We modelled the future of Leadbeater’s possum habitat and found bushfires, not logging, pose the greatest threat



Rohan Clarke, Author provided

Craig Nitschke, University of Melbourne; Andrew Robinson, University of Melbourne; Melissa Fedrigo, University of Melbourne; Patrick Baker, University of Melbourne, and Raphael Trouve, University of Melbourne

The Federal Court recently ruled that a timber harvesting company couldn’t log potential habitat of the critically endangered Leadbeater’s possum.

This decision led to the immediate protection of more Leadbeater’s possum habitat and will lead to further habitat set aside over the next ten years as native timber harvesting is phased out in Victoria.

But these short-term, site-based measures will not guarantee the long-term conservation of this iconic Victorian species.




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The Leadbeater’s possum finally had its day in court. It may change the future of logging in Australia


Our new study modelled changes in forests over the next 250 years, focusing on 280,000 hectares of Victoria’s Central Highlands, home to the majority of remaining Leadbeater’s possums.

We looked at different scenarios of how both climate change and timber harvesting might play out. And we identified three important findings.

First, Leadbeater’s possum habitat is dynamic. It’s transient across the landscape over time as disturbances, such as bushfires, continually change the spatial distribution of hollow-bearing trees and young forests.

Second, while timber harvesting poses a local-scale threat, at a larger scale – across hundreds of thousands of hectares – bushfire poses the greatest threat to the species’ habitat.

Last, we found less than half of the area within current parks, reserves, and timber harvest exclusion zones provided stable long-term habitat for Leadbeater’s possum over the next century.

The Black Saturday bushfires razed almost half of the Leadbeater’s possum habitat in 2009.
Shutterstock

Future habitat scenarios

Leadbeater’s possums live in ash and snow gum forests. They depend on two key habitat features: hollow-bearing trees for nesting and dense understorey for moving around the forest.

We used a set of four scenarios to explore how climate change and timber harvesting impact long-term habitat availability by focusing on the where and when hollow-bearing trees and dense understorey are found in the landscape.




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The scenarios included projecting current climate conditions, and projecting a 2℃ rise in average annual temperature with a 20% reduction in yearly rainfall.

For each of these climate scenarios, timber harvesting at current harvesting rates was either excluded or allowed in areas zoned for timber production.

Bushfires drive long-term habitat loss

Our simulations showed bushfire, not logging, is the biggest threat to habitat availability for Leadbeater’s possum in the Central Highlands. As the cumulative area burnt by fire increased, the quantity and quality of Leadbeater’s possum habitat decreased.

Tthe 2009 Black Saturday fires burned almost half of its habitat, causing its conservation status to jump from endangered to critically endangered.




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Bushfires have always been part of Australian landscapes and many species, including Leadbeater’s possum, have evolved alongside them. Eleven years later, Leadbeater’s possum are now recolonising areas burned in the 2009 bushfires.

But as climate change increases the frequency and scale of bushfires, our models suggest the Central Highlands landscape may support less suitable habitat.

Timber harvesting is less of a threat

While timber harvesting compounds the impacts of bushfires on Leadbeater’s possum habitat, across the landscape the effect is small in comparison. Timber harvesting reduced suitable habitat by only 1.4% to 2.3% over 250 years compared to scenarios without harvesting.

Within a coupe (the area of forest harvested in one operation), timber harvesting immediately reduces nesting and foraging habitat. But foraging habitat returns within 10 to 15 years and can be recolonised by Leadbeater’s possum – as long as nesting sites are nearby.




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Protecting vegetation around waterways, in particular, was critical for the development and survival of hollow-bearing trees in an increasingly fire-prone landscape.

But while timber harvesting had much smaller impacts than bushfires, the two did interact. Over time, the cumulative impacts of timber harvesting and bushfire homogenised forest structure across the landscape, leading to smaller patches of habitat that were less connected.

This increases the risk of local extinction for populations of Leadbeater’s possum living in these patches.

We need dynamic conservation areas

A core question for the conservation of any threatened species is: how well does the network of protected areas protect the species?

