It’s wrong to blame bats for the coronavirus epidemic



A small colony of Townsend’s big eared bats at Lava Beds National Monument, Calif.
Shawn Thomas, NPS/Flickr

Peter Alagona, University of California, Santa Barbara

Genomic research showing that the COVID-19 coronavirus likely originated in bats has produced heavy media coverage and widespread concern. There is now danger that frightened people and misguided officials will try to curb the epidemic by culling these remarkable creatures, even though this strategy has failed in the past.

As an environmental historian focusing on endangered species and biological diversity, I know that bats provide valuable services to humans and need protection. Instead of blaming bats for the coronavirus epidemic, I believe it’s important to know more about them. Here’s some background explaining why they carry so many viruses, and why these viruses only jump infrequently to humans – typically, when people hunt bats or intrude into places where bats live.

The challenges of life as a bat

It’s not easy being the world’s only flying mammal. Flying requires a lot of energy, so bats need to consume nutritious foods, such as fruits and insects.

As they forage, bats pollinate around 500 plant species, including mangoes, bananas, guavas and agaves (the source of tequila). Insect-eating bats may consume the equivalent of their body weight in bugs each night – including mosquitoes that carry diseases like Zika, dengue and malaria.

Grey-headed flying fox feeding on flower nectar, Queensland, Australia. Its face is covered with yellow pollen, which it will spread to other flowers.
Andrew Mercer/Wikipedia, CC BY

Bats convert these foods into droppings called guano, which nourish entire ecosystems, have been harvested for centuries as fertilizer, and have been used to make soaps and antibiotics.

Since fruits and insects tend to follow seasonal boom-and-bust cycles, most bats hibernate for long periods, during which their core body temperatures may fall as low as 43 degrees Fahrenheit (6 degrees Celsius). To conserve warmth, they gather in insulated places like caves, use their wings as blankets and huddle together in colonies.

When fruits ripen and insects hatch, bats wake up and flutter out of their roosts to forage. But now they have a different problem: Flying requires so much energy that their metabolic rates may spike as high as 34 times their resting levels, and their core body temperatures can exceed 104 degrees F.

To stay cool, bats have wings filled with blood vessels that radiate heat. They also lick their fur to simulate sweat and pant like dogs. And they rest during the heat of the day and forage in the cool of night, which makes their ability to navigate by echolocation, or reflected sound, handy.

The Congress Avenue Bridge in Austin, Texas, houses the largest urban bat colony in the world.

Diverse and unique

Humans are more closely related to bats than we are to dogs, cows or whales. But bats seem more alien, which can make it harder for people to relate to them.

Bats are the most unusual of the world’s 26 mammal orders, or large groups, such as rodents and carnivores. They are the only land mammals that navigate by echolocation, and the only mammals capable of true flight.

Many bats are small and have rapid metabolisms, but they reproduce slowly and live long lives. That’s more typical of large animals like sharks and elephants.

And a bat’s internal body temperatures can fluctuate by more than 60 degrees Fahrenheit in response to external conditions. This is more typical of cold-blooded animals that take on the temperature of their surroundings, like turtles and lizards.

Bats carry a range of viruses that can sicken other mammals when they jump species. These include at least 200 coronaviruses, some of which cause human respiratory diseases like SARS and MERS. Bats also host several filoviruses, including some that in humans manifest as deadly hemorrhagic fevers like Marburg and probably even Ebola.

Normally, these viruses remain hidden in bats’ bodies and ecosystems without harming humans. People raise the risk of transmission between species when they encroach on bats’ habitats or harvest bats for medicine or food. In particular, humans pack live bats into unsanitary conditions with other wild species that may serve as intermediate hosts. This is what happened at the Wuhan wet market where many experts believe COVID-19 emerged.

With a few exceptions, such as rabies, bats host their pathogens without getting sick. Recent media coverage attempting to explain this riddle has focused on a 2019 study suggesting that bats carry a gene mutation, which may enable them to remain healthy while harboring such viruses. But while the mutation may be of interest from a public health perspective, understanding where this novel coronavirus came from requires understanding what makes a bat a bat.

