More sightings of an endangered species don’t always mean it’s recovering



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Leadbeater’s possum sightings are up – but that doesn’t mean the critically endangered species is recovering.
David Lindenmeyer, Author provided

David Lindenmayer, Australian National University

If more sightings of an endangered species are recorded, does that mean its numbers are increasing? Australia’s native forest logging industry is arguing yes.

On the basis of an increase in sightings of Leadbeater’s possums, advocates for Victorian native forest logging industry has proposed to downgrade the possum’s conservation status from critically endangered (thus facilitating ongoing logging in and around potential habitat in Victoria’s Central Highlands).

But while this sounds reasonable, increased sightings aren’t always a reliable measure of endangered species’ viability. Often, an increase in sightings can be attributed to two things: either more people are trying to spot the animal in question; or new work that has used different parameters to previous studies.


Read more: Victoria must stop clearfelling to save Leadbeater’s possum


Why more sightings may not mean species recovery

One of the ultimate achievements in successful conservation is to downlist a threatened species – for example from critically endangered to endangered, or from endangered to vulnerable. But this requires high-quality, long-term survey data that shows substantial recovery, as well as proof that the key threats to a species’ persistence have been truly mitigated.

An example of a failure to do due diligence was the woylie in Western Australia, (also known as the brush-tailed bettong). It was downlisted in 1996 but then within 3 years suffered an enormous and still not well understood population crash (from which it has still not recovered). Its conservation status was uplisted in 2008.

There have been more records of Leadbeater’s possum in the last few years, but this growth is most likely a function of a large increase in the amount of effort invested in trying to find them.

In areas zoned for timber harvesting, locations with a confirmed Leadbeater’s possum sighting are excluded from logging. This has motivated large numbers of people who are concerned about the plight of the possum to devote many hours to finding animals.

The detection of more animals with greater searching is a well-known phenomenon in ecology and other disciplines. Last year, for example, sightings of wild tiger populations rose by 22% – but further investigation found that the increase was most likely caused by changes in methodology and greater effort in surveying.


Read more: Australia’s species need an independent champion


In fisheries this relationship is termed catch per unit effort. For example, even with rapidly declining numbers in a fishery, the number of fish caught can stay the same or even go up when more efficient and targeted techniques are adopted. Sadly, this intensified effort can often cause fish stocks to collapse.

The real evidence on Leadbeater’s possum

As stated earlier, the first critical piece of evidence required to justify downlisting is robust evidence of long-term improvement in population size. So what does the evidence tell us about Leadbeater’s possum?

For more than 34 years, the Australian National University has monitored Leadbeater’s possum including at more than 160 permanent sites since 1997. This large-scale, long-term data set shows that the possum is in significant decline. Over the past 19 years, the number of survey sites where the possum was detected has dropped by almost two-thirds.

The second critical requirement for delisting is evidence that the key processes threatening the species have been mitigated.

One of the principal threats facing Leadbeater’s possum is the rapid ongoing decline in large old trees which are the sole form of natural nesting sites for the species.

As part of ecological surveys in the wet forests of Victoria, which have been running since 1983, the Australian National University has been collecting information on hollow-bearing trees. The most recent analysis of this large and long-term data set suggests that if current declines continue, by 2040, populations of large old trees may be less than 10% of what they were in 1997.

Another key threatening processes which has not been addressed is fire. Victoria’s wet ash forests are extremely fire prone, in part because forests that regenerate after logging are significantly more likely to burn at elevated severity.

The significant risks facing the mountain ash forests in which Leadbeater’s possum lives has resulted in the forest itself being classified as critically endangered.

No grounds for reducing the conservation status

Efforts to downlist Leadbeater’s possum are misguided at best. The greater number of records in recent years is most likely a reflection of greater survey effort. In contrast, robust long-term monitoring data clearly shows a significant decline in population.

Most importantly, the key processes causing the decline of Leadbeater’s possum (and other threatened species in the same area, like the greater glider) have not been mitigated; indeed they are intensifying (such as the increasing fire burden with increasing area of logged forest).

There is little room to gamble with these species. Leadbeater’s possum and the greater glider currently do not breed in captivity, so expensive fallback options like captive breeding and reintroduction are not viable possibilities if wild populations crash.

The loss of these animals from ill-informed downlisting would add to Australia’s already appalling record on species loss. Approximately 10% of our mammal fauna has gone extinct – the worst rate in the world, and 30 times worse than places of equivalent size, such as the United States.

