Many of our plants and animals have adapted to fires, but now the fires are changing



Eucalypt seeds don’t fall far from the tree, meaning repopulating large areas of forest will be difficult.
from http://www.shutterstock.com

Cris Brack, Australian National University

Australia is a land that has known fire. Our diverse plant and animal species have become accustomed to life with fire, and in fact some require it to procreate.

But in recent decades the pattern of fires – also known as the fire regime – is changing. Individual fires are increasingly hotter, more frequent, happening earlier in the season and covering larger areas with a uniform intensity. And these changes to the fire regime are occurring too fast for our native flora and fauna to adapt and survive.




Read more:
Some say we’ve seen bushfires worse than this before. But they’re ignoring a few key facts


Our fire-adapted plants are suffering

Many of Australia’s iconic eucalypts are “shade intolerant” species that adapted to exist within a relatively harsh fire regime. These species thrive just after a major fire has cleared away the overstory and prepared an ash bed for their seeds to germinate.

Some of our most majestic trees, like the alpine ash, can only regenerate from seed. Those seeds germinate only on bare earth, where the leaf litter and shrubs have been burnt away.

But if fire is so frequent the trees haven’t matured enough to produce seed, or so intense it destroys the seeds present in the canopy and the ground, then even these fire-adapted species can fail.

The current fires are re-burning some forests that were burnt only a decade ago. Those regenerating trees are too young to survive, but also too young to have started developing seed.

With the disappearance of these tree species, other plants will fill the gap. Acacias (wattles) are potential successors as they mature much earlier than alpine ash. Our tall, majestic forests could easily turn into shrubby bushland with more frequent fires.

Wattles mature early and could take over Eucalypts.
from http://www.shutterstock.com

Even within a burnt area, there are usually some unburnt patches, which are highly valuable for many types of plants and animals. These patches include gullies and depressions, but sometimes are just lucky coincidences of the terrain and weather. The patches act as reserves of “seed trees” to provide regeneration opportunities.

Recent fires, burning in hotter and drier conditions, are tending to be severe over large areas with fewer unburnt patches. Without these patches, there are no trees in the fire zone to spread seeds for regeneration.

Eucalypt seed is small and without wings or other mechanisms to help the wind disperse it. Birds don’t generally disperse these seeds either. Eucalypt seed thus only falls within 100 – 200 metres of the parent tree. It may take many decades for trees to recolonise a large burnt area.

That means wind-blown or bird-dispersed seeds from other species may fully colonise the burnt area well before the Eucalypts. Unfortunately many of these windblown seeds will be weed species, such as African Love Grass, which may then cover the bare earth and exclude successful Eucalypt regeneration while potentially making fires even hotter and more frequent.

Animals have fewer places to hide

Young animals are significantly more vulnerable to disturbances such as fire than mature individuals. So the best time to give birth is a season when fire is rare.

Spring in the southern zones of Australia has, in the past, been wetter and largely free from highly destructive fires. Both flora and fauna species thus time their reproduction for this period. But as fire seasons lengthen and begin earlier in the year, vulnerable nestlings and babies die where they shelter or starve as the fires burn the fruits and seeds they eat.

Australian fauna have developed behaviours that help them survive fire, including moving towards gullies and depressions, climbing higher, or occupying hollows and burrows (even if not their own) when they sense fire.

Many native animals have learnt to sense fire and take cover, but with greater areas burning, there are fewer places to hide.
from http://www.shutterstock.com

But even these behaviours will fail if those refuges are uncharacteristically burning under hotter and drier conditions. Rainforest, marshes and the banks of watercourses were once safe refuges against fire, but we have seen these all burn in recent fires.




Read more:
Animal response to a bushfire is astounding. These are the tricks they use to survive


What can be done?

All aspects of fire regimes in Australia are clearly changing as a result of our heating and drying climate. But humans can have a deliberate effect, and have done so in the past.

Indigenous burning created a patchwork of burnt areas and impacted on the magnitude and frequency of fires over the landscape. These regular burns kept the understory under control, while the moderate intensity and patchiness allowed larger trees to survive.




