Climate change and humans together pushed Australia’s biggest beasts to extinction

25 11 2019

people-megafaunaOver the last 60,000 years, many of the world’s largest species disappeared forever. Some of the largest that we generally call ‘megafauna’ were first lost in Sahul — the super-continent formed by the connection of Australia and New Guinea during periods of low sea level. The causes of these extinctions have been heavily debated for decades within the scientific community.

Three potential drivers of these extinctions have been suggested. The first is climate change that assumes an increase in arid conditions that eventually became lethal to megafauna. The second proposed mechanism is that the early ancestors of Aboriginal people who either hunted megafauna species to extinction, or modified ecosystems to put the largest species at a disadvantage. The third and most nuanced proposed driver of extinction is the combination of the first two.

The primary scientific tools we scientists use to determine which of these proposed causes of extinction have the most support are dated fossil records from the extinct species themselves, as well as archaeological evidence from early Aboriginal people. Traditionally, the main way we use these data is to construct a timeline of when the last fossil of a species was preserved, and compare this to evidence indicating when people arrived. We can also reconstruct climate patterns back tens of thousands of years using models similar to the ones used today to predict future climates. Based on the comparison of all of these different timelines, we conclude that abrupt climate changes in the past were influential if they occurred at or immediately before a recorded extinction event. On the other hand, if megafauna extinctions occur immediately after humans are thought to have arrived, we attribute more weight to human arrival as a driver.

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Logbook of Australia’s ancient megafauna

20 11 2019

FosSahul_transparent_larger

Australia is home to some of the most unique species worldwide, including egg-laying mammals, tree-climbing, desert-bouncing and and burrow-digging marsupials, and huge flightless birds. While these animals are fascinating, the creatures that used to roam Australia’s landscape thousands of years ago were even more remarkable — these included wombat-like beasts as big as rhinos, birds more than two metres tall, lizards more than seven metres long, and a marsupial lion as big as a leopard.

Just how and why these animals went extinct has been challenging scientists for decades. But examining dated fossil records is one of the primary ways we can look into the past. The ever-increasing number of fossils and the advances in dating techniques have produced a wealth of material we can use to reconstruct the long-lost past.

DiprotodonEven with these data, it has been a struggle to gather enough fossils for large-scale analyses because reports of these records are usually scattered across the scientific literature, with no standardised quality control to make them comparable to each other. Designing a way to standardise these records is therefore important to avoid misleading conclusions.

The FosSahul database was first established in 2016 to try to alleviate these problems — it gathered all the fossil specimens for large animals (excluding humans) from the Late Quaternary (up to ~ 1 million years before present) across the region known as ‘Sahul’, the combined super-continent that included New Guinea and Australia when sea levels were much lower than they are today.

While FosSahul was an important step, the database needed to be updated. First, the quality rating of the fossil dates in the original version was a little subjective and lacked transparency in some cases. This is because the database did not capture enough detail to be able to reproduce all the steps leading to a particular quality rating. Second, given that new fossils are discovered regularly, updates are necessary to include the latest research. Read the rest of this entry »





Fancy a job in biosecurity controlling pest species?

13 12 2018

Rabbits-Western-NSW

My mate Dr Brad Page — Principal Biosecurity Officer (Pest Animals) at Biosecurity SA — asked me to post the following jobs he’s advertising for pest-animal control. Now, I’m near-completely opposed to ‘wild dog’ (i.e., dingo) control in Australia, but I’ve agreed to post the third position as well, despite my ecological misgivings. Brad has a different perspective.

We have exciting opportunities for three new pest animal control coordinators, who will be working to support and reinvigorate control of deer, rabbits, and ‘wild dogs’.

All three coordinators will be part of our Biosecurity SA Division within PIRSA. These new positions will report to our Principal Biosecurity Officer, Pest Animals.

cnt-deer

Deer and Rabbit Control Coordinators (two positions)

The Deer Control Coordinator and the Rabbit Control Coordinator will provide tailored professional support to natural resource management (NRM) staff and community groups doing control programs. These coordinators will aim to increase the impact of deer and rabbit control programs to support primary producers and biodiversity managers. The position will connect and empower existing community and industry groups, maximising impacts of their efforts to control feral deer and rabbits in agricultural landscapes. Read the rest of this entry »





Minister, why is the dingo no longer ‘fauna’?