The blood vessels in bats’ wings (shown: fruit bats, Northern Territory, Australia) radiate some of the heat they generate while flying.
shellac/Flickr, CC BY

Why do bats carry so many diseases but seem unaffected by them? Genetic mutations that boost their immune systems may help. But a better answer is that bats are the only mammals that fly.

With thousands of bats crowded together licking, breathing and pooping on one another, bat caves are ideal environments for breeding and transmitting germs. But when bats fly, they generate so much internal heat that, according to many scientists, their bodies are able to fight off the germs they carry. This is known as the “flight as fever hypothesis.”

Bats at risk

Bats may not always be around to eat insect pests, pollinate fruit crops and provide fertilizer. According to the International Union for the Conservation of Nature and Bat Conservation International, at least 24 bat species are critically endangered, and 104 are vulnerable to extinction. For at least 224 additional bat species, scientists lack the data to know their status.

Overharvesting, persecution and habitat loss are the greatest threats that bats face, but they also suffer from their own novel diseases. Since it was first documented in upstate New York in 2007, the fungal pathogen Pseudogymnoascus destructans (Pd), which causes white-nose syndrome, has infected 13 North American bat species, including two listed as endangered.

Nobody knows where Pd came from, but the fact that several bat species seem never to have encountered it before suggests that people probably introduced or spread it. The fungus thrives in cool, damp places like caves. It grows on bats while they’re hibernating, causing such irritation that they become restless, wasting precious energy during seasons when little food is available. White-nose syndrome has killed millions of bats, including more than 90% of the bats in some populations.

Bats are extraordinary creatures that benefit people in myriad ways, and our world would be a poorer, duller and more dangerous place without them. They need protection from the cruel treatment and wasteful exploitation that also threatens human health.

[Our newsletter explains what’s going on with the coronavirus pandemic. Subscribe now.]The Conversation

Peter Alagona, Associate Professor of History, Geography and Environmental Studies, University of California, Santa Barbara

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

Air-dropping poisoned meat to kill bush predators hasn’t worked in the past, and it’s unlikely to help now



Shutterstock

Justine M. Philip, Museums Victoria

After the summer’s devastating bushfires, the New South Wales government announced a plan to airdrop one million poisoned baits in the state’s most vulnerable regions over the next year. The plan is aimed at protecting surviving native animals from foxes, feral cats and wild dogs.

This isn’t the first time aerial baiting has been used in NSW recently. As the fire season got underway in September last year, the government’s biannual aerial baiting program scattered baits over nearly 8 million hectares in the Western Division alone – dispensing 43,442 aerial baits and 115,162 ground-laid baits over the drought-stricken region.

Biosecurity officers drying meat baits for the Autumn baiting program in Broken Hill last year.
NSW Government, Local Land Services, Western Region

In a study published this week, I explore Australia’s history as pioneers of this technology. The review raises serious concerns about the ethics and poor results of baiting programs, and the high uptake of baits by non-target species such as marsupials.

D-day for dingoes

Aerial baiting has been Australia’s foremost weapon against pest species for the past 74 years. The initial target was the dingo, to protect unguarded livestock from being killed.




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How Australia made poisoning animals normal


It started on Remembrance Day in 1946. Around 367,000 dry meat baits were airdropped across Queensland, each containing enough strychnine to kill an adult dingo. The campaign was considered a victory, despite only recovering one dingo carcass during the initial operation. Livestock predation apparently decreased; tracks in the sand vanished.

The following year, 1.5 million baits were distributed. Then in 1948 the quantity increased to 2.5 million baits across remote regions of Queensland and the Northern Territory.

Livestock predation decreased after airdropping baits, but at what cost?
CSIRO Science Image, CC BY

Thousands of baits to kill one dingo

The strychnine tablets took up to 12 tortuous hours for the poison to deliver its lethal kill. The baits used in research trials were still toxic after 14 weeks.

There was huge public criticism of the project at the time – much of it from graziers. They claimed ants and valuable pest-eating birds – magpies, small hawks, butcher birds, crows, ibis and curlew – were eating the baits.