Read more:
There’s no evidence ‘greenies’ block bushfire hazard reduction but here’s a controlled burn idea worth trying


There have been repeated calls of late to reintroduce Indigenous burning practices in Australia. But this would be difficult over vast areas. It requires knowledgeable individuals to regularly walk through each forest to understand the forest dynamics at a very fine scale.

More importantly, our landscapes are now filled with dry fuel, and shrubs that act as “ladders” – quickly sending any fire into tree canopies to cause very destructive crown fires. Given these high fuel conditions along with their potentially dangerous distribution, there may be relatively few safe areas to reintroduce Indigenous burning.

The changed fire conditions still require active management of forests, with trained professionals on the ground. Refuges could be developed throughout forests to provide places where animals can shelter and from which trees can recolonise. Such refuges could be reintroduced by reducing forest biomass (or fuel) using small fires where feasible or by mechanical means.

A Kangaroo Island landscape devastated by fire.
David Mariuz/AAP

Biomass collected by machines could be used to produce biochar or other useful products. Biochar could even be used to improve the soil damaged by the fires and excess ash.

Midstory species could be cut down to prevent the development of fire ladders to tree crowns. Even the overstory could be thinned to minimise the potential for crown fires. Seed could also be collected from thinned trees to provide an off-site bank as ecological insurance.

Such active management will not be cheap. But using machinery rather than fire could control biomass quantity and distribution in a much more precise way: leaving some biomass on the ground as habitat for insects and reptiles, and removing other patches to create safer refuges from the fires that will continue to come.The Conversation

Cris Brack, Associate Professor, Fenner School of Environment and Society, Australian National University

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

Australia’s threatened bats need protection from a silent killer: white-nose syndrome



Three North American little brown bats with signs of white-nose syndrome, which is virtually certain to hit Australian bats without further action.
KDFWR/Terry Derting, CC BY-SA

Christopher Turbill, Western Sydney University and Justin Welbergen, Western Sydney University

We already know how deadly this summer’s fires have been for mammals, birds, and reptiles across Australia. But beyond this bushfire season, many of those same species – including our bats, which make up around a quarter of all Australian mammal species – are facing another devastating threat to their survival.

White‐nose syndrome has recently decimated bat populations across North America. While the fungal pathogen responsible for this disease, Pseudogymnoascus destructans, currently doesn’t occur in Australia, the fungus is virtually certain to jump continents in the next decade.

Our recent research, published in the journal Austral Ecology, attempted to quantify this risk – and the results are not encouraging. Up to eight bat species occupy caves in south-eastern Australia that provide conditions suitable for the fungus to grow.

Large parts of southern Australia provides cave habitat suitable for growth by the cold-loving fungus responsible for white-nose syndrome.
Turbill & Welbergen 2019

Even before this summer’s fires, seven of those types of bats were listed on state or federal legislation as threatened with extinction. This includes the critically endangered southern bent-winged bat (Miniopterus orianae bassanii), a species whose caves would all provide optimal conditions for growth of the fungus.

All caves occupied by the critically endangered southern bent-winged bat provide ideal thermal conditions for white-nose syndrome.
Dr Lindy Lumsden

Millions of bats wiped out in North America

White-nose syndrome was first detected in the United States in 2006 at a popular tourist cave in the state of New York. Since then, the disease has spread across North America, killing millions of bats in its wake, with many local populations experiencing 90 to 100% mortality.

The novel pathogen hypothesis explains why P. destructans has such catastrophic impacts on North American bats: the immune system of these species is evolutionarily naive to this fungal attack. Accordingly, in Europe and Asia, where P. destructans is endemic and widespread, few bats exhibit white‐nose syndrome and mortalities are rare.

Australia’s unique wildlife is inherently at risk from invasive novel pathogens because of its long‐term biogeographical isolation. Thus Australian bats, like their distant North American relatives, probably lack an effective immune response to P. destructans and would be susceptible to developing white-nose syndrome.

Since its detection in the United States in 2006, white-nose syndrome has received extensive media attention globally.

