How we wiped out the invasive African big-headed ant from Lord Howe Island



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Not welcome: the African big headed ant might be small but it can be a pest if it gets in your home.
CSIRO, Author provided

Ben Hoffman, CSIRO

The invasive African big-headed ant (Pheidole megacephala) was found on Lord Howe Island in 2003 following complaints from residents about large numbers of ants in buildings.

But we’ve managed to eradicate the ant completely from the island using a targeted mapping and baiting technique than can be used against other invasive species.

Up to 15% of Lord Howe Island was thought to be infested with the ant.
CSIRO, Author provided

A major pest

The African big-headed ant is one of the world’s worst invasive species because of its ability to displace some native plants and wildlife, and adversely affect agricultural production.




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It’s also a serious domestic nuisance. People can become overwhelmed by the large number of ants living in their buildings – you can’t leave a bit of food lying around, especially pet food, or it will be covered in ants.

It remains unclear how long the ant had been on Lord Howe Island, in the Tasman Sea about 770 km northeast of Sydney, before being found. But it is likely to have been present for at least a decade.

Because of the significant threat this ant posed to the conservation integrity of the island, an eradication program was started. But on-ground work done from 2003 to 2011 had many failings and was not working.

In 2011, I was brought in to oversee the program. The last ant colony was killed in 2016, but it is only now, two years later, that we are declaring Lord Howe Island free from the ants.

No African big-headed ants have been seen on the island for two years.
CSIRO, Author provided

A super colony

The ability to eradicate this ant is largely due to its relatively unique social organisation. The queens don’t fly to new locations to start new nests – instead, they form interconnected colonies that can extend over large areas.

This makes the ant’s distribution easy to map and treat. The ant requires human assistance for long-distance transport, so the ant will only be found in predictable locations where it can be accidentally transported by people.

From 2012 to 2015, all locations on the island where the ant was likely to be present were formally inspected. Priority was given to places where an infestation was previously recorded or considered likely. The populations were mapped, and then treated using a granular bait available at shops.

In the latter years we found 16 populations covering 30 hectares. Limited by poor mapping in the early years, we estimate that the ant originally covered up to 55 hectares, roughly 15% of the island.

Stopping the spread

The widespread distribution of the ant through the populated area of the island is thought to have been aided by the movement of infested mulch and other materials from the island’s Waste Management Facility.

To prevent any more spread of the ant, movement restrictions were imposed in 2003 on the collection of green waste, building materials and other high risk items from the facility.

The baiting program used a product that contains a very low dose of insecticide that has an extremely low toxicity to terrestrial vertebrates such as pet cats and dogs, birds, lizard etc. The toxicant rapidly breaks down into harmless chemicals after exposure to light.

No negative impacts were recorded on any of the native wildlife on the island.

Importantly, the African ant usually kills most other ants and other invertebrates where it is present, so there are few invertebrates present to be affected by the bait.

Ecological recovery of the infested areas was rapid following baiting and the eradication of the African ant.

Another ant invader

One of the main challenges was getting the ground crew to correctly identify the ant.

It turns out there was a second (un-named) big-headed ant species present, also not native to the island, that created a lot of unnecessary work being conducted where the African ant wasn’t present.

CSIRO and Lord Howe Island Board team tackling the African big headed ant problem.
CSIRO, Author provided

Like numerous other exotic ant species present, this second species was of no environmental or social concern, so there are no plans to manage or eradicate it.

The protocols used in this program are essentially the same that are being used in other eradication programs against Electric ant in Cairns and Browsing ant in Darwin and Perth, because those two species also create supercolonies.




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It is highly likely that those programs will also achieve eradication of their respective species, the first instance where an ant species has been eradicated entirely from Australia.

The fire ant program in Brisbane has many similarities, but there are distinct differences in that the ants there don’t form supercolonies that are so easy to map, and the area involved is far greater.The Conversation

Ben Hoffman, Principal research scientist, CSIRO

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

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The backflip over Sydney’s marine park is a defiance of science



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Sydney’s iconic beaches are not yet part of a marine park.
John Turnbull

David Booth, University of Technology Sydney and John Turnbull, UNSW

The New South Wales government’s decision to back away from establishing no-fishing zones in waters around Sydney leaves significant question marks over the plan, which is open for public consultation until September 27.

Fisheries Minister Niall Blair explained the apparent backflip by saying he was “confident that fishing is not the key threat to the sustainability of our marine environment”, after receiving what he described as “robust” feedback from local communities and anglers.