In response, the Queensland government set up the first monitored trials. The 1954 report from the Chief Vermin Control Officer recorded:

In the dry season campaigns, the baits are dropped on water-holes, soaks, junctions of dried water courses, gorges in hills and all places where dogs must travel or gather in their search for water and game and in their movements with pups from the breeding areas.

The data recorded an average 14,941 baits dispensed for every dingo carcass recovered. Anecdotal evidence suggests the program was considered a success.

CSIRO research worker with young dingo, 1970.
National Archives of Australia

Then in 1968 – 21 years after aerial campaigns began – a four-year CSIRO study tested the effectiveness of aerial baiting. It found the 1954 report was far from conclusive – the dingoes may just have moved elsewhere. And it concluded: “clearly aerial baiting was not effective”.

But there was an important caveat:

It is important to emphasise that, though this aerial baiting campaign was a failure, such a conclusion does not necessarily apply to any other campaign.

On the strength of that, aerial baiting programs continued.

Not much has changed

Despite millions of baits applied annually to the environment since the 1940s, Australia’s biodiversity has plummeted.

What’s more, developments in the technology haven’t come far. Raw meat baits eventually replaced dry baits in some areas. Strychnine was superseded by 1080, a less harmful poison to non-target native species, and less persistent in the environment.

Trials in the 1980s brought the bait-to-kill rate down to 750 to 1 (baits per dingo carcass recovered). This was considered a cost-effective and successful outcome.

Soon after, aerial baiting found a new market, becoming the frontline defence against Australia’s plummeting biodiversity from invasive predators.

Baits are not benign to marsupials

In 2008, the Australian Pesticides and Veterinary Medicines Authority imposed a limit of ten baits per kilometre to reduce risk to non-target species.

Pest control agencies need four times that amount of poison to achieve a successful kill rate. Yet planes have been dispensing baits at this lower and ineffective rate since 2008.

Why? It seems a balance between wildlife safety and effective canine or predator eradication isn’t possible with this technology.




Read more:
Dingoes found in New South Wales, but we’re killing them as ‘wild dogs’


In fact, it has been impossible to accurately trace the fate of baits thrown from aeroplanes into remote terrain. Even ground baiting trials have proved difficult to monitor. A 2018 trial found non-target species consumed more than 71% of ground-laid meat baits, including ravens, crows, goannas, monitor lizards, marsupials and ants.

Four young dingoes died during this trial, representing only a 1.25% uptake by target. Despite monitoring with cameras and sand traps, 599 baits out of 961 in the trial disappeared without a trace.

These baits are not benign. Repeat doses can kill marsupials; non-lethal doses can kill pouch young. Secondary poisoning can also be lethal. Applying this outdated technology to vulnerable bushfire regions is from a historical viewpoint, potentially hazardous.

Surely there’s another way

There are new technologies available to help protect and repair Australia’s fragile and broken ecosystems. Remote surveillance, drones, AI, heat sensing equipment, and more could locate populations and dispatch dangerous animals.




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Guardian dogs, fencing, and ‘fladry’ protect livestock from carnivores


If aerial baiting continues, aerial surveillance could at least follow the fate of the one million baits and tell us what and who is eating them – who lives and who dies in the stripped-bare landscape.

One thing is for certain: halting the program would prevent hundreds of thousands of these poisoned meat baits ending up in the stomachs of our treasured native animals.The Conversation

Justine M. Philip, Doctor of Philosophy, Ecosystem Management, Museums Victoria

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

Sure, save furry animals after the bushfires – but our river creatures are suffering too


Jamie Pittock, Australian National University

The hellish summer of bushfires in southeast Australia triggered global concern for our iconic mammals. Donations flooded in from at home and around the world to help protect furry species.

But there’s a risk the government and public responses will not see the fish for the koalas.

Of the 113 priority fauna species identified by the federal government as worst impacted by bushfires, 61 (54%) are freshwater species that live in or around our inland rivers, such as fish, frogs, turtles and the iconic platypus.

These animals and ecosystems were already struggling due to prolonged drought and mismanagement of the Murray Darling Basin. Saving koalas and other mammals is of course important, but freshwater species should also be a priority for post-fire environmental programs.

