Tasmania’s salmon industry detonates underwater bombs to scare away seals – but at what cost?

Benjamin J. Richardson, University of TasmaniaAustralians consume a lot of salmon – much of it farmed in Tasmania. But as Richard Flanagan’s new book Toxic shows, concern about the industry’s environmental damage is growing.

With the industry set to double in size by 2030, one dubious industry practice should be intensely scrutinised – the use of so-called “cracker bombs” or seal bombs.

The A$1 billion industry uses the technique to deter seals and protect fish farming operations. Cracker bombs are underwater explosive devices that emit sharp, extremely loud noise impulses. Combined, Tasmania’s three major salmon farm operators have detonated at least 77,000 crackers since 2018.

The industry says the deterrent is necessary, but international research shows the devices pose a significant threat to some marine life. Unless the salmon industry is more strictly controlled, native species will likely be killed or injured as the industry expands.

pile of grey and white fish — Tasmanian salmon farming is a billion-dollar industry.
Shutterstock

Protecting a lucrative industry

Marine farming has been growing rapidly in Tasmania since the 1990s, and Atlantic salmon is Tasmania’s most lucrative fishery‑related industry. The salmon industry comprises three major producers: Huon Aquaculture, Tassal and Petuna.

These companies go to great effort to protect their operations from fur seals, which are protected in Australia with an exemption for the salmon industry.

Seals may attack fish pens in search of food and injure salmon farm divers, though known incidents of harm to divers are extremely rare.

The industry uses a number of seal deterrent devices, the use of which is approved by the government. They include:

lead-filled projectiles known as “beanbags”, which are fired from a gun
sedation darts fired from a gun
explosive charges or “crackers” thrown into the water which detonate under the surface.

In June this year, the ABC reported on government documents showing the three major salmon producers had detonated more than 77,000 crackers since 2018. The documents showed how various seal deterrent methods had led to maiming, death and seal injuries resulting in euthanasia. Blunt-force trauma was a factor in half the reported seal deaths.

A response to this article by the salmon industry can be found below. The industry has previoulsy defended the use of cracker bombs, saying it has a responsibility to protect workers. It says the increased use of seal-proof infrastructure means the use of seal deterrents is declining. If this is true, it’s not yet strongly reflected in the data.

salmon farm infrastructure in water — Seal deterrents are deployed to protect salmon farm operations.
Shutterstock

Piercing the ocean silence

Given the prevalence of seal bomb use by the salmon industry, it’s worth reviewing the evidence on how they affect seals and other marine life.

A study on the use of the devices in California showed they can cause horrific injuries to seals. The damage includes trauma to bones, soft tissue burns and prolapsed eye balls, as well as death.

And research suggests damage to marine life extends far beyond seals. For example, the devices can disturb porpoises which rely on echolocation to find food, avoid predators and navigate the ocean. Porpoises emit clicks and squeaks – sound which travels through the water and bounces off objects. In 2018, a study found seal bombs could disturb harbour porpoises in California at least 64 kilometres from the detonation site.

There is also a body of research showing how similar types of industrial noise affect marine life. A study in South Africa in 2017 showed how during seismic surveys in search of oil or gas, which produce intense ocean noise, penguins raising chicks often avoided their preferred foraging areas. Whales and fish have also shown similar avoidance behaviour.

The study showed underwater blasts can also kill and injure seabirds such as penguins. And there may be implications from leaving penguin nests unattended and vulnerable to predators, and leaving chicks hungry longer.

Research also shows underwater explosions damage to fish. One study on caged fish reported profound trauma to their ears, including blistering, holes and other damage. Another study cited official reports of dead fish in the vicinity of seal bomb explosions.

dolphin jumps out of waves — Man-made noise can disturb a variety of marine animals, including porpoises.
Shutterstock

Shining a light

Clearly, more scientific research is needed into how seal bombs affect marine life in the oceans off Tasmania. And regulators should impose far stricter limits on the salmon industry’s use of seal bombs – a call echoed by Tasmania’s Salmon Reform Alliance.

All this is unfolding as federal environment laws fail to protect Australian plant and animal species, including marine wildlife.

And the laws in Tasmania are far from perfect. In 2017, Tasmania’s Finfish Farming Environmental Regulation Act introduced opportunities for better oversight of commercial fisheries. However, as the Environmental Defenders Office (EDO) has noted, the director of Tasmania’s Environment Protection Authority can decide on license applications by salmon farms without the development necessarily undergoing a full environmental assessment.