The original plans for Sydney’s marine park. Click image to enlarge.
NSW government

The originally proposed Sydney Marine Park comprised 17 “sanctuary zones” (totalling 2.4% of the area, including estuaries), 3 “conservation zones” totalling 2.6%, and 21 “special purpose zones”, which would allow (and in some cases protect) fishing.

Sanctuary zones allow no fishing; conservation zones allow taking of lobster and abalone (see below); and special purpose zones have a range of restrictions or allowances, not necessarily of any conservation benefit. For instance, four offshore artificial reefs are classed as special purpose zones.

The plans cover the waters around Sydney, stretching from Newcastle in the north to Wollongong in the south. Formally known as the Hawkesbury Shelf marine bioregion, it is the only bioregion wholly in NSW that does not have a marine park. This is despite Sydney’s magnificent array of underwater and coastal habitats, which are home to more fish species than the entire British Isles.




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New zones and ranked threats

The original marine park proposal was far from ideal. A good marine park should have a string of closely connected sanctuary zones, but there was a large gap from southern Sydney to Wollongong where no sanctuary zones were proposed.

Instead, there was a new “conservation zone” to allow fishing for lobster and abalone. Yet lobster in particular are important to this ecosystem, because they protect kelp by preying on sea urchins.

Threats to the marine region around Sydney, as ranked in a NSW government report. Click image to enlarge.
NSW government

The NSW government based its earlier proposal on a principle called TARA, short for “threat and risk assessment”, in which all perceived factors are ranked according to their environmental, social and economic outcomes.

While other major threats such as climate change and pollution are ranked highly, fishing doesn’t appear until number 18 on the government’s list (see page 8 here. One reason for this is that fishing is split into eight categories (such as “recreational fishing by boat – line and trap”), masking its overall impact. Even 4WDs on beaches are ranked as a greater threat to the environment than many types of fishing.

Premier Gladys Berejiklian’s press release about the marine park public consultation didn’t mention the environmental threat posed by fishing at all. Yet there is clear evidence that fishing directly harms fish stocks.

One recent study shows that stocks of inshore fish species have declined in Australia by 30% in a decade, except in sanctuary zones. Worldwide, sanctuary zones (also called no-take zones) have been shown to help fish grow larger and more abundant. And recent studies in NSW coastal waters have reiterated the benefits of no-take zones for species such as morwong, bream, and snapper.

Partial protection doesn’t work

The latest proposals, which would allow recreational but not commercial fishing, would be much less effective than full protection. One recent study suggested that partial protection is no better than no protection at all.

According to a NSW government estimate, recreational fishing removes more than 3 million fish, crustaceans and molluscs from NSW coastal waters every year. But marine parks are primarily about conservation, and this requires us to face some stark realities. With more than 8 million people likely to call Sydney home in the next 40 years, pressures on our coasts will only increase.

Sanctuary zones are one of the best available conservation tools to guard against these impacts. These zones have also been shown to make wildlife more resilient to climate change.

Even before the government’s decision to rescind the proposed sanctuary zones, the original plan for no-take zones to cover just 2.4% of the region was a severe compromise. By comparison, the Great Barrier Reef Marine Park has 30% sanctuary zone coverage, and the rest of NSW has 7-8%. International best practice recommends at least 20%, and even the Commonwealth Marine Reserves Management Plan offers 6% no-take coverage.

But now, with no sanctuary zones, Sydney’s proposed “marine park” is not worthy of the name.

Wrong priorities

A peculiar contradiction is that despite one-quarter of the listed threats being fishing-related, the NSW government’s marine estate management strategy includes an initiative to encourage fishing. Pollution is also a high-priority threat, and fishing is the largest source of subtidal debris.

Kelp and a tangle of discarded fishing line.
John Turnbull

If local-level threats such as fishing and litter are not dealt with, resilience to climate change suffers as a result. We must tackle all threats – overfishing, pollution, climate change – and not shy away from one because it’s politically unpalatable.




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It is frustrating that the NSW government has opted to abolish these marine sanctuaries before the public consultation was complete. The wider public understands the value of sanctuary zones, as indicated in recent opinion polls showing clear support for the original plans among Sydneysiders – even many of those who fish.