Our modelling framework meant we could test whether current areas set aside for Leadbeater’s possum conservation actually provide long-term protection.

Over the next 100 years, less than 50% of existing parks, reserves and timber-harvest exclusion zones will provide continuous habitat for Leadbeater’s possum due to climate change.

Distribution of Leadbeater’s possum habitat in the Central Highlands landscape modelled in our paper. Stable zones provided suitable habitat throughout the scenarios. Loss and gain were areas that lost or became habitat over the scenario.
Author provided

However, we also identified approximately 30,000 hectares of forest outside the current network of protected areas that can provide stable habitat for Leadbeater’s possum over the next century.

It’s vital we put protection zones into the areas possums are likely to migrate to as the climate changes. These areas should be a priority for conservation efforts.

A new conservation strategy

Historically, conservation planning has taken a static, site-based approach to protecting species.

This approach is doomed to fail in dynamic landscapes – particularly in fire-prone landscapes in a warming climate. For conservation planning to be successful, we need coordinated forest, fire, and conservation management that accounts for these dynamics across the whole landscape, not just in individual locations.




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We need a vision for how to make our landscapes more resilient to the growing threat of climate change and provide better protection for the unique flora and fauna that inhabit them.

This will require government agencies responsible for land management and conservation to coordinate current management activities across tenures, while simultaneously implementing future-focused conservation planning. Our landscape-modelling approach provides a first step in that direction.The Conversation

Craig Nitschke, Associate Professor – Forest and Landscape Dynamics, University of Melbourne; Andrew Robinson, Managing Director for Biosecurity Risk Research, University of Melbourne; Melissa Fedrigo, Remote Sensing Scientist and Ecological Modeller, University of Melbourne; Patrick Baker, ARC Future Fellow and Professor of Silviculture and Forest Ecology, University of Melbourne, and Raphael Trouve, Post-Doctoral Research Fellow Ecosystem And Forest Sciences, University of Melbourne

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

The Leadbeater’s possum finally had its day in court. It may change the future of logging in Australia



Shutterstock

Julia Dehm, La Trobe University

The Federal Court last week ruled that VicForests – a timber company owned by the Victorian government – breached environmental laws when they razed the habitat of the critically endangered Leadbeater’s possum and the vulnerable greater glider.

Environmentalists welcomed the judge’s decision, which sets an important legal precedent.

Under so-called “regional forest agreements”, a number of logging operations around Australia are exempt from federal environment laws. This effectively puts logging interests above those of threatened species. The court ruling narrows these exemptions and provides an opportunity to create stronger forestry laws.

A legal loophole

Since 1971, the Leadbeater’s possum has been the faunal emblem of Victoria. But only about 1,200 adults are left in the wild, almost exclusively in the Central Highlands region.




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Official conservation advice identifies the greatest threat to the species as habitat loss and fragmentation caused by the collapse of hollow-bearing trees, wildfire, logging and climate change.

Australia’s federal environmental laws require environmental impact assessment of any action likely to significantly impact a matter of national environmental significance, such as a listed threatened species.

But thanks to exemptions under regional forest agreements, logging has continued in the Central Highlands – even in the aftermath of this summer’s devastating bushfires.

So what are regional forest agreements?

Regional forest agreements were designed as a response to the so-called “forest wars” of the 1980s and 1990s.

In 1995, after logging trucks blockaded parliament, then Prime Minister Paul Keating offered a deal to the states: the federal government would accredit state forest management systems, and in return federal law would no longer apply to logging operations. Drawing up regional forest agreements between state and federal governments achieved this.




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Between 1997 and 2001, ten different agreements were signed, covering logging regions in Victoria, New South Wales, Tasmania and Western Australia. These agreements were for 20 years, which means many have now either expired and been renewed or extended, or are about to expire.

The agreements are supposed to satisfy a number of conditions. This includes that they’re based on an assessment of environmental and social values of forest areas. They should also provide for the ecologically sustainable management and use of forested areas, and the long-term stability of forest and forest industries.