The ConversationMore formally protected areas, and not downlisting their conservation status, is the most scientifically robust option for the conservation of this iconic animal.

David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University

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

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Australia’s species need an independent champion


Euan Ritchie, Deakin University; Dale Nimmo, Charles Sturt University; Don Driscoll, Deakin University; Geoffrey Heard, Charles Sturt University; James Watson, The University of Queensland; Megan C Evans, The University of Queensland, and Tim Doherty, Deakin University

Furore erupted last week among many Australians who care for our native species.

First we heard that land clearing in Queensland soared to a staggering 400,000 or so hectares in 2015-16, a near 30% increase from the previous year. Second, the federal government’s outgoing Threatened Species Commissioner, Gregory Andrews, implied on national radio that land clearing was not a pressing issue for Australia’s threatened species.

This is a troubling public message, particularly as the government’s own State of the Environment Report 2016 lists “clearing, fragmentation and declining quality of habitat” as a primary driver of biodiversity decline across the continent.

What’s more, loss of vegetation cover can exacerbate threats to wildlife, by making it easier for cats and other invasive predators to kill native animals.

Habitat loss and fragmentation are major threats to Australian biodiversity. The down arrow represents a deteriorating trend and the straight line represents a stable trend.
State of the Environment Report 2016 – Biodiversity section

These comments highlight key issues with the Threatened Species Commissioner’s current remit, made more pressing due to timing: the federal government will soon appoint a new commissioner, a “TSC 2.0”, if you will.

Threatened Species Commissioner 1.0

The commissioner’s role was established in 2014 to address the dire state of threatened species; a key initiative of the then environment minister, Greg Hunt. The remit was sixfold, including bringing a new national focus to conservation efforts; raising awareness and support for threatened species in the community; and taking an evidence-based approach to ensure conservation efforts are better targeted and co-ordinated and more effective.

The increasing number of species listed as threatened under the Environment Protection and Biodiversity Conservation Act 1999. Some 492 species have been added since 2000.
Source: Federal Department of Environment and Energy

Did TSC 1.0 meet the objectives?

We can confidently say “yes” in relation to the objectives of collaboration, public awareness and promotion of threatened species conservation. Andrews travelled widely and engaged directly with stakeholders, maintained active social media feeds, developed a YouTube channel, and had numerous media engagements.

Also laudable was the 2015 Threatened Species Summit, attended by some 250 delegates from a diverse set of stakeholders, which garnered significant media coverage.

But elsewhere progress has been mixed. The development of the Threatened Species Strategy is welcome, but the plan does not go nearly far enough. Key targets by 2020 are improvements in the population trajectories of 20 mammals, 20 birds and 30 plants. But this represents a mere 4% of Australia’s threatened species, excluding all threatened reptiles, amphibians, fishes and invertebrates, and most of our threatened flora.

The focus on threatening processes is equally narrow. The science tells us that habitat loss is a top threat to Australia’s biodiversity. Land clearing has been listed as a key threatening process under federal legislation since 2001.

Yet the Threatened Species Strategy mentions land clearing zero times and habitat loss just twice. Feral cats, on the other hand, are mentioned 78 times, with the plan overwhelmingly focused on culling this one invasive species. Other major introduced pests – foxes, rabbits, feral pigs and goats – are mentioned 10 times between them.

Feral cats are a key threat to mammals, reptiles and birds, but not to Australia’s 1,272 threatened plants.

An on-ground focus and mobilising of financial and logistical resources to support threatened species recovery was a welcome development during Andrews’s tenure. His second progress report cites AU$131 million in funding for projects in support of threatened species since 2014.

This is a significant sum. But it is just 0.017% of the government’s AU$416.9 billion annual revenue – well short of what’s needed to reverse species declines.

Likewise, funding for threatened species must be better targeted. Of the 499 projects cited in the TSC second progress report, 361 were those of the Green Army and 20 Million Trees programs (costing AU$78 million, 60% of total funding). Neither program is specifically devoted to threatened species, and their benefit in this regard is doubtful.

The next commissioner’s checklist

Australians and democratic societies should have access to reliable, independent and objective information about the current state of our natural heritage, and how government decisions influence its trajectory. That’s a critical role that TSC 2.0 should play.