Some fishers are now calling for sanctuary zones to be scrapped or wound back in other iconic NSW marine parks, such as Lord Howe Island and Solitary Islands. This move would be a defiance of the science. The evidence shows that sanctuary zones are essential for restoring and preserving our marine estate for future generations.The Conversation

David Booth, Professor of Marine Ecology, University of Technology Sydney and John Turnbull, , UNSW

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

The Lord Howe screw pine is a self-watering island giant



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To grow tall enough to reach the canopy, a species of screw pine unique to Lord Howe Island has evolved its own rainwater harvesting system.
Matthew Biddick, CC BY-SA

Matthew Biddick, Victoria University of Wellington

If you’d like more content like this, sign up for the Beating Around the Bush newsletter for a dose of nature news every two weeks.


Pandanus forsteri, a species of screw pine endemic to Lord Howe Island, grows tall like no other tree on Earth. To reach the canopy, these trees have evolved a rainwater harvesting system that enables them to water themselves.

Originally from Micronesia, the palm-like P. forsteri belongs to a group of trees that have populated almost every coastal habitat of the Pacific. In fact, pandans are used by Oceanic cultures for everything from fishing and cooking to medicine and religious ceremonies.

Our research shows that pandans differ in several fundamental ways from more familiar trees, including how they capture water and grow.




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Welcome to Beating Around the Bush, wherein we yell about plants


Reaching for the canopy

Most trees lay down concentric rings of vascular tissue as they mature, thickening over time. This enables them to grow tall, yet maintain enough structural integrity to avoid toppling over. It is also arguably the most important evolutionary innovation that has enabled trees to colonise most of terrestrial Earth.

Together with palms, bamboo and yucca, pandans belong to a group known as monocots, because their seedlings produce a single embryonic leaf.

Pandans belong to a group of plants whose vascular tissue is still primitive, making it difficult to grow tall.
Ian Hutton, CC BY-SA

Their vascular tissue is not compartmentalised in the same way. It forms bundles that are positioned somewhat haphazardly within the stem. Consequently, monocots are unable to produce true secondary growth and thicken like other trees do – and reaching the canopy becomes a much more ambitious endeavour.

The canopy offers a good life. The sun is shining, seed-dispersing birds are abundant, and the herbivores of the forest floor are a distant concern. In monocots, natural selection has favoured some inventive ways of stretching to the top.

Pay-as-you-go growth

Palms overcome the limitations imposed by their physiology by spending their younger years laying down enough vascular girth to support their future stature. Think of it like putting aside money for your retirement. You may not need it now, but you will likely later depend on it.

Stilt roots support the crown as it matures.
Kevin Burns, CC BY-SA

Once thick enough, palms shift their efforts to vertical growth. The palm’s tactic of delayed vertical growth may be slow, but it functions well enough to thrust Columbian wax palms (Ceroxylon quindiuense) – the world’s tallest monocot – 45 meters into the clouds.

Pandans, on the other hand, are less patient. Unlike palms, they prefer a sort of “pay-as-you-go” method. They produce stilt roots that extend from the trunk to the ground for support as the crown matures. The end result gives the appearance of an ice cream cone perched on a tepee of stilts. It’s an odd strategy, but it works.

However, on Lord Howe Island, something quite remarkable has transpired. Isolated some 600 kilometres off the east coast of Australia, one species of screw pine has evolved into an island giant.

Lord Howe Island, some 600km off the Australian east coast, is home to countless endemic plants and animals.
Ian Hutton, CC BY-SA

Island syndrome

Most screw pines are lucky to reach four or five meters. Pandanus forsteri trees, however, regularly exceed 15 meters. These kinds of size changes are not uncommon on isolated islands. They are part of a repeated evolutionary phenomenon known as the island syndrome.

Species on isolated islands are free from the stressors of continental life, and they subsequently converge on a more optimal, ancestral form. Large continental species evolve into island dwarfs, while smaller species become comparatively gigantic. Support for the island syndrome primarily comes from animals. However, a growing body of evidence suggests island plants follow a similar evolutionary path.




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A network of aqueducts on the root surface guides water to the absorptive tissue at the tip of the growing root.
Matt Biddick, CC BY-SA

While gigantism may be favourable, it doesn’t come without risks – and for P. forsteri, they are serious. Thanks to their new-found stature, P. forsteri trees must produce enormous stilt roots to support themselves. This process that can take years. Exposed to the air, roots can form air bubbles, and an air bubble in a plant is bad in the same way it is bad in your artery. It is potentially lethal.

Nature appears to have solved this problem through the evolution of a rainwater harvesting system that enables P. forsteri to water its own stilt roots before they reach the ground.