But conservation experts argue the agreements have failed both to deliver certainty to forestry operations or to protect environmental values and ensure the conservation of biodiversity.

History of the court case

The legal proceedings against VicForests were initiated in 2017 by Friends of the Leadbeater’s Possum, a small community group which relied on crowd funding to cover legal costs.

Initially, the group argued Victoria’s failure to undertake a required review of the Central Highlands regional forest agreements every five years meant the usual exemption to federal environment laws should not apply.




Read more:
Environment laws have failed to tackle the extinction emergency. Here’s the proof


But in early 2018, Justice Mortimer ruled against this. But she also rejected VicForests’ arguments that any operation in an area covered by a regional forest agreement is automatically exempt from federal law.

She ruled that the logging operations will only be exempt from federal law if they comply with Victoria’s accredited system of forest management. This includes the requirements for threatened species, as specified in official action and management plans.

In response to this ruling, Friends of the Leadbeater’s Possum reformulated their claim.

They argued logging operations in 66 coupes (small areas of forest harvested in one operation) didn’t meet these requirements for threatened species, and so the exemption from federal laws didn’t apply.

The court ruling

In her ruling last week, the judge found VicForests unlawfully logged 26 coupes home to the Leadbeater’s possum and greater glider, and that logging a scheduled 41 other sections would put them at risk.

The court found the company breached a number of aspects of the Code of Practice for Timber Production 2014. This code is part of the Victorian regulatory system accredited by the regional forest agreement.

In particular, VicForests had not, as required, applied the “precautionary principle” in planning and conducting logging operations in coupes containing the greater glider.




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Nor had VicForests developed a comprehensive forest survey system, or engaged in a careful evaluation of management options to avoid dangers to these threatened species.

These failures meant the logging operations were not covered by the exemption from federal laws. As such, the court found VicForests had breached federal environmental law, as the logging operation had, or were likely to have, a significant impact on the two threatened species.

What now?

This case will have clear implications for logging operations governed by regional forest agreements.

In fact, the timber industry has called for state and federal governments to urgently respond to the case, and clarify the future of regional forest agreements.




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Arguably, logging operations conducted under a regional forest agreement can no longer rely on the exemption from federal environmental laws if those operations don’t comply with the state regulatory frameworks accredited under the regional forest agreements, especially provisions that protect threatened species.

And while making logging operations subject to federal environmental laws is a good thing, it’s not enough. Federal environmental laws are weak and don’t prevent species extinctions.

In any case, the result is the perfect opportunity for state and federal governments to rethink forest management. That means properly taking into account the ongoing threats to threatened species from climate change, wildfires and habitat loss.The Conversation

Julia Dehm, Lecturer, La Trobe University

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

Looks like an ANZAC biscuit, tastes like a protein bar: Bogong Bikkies help mountain pygmy-possums after fire



Zoos Victoria/Tim Bawden, Author provided

Marissa Parrott, University of Melbourne and Naomi Ezra Davis, University of Melbourne

Australia’s recent bushfires have razed over ten million hectares, and killed at least a billion animals. It’s likely countless more will die in the aftermath, as many species face starvation as the landscape slowly regenerates.

Even before the bushfires hit, we were working on supplementary food to help recover the critically endangered mountain pygmy-possum. They are seriously threatened by climate change, historic habitat destruction and more frequent intense fires.

Just months ago we landed on a recipe for Bogong Bikkies, nutritionally suitable baked biscuits that have the consistency of an ANZAC biscuit, taste a bit like a nutty gym protein bar and smell a little like Cheds crackers.

We never imagined our work would be needed so quickly – or urgently – but now our Bogong Bikkies are being deployed across the boulder fields of NSW, providing vital supplementary food to native species such as pygmy-possums, native bush rats and dusky antechinus.




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Hungry, hungry possums

Mountain pygmy-possums are the only Australian marsupial that hibernate every winter under snow, making it essential they build fat reserves before their long winter sleep. The main food source during their spring/summer breeding season is the migratory bogong moth.