Expertise will be crucial for the new appointee. Given the complex science of species conservation, a background in environmental science is a clear requirement, just as a background in economics would be expected for the chair of the Productivity Commission, or a grounding in law for a human rights commissioner.

For a commissioner to work effectively, they must also be willing to comment on politically sensitive issues and put themselves at odds with the government when necessary. Commissioners typically work as the head of an independent statutory body, such as the Productivity Commission, the Australian Securities and Investments Commission, and the Australian Electoral Commission.

However, the TSC position sits within the Department of Environment and Energy and so, like any public servant, the commissioner is restricted in what they can say in public forums. A more accurate name for the current position would be Threatened Species Ambassador.

The ConversationBut if the TSC 2.0 is to be a truly informed and independent voice for Australia’s threatened species, the role must sit within a statutory authority, at arm’s length from government. This is the case in New Zealand, where an independent environment commission has operated since 1986. It’s time for Australia to follow suit.

Euan Ritchie, Senior Lecturer in Ecology, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University; Dale Nimmo, ARC DECRA Fellow, Charles Sturt University; Don Driscoll, Professor in Terrestrial Ecology, Deakin University; Geoffrey Heard, Lecturer in Wildlife Ecology and Management, Charles Sturt University; James Watson, Associate Professor, The University of Queensland; Megan C Evans, Postdoctoral Research Fellow, Environmental Policy, The University of Queensland, and Tim Doherty, Research Fellow, Deakin University

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

What whales and dolphins can tell us about the health of our oceans



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Dolphins contribute important knowledge about ocean health.
Shutterstock

Stephanie Plön, Nelson Mandela University

From the poles to the equator, marine mammals such as seals, dolphins and whales, play an important role in global ecosystems as apex predators, ecosystem engineers and even organic ocean fertilisers. The ocean off the coast of South Africa is home to a high diversity of these mammals and is recognised as a global marine biodiversity hotspot.

Marine mammals are often referred to as “sentinels” of ocean health. Numerous studies have explored the effects of both noise and chemical pollution, habitat degradation, changes in climate and food webs on these marine apex predators. Yet the interplay of these factors isn’t well understood.

Our research on the unfortunate dolphins incidentally caught in shark nets off South Africa’s KwaZulu-Natal coast has helped fill in some of the gaps. By assessing the health of these dolphins we have provided valuable baseline information on conditions affecting coastal dolphin populations in South Africa. This is the first systematic health assessment in incidentally caught dolphins in the Southern Hemisphere.

But to gain a fuller picture of the health of marine mammals in these waters I am now combining this contemporary field research with historical data, like the collection at the Port Elizabeth Museum Bayworld.

The combination of data on diet, reproduction, population structure and health helps us gain a better understanding of the pressures and changes these apex predator populations face. And it helps us understand it in relation to global change, including both climate change and pressures brought about by human behaviour.

My research sheds light on multiple factors: pollutant levels, parasites, and availability of prey, all have an impact on individuals as well as populations.

Understanding the health of these animals also gives us insight into the state of the world’s oceans. This is relevant because oceans affect the entire ecosystem including food security, climate and people’s health. This degree of connectedness is highlighted by recent discoveries about how whales act as ecosystem engineers.

The accumulation of this knowledge is important because the planet’s oceans aren’t being protected. Recent popular documentaries such as “Sonic Sea” and “Plastic Ocean” have highlighted their exploitation and pollution.

What’s missing

Without baseline knowledge it’s challenging to establish the potential effects that new anthropogenic developments (those caused by human behaviour) have on local whale and dolphin populations.

For example, we know that whales are sensitive to shipping noise, so what potential impact could a new deep water port have on mothers and their calves? Could it drive them away from these nursery areas, or could it lead to an increased risk of whales and ships colliding? To answer this and monitor the change that a new port brings with it, we are investigating the soundscape of two bays in the Eastern Cape (one with a new port, one without) in parallel with baleen whale mother-calf behaviour.

Another example is understanding how changes in the Sardine run over the past 15 years have affected the diets of these mammals. The Sardine run is an annual phenomenon when large shoals of Sardine migrate northwards along the coast into KwaZulu-Natal waters to spawn. Using long-term data and samples from the Port Elizabeth Museum research collection, we have been able to establish that over the the past 20 or so years the main predator in the Sardine run – the long-beaked common dolphin – has shifted its diet to mackerel. Although such changes in diet can have potential impacts on the health of the dolphins, parallel investigations on the trophic level these animals feed at (using isotope data from teeth) and the body condition of the dolphins (using long-term data on blubber thickness), indicated no adverse effects to the dolphins.