Gutter-like leaves collect rainwater and transport it to the trunk, where it descends. The flow of water is then couriered by a network of aqueducts formed by the root surface. Finally, water is stored in a specialised organ of absorptive tissue encasing the growing root tip.

Back to the drawing board

This is dramatically different from how we traditionally think about plants. It is far from our concept of sessile beings that passively absorb everything they need from the soil, thanks to the capillary action of their vascular tissues. Never before has a plant species been shown to possess a system of traits that operate jointly to capture, transport and store water external to itself.

This species has opened our eyes to an entirely new field of scientific inquiry. It forces scientists to rethink the function of organs like leaves and roots outside of the contexts of photosynthesis and the conduction of soil water.

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The Conversation

Do other plants harvest rainwater in this way? Why have we only just discovered this? Has our overly simplistic view of plants hindered our ability to comprehend their true complexity? Only time, and more research, will tell.

Matthew Biddick, PhD Researcher, Victoria University of Wellington

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

Proposed NSW logging laws value timber over environmental protection



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Increased logging in NSW could affect threatened species.
Nativesrule, Author provided

Oisín Sweeney, University of Sydney

New South Wales is revamping its logging laws for the first time in two decades, drafting regulations that will govern more than two million hectares of public native forest.

Among the changes are proposals to permit logging in exclusion zones – part of the reserve system – and dramatic increases to the scale and intensity of logging, putting several threatened species at direct risk.

NSW can implement these changes unilaterally. But if it does, NSW will effectively be asking the federal government to agree to changes that directly contradict the federal Threatened Species Strategy and several species recovery plans, and reduce the extent of the reserve system.




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Regional Forest Agreements

The federal government has arrangements with the states called Regional Forest Agreements (RFAs). They provide certainty to logging operations by accrediting state logging rules under federal environment law. No other industry gets this treatment – but RFAs are now expiring after having been in place for 20 years.

But the proposed changes to NSW logging laws clearly prioritise timber extraction over environmental protection. In 2014 the NSW government extended wood supply agreements with timber companies, locking in a commitment to logging at a certain level. The changes are cited as necessary to meet these wood supply agreements.

This means abandoning commitments made under the National Forest Policy Statement in 1992, including the concept of ecologically sustainable forest management. This is a fundamental shift and, because of the impacts on the reserve system and threatened species, against the national interest.




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Overlogging is behind the changes

In its 2016 Forestry Industry Roadmap the NSW government made a dual commitment to maintain logging levels without eroding environmental protection. However, the NSW Natural Resources Commission tasked with finding a way to do this reported “it is not possible to meet the government’s commitments around both environmental values and wood supply”.

The commission therefore recommended the NSW government “remap and rezone” old-growth forest and rainforest to increase the area that can be logged and make up timber shortfalls.

There are three kinds of zones that make up protected forest reserves. The first zone requires an act of state parliament to revoke, but the second and third can be revoked by the state forestry minister.

To further increase timber supply, headwater stream buffers – areas around waterways that cannot be logged – will be reduced from 10 metres to five.

The new laws also permit the logging of giant trees up to 140cm in diameter, or 160cm in the case of blackbutt and alpine ash (preferred timber species).

Northeast NSW to see the biggest changes

In northeast NSW, a new “intensive harvesting zone” will cover 140,000 hectares of coastal forests between Taree and Grafton. These forests are in the Forests of East Australia global biodiversity hotspot and many are included in a proposed Great Koala National Park.




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This will see 45-hectare patches of forest cleared of all but a smattering of small trees. The intensity of logging everywhere else in the “selective” harvesting zone will, on average, double.

Implications for wildlife and forest ecosystems

The new proposals move towards a retention model where habitat features are to be retained in clumps over several logging cycles. This “retention approach” is good in theory, but is undermined by the landscape-wide intensification of logging – particularly in the intensive zone – and the need to maximise timber production, not the conservation of forest species.

Although hollow-bearing trees are to be retained, no younger trees – which will eventually replace their elders – are required to be protected. This means the inevitable loss of hollow-bearing trees, exacerbated by logging rezoned old-growth. There is no longer any requirement to protect eucalypt nectar trees, vital resources for the critically endangered regent honeyeater and swift parrot.

A report on the proposals from the Threatened Species Expert Panel reveals that almost no data was available to design the new environmental protections, and there was great uncertainty as to whether they will work. One panel member commented:

The intensive harvesting zones are being formally introduced to prop up an unsustainable wood supply arrangement at the expense of the environment.