However in 2017 and 2018 the billions of expected bogong moths largely failed to arrive, leaving many females underweight and unable to produce enough milk for their young. Due to a lack of food, 50-95% of females in monitored Victorian locations lost their entire litters.




Read more:
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In response, Zoos Victoria’s Healesville Sanctuary proposed creating a new supplementary food that could be used in the wild to support possums and their young until moth numbers recover.

Ten years ago, we analysed bogong moths to determine the fats, proteins, carbohydrates, vitamins and minerals required for a suitable breeding diet for possums in our captive breeding program.

While we have a successful diet for the possums in our care that includes nuts, insects, vegetables and a specially developed “bogong moth substitute”, the blend has the consistency of a soft caramel (or bogong moth abdomen) – not suitable for feeding in the wild. We needed a shelf-stable, long-lasting, nutritionally suitable food that could feed remote wild populations.

That’s the way the cookie crumbles

Throughout 2019, using our existing analyses of bogong moths, we worked with world experts in veterinary nutrition to develop Bogong Bikkies – nutritionally suitable baked biscuits for mountain pygmy-possums, and other species that live alongside them. We collaborated with Australian wildlife diet experts, Wombaroo, to have our new product commercially developed.

We then trialled the bikkies with the possums in our care at Healesville Sanctuary, so we could monitor whether the food was palatable or caused any health issues. It was a huge success. The possums liked the food, but happily ate other food too. This was exactly what we wanted: something that was completely safe and would be readily accepted, but not chosen over natural food sources.

Mountain Pygmy-possum mum and joeys.
Tim Bawden/Zoos Victoria., Author provided

Once satisfied our captive trials were a success, we had to find the best way to deliver food safely to possums in boulder fields in the wild. This meant buying or making 12 different feeder prototypes. Our local hardware store knew us all by name! We tested four feeders, most of which were designed and built on-site, and chose the most successful three for trials in the wild.

Working with Parks Victoria and the Victorian Mountain Pygmy-possum Recovery Team, we tested these three feeders at 20 stations deep in the Alpine National Park, monitored with remote infrared cameras.

Over the last few months, Zoos Victoria and Parks Victoria staff have been refilling feeders, changing camera batteries and analysing hundreds of thousands of images and videos. After months of work, watching wild mountain pygmy-possums, native bush rats and dusky antechinus visiting our feeders and eating the food was a triumph.

A possum feeder in the wild.
Zoos Victoria, Author provided

A raging inferno

Halfway through our research, some of the worst bushfires ever seen in Australia left habitats destroyed and our precious wildlife dead or starving. Victoria mountain pygmy-possum populations have so far not been directly impacted by fires this season, but the populations of northern Kosciuszko National Park, New South Wales, were hard hit.

While the habitat was destroyed, we hoped some possums had survived deep in the boulder fields, as they have with previous fires. But surviving the initial fire is no help, if their environment and food sources have been so devastated that they can’t gain enough weight to hibernate before winter’s snow.

Within days of the January fires, we had packaged up our most successful feeder type, examples of our cooked bikkies, our best recipe and 30kg of Bogong Bikkie mix, and rushed it urgently to our NSW partners.

An infrared image showing a wild mountain pygmy-possum eating a Bogong Bikkie from a feeder.
Zoos Victoria, Author provided

Teams from the NSW government’s Saving Our Species and NSW National Parks and Wildlife Service have now built and deployed 62 feeders and water stations in six boulder fields, baked batches of bikkies and started emergency feeding.

We’re thankful to have the food developed and research ready to assist. It is important to note, though, that such supplementary feeding is very intensive, and only appropriate for native species facing emergency situations, such as catastrophic fires.

If these bushfires teach us nothing else, it is the value of preparation, hard work and early funding to develop a range of conservation tools.

While we should all hope for the best, we must plan for the worst.


This article was co-authored Dr Kim Miller, Life Sciences Manager, Conservation and Research, at Healesville Sanctuary, Zoos Victoria, and Dr Leanne Wicker, Senior Veterinarian at Healesville Sanctuary, Zoos Victoria. The authors acknowledge Dr Linda Broome and the team from Biodiversity and Conservation (South East Branch) of the NSW Department of Planning, Industry and Environment for their work protecting the Mountain Pygmy-possum.