Hibernation is the key risk period

Most fungal pathogens grow best at cool temperatures, and a high body temperature in mammals and birds provides an effective barrier against fungal diseases. The fungus causing white-nose syndrome is also cold-loving, ceasing to grow at temperatures above 20°C. The only time it can infect and kill bats is when they hibernate.

Bats go cold (use torpor) during hibernation to prevent starvation over winter in temperate climates. Hibernating bats that are infected by P. destructans rewarm more frequently than normal. These unscheduled bursts of metabolic heat production prematurely burn up the body fat of overwintering bats. Hence, despite the damage caused by white-nose syndrome to the bat’s skin tissue, they apparently die due to starvation or dehydration.

The infection is easily visible under UV light.
Turner et al. 2014

Hibernation is key to predicting the susceptibility of bat populations to mortality from white-nose syndrome: those with less energy to spare over winter are more at risk. Consequently, white-nose syndrome has fuelled a large research program on the winter ecology and hibernation physiology of North American bats.

Bats in south-eastern Australia do enter a period of winter hibernation, but that is about the extent of what we know. This knowledge gap makes it impossible to predict how they will respond if exposed to P. destructans. Even non-lethal impacts, however, will worsen the extinction-bound trajectory of several cave-roosting species, most notably the eastern and southern bent-winged bats.

What can Australia do?

Given the impending arrival of P. destructans in Australia, and our study’s findings of widespread thermal cave suitability in south-eastern Australia, we urge immediate action. This includes tightening biosecurity measures and gaining missing information on bat biology so we are better prepared for a possible white-nose syndrome epidemic.

The importance of this threat has not been missed by Wildlife Health Australia, which has produced guidelines for reporting and response to incursion. Advice is also available from the Commonwealth. Just recently, white-nose syndrome was listed in the national priority list for exotic environmental pests and diseases, ranking in the top five of native animal diseases and their pathogens.

Cave enthusiasts have also been proactive in alerting members to white-nose syndrome and the risk of accidentally introducing P. destructans, especially when returning from overseas caving adventures. And the Australasian Bat Society – a strong advocate for bat conservation – has alerted the public and government agencies to this potential new threat.

Action now is critical

At present, there is little that would prevent P. destructans from making it its way to Australian caves, despite two years passing since experts assessed the risk of incursion as almost certain.

We need effective measures at all levels, from requiring incoming visitors to identify contact with cave environments, to decontamination procedures at caves popular with international tourists.

The US Fish and Wildlife Service’s White-nose Syndrome Response Team produced this infographic, including what you can do to help bats.

Predicting the impact of white-nose syndrome on Australian bats is currently not possible because we know so little about their winter biology. We urge the Australian government to fund specific research to gain this information.

The US Fish and Wildlife Service has injected more than US$46 million since 2008 into research and fieldwork to address the threat. Australian researchers can use this work to focus on the critical data needed to inform models that predict the vulnerability of local bat populations.

Why we need bats to survive

Bats are incredibly valuable in their own right. But the world needs healthy bat populations: a single insectivorous bat can eat up to half its body mass in insects each night, and together colonies of bats provide a service with an estimated value to the agricultural industry alone in the billions of dollars per year.

We hope this terrible disease will not threaten Australian bats. But the precautionary principle dictates we should plan and act now, assuming the worst-case scenario. Alarm bells are ringing.


Read more: The importance of Australia’s weird and wonderful batsThe Conversation


A selection of Australia’s bat diversity. Top row from left: grey-headed flying-fox; orange leaf-nosed bat; common blossom bat; large-footed myotis. Bottom row: golden-tipped bat; eastern horseshoe bat; common sheath-tailed bat; ghost bat.
Justin Welbergen (grey-headed flying-fox, eastern horseshoe bat); Nicola Hanrahan (ghost bat); Bruce Thomson (golden-tipped bat); Steve Parish & Les Hall for remainder of species

Christopher Turbill, Senior Lecturer in Animal Ecology, Western Sydney University and Justin Welbergen, President of the Australasian Bat Society | Associate Professor of Animal Ecology, Western Sydney University

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

Six million hectares of threatened species habitat up in smoke



At least 250 threatened species have had their habitat hit by fires.
Gena Dray

Michelle Ward, The University of Queensland; Aaron Greenville, University of Sydney; April Reside, The University of Queensland; Ayesha Tulloch, University of Sydney; Brooke Williams, The University of Queensland; Emily Massingham, The University of Queensland; Helen Mayfield, The University of Queensland; Hugh Possingham, The University of Queensland; James Watson, The University of Queensland; Jim Radford, La Trobe University, and Laura Sonter, The University of Queensland

More than one billion mammals, birds, and reptiles across eastern Australia are estimated to have been affected by the current fire catastrophe.