It is frustrating trying to be part of the solution when the underlying driver of the wood supply agreements fundamentally restricts any chance of a balanced approach.

The federal government has a problem

The federal government has already committed to extending Regional Forest Agreements with the states. Yet besides potentially reducing the size of the reserve network, NSW’s proposals directly threaten federally-listed species.

Conservation advice for the marsupial greater glider clearly states the impact of habitat loss and fragmentation through intensive logging.

Greater gliders (Petauroides volans) are vulnerable to loss of tree hollows and habitat fragmentation, which will both be exacerbated under NSW’s proposals.
Dave Gallan

Koalas prefer large trees and mature forests, yet the intensive logging zone will cover almost half of identified high quality koala habitat. Legally, loggers will only have to keep 10 trees of 20cm diameter per hectare – far too few and too small for koalas.

The national recovery plan for the swift parrot proposes the retention of all trees over 60cm diameter – clearly incompatible with the proposed intensive harvesting zone – while the recovery plan for the regent honeyeater identifies all breeding and foraging habitat as critical to survival.

Recent research has predicted a 31% probability of swift parrot extinction in the next 20 years, and a 57% probability for the regent honeyeater. Both birds are priority species under the Australian government’s Threatened Species Strategy.

Public feedback on the proposed changes is invited until June 29. After that, the federal government must decide whether it deems the proposals to be consistent with national environment law in a new Regional Forest Agreement. Signing off on these changes will cast serious doubt on the federal government’s commitment to the national environmental interest.




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The ConversationThe author would like to acknowledge the contribution of Dailan Pugh, OAM and co-founder of the North East Forest Alliance, to this article.

Oisín Sweeney, Senior Ecologist at the National Parks Association of NSW, Research Fellow, University of Sydney

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

Wollemi pines are dinosaur trees



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Wollemi pines once covered prehistoric Australia.
The Conversation/Wikipedia

Cris Brack, Australian National University

Welcome to Beating Around the Bush, a series that profiles native plants. Read more about the series here or get in touch to pitch a plant at batb@theconversation.edu.au.


There’s a tree that once covered the whole of Australia, then dwindled to a dozen examples, and is now spread around the world. We call it the Wollemi pine (Wollemia nobilis), but you could call it the dinosaur tree.

Fossil evidence indicates that between 200 million and 100 million years ago, Wollemi pine was present across all of Australia. A dryer, more flammable continent is likely to have driven the tree to near extinction over the millennia, leaving just a very small remnant of the Wollemi in a secluded deep gully not far from Sydney.




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And there these trees remained, hidden, until they were discovered by a canyoning National Park worker in 1994.

The Conversation.
CC BY

A spectacular discovery

The reaction to the discovery of this tree, thought to have disappeared 100 million years ago and only known through its fossils, was spectacular. Great secrecy was maintained around the site of the find. Because there were so few, the individual trees in the gorge were given their own names to celebrate their importance and acknowledge the efforts of those trying to protect them.

Scientists, arborists and botanists swung into action to discover ways to propagate more trees and establish other colonies of the Wollemi as insurance against that single refuge being lost.




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There was a great sigh of relief when it was discovered that trees could be successfully cloned, and new trees were potted up in the Sydney and Mount Annan Botanic Gardens. The interest in these original cloned offspring was so great that they were auctioned off by Sotheby’s, with the profits going back to support more research into this little-known living fossil.

Students and staff from my school at the Australian National University pooled together to bid for a clone of the Wollemi, christened the “John Banks” – named for our colleague Dr John C.G. Banks, who was one of the first researchers to describe the tree’s dendrology. We planted our tree in memory of John, with a cage around it because it was so rare and valuable.

Sent around the world

In 2006, just over a decade after the original discovery, huge numbers of cloned Wollemi Pine seedlings were released from the official nursery in Queensland.

Every major nursery in Australia stocked potted Wollemi Pines for sale to a public who were keen to own a piece of ancient life and help ensure it didn’t go extinct. Enthusiasts around the world also bought their own dinosaur trees.

But it’s not just gardeners who have spread the Wollemi back to all corners of Australia and across the seas. Special Wollemi pines are also in the diplomatic service, having been presented by Australian prime ministers and foreign affairs ministers to various dignitaries.

Seedlings are an obvious choice to represent long-term friendship and trust, as the act of planting a tree is one of hope for the future and a common good. A seedling that can trace its history back more than 100 million years, and which represents the reversal of an extinction, is even better.

