Are Australia’s native pigeons sitting ducks?

These migratory pied imperial-pigeons in Far North Queensland, like many of Australia’s 22 species of native pigeons and doves, play an important role in our ecosystems but may be at risk from emerging viruses in domestic pigeons.
Dejan Stojanovic, CC BY-SA

Andrew Peters, Charles Sturt University

The word “pigeon” evokes thoughts of gentle cooing, fluttering in rafters, and poo-encrusted statues. The species responsible for the encrustation is deeply familiar to us, having ridden waves of European expansionism to inhabit every continent, including Australia. First domesticated thousands of years ago, urban pigeons have turned feral again.

Less familiar are the native species that are not your stereotypical pigeons: a posse of pointy-headed crested pigeons in a suburban park, or a flock of topknot pigeons feeding in a camphor laurel.

Crested pigeons (left), brush bronzewings (centre) and pied imperial-pigeons (right) are amongst the 22 species of native pigeons and doves in Australia. Their charm and beauty belies the important functions they play in ecosystems.
Author provided

Australia and its neighbouring islands are the global epicentre of pigeon and dove (or “columbid”) diversity with the highest density of different columbids – an impressive 134 species – found in the region. Twenty-two of these native species are found in Australia alone, in just about every habitat.

These native species play an important role in ecosystem functioning: they forage for and disperse seeds, concentrate nutrients in the environment, and are a source of food for predators. Fruit doves for example, are zealous fruitarians, and the region’s tropical rainforests depend on them for tree diversity. Where fruit-doves have disappeared in the South Pacific, numerous plant species have lost an effective dispersal mechanism.

The rose-crowned fruit-dove is not only beautiful but also plays an important role in dispersing seeds in Australian rainforests.
Author provided

The future of Australia’s native pigeons however, may depend on our domestic pigeons. Australia’s domestic pigeon population — both feral and captive – is large and interconnected by frequent local and interstate movements. Pigeon racing, for example, involves releasing captive birds hundreds of kilometres from their homes only so they may find their way back. While most birds do navigate home, up to 20% will not return, of which some will join feral pigeon populations. Birds are also traded across the country and illegally from overseas. These movements, together with poor biosecurity practices, mean that captive pigeons can and do mingle with feral domestic pigeons.

And here’s a paradox. Could Australia’s feral domestic pigeons become the vector for a dramatic decline of columbids – native species on which Australian ecosystems rely?

Emerging viral epidemics

In recent years, two notable infectious diseases have been found to affect our captive domestic pigeons: the pigeon paramyxovirus type 1 (PPMV1) and a new strain of the pigeon rotavirus (G18P). These diseases are notable because in captive domestic flocks they are both spectacularly lethal and difficult to control.

PPMV1, although likely to have originated overseas, is now endemic in Australia. This virus has jumped from captive to feral domestic pigeon populations on several occasions, but fortunately has yet to establish in feral populations.

Domestic pigeons suffer high mortality rates after being infected with either pigeon paramyxovirus ‘PPMV1’ or pigeon rotavirus ‘G18P’.
Dr Colin Walker

G18P is thought to have spread to Victoria and South Australia from a bird auction in Perth in 2016. PPMV1 also spread rapidly to multiple states following its first appearance in Melbourne in 2011.

The movements of captive pigeons, and their contact with their feral counterparts, can be the route through which virulent and lethal diseases – such as the PPMV1 and the G18P – may spread to Australia’s native columbids.

Pigeon paramyxovirus and pigeon rotavirus are known to have escaped from captive domestic pigeons into feral domestic pigeons (black arrow). The risk is that these viruses will establish in feral pigeon populations and cause epidemics in our diverse and ecologically important wild native columbids (red arrow).
Author provided

What have we got to lose?

Fortunately, neither PPMV1 nor G18P has crossed over to Australia’s native columbids. We can’t say how likely this is, or how serious the consequences would be, because we have not previously observed such viral infections among our native pigeons.

If the viruses prove equally lethal to native columbids as they are to domestic pigeons, we could see catastrophic population declines across numerous columbid species in Australia over a short period of time.

Should these viruses spread (via feral domestic pigeons), the control and containment of losses among our native pigeon species would be near impossible. Such a nightmare scenario can only be avoided by predicting if and how these viruses might “spill over” into wild columbids so that we can prevent this in the first place.

Maps of Australia showing the overlapping distribution of our 22 native pigeon and dove species (left) and the distribution (in orange) and verified individual records (red dots) of introduced feral domestic pigeons (right).
Atlas of Living Australia, Birdlife International

Protecting our pigeons

Agricultural poultry is routinely screened to check their vulnerability to threats like the PPMV1 and G18P. Such screening is an appropriate response to protect our agricultural industry.

For our native pigeons and doves however, no such similar testing is planned. Based on progress in veterinary vaccine development and advancements in understanding of feral pigeon control, the knowledge and technology required to mitigate this threat should be relatively inexpensive. The threat for these species can be actively managed, now, by improving our biosecurity and vaccination programs for captive domestic pigeons, and eradicating feral domestic pigeons.

The protection of our native columbids however, ultimately relies on valuing their ecosystem functions in the first place.