Our analysis highlights how marine mammals may be used as indicators of environmental change and why research is important.

Finding answers to intricate questions on environmental change is not always easy. But a better understanding and knowledge of the environment these animals live in has to be incorporated into studies contributing to their conservation and management. Such studies are becoming increasingly relevant as they highlight the fast degradation of the marine environment.

For example, a recent study identified antibiotic resistant bacteria in both sea water samples and exhaled breath samples from killer whales. This suggests that the marine environment has been contaminated with human waste which in turn has significant medical implications for humans.

Gaining such information is particularly important given the rapid changes taking place in the oceans, such as those on South Africa’s southern and eastern coastline. This includes increasing coastal development, new deep water ports being built or expanded, and parts of the deep sea being explored for oil and gas.

To assess these changes and what they mean for the environment, baseline studies need to be carried out so that potential effects can be assessed. Whales and dolphins are increasingly being recognised as indicators of ocean health in this endeavour.

And a continuation of the research we did on dolphins caught in nets will help document the cyclic changes that can be seen as normal variation in a population. This could prove important for assessing future catastrophic events, such as the Deep Horizon oil spill.

What next

The oceans absorb over 25% of the world’s carbon pollution as well as heat generated by global warming. They also produce at least 50% of the planet’s oxygen, and are home to 80% of all life on earth. Yet only 5% of this vital component of our planet has been explored.

The ConversationResearch on whales and dolphins contributes important knowledge about ocean health. Historical data increasingly provides a guideline to teasing out natural variations in populations and assessing the contribution that multiple factors have on these animals. In time, this will ensure that policy makers are being given sound scientific information. It will also provide us with a good barometer of the overall health of our oceans.

Stephanie Plön, Researcher, Earth Stewardship Science Research Institute, Nelson Mandela University

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

From feral camels to ‘cocaine hippos’, large animals are rewilding the world



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Most of the world’s wild horses, such as the Australian brumby, are outside their historic native range.
Andrea Harvey

Erick Lundgren, University of Technology Sydney; Arian Wallach, University of Technology Sydney; Daniel Ramp, University of Technology Sydney, and William Ripple, Oregon State University

Throughout history, humans have taken plants and animals with them as they travelled the world. Those that survived the journey to establish populations in the diaspora have found new opportunities as they integrate into new ecosystems.

These immigrant populations have come to be regarded as “invaders” and “aliens” that threaten pristine nature. But for many species, migration may just be a way to survive the global extinction crisis.

In our recently published study, we found that one of the Earth’s most imperilled group of species is hanging on in part thanks to introduced populations.

Megafauna – plant-eating terrestrial mammals weighing more than 100kg – have established in new and unexpected places. These “feral” populations are rewilding the world with unique and fascinating ecological functions that had been lost for thousands of years.

Today’s world of giants is only a shadow of its former glory. Around 50,000 years ago, giant kangaroos, rhino-like diprotodons, and other unimaginable animals were lost from Australia.


Read more: Giant marsupials once migrated across an Australian Ice Age landscape


Later, around 12,000 years ago, the last of the mammoths, glyptodonts, several species of horses and camels, house-sized ground sloths and other great beasts vanished from North America.

In New Zealand, a mere 800 years ago, a riot of giant flightless birds still grazed and browsed the landscape.

The loss of Earth’s largest terrestrial animals at the end of the Pleistocene was most likely caused by humans.

Sadly, even those large beasts that survived that collapse are now being lost, with 60% of today’s megafauna threatened with extinction. This threat is leading to international calls for urgent intervention to save the last of Earth’s giants.

A wilder world than we think

Formal conservation distribution maps show that much of Earth is empty of megafauna. But this is only a part of the picture.

Many megafauna are now found outside their historic native ranges. In fact, thanks to introduced populations, regional megafauna species richness is substantially higher today than at any other time during the past 10,000 years.

Megafauna have expanded beyond their historic native range to rewild the world. Number of megafauna per region, in their ‘native’ range only (a) and in their full range (b)
Modified and reproduced from Lundgren et al. 2017

Worldwide introductions have increased the number of megafauna by 11% in Africa and Asia, by 33% in Europe, by 57% in North America, by 62% in South America, and by 100% in Australia.