Wollemi were thought to be extinct long before humans arrived in Australia, so there is no opportunity for humans to have used it in any specific way. However, ancient species may have properties or traits that are no longer present in evolved plants and these may be useful. For example, extracts from Wollemi pine leaves have been found to be successful in inhibiting a pest that affects winter wheat production – which may help control an expensive problem without herbicides.

Scientists found that extracts from the leaves of the Wollemi contained chemicals that had never previously been described, and which suppressed annual ryegrass (Lolium rigidum). The ryegrass, like many modern weeds, has evolved in the absence of Wollemi and thus was unlikely to have developed resistance to its chemistry.

How does it grow?

Little was known about Wollemi pines when the remnant was found. We knew the conditions of the gorge where they grew, but not whether these were optimal. Could the tree survive in hotter or cooler, drier or wetter, more clay or gravelly soils?

We now know from planting experience outside the National Park that Wollemi pines can grow on exposed rock slopes, surviving frost and temperatures lower than -5℃ with the help of a waxy coat it puts on top of its growing buds. They can also survive heat greater than 45℃ in full sun.

Some Wollemi pines have been known to happily sit in small pots on verandas or decks, growing to over 3 metres – only to die within weeks of being transplanted into carefully prepared holes. They can be slow-growing, but given good light and moisture they can grow more than 50cm per year. Horticulturalists and the Sydney Royal Botanic Gardens continue to work on finding the best ways of tending these pines.




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Wollemi pines, unlike their nearest neighbours in the Araucariaceae, can also produce coppice or epicormic shoots in response to drought or fire. It is likely that this ability is responsible for the survival of the original remanants in the National Park, with new upper stems regenerating from below-ground stocks century after century.

A potential issue with clonal reproduction is the lack of genetic diversity, which could make the pines susceptible to further environmental changes or pests. However, many trees are maturing and producing viable seeds, and there is certainly diversity in the phenology with some Wollemi of the same age producing female cones, some male cones (and some both).




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The ConversationDespite the ability to survive cold and heat and even recover from damage using epicormics, Wollemi Pines may not make ideal street trees, as the branches on the trunk shed relatively quickly. Shedding leaves, bark or branches are regularly complained about by residents in cities. But in the right place in a backyard – with low frost intensity, warm summers and enough moisture – you can grow your very own dinosaur tree.

Cris Brack, Assoc Professor Forest measurement & management, Australian National University

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

Hold your horses – brumby fertility control isn’t that easy



File 20180528 51141 u4n53e.jpeg?ixlib=rb 1.1
A government plan to ‘dart’ wild horses with fertility control drugs ignores science and expert advice.
Author provided

Andrea Harvey, University of Technology Sydney; Carolynne Joone, James Cook University, and Jordan Hampton, Murdoch University

A proposed Kosciuszko Wild Horse Heritage Bill that rules out shooting horses is based on a flawed understanding of fertility control. Unfortunately, by ignoring scientific evidence and expert advice horses will be condemned to slow starvation.




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The bill, which also proposes relocating horses within the park, or removal and domestication, intends to use fertility control for longer-term population control. But this simply isn’t feasible, and is unlikely to become so in the near future.

Vaccine darts are not a panacea

Immunocontraceptive vaccines that have been used for fertility control in wild horses in North America include the gonadotrophin releasing hormone (GnRH) vaccine, GonaCon, and porcine zona pellucida (PZP) vaccines. Administration requires injection: there is no effective oral vaccine. Injection requires either trapping horses and injecting them by hand, or darting them.

Darting brumbies requires getting very close, which is impossible in many parts of the Kosciuszko National Park.
Author provided

Immunocontraception has only been successfully used in smaller and more isolated populations (such as islands). Population modelling has estimated that over 50% of mares would need to be treated in KNP just to slow the rate of population increase within 2–5 years.

Although the precise number of horses in KNP is hotly debated, even at the lowest estimates almost 1,000 mares would need to be treated to have the desired impact on population growth – and it would still take 10–20 years before the population size was reduced substantially through natural mortality. And that is on the proviso that we could actually administer the vaccine to this number of mares.

Trapping enough horses across KNP (an area of about 700,000 hectares) would likely be impossible. Dart administration sounds intuitively appealing but is a complex process and will not be possible for large numbers of horses in difficult, mountainous terrain.

