

This trend, repeated around the world, is largely due to small population sizes and vulnerability to newly introduced predators.

We must learn from the past

The 100 recognised extinctions followed the loss of Indigenous land management, its replacement with entirely new land uses and new settlers introducing species with little regard to detrimental impacts.

Introduced cats and foxes are implicated in most mammal extinctions; vegetation clearing and habitat degradation caused most plant extinctions. Disease caused the loss of frogs and the accidental introduction of an Asian snake caused the recent loss of three reptile species on Christmas Island.

The causes have changed over time. Hunting contributed to several early extinctions, but not recent ones. In the last decade, climate change contributed to the extinction of the Bramble Cay melomys, which lived only on one Queensland island.

The prospects for some species are helped by legal protection, Australia’s fine national reserve system and threat management. But these gains are subverted by the legacy of previous habitat loss and fragmentation, and the ongoing damage caused by introduced species.

Our own population increase is causing further habitat loss, and new threats such as climate change bring more frequent and intense droughts and bushfires.

Environment laws have demonstrably failed to stem the extinction crisis. The national laws are now under review, and the federal government has indicated protections may be wound back.

But now is not the time to weaken environment laws further. The creation of modern Australia has come at a great cost to nature – we are not living well in this land.

The study on which this article is based was also co-authored by Andrew Burbidge, David Coates, Rod Fensham and Norm McKenzie.The Conversation

John Woinarski, Professor (conservation biology), Charles Darwin University; Brett Murphy, Associate Professor / ARC Future Fellow, Charles Darwin University; Dale Nimmo, Associate professor/ARC DECRA fellow, Charles Sturt University; Michael F. Braby, Associate Professor, Australian National University; Sarah Legge, Professor, Australian National University, and Stephen Garnett, Professor of Conservation and Sustainable Livelihoods, Charles Darwin University

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

Advertisement

Australia’s threatened birds declined by 59% over the past 30 years


Elisa Bayraktarov, The University of Queensland and Jaana Dielenberg, The University of Queensland

Australia’s threatened birds declined by nearly 60% on average over 30 years, according to new research that reveals the true impact on native wildlife of habitat loss, introduced pests, and other human-caused pressures.

Alarmingly, migratory shorebirds have declined by 72%. Many of these species inhabit our mudflats and coasts on their migration from Siberia, Alaska or China each year.



Read more:
For the first time we’ve looked at every threatened bird in Australia side-by-side

These concerning figures are revealed in our world-first Threatened Bird Index. The index, now updated with its second year of data, combines over 400,000 surveys at more than 17,000 locations.

It’s hoped the results will shed light on where conservation efforts are having success, and where more work must be done.

Bringing conservation efforts together

The index found a 59% fall in Australia’s threatened and near threatened bird populations between 1985 and 2016.

Migratory shorebirds in South Australia and New South Wales have been worst hit, losing 82% and 88% of their populations, respectively. In contrast, shorebirds in the Northern Territory have increased by 147% since 1985, potentially due to the safe roosting habitat at Darwin Harbour where human access to the site is restricted.

Habitat loss and pest species (particularly feral cats) are the most common reasons for these dramatic population declines.

Many of Australia’s threatened species are monitored by various organisations across the country. In the past there has never been a way to combine and analyse all of this evidence in one place.



Read more:
Scientists re-counted Australia’s extinct species, and the result is devastating

The Threatened Species Recovery Hub created the index to bring this information together. It combines 17,328 monitoring “time series” for threatened and near threatened bird species and subspecies. This means going back to the same sites in different years and using the same monitoring method, so results over time can be compared.

Over the past year the amount of data underpinning the index has grown considerably and now includes more than 400,000 surveys, across 43 monitoring programs on 65 bird species and subspecies, increasing our confidence in these alarming trends.

Threatened species like the Gilbert’s Whistler, Chestnut quail-thrush and Swift parrot are all on the decline.
Glenn Ehmke, BirdLife Australia, Author provided

About one-third of Australia’s threatened and near threatened birds are in the index but that proportion is expected to grow. As more quality data becomes available, the index will get more powerful, meaningful and representative. For the first time Australia will be able to tell how our threatened species are going overall, and which groups are doing better or worse, which is vital to identifying which groups and regions most need help.

Finding the trends

Trends can be calculated for any grouping with at least three species. A grouping might include all threatened species in a state or territory, all woodland birds or all migratory shorebirds.

The 59% average decrease in threatened bird relative abundance over the last 30 years is very similar to the global wildlife trends reported by the 2018 Living Planet Report. Between 1970 and 2014, global average mammal, fish, bird, amphibian and reptile populations fell by 60%.

One valuable feature of the Threatened Species Index is a visualisation tool which allows anyone to explore the wealth of data, and to look at trends for states and territories.

For instance, in Victoria by 2002 threatened birds had dropped to a bit more than half of their numbers in 1985 on average (60%), but they have remained fairly constant since then.

We can also look at different bird groups. Threatened migratory shorebirds have had the largest declines, with their numbers down by more than 72% since 1985. Threatened terrestrial birds, on the other hand, have decreased in relative abundance by about 51% between 2000 and the year 2016, and show a relatively stable trend since 2006.

Eastern Great Egret, and Bar-tailed Godwit. Pictures kindly provided by Glenn Ehmke, BirdLife Australia.

Making the index better

The index is being expanded to reveal trends in species other than birds. Monitoring data on threatened mammals and threatened plants is being assembled. Trends for these groups will be released in 2020, providing new insights into how a broader range of Australia’s threatened species are faring.

This research is led by the University of Queensland in close partnership with BirdLife Australia, and more than 40 partners from research, government, and non-government organisations. Collaboration on such a scale is unprecedented, and provides extremely detailed information.



Read more:
Citizen scientists count nearly 2 million birds and reveal a possible kookaburra decline

The index team are continuing to work with monitoring organisations across Australia to expand the amount of sites, and the number of species included in the index. We applaud the dedicated researchers, managers and citizen scientists from every corner of the country who have been assembling this data for the nation.

We’d also like to hear from community groups, consultants and other groups that have been monitoring threatened or near-threatened species, collecting data at the same site with the same method in multiple years.

The Threatened Species Index represents more than just data. Over time it will give us a window into the results of our collective conservation efforts.

This article also received input from James O’Connor (BirdLife Australia) and Hugh Possingham (The Nature Conservancy).The Conversation

Elisa Bayraktarov, Postdoctoral Research Fellow in Conservation Biology, The University of Queensland and Jaana Dielenberg, Science Communication Manager, The University of Queensland

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