This article was corrected to clarify the impact on the mountain pymy-possum populations of northern Kosciuszko National Park.The Conversation

Marissa Parrott, Reproductive Biologist, Wildlife Conservation & Science, Zoos Victoria, and Honorary Research Associate, BioSciences, University of Melbourne and Naomi Ezra Davis, Environmental Scientist – Fauna, Parks Victoria; Honorary Fellow, School of BioSciences, University of Melbourne

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

You can help track 4 billion bogong moths with your smartphone – and save pygmy possums from extinction



Healesville Sanctuary, Werribee Open Range Zoo

Sally Sherwen, University of Melbourne and Therésa Jones, University of Melbourne

Each year, from September to mid-October, the tiny and very precious mountain pygmy-possums arise from their months of hibernation under the snow and begin feasting on billions of bogong moths that migrate from Queensland to Victoria’s alpine region.

But for the past two springs, moth numbers have collapsed from around 4.4 billion in alpine areas to an almost undetectable number of individuals. And the mountain pygmy-possums went hungry, dramatically affecting breeding success among the last remaining 2,000 that live in the wild.




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This year’s migration of bogong moths to the possums’ alpine home is crucial for the critically endangered mountain pygmy-possums. That’s why we’re asking you to do two simple things: turn off your lights at night, and if you see a bogong moth, take a picture.

What’s happened to the moths?

Bogong moths make an epic migration through Australia every spring.
Credit: Donald Hobern

We don’t know exactly why the moths are not making it to their summer alpine destination. It’s likely extreme drought, pesticides and changes in agricultural practices are all major factors. However, scientists believe that because moths use both the Earth’s magnetic field and visual cues on the horizon to navigate, light pollution from urban centres can confuse the moths and stall their journey.

Some of the greatest beacons on their path are Parliament House and Canberra’s bright surrounds. Both parliamentarians and the general public are being asked to turn unnecessary outdoor lights off from September 1 to October 31, as part of the Lights Off for Moths campaign.

Artificial night lighting has dramatically changed the nocturnal environment. In urban environments, the soft glow of moonlight is overpowered by bright streetlights, security lights and car headlamps. These light sources can be more than 1,000 times as bright as moonlight, and their biological impact is increasingly visible and widespread.

One of the most obvious impacts of artificial light at night is that it can attract animals (sometimes fatally). While a “moth to a flame” may be somewhat poetic, when one moth becomes hundreds, or potentially thousands, the ecological impact may be catastrophic. Current global lighting practices may be creating this very scenario.

Recent evidence links the presence of artificial light at night with large-scale deaths and shifts in nocturnal migration patterns in birds. In insects, artificial night lighting disrupts nocturnal pollination networks and is strongly linked with observed mass declines in insect (and particularly moth) populations.

No moths means hungry possums

When a species like bogong moths decline, it has huge ramifications. Insects in particular are vital pillars supporting whole ecosystems – without bees and other insect pollinators, for example, we risk the extinction of our flowering plants. Many birds, reptiles and mammals depend on insects as part of their diet.

Tiny mountain pygmy possums, like many other animals, depend on the annual bogong moth migration for food.
Tim Bawden

For mountain pygmy possums, the fatty, nutrient-rich bounty of bogong moths arrives right as they are waking up in the spring. They are one of the only Australian mammals that hibernate, and can spend up to seven months sleeping under the alpine snow.

The possums awake ravenously hungry, and devour the bogong moths to regain crucial fat stores. Without the moths there at the right time, the possums struggle to secure enough energy to breed successfully.

Snap that moth

Alongside the Lights Off for Moths campaign, Zoos Victoria has launched Moth Tracker, an app that allows Australians to photograph and log any potential sightings of migrating bogong moths.

Moth Tracker, which can be accessed through any laptop or smartphone, is adapted from the popular Southern Right Whale watching app in collaboration with Federation University and Victorian conversation network SWIFFT.

