Friday, 21 September 2018

Scientists calculate likelihood Australian birds, mammals will not survive next 20 years on Earth

Scientists calculate likelihood Australian birds, mammals will not survive next 20 years on Earth
23 Apr

Posted April 24, 2018 04:48:40

Seventeen unique Australian birds and mammals are likely to disappear from the face of the Earth in the next 20 years unless Australia improves its protection of threatened species.

Researchers at Australia’s Threatened Species Recovery Hub have been working to calculate the precise risk of extinction for the country’s most imperilled birds and mammals.

If their numbers are correct — and nothing is done to slow things down — the losses would accelerate Australia’s already world-leading extinction rate, which has seen it lose at least 30 mammals and 29 birds since colonisation — the highest mammalian extinction rate in the world.

The birds at risk

The top five looks like this:

  1. King Island brown thornbill
  2. Orange-bellied parrot
  3. King Island scrubtit
  4. Western ground parrot
  5. Houtman Abrolhos painted button-quail

At the top of the extinction risk was the King Island brown thornbill, almost doomed to the history books, with only a 6 per cent chance of surviving the next 20 years, according to the work published this month in the journal Pacific Conservation Biology.

The main cause of the King Island brown thornbill’s decline is likely to be loss of habitat through land clearing, according to the Federal Government.

The mammals at risk

The top five looks like this:

  1. Central rock-rat
  2. Northern hopping-mouse
  3. Carpentarian rock-rat
  4. Christmas Island flying-fox
  5. Black-footed tree-rat

The most at-risk mammal was found to be the Central rock-rat.

If lost, it would follow the most recent mammalian extinction in Australia, the Bramble Cay Melomys.

It was a rodent thought to have been lost in 2016, gaining the dubious honour of being the first mammalian extinction anywhere in the world to be caused by climate change.

The central rock-rat had an official recovery plan created for it in 1999, but it only had recovery actions and aims for 1999 and 2000.

Nevertheless, the rodent is one of 20 mammals the Federal Government has prioritised for protection in its Threatened Species Strategy.

Professor John Woinarski is the deputy director of the Threatened Species Recovery Hub at the National Environmental Science Program and co-author on the paper.

“The fate of these species depends upon support from governments and communities, and public interest, awareness and involvement,” he said.

Surviving shouldn’t be popularity contest: researcher

The researchers estimated there were nine species of bird and one mammal more likely than not to become extinct within the next 20 years.

Across the 40 most threatened, birds and mammals, they calculated about 17 were likely to disappear over that time.

The results are the first time Australia’s threatened species have been given precise risk of extinction, with most previous assessments merely breaking the risk down into broad categories including “critically endangered”, “endangered” and “vulnerable”.

Lead researcher on the paper Hayley Geyle from Charles Darwin University said stopping extinctions in Australia required knowing which species were most at risk, and so more fine-grained estimates were needed.

“The Federal Government’s Threatened Species Strategy — the point of that was to halt further extinctions. In order to do that we needed to know what were the most likely to be lost,” she said.

She said among the broad category of “critically endangered” species, those that usually got the most attention and funding were those that were the most “charismatic” — not necessarily those most at risk.

The researchers mapped the overlapping distribution of Australia’s most threatened birds and mammals, and found a surprising picture.

The most at-risk birds were heavily distributed around the most long-developed parts of Australia, around the south-east of the continent.

The most threatened mammals were located in regions experiencing more recent development, especially in the Top End.

Ms Geyle said that was because mammalian extinctions happened faster, and so were most threatened at the frontlines of development, but there was a lag between development and bird extinctions, she said.

“The birds have been able to hold on a bit longer, so are still persisting in remnant pockets of vegetation adjacent to some of the more intensely modified regions around population centres,” she said.

The researchers used three different techniques to calculate the risk. They combined two existing measures of extinction risk with comprehensive interviewing of 30 experts.

They noted that method had limitations but they made attempts to control for biases and combined it with other methods to minimise its deficiencies.

Energy and Environment Minister Josh Frydenberg told the ABC the Government was committed to threatened species protection and recovery, having appointed a Threatened Species Commissioner and launched the Threatened Species Strategy.

“There is a big task ahead, but the Government is working with the community, scientists, land managers and state and territory governments to ensure that we are all working together in the fight against extinction,” Mr Frydenberg said.

Ranking Bird Percentage chance of extinction within 20 years Mammal Percentage chance of extinction within 20 years
1 King Island brown thornbill 94 Central rock-rat 65
2 Orange-bellied parrot 87 Northern hopping-mouse 48
3 King Island scrubtit 83 Carpentarian rock-rat 44
4 Western ground parrot 75 Christmas Island flying-fox 41
5 Houtman Abrolhos painted button-quail 71

Black-footed tree-rat

(Kimberley and mainland NT)

6 Plains-wanderer 64 Gilbert’s potoroo 36
7 Regent Honeyeater 57 Leadbeater’s possum 29
8 Grey-range thick-billed grasswren 53 Nabarlek (Top End) 29
9 Herald petrel 52 Brush-tailed phascogale (Kimberley) 25
10 Black-eared miner 47

Brush-tailed rabbit-rat

(Kimberley, Top End)

11 Northern eastern bristlebird 39 Western ringtail possum 25
12 Mallee emu-wren 34 Northern brush-tailed phascogale 23
13 Swift parrot 31 Mountain pygmy-possum 22
14 Norfolk island boobook 27 Kangaroo Island dunnart 22
15 Mount Lofty Ranges chestnut-rumped 24 Brush-tailed rabbit-rat (Tiwi Islands) 21
16 Fleurieu Peninsula southern emu-wren 17 Silver-headed antechinus 20
17 Helmeted honeyeater 17 Southern bent-winged bat 18
18 Cocos buff-banded rail 17 Black-tailed antechinus 17
19 Western bristlebird 16 Northern bettong 14
20 Alligator Rivers yellow chat 15 Tasman Peninsula dusky antechinus 14

(Source: National Environmental Science Program)

Topics: endangered-and-protected-species, environment, animal-science, birds, australia

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