A picture of devastation

The government’s priority species list includes three turtle species, 17 frogs, 22 crayfish, 17 fish and the platypus. Rounding out the list is an alpine stonefly, although many other invertebrates are also likely to be affected (as well as other species that depend on moist, streamside forest habitats).

Excluding tropical savannah, the recent bushfires burnt more than 7.7 million hectares in Victoria, South Australia, New South Wales, Queensland and Western Australia. Rainforests and riparian (riverside) forests were extensively damaged along the Australian east coast and alps. These are normally moist environments, which are not adapted to fire.

Plant and animal species at the edge of waterways, in peat wetlands and in riverside forests are likely to have been burnt or killed by heat, such as crustaceans , lizards, and corroboree and mountain frogs in the alps and east coast rainforests.




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Fire almost wiped out rare species in the Australian Alps. Feral horses are finishing the job


Burnt riverside forests no longer shade the water, making water temperatures hotter and leading to increased evaporation that may stress surviving wildlife. The loss of vegetation cover also leaves prey exposed to predators.

Following recent rain, water flowing into rivers has washed ash into streams. This clogs fish gills and brings nutrients that drive algal blooms. Sediment washed into waterways fills in the gaps between rocks and holes in river beds – places where many species shelter and breed. For instance, the River Murray catchment’s last population of Macquarie perch was impacted as rain washed ash and sediment into Mannus Creek in southern NSW.

Fires tend to burn forests in patches, sometimes leaving refuges for land-based animals. However fire damage to waterways flows downstream, systematically degrading the habitat of aquatic animals by leaving little clean water to hide in.

Bushfire silt clogging the usually pristine Tambo river in the Victorian high country in January.
David Crosling/AAP

Long-term damage

The devastating impact of the fires in river environments may be long-lived.

When aquatic animals species are wiped out in particular rivers, they may not be able to recolonise from surviving populations in other unconnected rivers.

Some species will invariably now be closer to extinction. For example many key peat swamp habitats of the critically endangered northern corroboree frog have been burnt in the Bogong Peaks and Brindabella mountains of NSW and the ACT.




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The sweet relief of rain after bushfires threatens disaster for our rivers


And after fires, fast-growing young eucalyptus forests transpire much more water than older burnt trees. This may reduce inflows into streams for a century.

The recent bushfires followed several years of extreme drought across much of Australia. In the Murray-Darling Basin, these challenges were compounded by poor water management that contributed to dried-up rivers and mass fish deaths.

Water-sharing rules in the basin determine how much water is allocated to agriculture and the environment. Current water-sharing plans do not explicitly include allocations to manage losses due to climate change, and as the plans will only be updated once a decade, it is questionable whether they will be adjusted to sustain flows needed to conserve threatened species.

Much corroboree frog habitat was destroyed during the fires.
Melbourne Zoo

Here’s what to do

After the fires, government officials and scientists rescued a number of “insurance” populations of threatened aquatic animals such as turtle and fish species, and took them to captive breeding facilities, such as the stocky galaxias fish in the alps. We must ensure healthy habitat is available for these animals to re-establish viable populations when released.

In the short term, we must protect surviving and regenerating habitat. Government programs are off to a good start in promising to cull feral predators such as cats and foxes, as well as grazing animals such as pigs, deer and goats. The NSW and Victorian governments must also remove feral horses in the Australian Alps that are damaging the swamp habitats and streams.

Now so many infested riverside forests are accessible, it is a key time to control weed regrowth.




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In the medium term, we should expand programs to fence livestock out of waterways, install other watering points for these animals and revegetate stream banks.

Deep holes in rivers and streams with cool water are important refuges for aquatic animals, and ways to restore them should be investigated.

Impediments to fish migration, such as weirs, should be removed or fish “ladders” installed to aid fish movement. Aquatic species often won’t breed unless the water is the right temperature in the right season; to prevent the release of overly cold water from the bottom of dams, better water release structures should be installed.

Years of drought meant rivers and aquatic life were already vulnerable before the fires.
Dean Lewins/AAP

An opportunity for change

Successive governments have been asleep at the tiller when it comes to threatened aquatic animals. Official recovery plans for many fire-affected species have not been adequately funded or implemented.