Many animals and plants have been incinerated or suffocated by smoke and ash. Others may have escaped the blaze only to die of exhaustion or starvation, or be picked off by predators.



But even these huge losses of individual animals and plants do not reveal the full scale of impact that the recent fires have had on biodiversity.

Plants, invertebrates, freshwater fish, and frogs have also been affected, and the impact of the fires is likely to be disproportionately greater for threatened species.




Read more:
A season in hell: bushfires push at least 20 threatened species closer to extinction


To delve deeper into the conservation impact, we used publicly available satellite imagery to look at the burnt areas (up to January 7, 2020) and see how they overlapped with the approximate distributions of all the threatened animals and plants listed under the Environment Protection and Biodiversity Conservation Act.

We restricted our analysis to the mediterranean and temperate zone of south-east and south-west Australia.

The bad news

We found that 99% of the area burned in the current fires contains potential habitat for at least one nationally listed threatened species. We conservatively estimate that six million hectares of threatened species habitat has been burned.



Given that many fires are still burning and it is not yet clear how severe the burning has been in many areas, the number of species affected and the extent of the impact may yet change.

What we do know is that these species are already on the brink of extinction due to other threats, such as land clearing, invasive species, climate change, disease, or previous fires.

Approximately 70 nationally threatened species have had at least 50% of their range burnt, while nearly 160 threatened species have had more than 20% of their range burnt.

More threatened plants have been affected than other groups: 209 threatened plant species have had more than 5% of their range burnt compared to 16 mammals, ten frogs, six birds, four reptiles, and four freshwater fish.


Author supplied

Twenty-nine of the 30 species that have had more than 80% of their range burnt are plants. Several species have had their entire range consumed by the fires, such as the Mountain Trachymene, a fire-sensitive plant found in only four locations in the South Eastern Highlands of NSW.

Other species that have been severely impacted include the Kangaroo Island dunnart and the Kangaroo Island glossy black cockatoo. These species’ entire populations numbered only in the hundreds prior to these bushfires that have burned more than 50% of their habitat.

The Kangaroo Island glossy black cockatoo has had more than 50% its habitat impacted by fire.
Mike Barth

Glossy black cockatoos have a highly specialised diet. They eat the seeds of the drooping sheoak (Allocasuarina verticillata). These trees may take anywhere from 10 to 50 years to recover enough to produce sufficient food for the black cockatoos.

The populations of many species will need careful management and protection to give their habitats enough time to recover and re-supply critical resources.

The figures above do not account for cumulative impacts of previous fires. For example, the critically endangered western ground parrot had around 6,000 hectares of potential habitat burnt in these fires, which exacerbates the impact of earlier extensive fires in 2015 and early 2019.

Threatened species vary in their ability to cope with fire. For fire-sensitive species, almost every individual dies or is displaced. The long-term consequences are likely to be dire, particularly if vegetation composition is irrevocably changed by severe fire or the area is subject to repeat fires.

More than 50% of the habitat of several species known to be susceptible to fire has been burnt – these include the long-footed potoroo and Littlejohn’s tree frog.

The endangered long-footed potoroo has had more than 50% of its potential habitat impacted by fire.
George Bayliss

Some species are likely to thrive after fire. Indeed, of the top 30 most impacted species on our list, almost 20% will likely flourish due to low competition in their burnt environments – these are all re-sprouting plants. Others will do well if they are not burnt again before they can set seed.

Rising from the ashes

For fire-sensitive threatened species, these fires could have substantially increased the probability of extinction by virtue of direct mortality in the fires or reducing the amount of suitable habitat. However, after the embers settle, with enough investment and conservation actions, guided by evidence-based science, it may be possible to help threatened species recover.