Tasmania’s Marine Farming Planning Act covers salmon farm locations and leases. As the EDO has noted, the public is not notified of some key decisions under the law and has very limited public rights of appeal.

Two relevant public inquiries are underway – a federal inquiry into aquaculture expansion and a Tasmanian parliamentary probe into fin-fish sustainability. Both have heard evidence from community stakeholders, such as the Tasmanian Alliance for Marine Protection and the Tasmanian Conservation Trust, that the Tasmanian salmon industry lacks transparency and provides insufficient opportunities for public input into environmental governance.

The Tasmanian government has thrown its support behind rapid expansion of the salmon industry. But it’s essential that the industry is more tightly regulated, and far more accountable for any environmental damage it creates.

In a statement in response to this article, the Tasmanian Salmonid Growers Association, which represents the three producers named above, said:

Around $500 million has been spent on innovative pens by the industry. These pens are designed to minimise risks to wildlife as well as to fish stocks and the employees. We believe that farms should be designed to minimise the threat of seals, but we also understand that non-lethal deterrents are a part of the measures approved by the government for the individual member companies to use. If these deterrents are used it is under strict guidelines, sparingly, and in emergency situations when staff are threatened by these animals, which can be very aggressive.

Tasmania has a strong, highly regulated, longstanding salmon industry of which we should all be proud. The salmon industry will continue its track record of operating at world’s best practice now and into future. Our local people have been working in regional communities for more than 30 years, to bring healthy, nutritious salmon to Australian dinner plates, through innovation and determination.

Benjamin J. Richardson, Professor of Environmental Law, University of Tasmania

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

Destroying vegetation along fences and roads could worsen our extinction crisis — yet the NSW government just allowed it

Euan Ritchie, Deakin University; Ben Moore, Western Sydney University; Jen Martin, The University of Melbourne; Mark Hall, Western Sydney University; Megan C Evans, UNSW, and Ross Crates, Australian National UniversityWhat do koalas, barking owls, greater gliders, southern rainbow skinks, native bees, and regent honeyeaters all have in common? Like many native species, they can all be found in vegetation along fences and roadsides outside formal conservation areas.

They may be relatively small, but these patches and strips conserve critical remnant habitat and have disproportionate conservation value worldwide. They represent the last vestiges of once-expansive tracts of woodland and forests, long lost to the chainsaw or plough.

And yet, the NSW government last week made it legal for rural landholders to clear vegetation on their properties, up to 25 metres from their property boundaries, without approval. This radical measure is proposed to protect people and properties from fires, despite the lack of such an explicit recommendation from federal and state-based inquiries into the devastating 2019-20 bushfires.

This is poor environmental policy that lacks apparent consideration or justification of its potentially substantial ecological costs. It also gravely undermines the NSW government’s recent announcement of a plan for “zero extinction” within the state’s national parks, as the success of protected reserves for conservation is greatly enhanced by connection with surrounding “off-reserve” habitat.

Small breaks in habitat can have big impacts

A 25m firebreak might sound innocuous, but when multiplied by the length of property boundaries in NSW, the scale of potential clearing and impacts is alarming, and could run into the hundreds of thousands of kilometres.

Some plants, animals and fungi live in these strips of vegetation permanently. Others use them to travel between larger habitat patches. And for migratory species, the vegetation provides crucial refuelling stops on long distance journeys.

For example, the roadside area in Victoria’s Strathbogie Ranges shown below is home to nine species of tree-dwelling native mammals: two species of brushtail possums, three species of gliders (including threatened greater gliders), common ringtail possums, koalas, brush-tailed phascogales, and agile antenchinus (small marsupials).

Roadside and fenceline vegetation is often the only substantial remnant vegetation remaining in agricultural landscapes. This section, in northeast Victoria’s Strathbogie Ranges, running north to south from the intersection, is home to high arboreal mammal diversity, including the threatened greater glider.
Google Earth

Many of these species depend on tree hollows that can take a hundred years to form. If destroyed, they are effectively irreplaceable.

Creating breaks in largely continuous vegetation, or further fragmenting already disjointed vegetation, will not only directly destroy habitat, but can severely lower the quality of adjoining habitat.

This is because firebreaks of 25m (or 50m where neighbouring landholders both clear) could prevent the movement and dispersal of many plant and animal species, including critical pollinators such as native bees.

An entire suite of woodland birds, including the critically endangered regent honeyeater, are threatened because they depend on thin strips of vegetation communities that often occur inside fence-lines on private land.