In the Murray-Darling Basin for example, a native fish strategy was shelved in 2013 after the NSW government reportedly pulled funding.

The impending release of a new fish strategy, and other post-fire recovery actions, are an opportunity for governments to right past wrongs and ensure our precious freshwater species thrive into the future.The Conversation

Jamie Pittock, Professor, Fenner School of Environment & Society, Australian National University

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

B&Bs for birds and bees: transform your garden or balcony into a wildlife haven



Wes Mountain/The Conversation, CC BY-NC

Judith Friedlander, University of Technology Sydney

Just like humans, animals like living near coastal plains and waterways. In fact, cities such as Sydney and Melbourne are “biodiversity hotspots” – boasting fresh water, varied topographies and relatively rich soil to sustain and nourish life.

Recent research showed urban areas can support a greater range of animals and insects than some bushland and rural habitat, if we revegetate with biodiversity in mind.




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How you can help – not harm – wild animals recovering from bushfires


Urban regeneration is especially important now, amid unfathomable estimates that more than one billion animals were killed in the recent bushfires. Even before the fires, we were in the middle of a mass extinction event in Australia and around the world.

Losing animals, especially pollinators such as bees, has huge implications for biodiversity and food supplies.

My team and I are creating a B&B Highway – a series of nest boxes, artificial hollows and pollinating plants – in Sydney and coastal urban areas of New South Wales. These essentially act as “bed and breakfasts” where creatures such as birds, bees, butterflies and bats can rest and recharge. Everyday Australians can also build a B&B in their own backyards or on balconies.

City living for climate refugees

I spoke to Charles Sturt University ecologist Dr Watson about the importance of protecting animals such as pollinators during the climate crisis. He said:

The current drought has devastated inland areas – anything that can move has cleared out, with many birds and other mobile animals retreating to the wetter, more temperate forests to the south and east.

So, when considering the wider impacts of these fires […] we need to include these climate refugees in our thinking.

Native birds like the white-winged triller have been spotted in urban areas.
Shutterstock

Many woodland birds such as honeyeaters and parrots have moved in droves to cities, including Sydney, over the last few years because of droughts and climate change, attracted to the rich variety of berries, fruits and seeds.

I also spoke to BirdLife Australia’s Holly Parsons, who said last year’s Aussie Backyard Bird Count recorded other inland birds – such as the white-winged triller, the crimson chat, pied honeyeater, rainforest pigeons and doves – outside their usual range, attracted to the richer food variety in coastal cities.




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What’s more, there have been increased sightings of powerful owls in Sydney and Melbourne, squirrel gliders in Albury, marbled geckos in Melbourne, and blue-tongue lizards in urban gardens across south-east Australia.

With so many birds and pollinators flocking to the cities, it’s important we support them with vegetated regions they can shelter in, such as through the B&B Highway we’re developing.

The B&B Highway: an urban restoration project

B&Bs on our “highway” are green sanctuaries, containing pollinating plants, water and shelters such as beehives and nesting boxes.




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We’re setting up B&Bs across New South Wales in schools and community centres, with plans to expand them in Melbourne, Brisbane and other major cities. In fact, by mid-2020, we’ll have 30 B&Bs located across five different Sydney municipalities, with more planned outside Sydney.

The NSW Department of Education is also developing an associated curriculum for primary and early high school students to engage them in ecosystem restoration.

One of the biodiversity havens the author developed to attract pollinators.
Author provided

If you have space in your garden, or even on a balcony, you can help too. Here’s how.

For birds

Find out what bird species live in your area and which are endangered using the Birdata directory. Then select plants native to your area – your local nursery can help you out here.

The type of plants will vary on whether your local birds feed on insects, nectar, seed, fruit or meat. Use the guide below.



Wes Mountain/The Conversation, CC BY-ND

More tips

Plant dense shrubs to allow smaller birds, such as the superb fairy-wren, to hide from predatory birds.

Order hollows and nesting boxes from La Trobe University to house birds, possums, gliders and bats.

Put out water for birds, insects and other animals. Bird baths should be elevated to enable escape from predators. Clean water stations and bowls regularly.