Australia lost all of its native megafauna tens of thousands of years ago, but today has eight introduced megafauna species, including the world’s only wild population of dromedary camels.

Australia lost all of its native megafauna tens of thousands of years ago, but is now home to eight introduced species, including the world’s only population of wild dromedary camels. Remote camera trap footage from our research program shows wild brumbies, wild donkeys and wild camels sharing water sources with Australian dingoes, emus and bustards in the deserts of South Australia.

These immigrant megafauna have found critical sanctuary. Overall, 64% of introduced megafauna species are either threatened, extinct, or declining in their native ranges.

Some megafauna have survived thanks to domestication and subsequent “feralisation”, forming a bridge between the wild pre-agricultural landscapes of the early Holocene almost 10,000 years ago, to the wild post-industrial ecosystems of the Anthropocene today.

Wild cattle, for example, are descendants of the extinct aurochs. Meanwhile, the wild camels of Australia have brought back a species extinct in the wild for thousands of years. Likewise, the vast majority of the world’s wild horses and wild donkeys are feral.

There have been global calls to rewild the world, but rewilding has already been happening, often with little intention and in unexpected ways.

A small population of wild hippopotamuses has recently established in South America. The nicknamed “cocaine hippos” are the offspring of animals who escaped the abandoned hacienda of Colombian drug lord Pablo Escobar.

Colombia’s growing ‘cocaine hippo’ population is descended from animals kept at Pablo Escobar’s hacienda.

By insisting that only idealised pre-human ecosystems are worth conserving, we overlook the fact that these emerging new forms of wilderness are not only common but critical to the survival of many existing ecosystems.

Vital functions

Megafauna are Earth’s tree-breakers, wood-eaters, hole-diggers, trailblazers, wallowers, nutrient-movers, and seed-carriers. By consuming coarse, fibrous plant matter they drive nutrient cycles that enrich soils, restructure plant communities, and help other species to survive.

The wide wanderings of megafauna move nutrients uphill that would otherwise wash downstream and into the oceans. These animals can be thought of as “nutrient pumps” that help maintain soil fertility. Megafauna also sustain communities of scavengers and predators.

In North America, we have found that introduced wild donkeys, locally known as “burros”, dig wells more than a metre deep to reach groundwater. At least 31 species use these wells, and in certain conditions they become nurseries for germinating trees.

Introduced wild donkeys (burros) are engineering the Sonoran Desert, United States.

The removal of donkeys and other introduced megafauna to protect desert springs in North America and Australia seems to have led to an exuberant growth of wetland vegetation that constricted open water habitat, dried some springs, and ultimately resulted in the extinction of native fish. Ironically, land managers now simulate megafauna by manually removing vegetation.

It is likely that introduced megafauna are doing much more that remains unknown because we have yet to accept these organisms as having ecological value.

Living in a feral world

Like any other species, the presence of megafauna benefits some species while challenging others. Introduced megafauna can put huge pressure on plant communities, but this is also true of native megafauna.

Whether we consider the ecological roles of introduced species like burros and brumbies as desirable or not depends primarily on our own values. But one thing is certain: no species operates in isolation.

Although megafauna are very large, predators can have significant influence on them. In Australia, dingo packs act cooperatively to hunt wild donkeys, wild horses, wild water buffalo and wild boar. In North America, mountain lions have been shown to limit populations of wild horses in some areas of Nevada.

Visions of protected dingoes hunting introduced donkeys and Sambar deer in Australia, or protected wolves hunting introduced Oryx and horses in the American West, can give us a new perspective on conserving both native and introduced species.

Nature doesn’t stand still. Dispensing with visions of historic wilderness, and the associated brutal measures usually applied to enforce those ideals, and focusing on the wilderness that exists is both pragmatic and optimistic.

After all, in this age of mass extinction, are not all species worth conserving?


The ConversationThis research will be presented at the 2017 International Compassionate Conservation Conference in Sydney.

Erick Lundgren, PhD Student, Centre for Compassionate Conservation, University of Technology Sydney; Arian Wallach, Chancellor’s Postdoctoral Research Fellow, Centre for Compassionate Conservation, University of Technology Sydney; Daniel Ramp, Associate Professor and Director, Centre for Compassionate Conservation, University of Technology Sydney, and William Ripple, Distinguished Professor and Director, Trophic Cascades Program, Oregon State University

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

I’ve always wondered: Why don’t hippos get cholera?