For species on the brink of extinction, insurance populations need to be established. Captive breeding and release can complement wild populations, as occurs for the regent honeyeater.
Dean Ingwersen / BirdLife Australia

Protection and conservation-focussed management of areas that have not burned will be the single most important action if threatened species are to have any chance of persistence and eventual recovery.

Management of threatening processes (such as weeds, feral predators, introduced herbivores, and habitat loss through logging or thinning) must occur not just at key sites, but across the landscapes they sit in. Maintaining only small pockets of habitat in a landscape of destruction will lock many species on the pathway to extinction.

In some cases, rigorous post-fire restoration will be necessary to allow species to re-colonise burnt areas. This may include intensive weed control and assisted regeneration of threatened flora and specific food sources for fauna, installing nest boxes and artificial cover, or even targeted supplementary feeding.

Unconventional recovery actions will be needed because this unique situation calls for outside-the-box thinking.




Read more:
The science of drought is complex but the message on climate change is clear


Playing the long game

These fires were made larger and more severe by record hot, dry conditions. Global temperatures have so far risen by approximately 1°C from pre-industrial levels.

Current projections indicate that we are on track for a 3°C increase. What will that look like?

We are in a moment of collective grief for what has been lost. A species lost is not just a word on a page, but an entire world of unique traits, behaviours, connections to other living things, and beauty.

These losses do not need to be in vain. We have an opportunity to transform our collective grief into collective action.

Australians are now personally experiencing climate impacts in an unprecedented way. We must use this moment to galvanise our leaders to act on climate change, here in Australia and on the world stage.

The futures of our beloved plants and animals, and our own, depend on it.The Conversation

Michelle Ward, PhD Candidate, The University of Queensland; Aaron Greenville, Lecturer in Spatial Agricultural and Environmental Sciences, University of Sydney; April Reside, Researcher, Centre for Biodiversity and Conservation Science, The University of Queensland; Ayesha Tulloch, DECRA Research Fellow, University of Sydney; Brooke Williams, PhD Candidate, The University of Queensland; Emily Massingham, PhD Student, The University of Queensland; Helen Mayfield, Postdoctoral Research Fellow School of Earth and Environmental Sciences, The University of Queensland; Hugh Possingham, Professor, The University of Queensland; James Watson, Professor, The University of Queensland; Jim Radford, Principal Research Fellow, Research Centre for Future Landscapes, La Trobe University, and Laura Sonter, PhD Candidate in Global Environmental Change, The University of Queensland

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

Australian sea lions are declining. Using drones to check their health can help us understand why



Australian sea lions (Neophoca cinerea) are one of the rarest pinnipeds in the world and they are declining.
Jarrod Hodgson, CC BY-ND

Jarrod Hodgson, University of Adelaide; Lian Pin Koh, University of Adelaide, and Simon Goldsworthy, University of Adelaide

Australian sea lions are in trouble. Their population has never recovered from the impact of the commercial sealing that occurred mainly in the 19th century.

Low-lying rock islands and outcrops make important breeding sites for Australian sea lions but many are threatened by sea-level rise.
J. Hodgson

Currently, the Australian sea lion is a threatened species (listed as endangered by the International Union for Conservation of Nature or IUCN) with the population estimated at 10,000 – 12,000. More than 80% of these animals live in the coastal waters of South Australia, where their numbers are estimated to have fallen by more than half over the past 40 years.

The sea lions’ survival is threatened by many factors, including bycatch in commercial fisheries, entanglement in marine debris and impacts related to climate change.

With time running out, the sea lions’ survival depends on informed management. One important step is to establish a low-risk way of quickly assessing the health of the current population. The results could help us identify how to stop the population declining.




Read more:
Australia’s ‘other’ reef is worth more than $10 billion a year – but have you heard of it?


Technological insight

One common way to get a quick idea of an animal’s health is to assess its body using a measure equivalent to the body mass index (BMI) for humans, which is calculated from a person’s mass divided by the square of their height. But using a tape measure and scales to obtain the size and mass of Australian sea lions is time consuming, costly and involves risky anaesthesia of endangered animals.