Staff must be extensively trained for licences before they can administer darts. More importantly, darting can only be safely performed within around 40 metres of a stationary horse, and with a clear line of vision. This must be done accurately and without causing ballistic injuries.

Injected animals must be marked (with dye, for example) so that they can be identified for booster shots as needed.

As demonstrated in a recent trial of fertility control darting for eastern grey kangaroos in the ACT, it is extremely challenging to manage all of these goals in the field. Helicopters can be used to dart animals, but this adds animal welfare impacts due to pursuit and lower levels of accuracy.

In other parts of the world where dart administration of immunocontraceptives has been successful, they have been applied to horses that are used to people, allowing staff to approach horses on foot. This is a very different situation to KNP.

Although it is possible to closely approach some horses in KNP, ongoing research has revealed that it is only possible to get within 200–500m of most horses in the larger populations.

Furthermore, it would be close to impossible to both identify and locate the same horses on multiple occasions, as required for booster vaccination injections. In more densely forested areas, it can be challenging to even see horses, let alone dart them.

There is no vehicle access to many parts of KNP where horses live, and long treks across challenging terrain would make attempts to locate all horses very labour-intensive. Furthermore, many areas of KNP are completely inaccessible in winter due to snow, making darting before the spring breeding season even more problematic.

What would we be vaccinating the horses with?

There’s also the question of what exactly the horses would be vaccinated with. GonaCon and PZP are not produced in commercial quantities, are not currently available in Australia and are not straightforward to import. Australian quarantine regulations may prevent the import of reagents derived from animals, such as conventional PZP which is derived from pig ovaries.

Producing PZP in Australia brings additional challenges, without guaranteeing the same efficacy. While work on a synthetic PZP formulation is ongoing, initial results in mares were disappointing.

There are two alternative GnRH vaccines available in Australia. One has shown less effectiveness than required in a pilot trial and while the other is registered for use in domestic mares, it lasts a relatively short time and is prohibitively expensive.

Most contraceptive vaccines require an initial injection followed by a second injection about one month later to achieve maximum efficacy, and then annual booster injections. GonaCon is promoted as having 3-year efficacy after a single injection, but that significantly reduces after the first 12 months. Long-acting PZP formulations have been investigated in North America; while results appeared promising initially, more recent work showed a contraceptive efficacy of under 60% beyond one year after treatment. Furthermore, the viscous nature of these longer-acting formulations make administration by dart more challenging.

Alternative fertility control options such as surgical sterilisation or intra-uterine devices have even more practical hurdles. For all of these reasons, a recent peer-reviewed study by two Australian reproductive experts concluded that current fertility control methods are not feasible for halting the population growth of wild horses in Australia.

Although some newer technologies are undergoing investigation, realistically it will be a long time before contraception for wild horses becomes an effective reality in Australia.

‘No-kill’ bill means slow starvation

Without a feasible method for sterilising horses, the newly proposed bill will mean population control is mainly through food limitation.

While “no kill” is seemingly more compassionate, it may ultimately and unintentionally be crueller.

As horse populations reach the carrying capacity of their habitats, they become malnourished and their fertility declines. Horses in very poor condition will not produce foals. When malnutrition persists, many horses will die young and many will die slowly.

This was dramatically demonstrated four years ago, when researchers discovered emaciated brumbies in the Snowy Mountains cannibalising their fellows and more emerging research is further confirming that extreme malnutrition is ongoing in parts of KNP.




Read more:
The grim story of the Snowy Mountains’ cannibal horses


The ConversationIn time, the number of horses suffering chronic malnutrition and dying of starvation is likely to increase. Is this truly humane population control?

Andrea Harvey, Veterinary Specialist, PhD scholar (wild horse ecology & welfare), University of Technology Sydney; Carolynne Joone, , James Cook University, and Jordan Hampton, Adjunct Lecturer, Murdoch University

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

NSW’s no-cull brumby bill will consign feral horses to an even crueller fate



File 20180521 42242 2iay92.jpg?ixlib=rb 1.1
Research suggests there is no “safe number” of brumbies that will avoid harm to mountain ecosystems.
Jimmyvanderwall/Wikimedia Commons, CC BY-SA

Don Driscoll, Deakin University

New South Wales’ proposed brumby legislation – which abandons plans to cull feral horses in Kosciuszko National Park – is a dangerously reckless policy that will escalate environmental impacts, escalate costs, and put horses at risk of extreme suffering.

The New South Wales’ Deputy Premier John Barilaro was reported as saying the cultural significance of the brumbies needed to be recognised.