7 09 2018

dead dingoSo, a few of us have just submitted a letter contesting the Western Australia Government’s recent decision to delist dingoes as ‘fauna’ (I know — what the hell else could they be?). The letter was organised brilliantly by Dr Kylie Cairns (University of New South Wales), and she and the rest of the signatories have agreed to reproduce the letter in full here on ConservationBytes.com. If you feel so compelled, please voice your distaste of this decision officially by contacting the Minister (details below).

CJA Bradshaw

Honourable Stephen Dawson MLC
Minister for Environment; Disability Services
Address: 12th Floor, Dumas House
2 Havelock Street, WEST PERTH WA 6005
(minister.dawson@dpc.wa.gov.au)

cc: Department of Biodiversity, Conservation and Attractions (biodiversity@dbca.wa.gov.au)
cc: Brendan Dooley (brendan.dooley@dpc.wa.gov.au)

Dear Minister,

The undersigned welcome the opportunity to comment on and recommend alteration of the proposed section (9)(2) order of the Biodiversity Conservation Act 2016 (BC Act) that changes the listing of the dingo from “fauna” to “non-fauna” in Western Australia. Removing the “fauna” status from dingoes has serious consequences for the management and conservation of this species and other native biota it benefits. Currently, dingoes are classed as A7, or fauna that requires a management policy. The proposed section (9)(2) order will move dingoes (as “non-fauna”) to the A5 class, meaning that dingoes must be (lethally) controlled and there will be no obligation for the Department of Biodiversity, Conservation and Attractions to have an appropriate management policy (or approval).

Currently, under the Wildlife Conservation Act 1950 (WC Act) the dingo is considered “unprotected” fauna allowing management under a Department of Biodiversity, Conservation and Attractions management policy. A section (9)(2) order demoting dingoes to “non-fauna” will remove the need for Department of Biodiversity, Conservation and Attractions management policy and instead mandate the lethal control of dingoes throughout Western Australia.

As prominent researchers in top predator ecology, biology, cultural value and genetics, we emphasise the importance of dingoes within Australian, and particularly Western Australia’s ecosystems. Dingoes are indisputably native based on the legislative definition of “any animal present in Australia prior to 1400 AD” from the BC Act. Dingoes have been present in Australia for at least 5000 years. On the Australian mainland they are now the sole non-human land-based top predator. Their importance to the ecological health and resilience of Australian ecosystems cannot be overstated. Read the rest of this entry »





Cartoon guide to biodiversity loss XLV

6 12 2017

The last set of biodiversity cartoons for 2017. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Cartoon guide to biodiversity loss XLIV

9 10 2017

Here’s another set of biodiversity cartoons to make you giggle, groan, and contemplate the Anthropocene extinction crisis. See full stock of previous ‘Cartoon guide to biodiversity loss’ compendia here.

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Protecting one of the world’s marine wonders

17 06 2017
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© CJA Bradshaw

While I’m in transit (yet a-bloody-gain) to Helsinki, I wanted to take this opportunity to reflect on one of the most inspiring eco-tourism experiences I recently had in South Australia.

If you are South Australian and have even the slightest interest in wildlife, you will have of course at least heard of the awe-inspiring mass breeding aggregation of giant cuttlefish (Sepia apama) that occur in May-July every year in upper Spencer Gulf near the small town of Whyalla. If you have been lucky enough to go there and see these amazing creatures themselves, then you know exactly what I’m talking about. And if you haven’t yet been there, take it from me that it is so very much worth it to attempt the voyage.

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Father-daughter giant-cuttlefish-snorkelling selfie. © CJA Bradshaw

Despite having lived in South Australia for nearly a decade now, I only got my chance to see these wonderful creatures when a father at my daughter’s school organised a school trip. After driving for five hours from Adelaide to Whyalla, we hired our snorkelling gear and got into the water the very next morning. Read the rest of this entry »