Bogong moths migrate from their winter breeding grounds throughout Queensland, New South Wales and western Victoria in search of cooler climates for the spring and summer in the Victorian and NSW Alpine regions where the mountain pygmy-possums live.

Before they become moths, the larvae look like tiny, shiny brown capsules and are commonly referred to as cutworm. Migratory bogong moths are dark brown, with two lighter spots on each wing. They are small, only about the length of a paper clip. During the day they’re often seen grouped together like roof tiles. At night, they are more active and flying around.

If you see a bogong moth (or something you think might be a bogong month), we need you to take a photograph and log the location, day and time with Moth Tracker. Scientists will use the data to determine whether any moths are making their way to the precious, and very hungry, possums that are just starting to wake from their winter hibernation.




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The Victorian Mountain Pygmy-possum Recovery Team, together with partner organisations, is also investigating options for interventions in the wild if needed. These may include a world-first airdropping of “bogong balls” to feed the hungry possums, as well as improving habitat connectivity and captive measures to support populations through the breeding season.

But with unnecessary outdoor lights switched off and citizen scientists looking out for bogong moths, there is still hope for the mountain pygmy-possums.The Conversation

Sally Sherwen, Director Wildlife Conservation and Science, Zoos Victoria, University of Melbourne and Therésa Jones, Lecturer in Evolution and Behaviour, University of Melbourne

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

Explainer: what is tularemia and can I catch it from a possum?


File 20170623 27895 1f3iigw
Researchers have found Australia’s first confirmed case of tularemia in a ringtail possum.
Andrew Mercer/flickr, CC BY-NC-SA

John-Sebastian Eden, University of Sydney

Tularemia is a disease that affects humans and other animals. It is caused by infection with the bacterium Francisella tularensis and is commonly spread by biting insects or by direct contact with an infected animal.

Human infection is less common than infection in small animals like rabbits and rodents. But it is important human cases are recognised and diagnosed quickly because without appropriate treatment the disease can be life-threatening.

Our team has recently confirmed its presence in Australia in samples taken from ringtail possums who died in two outbreaks in early 2000.

While this is clearly a newly identified risk to public health, it’s important to recognise how rare the disease is and how well the infection responds to treatment.

How is it transmitted to humans?

Tularemia is a “zoonotic disease”, an animal disease that can be transmitted to humans. The most common way someone might be infected is by being directly exposed to an infected animal through a bite or scratch, or even handling infected tissue, like when hunters skin animals.


Further reading: First Hendra, now bat lyssavirus, so what are zoonotic diseases?


Human infections can also occur indirectly from an animal through a biting insect vector, like ticks or deer flies. So, a fly might feed on an infected animal then also bite a human, transferring the bacterium via its mouth parts.

Humans can also catch the disease from animals by coming into contact with environmental sources such as water or soil that have been contaminated by an infected carcass. The bacteria might then infect humans through the eye, or an open wound, or even if digested from contaminated food.

How rare is tularemia in humans?

Fortunately, human cases of tularemia are relatively rare and appear to be limited to the Northern Hemisphere. Yet, even in the US, where the disease is well described, human cases rarely exceed 100-200 a year.

Australia has long been considered tularemia-free. So, it was surprising when, in 2011, two human cases were reported in Tasmania after exposure to ringtail possums.

While diagnostic tests on the patients’ samples suggested an infection with the bacterium, no samples were obtained from the offending possums to corroborate the unusual infection.

More importantly, researchers couldn’t grow and isolate the bacteria from any of the patients’ samples. Follow-up surveys of native animals in the area failed to detect the organism. So, the story of tularemia in Australia had, until recently, remained somewhat of a mystery.

How can I protect myself?

While our study has confirmed the presence of tularemia in Australia and identified ringtail possums as a reservoir for the disease, no-one knows if it’s present in other wildlife along the east coast.


Further reading: Bites and parasites: vector-borne diseases and the bugs spreading them


So, to minimise the chances of infection, take care when handling sick, distressed or dead animals. Similarly, when travelling in an area with ticks or other biting insects, wear protective clothing and repellents.