Julie Old, Western Sydney University

This is an article from I Have Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to alwayswondered@theconversation.edu.au


Why don’t hippopotamuses get cholera? Why are some animals resistant to waterborne disease? – Phil Morey

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The short answer is that cholera has evolved to infect humans, not hippos. Cholera is a disease caused by a curved rod-shaped bacterium called Vibrio cholerae. The disease is characterised by a profuse diarrhoea that resembles “rice water”, and can lead to death within hours.

Transmission electron microsope image of Vibrio cholerae that has been negatively stained.
Dartmouth Electron Microscope Facility via Wikipedia

Humans contract the disease from water contaminated with human sewage containing the bacteria. As cholera is a waterborne disease, it is prevalent in areas where human sanitation is lacking or less than ideal. Unlike many other diseases, it can’t be passed to us from animals, as malaria is from mosquitoes.

Once ingested by humans, the bacteria attach to the small intestine wall. There they reproduce, and prodcue a toxin called choleragen. The choleragen toxin is made up of two parts, called A and B. The B portion attaches the toxin to the cells in the intestine and the A portion chemically forces electrolytes and water from the intestinal cells themselves, thus leading to massive dehydration, diminished blood loss and ultimately death.

Vibrio cholerae, the bacteria that causes cholera, only impacts humans, and can only be transmitted to new human hosts via contaminated water. It’s likely that the disease mechanism is precisely adapted to human-specific molecules in the cell walls of our small intestine, and the molecular structure of the bacteria’s toxins.

The annotation on this 19th century medical illustration reads. ‘A young woman of Vienna, 23. The same woman one hour after the onset of cholera, and four hours before death.’
Wellcome Library, London, via Flickr/the lost gallery

Over millennia, both the disease-causing organism (pathogen) and host have been evolving counter-strategies against each other: the host to evade the pathogen, and pathogen to invade the host. These battles have led to the bacteria becoming host-specific, and now only able to infect humans.

The cholera vaccine works by taking advantage of this close host/pathogen relationship. It inhibits the action of the B portion of the cholera toxin, hence it prevents the bacteria from attaching to the intestinal wall.

Other waterborne diseases are caused by other pathogens (although the specific mechanisms or molecules involved differ). In some cases, as in cholera, the molecules required for infection are host-specific. Whilst other pathogens are not species specific, they are often associated with more closely-related species than less closely-related species. For example, foot and mouth disease affects cattle, sheep, deer and pigs, because they are all cloven-hoofed animals (Artiodatyla) and thus closely-related species.

Hippopotamuses (Hippopotamus amphibious and Choeropsis liberiensis) are more closely related to cetaceans (whales and dolphins), than humans, and therefore it is not surprising that they have different pathogens. That being said, hippopotamuses, like other animals, are likely to suffer from loose stools (dung) from time to time, whether due to other pathogens, or the quality of the huge amounts of plant material they ingest on a daily basis.

Dung is super important in hippopotamus society. Hippopotamus defecation or “dung showering” involves flicking their tail at the same time as defecating to distribute their dung far and wide, hence dung is used to mark their territory and assert dominance.

If hippopotamus dung spread a disease like cholera, it could be rapidly fatal for large populations. It is likely that the individuals affected would be removed by natural selection. Those that were resistant, or only mildly affected, would overcome the disease and live on to produce disease-resistant offspring. Over time, it is therefore likely hippopotamuses have adapted to their aquatic environments and thus rarely, if ever, become infected with waterborne diseases.

The Conversation* Email your question to alwayswondered@theconversation.edu.au

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Julie Old, Associate Professor, Biology, Zoology, Animal Science, Western Sydney University

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

Review of historic stock routes may put rare stretches of native plants and animals at risk


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The travelling stock routes are a precious national resource.
Author provided

Luke S. O’Loughlin, Australian National University; Damian Michael, Australian National University; David Lindenmayer, Australian National University, and Thea O’Loughlin, Charles Sturt University

Since the 19th century, Australian drovers have moved their livestock along networks of stock routes. Often following traditional Indigenous pathways, these corridors and stepping-stones of remnant vegetation cross the heavily cleared wheat and sheep belt in central New South Wales.