But the evidence regarding feral horse (brumby) impacts on the environment in the Australian alps makes it clear that large numbers of feral horses are incompatible with maintaining the ecological values of Kosciuszko National Park.




Read more:
Without culling, Victoria’s feral horse plan looks set to fail


In a letter to the then premier Mike Baird in 2016, I and 40 other ecologists noted that feral horses have well documented impacts on streams and catchments:

Feral horses damage waterways, degrade soil, spread weeds and alter vegetation. These changes are likely to have negative impacts on native fauna.

Reports to both the Victorian and NSW governments have expressed concern over the impact on threatened species unless horses are culled. In NSW, horses directly destroy the habitat of already threatened species, including two species of critically endangered corroboree frogs, the critically endangered smoky mouse, endangered reptiles like the alpine she-oak skink and Guthega skink, and several plant species.

In its report, Parks Victoria suggested that native mammals such as wallabies and kangaroos are also out-competed and driven away by feral horses.

The threat posed by feral horses to native species and communities is so great that the NSW Threatened Species Scientific Committee has released a preliminary determination to list feral horses as a key threatening process. This report demonstrates that feral horses have well established environmental impacts and that action to reduce this threat is now urgent.

What’s more, there may be no “safe level” of feral horse numbers, below which the environment can cope with the damage. In a new report for the Victorian government, the impacts of feral horses on the Bogong High Plains was found to be cumulative, meaning that the damage caused by even a small number of horses accumulates over time, because the rate of recovery in alpine conditions is extremely slow.

Horse-free zones

Contrary to the “brumby bill” which would leave thousands of feral horses in Kosciuszko National Park, and contrary to the draft management plan that would reduce feral horses down to 600 over 20 years, to prevent horse damage, all of the horses must be removed.

Removing all of the feral horses from Kosciuszko National Park is also a value judgement. NSW sets aside only 9.2% of its land in protected areas. That’s less than 10% where nature conservation has priority, and more than 90% where people and our livestock and crops take precedence. This is already an extreme compromise, and does not even reach international targets under the Convention on Biological Diversity to have 17% of land area in protected areas.

The brumby bill will worsen this already below-par compromise by reneging on commitments to protect Australian native species, and transforming our national park into a playground for escaped exotic livestock.

The bill proposes to move horses from sensitive areas into less sensitive parts of the national park. But this is likely to fail, for two reasons. First, there is no clear way that this could be achieved without great cost and horse suffering.

Trapping horses has been experimented with since 2008, with, on average, 450 horses removed from Kosciuszko each year, at a cost of more than A$1,000 per horse. This was from open woodland habitat with good road access. But many of the most sensitive environments are in the least accessible areas, such as the main Kosciuszko range.

Without culling, it is not clear how parks staff could remove horses from these areas. At best, it would be expensive because it would be so labour-intensive. It would require new infrastructure in remote areas (which is undesirable for several reasons), and could require mustering with helicopters, also very costly. Mustering, trapping and trucking horses have serious animal welfare concerns, making them a crueller alternative than culling.

Second, moving more horses into areas that are already overrun by these quadrupeds places the horse population at risk of ecological collapse. Horse populations can increase at 20% or more every year. There were 6,000 horses in Kosciuszko National Park in 2014, so there could be more than twice that number by now.

By moving horses from one part of the park to another, the brumby bill will inevitably lead to unprecedented horse densities relative to the food available. There would be a real risk of mass horse starvation. By ignoring these basic ecological processes, the bill is likely to preside over more horse suffering than would be caused by a cull.




Read more:
The grim story of the Snowy Mountains’ cannibal horses


The proposed legislation is bad for horses, disastrous for the environment and, if relocations are actually implemented, extremely expensive. There are less cruel, cheaper, and more environmentally friendly solutions to this problem. Cull the horses in the national park (the least cruel of the range of viable methods), constrain brumby herds to the many private properties around the park to foster innovation in ecotourism, and invest in other environmentally friendly cultural activities to celebrate brumby culture, such as horse events outside the park, signs such as those around Victoria’s alpine huts, sculptures, poetry and movies.

This is the win-win solution we should be aiming for, not the reckless version on the table at the moment.


The ConversationThis article was amended on May 22, 2018, to clarify that the brumby population in Kosciuszko National Park was 6,000 in 2014, not 2016 as previously stated.

Don Driscoll, Professor in Terrestrial Ecology, Deakin University

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