How do I know if I’m infected?

In humans, tularaemia symptoms can vary but typically depend on how someone was exposed.

An ulcer forms at the site of infection, like this one on someone’s hand.
CDC Public Health Image Library/Wikimedia

The most common form of disease in humans is known as ulceroglandular tularemia, which develops after an infected animal or insect bites or wounds you. As the name suggests, you develop a sudden fever, an ulcer forms at the site of infection, and the lymph glands near the wound swell.

Another and perhaps more serious form of the disease is pneumonic tularemia. This can occur when you breathe in bacteria from contaminated dust or aerosols, and your lungs become infected. Symptoms include cough, chest pain and difficulty breathing, and can be difficult to treat.

Yes, it can be treated

While infection can potentially cause severe disease and can kill, timely treatment with commonly available antibiotics should clear the infection. However, it is important the disease is correctly diagnosed as the most effective antibiotics (such as streptomycin) are often different to those used to treat other bacterial skin or wound infections.

There have been no reported cases of humans infecting other humans. While being exposed to someone infected with tularemia might pose some risk, the rarity of the cases and the effectiveness of antibiotic treatments to control the infection minimise this.

Looking to the future

What our study highlights more than anything is the need to investigate wildlife disease to understand potential risks to our environment and our own health.

So, we plan to conduct further surveys of animal and tick-borne diseases to explore undiscovered pathogens that may affect public health or impact our native animal populations.

We are also applying the same technology used to confirm the presence of tularemia in Australian wildlife for the first time to investigate other cold cases of the animal disease world – neglected and undiagnosed animal diseases.

We do this using a powerful technique called “RNA-Seq”, short for RNA sequencing, to analyse samples. With RNA-Seq, there’s no need to know what diseases might be present; researchers sequence all the genetic material in the sample, whether it has come from a host such as a human or animal, or from an infecting organism such as a virus, bacteria, or parasite.

This “metagenome” data is then pieced together and compared to databases containing genome data from previously sequenced pathogens.

The ConversationThrough these studies, we hope to reveal the full diversity of pathogens present in our native wildlife, and particularly, those that sit at the human-animal interface, a fault line that allows microbes to flow from one host to another. Most novel emerging diseases are spill-overs from zoonotic sources, so this research is critical for human health.

John-Sebastian Eden, NHMRC early career fellow, Faculty of Science, University of Sydney

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

Hidden housemates: when possums go bump in the night


Emma Power, Western Sydney University and Jane DeGabriel, Western Sydney University

You’re drifting off to sleep when, suddenly, there’s a bump and a thump and an unearthly shriek. But never fear, if your home is making these noises you probably don’t have ghosts, but a family of common brushtail possums.

Researchers have documented 18 different brushtail possum sounds. These include “grunting, growling, hissing, screeching, clicking and teeth-chattering calls, many of which would not be out of place on a horror movie soundtrack”.

Common brushtail possums (Trichosurus vulpecula) live across much of suburban Australia. Although often associated with bushland environments and commonly considered a tree-dweller, these adaptable creatures are also highly attracted to human houses.

The biggest hidden housemate?

Despite being the same size as a domestic cat, these lively, nocturnal marsupials frequently make their dens in the ceiling and wall cavities of homes. In fact, one study of possums in urban Tasmania found that 87% of their visits to dens were associated with buildings (mostly older houses), while 45% of den visits were to roof cavities.

These hidden animals make themselves known to their human housemates as they run across the ceiling. A Sydney study found that as many as 67% of people whose properties were visited by possums heard possum activity on or in roof cavities, while 58% reported possums living in these spaces.

A young possum discovers pineapple, via mum.
Peter Firminger/Flickr, CC BY

Possums in the city

At the time of European arrival, common brushtail possums were abundant across mainland Australia and Tasmania. However, intensive hunting for a burgeoning fur trade in the 19th and early 20th centuries led to a drastic decline in possum numbers. Since the end of hunting, habitat degradation and fragmentation, fires and fox predation have put further pressure on possum populations. In contrast, they appear to be flourishing in our cities.