For native stingless bees

If you live on the eastern seaboard from Sydney northward, consider installing a native stingless beehive. They require very little maintenance, and no permits or special training.

These bees are perfect for garden pollination. Suppliers of bees and hives can be found online – sometimes you can even rescue an endangered hive.

A blue banded bee at a B&B rest stops in NSW.
Author provided

Also add bee-friendly plants – sting or no sting – to your garden, such as butterfly bush, bottlebrush, daisies, eucalyptus and angophora gum trees, grevillea, lavender, tea tree, honey myrtle and native rosemary.

For other insects

Wherever you are in Australia, you can buy or make your own insect hotel. There is no standard design, because our gardens host a wide range of native insects partial to different natural materials.

An insect hotel. Note the holes, at a variety of depths, drilled into the material.
Dietmar Rabich/Wikimedia Commons, CC BY-SA

Building your insect hotel

Use recycled materials (wooden pallets, small wooden box or frames) or natural materials (wood, bamboo, sticks, straw, stones and clay).

Fill gaps in the structure with smaller materials, such as clay and bamboo.

In the wood, drill holes ranging from three to ten millimetres wide for insects to live in. Vary hole depths for different insects – but don’t drill all the way through. They shouldn’t be deeper than 30 centimetres.

Give your hotel a roof so it stays dry, and don’t use toxic paints or varnishes.

Place your insect hotel in a sheltered spot, with the opening facing the sun in cool climates, and facing the morning sun in warmer climates.

Apartment-dwellers can place their insect hotels on a balcony near pot plants. North-facing is often best, but make sure it’s sheltered from harsh afternoon sunshine and heavy rain.The Conversation

Judith Friedlander, Post-graduate Researcher, Institute for Sustainable Futures, University of Technology Sydney

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

From crocodiles to krill, a warming world raises the ‘costs’ paid by developing embryos




Dustin Marshall, Monash University

Apart from mammals and birds, most animals develop as eggs exposed to the vagaries of the outside world. This development is energetically “costly”. Going from a tiny egg to a fully functioning organism can deplete up to 60% of the energy reserves provided by a parent.

In cold-blooded animals such as marine invertebrates (including sea stars and corals), fish and reptiles, and even insects, embryonic development is very sensitive to changes in the temperature of the environment.

Thus, in a warming world, many cold-blooded species face a new challenge: developing successfully despite rising temperatures.




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For our research, published today in Nature Ecology and Evolution, we mined existing literature for data on how temperature impacts the metabolic and development rates of 71 different species, ranging from tropical crocodiles to Antarctic krill.

We found over time, species tend to fine-tune their physiology so that the temperature of the place they inhabit is the temperature needed to minimise the “costs” of their embryonic development.

Temperature increases associated with global warming could substantially impact many of these species.

The perfect weather to grow an embryo

The energy costs of embryonic development are determined by two key rates. The “metabolic” rate refers to the rate at which energy is used by the embryo, and the “development” rate determines how long it takes the embryo to fully develop, and become an independent organism.

Both of these rates are heavily impacted by environmental temperature. Any change in temperature affecting them is therefore costly to an embryo’s development.

Generally, a 10°C increase in temperature will cause an embryo’s development and metabolic rate to more than triple.

This photo shows a developing sea urchin, from egg (top left) to larva, to a metamorphosed (matured into adult form) individual.
Dustin Marshall, Author provided

These effects partially cancel each other out. Higher temperatures increase the rate at which energy is used (metabolic), but shorten the developmental time.

But do they balance out effectively?

What are the costs?

For any species, there is one temperature that achieves the perfect energetic balance between relatively rapid development and low metabolism. This optimal temperature, also called the “Goldilocks” temperature, is neither too hot, nor too cold.

When the temperature is too cold for a certain species, development takes a long time. When it’s too hot, development time decreases while the metabolic rate continues to rise. An imbalance on either side can negatively impact a natural population’s resilience and ability to replenish.

As an embryo’s developmental costs increase past the optimum, mothers must invest more resources into each offspring to offset these costs.

When offspring become more costly to make, mothers make fewer, larger offspring. These offspring start life with fewer energy reserves, reducing their chances of successfully reproducing as adults themselves.