The publicly owned Travelling Stock Reserve network of New South Wales is now under government review, which could see the ownership of much of this crown land move into private hands.

But in a study published today in the Australian Journal of Botany we suggest that privatising stock routes may endanger vital woodlands and put vulnerable species at risk.


Read more: How ancient Aboriginal star maps have shaped Australia’s highway network


The review will establish how individual reserves are currently being used. Although originally established for graziers, the patches of bush in the network are now more likely to be used for recreation, cultural tourism, biodiversity conservation, apiary and drought-relief grazing.

This shift away from simply moving livestock has put pressure on the government to seek “value” in the network. The review will consider proposals from individuals and organisations to buy or acquire long-term leases for particular reserves.

It is likely that most proposals to purchase travelling stock reserves would come from existing agricultural operations.

A precious national resource

Travelling stock reserves across New South Wales represent some of the most intact examples of now-endangered temperate grassy woodland ecosystems.

Our research found that changing the status or use of these reserves could seriously impact these endangered woodlands. They criss-cross highly developed agricultural landscapes, which contain very limited amounts of remnant vegetation (areas where the bush is relatively untouched). Travelling stock reserves are therefore crucially important patches of habitat and resources for native plants and animals.

This isn’t the first time a change in ownership of travelling stock reserves has been flagged. Over the last century, as modern transport meant the reserves were used less and less for traditional droving, pressure to release these areas for conventional agriculture has increased.

Historic stock routes are still used for grazing cattle.
Daniel Florance, Author provided

To understand what a change in land tenure might mean to the conservation values of these woodlands, we spent five years monitoring vegetation in stock reserves in comparison to remnant woodlands on private farmland.

We found that travelling stock reserves contained a higher number of native plant species, more native shrubs, and less exotic plants than woodland remnants on private land.

The higher vegetation quality in travelling stock reserves was maintained over the five years, which included both the peak of Australia’s record-breaking Millennium Drought and the heavy rainfall that followed, referred to as the “Big Wet”.

The take-home message was that remnant woodland on public land was typically in better nick than in private hands.

Importantly, other studies have found that this high-quality vegetation is critical for many threatened and vulnerable native animals. For example, eastern yellow robins and black-chinned honeyeaters occur more frequently in places with more shrubs growing below the canopy.

The vulnerable superb parrot also uses travelling stock reserves for habitat.
Damian Michael, Author provided

The contrast we saw between woodlands in travelling stock reserves and private land reflects the different ways they’re typically managed. Travelling stock reserves have a history of periodic low-intensity grazing, mostly by cattle, with long rest periods. Woodland on active farms tend to be more intensively grazed, by sheep and cattle, often without any strategic rest periods.

The stock reserves’ future

The uncertain future of travelling stock reserves casts doubt on the state of biodiversity across New South Wales.

The current review of travelling stock reserves is considering each reserve in isolation. It flies in the face of the belief of many managers, practitioners and researchers that the true value of these reserves is in the integrity of the entire network – that the whole is greater than the sum of its parts.

Travelling stock reserves protect threatened species, allow the movement of wildlife, are seed sources for habitat restoration efforts, and support the ecosystem of adjacent agricultural land. These benefits depend on the quality of the remnant vegetation, which is determined by the grazing regime imposed by who owns and manages the land.

Of course, not all travelling stock reserves are in good condition. Some are subject to high-intensity livestock grazing (for example, under longer-term grazing leases) coupled with a lack of funding to manage and enhance natural values.

Changing the land tenure status of travelling stock reserves risks increasing grazing pressure, which our study suggests would reduce ecosystem quality and decrease their conservation value.

The travelling stock routes are important parts of our ecosystem, our national heritage, and our landscape. They can best be preserved by remaining as public land, so the entire network can be managed sustainably.

This requires adequate funding for the Local Land Services, so they can appropriately manage pest animals, weeds, erosion and illegal firewood harvesting and rubbish dumping.

The ConversationTravelling stock reserves are more than just The Long Paddock – they are important public land, whose ecological value has been maintained under public control. They should continue to be managed for the public good.

Luke S. O’Loughlin, Research fellow, Australian National University; Damian Michael, Ecologist, Australian National University; David Lindenmayer, Professor, The Fenner School of Environment and Society, Australian National University, and Thea O’Loughlin, Ecologist, Adjunct Researcher, Charles Sturt University

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