Common brushtail possums are territorial creatures, usually sleeping alone during the day in dens in tree hollows, rock piles or logs. Dens are often in limited supply in the bush and possums will compete for nesting sites, sometimes fighting to the death. In contrast, suburbia provides an abundance of potential nesting spaces.

In fact, urban possums seem to prefer living in human-built structures, even when hollow trees are available. A single roof can provide a home for many cohabiting possums, although disputes among roommates may become raucous.

Abundant food and a broad palate mean people and possums were made for each other.
Peter Firminger/Flickr, CC BY

Another reason that brushtail possums have adapted so successfully to our cities is their generalised diet. Unlike specialised eucalypt feeders like the koala, brushtail possums eat the leaves, flowers and fruit of a range of native and exotic plants, as well as Eucalyptus leaves. They also sometimes eat insects and bird eggs.

Thus suburban gardens, with their abundance of fruit trees, roses and vegie patches, provide a “possum supermarket”, conveniently offering a diverse array of tasty, nutritious foods year round – much to the frustration of many gardeners!

In a study in eucalypt woodlands in north Queensland, Jane and her colleagues showed that female possums with access to the greatest amounts of available protein within their home ranges were more likely to breed twice, rather than just once per year.

Eucalypts are generally a poor source of protein and this is likely to limit populations of possums in natural bushland. However, given the abundance of high-quality food sources and limitless den sites in urban environments, it is not surprising that common brushtail possums seem to thrive there.

A possum in the roof!

People who share their homes with possums describe hearing them walking around the roof cavity. Emma’s research heard residents speak about the “thump, thump, thump” of possums walking across the ceiling. Others described being jolted awake at dawn to crashing and scraping sounds, and a feeling that someone was in the house. Some people admitted thinking their house was haunted, a feeling that was triggered by night-time noises coming from hidden spaces.

Hello, possum.
play4smee/Flickr, CC BY-NC

Many people enjoy living with possums, because they feel like it connects them to a time before Australia was urbanised. Some people also value personal connections with possums, becoming familiar with the individuals that share their garden – even giving them names and pointing them out to visitors.

However, people also often describe possums as a pest. They complain about the noise and damage that possums can cause. Damage to ceiling cavities, urine stains and odours in the ceiling are reported, and some people experience possums dying in the ceiling. These rotting bodies can be overwhelmingly smelly and extremely difficult to find.

It is interesting that many people both value possums and find them to be a pest. This is evidence of the complicated relationship that we have with native animals that live inside our homes. We enjoy their wildness, but are also challenged by the way that they make our homes a little bit less human and a little bit closer to nature.

Living well with common brushtail possums

Despite the fact that some people are less keen on house-sharing with possums, they are protected under the wildlife acts of most states in Australia. Although these laws vary, they generally require that residents seek a licence before trapping or moving a possum.

In New South Wales the relevant law is the National Parks and Wildlife Act 1974. If a possum is living in your ceiling, in NSW you can apply to the Office of Environment and Heritage (OEH) for a licence to trap it. Possums must be trapped humanely and released on the property where they were found within 150 m of the place where they were caught.

Note, however: possums moved outside of their home range typically die. They are also usually replaced within four weeks by another possum that moves into their territory.

The OEH suggests that people live alongside possums that share their garden, explaining that “if you encourage a possum to stay around and claim your yard as its territory, other possums will be discouraged from taking up residence”. The OEH also recommends installing nest boxes in trees away from the house to discourage possums from nesting in roofs, and carrying out repairs to close up any holes after possums are removed.

Wildlife protection laws mean that common brushtail possums have a right to live in urban Australia. This means that we need to learn to live well together.

This article is part of a series profiling our “hidden housemates”. Are you a researcher with an idea for a “hidden housemates” story? Get in touch.

The Conversation

Emma Power, Senior Research Fellow, Geography and Urban Studies, Western Sydney University and Jane DeGabriel, Research Fellow in Ecology, Hawkesbury Institute for the Environment, Western Sydney University

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