Ecologically-sensitive fence replacement in regent honeyeater breeding habitat.
Ross Crates

For instance, scientific monitoring has shown five pairs of regent honeyeaters (50% of all birds located so far this season) are nesting or foraging within 25m of a single fence-line in the upper Hunter Valley. This highlights just how big an impact the loss of one small, private location could have on a species already on the brink of extinction.

But it’s not just regent honeyeaters. The management plan for the vulnerable glossy black cockatoo makes specific recommendation that vegetation corridors be maintained, as they’re essential for the cockatoos to travel between suitable large patches.

Native bee conservation also relies on the protection of remnant habitat adjoining fields. Continued removal of habitat on private land will hinder chances of conserving these species.

Glossy black cockatoos rely on remnant patches of vegetation.
Shutterstock

Disastrous clearing laws

The new clearing code does have some regulations in place, albeit meagre. For example, on the Rural Fire Service website, it says the code allows “clearing only in identified areas, such as areas which are zoned as Rural, and which are considered bush fire prone”. And according to the RFS boundary clearing tool landowners aren’t allowed to clear vegetation near watercourses (riparian vegetation).

Even before introducing this new code, NSW’s clearing laws were an environmental disaster. In 2019, The NSW Audit Office found:

clearing of native vegetation on rural land is not effectively regulated [and] action is rarely taken against landholders who unlawfully clear native vegetation.

The data back this up. In 2019, over 54,500 hectares were cleared in NSW. Of this, 74% was “unexplained”, which means the clearing was either lawful (but didn’t require state government approval), unlawful or not fully compliant with approvals.

Landholders need to show they’ve complied with clearing laws only after they’ve already cleared the land. But this is too late for wildlife, including plant species, many of which are threatened.

Landholders follow self-assessable codes, but problems with these policies have been identified time and time again — they cumulatively allow a huge amount of clearing, and compliance and enforcement are ineffective.

Vegetation along roadsides and close to fences can be critical habitat for greater gliders.

We also know, thanks to various case studies, the policy of “offsetting” environmental damage by improving biodiversity elsewhere doesn’t work.

So, could the federal environment and biodiversity protection law step in if habitat clearing gets out of hand? Probably not. The problem is these 25m strips are unlikely to be referred in the first place, or be considered a “significant impact” to trigger the federal law.

The code should be amended

Nobody disputes the need to keep people and their assets safe against the risks of fire. The code should be amended to ensure clearing is only permitted where a genuinely clear and measurable fire risk reduction is demonstrated.

Many native bees, like this blue-banded bee (*Amegilla* sp.), will use the nesting and foraging resources available in remnant vegetation patches.
Michael Duncan

Granting permission to clear considerable amounts of native vegetation, hundreds if not thousands of metres away from homes and key infrastructure in large properties is hard to reconcile, and it seems that no attempt has been made to properly justify this legislation.

We should expect that a comprehensive assessment of the likely impacts of a significant change like this would inform public debate prior to decisions being made. But to our knowledge, no one has analysed, or at least revealed, how much land this rule change will affect, nor exactly what vegetation types and wildlife will likely be most affected.

A potentially devastating environmental precedent is being set, if other regions of Australia were to follow suit. The environment and Australians deserve better.

Clarification: some text has been added to clarify the land cleared is on the landowner’s property, not outside their property boundary

Euan Ritchie, Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University; Ben Moore, Senior Lecturer in Ecology, Hawkesbury Institute for the Environment, Western Sydney University; Jen Martin, Leader, Science Communication Teaching Program, The University of Melbourne; Mark Hall, Postdoctoral research fellow, Hawkesbury Institute for the Environment, Western Sydney University; Megan C Evans, Lecturer and ARC DECRA Fellow, UNSW, and Ross Crates, Postdoctoral fellow, Australian National University

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

How urban soundscapes affect humans and wildlife — and what may have changed in the hush of lockdown

Kurt Iveson, University of Sydney and Dieter Hochuli, University of SydneyThe dull roar of traffic, the barking of dogs in backyards and the screeching of cockatoos at dusk. The shattering of early morning quiet by the first plane overhead or the garbage truck on its rounds. The squealed delights and occasional fights of a children’s playground.

These sounds and many more create what Canadian composer R Murray Schafer famously called a “soundscape”. Schafer, who passed away last month, helped us realise we experience cities with our ears as well as our eyes.