Thus, when it comes to embryonic development, higher-than ideal temperatures pack a nasty punch for natural populations.

Since the temperature dependencies of metabolic rate and development rate are fairly similar, the slight differences between them had gone unnoticed until recently.




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Why cold-blooded animals don’t need to wrap up to keep warm


Embryos at risk

For each species in our study, we found a narrow band of temperatures that minimised developmental cost. Temperatures that were too high or too low caused massive blow-outs in the energy budget of developing embryos.

This means temperature increases associated with global warming are likely to have bigger impacts than previously predicted.

Predictions of how future temperature changes will affect organisms are often based on estimates of how temperature affects embryo survival. These measures suggest small temperature increases (1°C-2°C) do not reduce embryo survival by much.

But our study found the developmental costs are about twice as high, and we had underestimated the impacts of subtle temperature changes on embryo development.

In the warming animal kingdom, there are winners and losers

Some good news is our research suggests not all species are facing rising costs with rising temperatures, at least initially.

We’ve created a mathematical framework called the Developmental Cost Theory, which predicts some species will actually experience slightly lower developmental costs with minor increases in temperature.




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In particular, aquatic species (fish and invertebrates) in cool temperate waters seem likely to experience lower costs in the near future. In contrast, certain tropical aquatic species (including coral reef organisms) are already experiencing temperatures that exceed their optimum. This is likely to get worse.

It’s important to note that for all species, increasing environmental temperature will eventually come with costs.

Even if a slight temperature increase reduces costs for one species, too much of an increase will still have a negative impact. This is true for all the organisms we studied.

A key question now is: how quickly can species evolve to adapt to our warming climate?The Conversation

Dustin Marshall, Professor, Marine Evolutionary Ecology, Monash University

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

One little bandicoot can dig up an elephant’s worth of soil a year – and our ecosystem loves it



Catching The Eye/Flickr, CC BY

Euan Ritchie, Deakin University; Amy Coetsee, University of Melbourne; Anthony Rendall, Deakin University; Duncan Sutherland, University of Melbourne, and Leonie Valentine, University of Western Australia

On Churchill Island, southeast of Melbourne, small cone-shaped, shallow holes (digs) puncture the grass. They’re widespread, and reveal moist soil below the surface. A soil heap at the entrance of a dig is a sign it was made recently.

Older digs are filled with leaves, grass, spiders, beetles and other invertebrates. They are made by hungry eastern barred bandicoots – small, roughly rabbit-sized digging marsupials – looking for a juicy worm or grub.




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How you can help – not harm – wild animals recovering from bushfires


It turns out these bandicoot digs are far from just environmental curiosities – they can improve the properties and health of soils, and even reduce fire risk.

But eastern barred bandicoots are under threat from introduced predators like foxes and cats. In fact, they’re considered extinct in the wild on mainland Australia, so conservation biologists are releasing them on fox-free islands to help establish new populations and ensure the species is conserved long-term.

Our recent research on Churchill Island put a number on just how much the eastern barred bandicoot digs – and the results were staggering, showing how important they are for the ecosystem. But more on that later.

A dig from an eastern barred bandicoot.
Amy Coetsee

Why you should dig marsupial diggers

Digging mammals – such as bettongs, potoroos, bilbies and bandicoots – were once abundant and widespread across Australia, turning over large amounts of soil every night with their strong front legs as they dig for food or create burrows for shelter.




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Their digs improve soil health, increase soil moisture and nutrient content, and decrease soil compaction and erosion. Digs also provide habitat for invertebrates and improve seed germination.

What’s more, by digging fuel loads (dry, flammable vegetation, such as leaves) into the soil, they can help bring down the risk of fire.

Rather than leaves and other plant matter accumulating on the soil surface and drying out, this material is turned over faster, entering the soil when the badicoots dig, which speeds up its decay. Research from 2016 showed there’s less plant material covering the soil surface when digging mammals are about. Without diggers, models show fire spread and flame height are bigger.

In fact, all their functions are so important ecologists have dubbed these mighty diggers “ecosystem engineers”.