Andrew Peters, Senior Lecturer in Veterinary Pathology, Charles Sturt University

This article was originally published on The Conversation. Read the original article.

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The electricity sector needs to cut carbon by 45% by 2030 to keep Australia on track

Amandine Denis, Monash University

Our new ClimateWorks Australia report, released today, shows that the electricity sector needs to deliver a much greater cut than the 28% emissions reduction modelled in the Finkel Review if Australia is to meet its overall climate target for 2030.

When Australia’s energy ministers meet this Friday to discuss (among other things) the Finkel Review released last month, they will hopefully consider its recommendations for the electricity sector in the broader context of developing a long-term national climate policy.

According to our analysis, the electricity sector should cut emissions by at least 45% by 2030, as part of a move towards net zero emissions by 2050. This is well beyond current government policies, but is crucial if Australia is to meet its climate obligations in an economically responsible way.

Climate commitments

The federal government has agreed to cut emissions by 26-28% on 2005 levels by 2030. As a signatory to the Paris climate agreement, Australia has also committed to global action to limit global warming to well below 2℃ – and as a developed nation, that means reaching net zero emissions across the whole economy by about 2050.

Our analysis suggests that the electricity sector will need do a larger share than other sectors of the economy, because it has more technical potential to do so and can support emissions reductions in other sectors. In practice, reaching net zero emissions means shifting from coal and other fossil fuels to zero- or near-zero-carbon energy sources such as renewable electricity and bioenergy. Coal or gas will only be feasible if fitted with carbon capture and storage. Achieving near zero-emissions electricity is a key step in the transition to a net zero-emissions economy, not least because of the future importance of electrically powered transport.

The good news is that our previous research has shown that this is achievable with existing technologies, thanks to Australia’s rich renewable resources.

CSIRO and Energy Networks Australia have also shown that the electricity sector can reach zero emissions by 2050 while still maintaining security and reliability, and that this will actually save households an estimated A$414 a year compared with business as usual.

The 2030 target matters

Cutting emissions faster now will make it easier and less economically disruptive to reach net zero by 2050. Yet the latest government emissions projections forecast that Australia’s emissions will grow by 9% by the end of the next decade, from 543 megatonnes of carbon dioxide equivalent (CO₂e) in 2016 to 592Mt CO2e in 2030.

If the impact of existing policies (such as the National Energy Productivity Plan, the phase-down of hydroflurocarbon emissions, and state renewable energy targets) are taken into account in the projections, emissions could drop to 531Mt CO2e in 2030. This still leaves an 82-megatonne gap to reach even the minimum emissions reduction target of 26% percent below 2005 levels.

Time to do more

Our report, Power Up: Australia’s electricity sector can and should do more to deliver on our climate commitments shows that Australia’s electricity sector can cut emissions by up to 60% below 2005 levels by 2030. This is nearly six times more carbon reduction than is expected to be delivered by current policies, and could by itself fill the whole emissions reduction gap.

However, should the electricity sector only make a 28% reduction in its emissions, in line with the Finkel analysis, then it would only reduce emissions by 6Mt CO2e beyond current policies, leaving most of the effort of reducing emissions to other sectors such as buildings, transport, industry, waste and land management, where cutting carbon is likely to be significantly more expensive.

To reach this level of emissions reductions in the land sector, for instance, we would need to increase forest planting by more than three times the amount estimated to be delivered by the federal government’s Emission Reduction Fund in 2018, its peak year.

In its defence, the Finkel Review focused exclusively on the electricity sector and its analysis did not look at the impact that limited change in this sector would have on the required effort from other parts of the economy.

We therefore modelled various other scenarios, including one in which the share of renewables increases from 40% to 50% by 2030. This could enable the electricity sector to achieve double the carbon reductions delivered by efforts in line with the Finkel review.

Our third and fourth scenarios are aimed at meeting the more ambitious emissions target range recommended by the Climate Change Authority, corresponding to a more progressive and therefore economically responsible trajectory towards net zero emissions. This requires Australia achieving a 45-60% reduction in emissions from the electricity sector by 2030.

Expected emissions reductions by 2030 (in megatonnes CO₂ equivalent) in four different policy areas under four different electricity scenarios.
ClimateWorks Australia, Author provided

The long view

Like the Finkel Review, our report recommends that the federal government defines a specific emissions-reduction policy for the electricity sector, which in Finkel’s case was the Clean Energy Target. This will help to ensure a smooth shift to reliable, affordable, low-carbon energy.

Our report outlines the key principles that Australian governments need to consider in order to make effective decisions on climate change policy, with a view to achieving net zero emissions by mid-century.

These include providing clear long-term direction to support the industry’s investment decisions, and ensuring that decision-making to 2030 is compatible with reaching net zero emissions by 2050.

Climate policy should also be flexible so that it can be scaled up to meet future targets and allow a range of solutions, including the uptake of emerging technologies to make the transition faster and cheaper.

Given that net zero emissions is the ultimate goal, we need to move faster and achieve greater emissions reductions by 2030 to help deliver a fully decarbonised electricity system, on time and on budget.

Amandine Denis, Head of Research, ClimateWorks Australia, Monash University

This article was originally published on The Conversation. Read the original article.