With our colleagues Dirk Holman and Aleks Terauds, we recently developed a technique to non-invasively estimate the body condition of Australian sea lions by using a drone to collect high-resolution photos of sedated sea lions. We then used the photos to digitally reconstruct a 3D model of each animal to estimate its length, width and overall volume – and compared these to physical measurements.

The technique, recently published in Biological Conservation, worked better than expected.

Drone-captured photographs were processed to create 2D mosaics of images and 3D models. These were used to measure area and volume, both of which approximated animal mass.
J. Hodgson

The measurements were accurate, and we found a strong correlation between the mass of an individual and the area and volume measurements derived from the drone pictures. These are the key ingredients needed to assess sea lion condition without handling animals.

Conserving an iconic species

While simple body condition measurements have limitations, they are useful for conservation because they provide rapid health insights across a species’ range.

Australian sea lions breed at around 80 known sites spanning more than 3,000 km of southern Australian coastline within the Great Southern Reef.

Our technique can be used to study free-ranging animals at colonies across this range, from Kangaroo Island in South Australia to the Houtman Abrolhos Islands in Western Australia, and test for differences in condition.

3D models of animals measured in the study.
J. Hodgson

This can give us valuable information about how individual health and colony trends in abundance are related. For example, if a colony is in decline and its members are in poor condition, it could be that factors such as food availability and disease are driving the decline.

However, if there is no difference in the condition of animals from declining and recovering colonies, then declines may be due to direct human impacts such as bycatch in commercial fisheries and entanglement in marine debris. We could then target the most likely threats identified using this technique to better understand their impact and how to protect the sea lions against them.

These two adult male Australian sea lions differed by just 11 cm in length but more than 130 kg in mass.
J. Hodgson

This technique could be used to complete a population-wide survey of Australian sea lion condition and help ensure the species’ survival. It would build on past mitigation measures which include successfully reducing by-catch from gillnet fishing along the sea floor.

It will also complement current initiatives, including a trial to control a parasite that may improve pup survival.

Australian sea lions are an icon of Australia’s Great Southern Reef. As an important top-order predator in these coastal waters, they are indicators of ocean health. Understanding and mitigating the causes of their decline will not only help the species recover, but it will also help to ensure the unique coastal ecosystems on which Australian sea lions depend remain intact and functional.The Conversation

Jarrod Hodgson, PhD Candidate, University of Adelaide; Lian Pin Koh, Professor, University of Adelaide, and Simon Goldsworthy, Principal Scientist, Ecosystem Effects of Fishing & Aquaculture, South Australian Research and Development Institute, and Affiliate Professor, University of Adelaide

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

Bushfires left millions of animals dead. We should use them, not just bury them


Emma Spencer, University of Sydney; Chris Dickman, University of Sydney; Philip Barton, Australian National University, and Thomas Newsome, University of Sydney

Bushfires this season have left an estimated 1 billion dead animals in their wake, their carcasses dotting the blackened landscape.

Adding to the toll, farmers are being forced to euthanise injured and starving livestock and there are also calls to cull feral animals in fire-affected areas, including by aerial shooting.

The carcasses have already been flagged as a potential biosecurity threat, and the Australian Defence Force is tasked with collecting and burying the dead in mass graves.




Read more:
Australia’s bushfires could drive more than 700 animal species to extinction. Check the numbers for yourself


There’s logic in this. Carcasses can harbour nasty diseases such as botulism that threaten human, livestock and wildlife health. They also provide food for invasive pests like feral cats and red foxes.

But carcasses can play a positive role as landscapes recover from fire, providing rich nutrients for other native animal, microbial and plant species.

Carcasses provide important food sources to native animals, such as the lace goanna.

The Morrison Government has announced a A$50 million package to help wildlife and habitat recover from the fires, and yesterday met leading wildlife experts and environment groups to get advice on the recovery process.

We suggest this process should examine carcass disposal methods other than burial, such as composting – effectively “recycling” the dead. It should also involve monitoring the carcasses that remain to understand both their positive and negative roles in fire-ravaged areas.