How bandicoot digs affect soil.
Leonie Valentine, Author provided

Losing diggers leads to poorer soil health

Of Australia’s 29 digging mammals, 23 are between 100 grams and 5 kilograms. Most are at risk of cat and fox predation, and many of these are officially listed as threatened species by the International Union for Conservation of Nature.

Since European settlement, six of Australia’s digging mammals have gone extinct, including the lesser bilby, desert rat kangaroo and pig-footed bandicoots. Many others have suffered marked population declines and extensive range contraction through habitat destruction and the introduction of foxes and cats.




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Rockin’ the suburbs: bandicoots live among us in Melbourne


Tragically, the widespread decline and extinction of many digging mammals means soil and ecosystem health has suffered as well.

Soils that were once soft textured, easy to crumble, rich and fertile are now often compact, repel water and nutrient poor, impeding seed germination and plant growth. Fuel loads are also likely to be much higher now than in the past, as less organic matter is dug into the soil.

To date, most research on digging mammals has focused on arid environments, with much less known about how digging influences wetter (mesic) environments. But our recently published study on eastern barred bandicoots provides new insights.

Just how much do bandicoots dig anyway?

In 2015, 20 mainland eastern barred bandicoots were released onto Churchill Island in Victoria’s Westernport Bay.

When eastern barred bandicoots were released on Churchill Island.

On mainland Australia, fox predation has driven this species to near extinction, and it’s classified as extinct in the wild. All Victoria’s islands are beyond the historic range of eastern barred bandicoots, but fox-free islands could be how we recover them.

Introducing bandicoots on Churchill Island presented the perfect opportunity to quantify how they influence soil properties when digging for food.




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To do this we recorded the number of digs bandicoots made each night and measured the volume of soil they displaced through digging. We also compared soil moisture and compaction within the digs, versus un-dug soil – and we didn’t expect what we found.

In one night on Churchill Island, one bandicoot can make 41 digs an hour. That’s nearly 500 digs a night, equating to around 13 kilograms of soil being turned over every night, or 4.8 tonnes a year. That’s almost as much as the average weight of a male African elephant.

Bandicoots turn over huge amounts of soil in their search for food.
Amy Coetsee

So, an astonishing amount of soil is being turned over, especially considering these bandicoots typically weigh around 750 grams.

If you multiply this by the number of bandicoots on Churchill Island (up from 20 in 2015 to around 130 at the time of our study in 2017), there’s a staggering 1,690 kilos of soil being dug up every night. That’s some major earthworks!

However, we should note our study was conducted during the wetter months, when soils are typically easier to dig.

In summer, as soil becomes harder and drier on Churchill Island, digging may become more difficult. And bandicoots, being great generalists, feed more on surface invertebrates like beetles and crickets, resulting in fewer digs. So we expect in summer that soil is less disturbed.

Bandicoots might help agriculture too

All this digging was found to boost soil health on Churchill Island. This means eastern barred bandicoots may not only play an important role in ecosystem health and regeneration, but also potentially in agriculture by assisting pasture growth and condition, reducing topsoil runoff, and mitigating the effects of trampling and soil compaction from livestock.

One of 20 eastern barred bandicoots being released on Churchill Island.
Zoos Victoria

The benefits bandicoot digs have across agricultural land is of particular importance now that eastern barred bandicoots have also been released on Phillip Island and French Island, and are expected to extensively use pasture for foraging.

These island releases could not just help to ensure eastern barred bandicoots avoid extinction, but also promote productive agricultural land for farmers.




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So, given the important ecological roles ecosystem engineers like bandicoots perform, it’s also important we try to reestablish their wild populations on the mainland and outside of fenced sanctuaries so we can all benefit from their digging, not just on islands.


Lauren Halstead is the lead author of the study reported, which stemmed from her honours research at Deakin University. She also contributed to the writing of this article.The Conversation

Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University; Amy Coetsee, Threatened Species Biologist, University of Melbourne; Anthony Rendall, Associate Lecturer in Conservation Biology, Deakin University; Duncan Sutherland, Deputy Director of Research, Phillip Island Nature Parks; Research Fellow, University of Melbourne, and Leonie Valentine, Research Associate, School of Plant Biology, University of Western Australia

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