The positives: carcasses feed the living

Carcasses feed a range of native animals, including goannas, wedge-tailed eagles and dingoes. Post-fire, they can provide an alternative source of food for struggling native predators and pollinators. And feeding hungry predators with carcasses could redirect them away from vulnerable prey.

Carcasses also feed insects such as flies, ants, beetles, and their larvae, and support important ecological processes such as pollination.

As they decompose, nutrients leach from carcasses into the surrounding environment and create “halos” of greenery in the landscape, where vegetation thrives around carcass sites. Their influence on soil and plant communities can last for years.

Vegetation growth ‘halo’ around a kangaroo carcass. When animals die their nutrients can influence the landscape for years.

The negatives: spreading disease and sustaining feral animals

Carcasses are home to bacteria that help break down animal tissues. But some carcasses also harbour harmful pathogens that bring disease.

For a disease outbreak to happen, the animal must generally have already been carrying dangerous infectious agents, like Anthrax or the Hendra virus, before they died. And many of these pathogens will not survive long on dead hosts.




Read more:
Predators get the advantage when bushfires destroy vegetation


Leaving carcasses out in the open can also feed introduced predators such as feral cats and red foxes, putting small native animals at risk. Some weeds thrive in the nutrient-rich soils around carcasses too.

Introduced insects like the European wasp, which appeared en masse following fires in Kosciuszko National Park, also take advantage of carcass resources. These wasps are highly aggressive and attack and kill other native insects.

How long does a carcass stick around?

We know very little about the ecological role of carcasses in fire-affected areas, and it’s important that more research is carried out.

We know burnt animals can decompose faster than other carcasses and harbour different types of insect scavengers.

However the recent fires are likely to have wiped out entire scavenger communities, including larger scavengers like dingoes and eagles, that help to clean our landscapes of dead animals.

The effects of this are unknown, but could mean that carcasses stick around in the environment for prolonged periods, even months.

A feral cat scavenging on an animal carcass. Animal carcasses could increase the number of feral predators.

Finding the right solution to a grisly problem

As climate change accelerates the number of natural disasters and mass animal deaths, more thought and planning must be put into carcass management.

In Australia, carcasses are often dealt with by not dealing with them: they’re left to rot. This happened for almost 100 feral horses that died last year at an empty water hole during a heatwave.

Animals culled in national parks and on farmlands are also often left to decay, untouched, as are the many dead animals that commonly line our country roads. But in landscapes where feral species are common, or where livestock or people are likely to encounter carcasses, leaving them alone isn’t the best option.




Read more:
A season in hell: bushfires push at least 20 threatened species closer to extinction


Carcasses are more often buried following disease outbreaks or when livestock die. We saw this during the 2019 Queensland floods, where thousands of drowned cattle were buried in mass graves.

Burial is a relatively inexpensive, fast and effective method of dealing with the dead. But it must be done carefully to avoid polluting groundwater sources and causing nutrients like nitrogen to build up.

Burying carcasses can also be compared to sending rubbish to the tip. Breakdown will be slow, and no useful end product is created.

A more useful option

An alternative option is to “recycle” carcasses by composting them. Composting can accelerate the decomposition of animal tissues and is environmentally friendly, capturing nutrients.




Read more:
Animal response to a bushfire is astounding. These are the tricks they use to survive


Composting kills most pathogens, whereas burial just moves the problem underground. It also suppresses smelly odours and doesn’t attract scavengers. The usable organic material resulting from the composting can also be applied to nutrient-poor soil.

Getting used to the ‘yuck’ factor of carcasses.

Composting can be time-consuming and hard to get right. It requires careful monitoring of temperature and moisture content to ensure all disease-causing pathogens are killed, and odours are suppressed.

There’s also a “yuck” factor and the public would probably need convincing for the method to be widely adopted.

But whatever option we choose, it’s clear there’s more we can do with carcasses than simply burying them.The Conversation

Emma Spencer, Ph.D. student, University of Sydney; Chris Dickman, Professor in Terrestrial Ecology, University of Sydney; Philip Barton, Honorary Senior Lecturer, Fenner School of Environment and Society, Australian National University, and Thomas Newsome, Lecturer, University of Sydney

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