In recent years, studies have confirmed these soundscapes affect the well-being of urban inhabitants — both human and non-human. But with much of the country back under lockdown, urban soundscapes have changed, sometimes bringing delight, but sometimes causing new distress.

So let’s take a moment to consider how soundscapes influence our lives, and the lives of urban wildlife.

When sounds become ‘noise’

Whether it’s housemates, traffic, or construction, we tend to respond to many urban sounds by defining them as “noise”, and try to shut them out. We do this using a range of techniques and technologies: building regulations on soundproofing, controls on the times for certain activities like construction, and planning measures.

But noise mapping efforts show such regulations tend to produce uneven urban soundscapes — some people are more exposed to loud or annoying sounds than others.

Housing quality is a major factor here, and noise problems are likely exacerbated under lockdown. A recent study of pandemic housing inequality in Sydney found increased exposure to noise during lockdown is significantly contributing to poor well-being.

For example, sounds travelling across internal and external walls of apartments were frequently a source of tension in pre-pandemic times. Now, with so many more people spending more time at home, these domestic sounds inevitably increase.

It’s not just humans whose lives are disrupted by city noise, as many animals use sound to communicate.

The ever-vigilant New Holland honeyeaters of Australian cities use their alarm calls to warn their friends and neighbours of danger, while the iconic chorus of banjo frogs in wetlands are the hopeful calls of males seeking mates.

This is the sound a banjo frog makes.

Noisy environments can dramatically change how these animals behave. In some cases, animals adapt to their noisy environment. Some frogs, for example, overcome traffic noise disrupting their sex lives by calling at a higher pitch. Likewise, populations of bow-winged grasshoppers in Germany exposed to road noise sing at higher frequencies than those living in quieter areas.

For other animals, such as microbats in England, disruptive noise changes how they forage and move around their environments.

In extreme cases, these human-associated noises can drive animals away from their homes, as the disruptions to their lives becomes untenable.

Urban black-tufted marmosets in Brazil have been shown to avoid areas with abundant food where noise may interfere with their vocal communication. And research shows intruding noise in stopovers for migratory birds in the United States reduces their diversity by 25%, with some species avoiding the stopovers altogether.

Black-tufted marmosets in Brazil avoid noisy habitats even when there’s plenty of food.
Shutterstock

A new quiet?

The soundscape of cities in lockdown can be dramatically different from what we have come to accept as normal.

First, there are new noises. For example, in Sydney’s areas of concern subject to tighter lockdown restrictions, people are living with the frequent intrusive noise of police helicopters patrolling their neighbourhoods, making announcements over loudspeakers about compliance.

But in other cases, as our movements and activities are restricted, some city sounds associated with a negative impact on well-being are significantly reduced. People who live near major roads, aircraft flight paths, or construction sites will certainly be noticing the quiet as road traffic is greatly reduced and non-essential construction is paused.

But of course, while this silence might be golden for some, for others the sound of silence is the sound of lost work and income. This quietude may even be considered as unwelcome or even eerie — the sonic signature of isolation, confinement and loss.

The bow-winged grasshopper adapts to noisy soundscapes by singing at higher frequencies.
Quartl/Wikimedia, CC BY-SA

Just as many animals adapt to or avoid noisy urban environments, there is a chance many will respond to this natural experiment playing out. Quieter urban environments may see the return of some of our more noise sensitive species, but this depends on the species.

The Brazilian marmosets mentioned earlier didn’t return to those locations even during quieter times, suggesting the noise left a disruptive legacy on their habitat choice, well after it was experienced. On the other hand, other experiments show some species of birds rapidly returned to sites after noise was removed from the landscape.

While it’s too early to confirm any early speculation about nature returning to quieter urban environments during lockdown, there is compelling evidence many people will benefit from engaging with local nature more actively than they did before.

Birdwatching increased tenfold in lockdown last year.
Matthew Willimott/Unsplash

Many more Australians are acting as urban field naturalists. Birdwatching, for example, increased tenfold in lockdown last year.

It’s clear people are seeing novelty and wonder in animals and plants that have survived and even thrived in our cities right beneath our noses the whole time. Our increased use of local greenspace during the pandemic has created new opportunities to find the extraordinary in the ordinary.

Rethinking post-pandemic soundscapes

What might we learn from this natural experiment about the soundscapes we take for granted and the soundscapes we actually want?

This is an invitation to think about whether we ought to do more to control sounds we consider “noise”. Yes, decibel levels of activities like car and air traffic matter. But it’s also an opportunity to think beyond controlling sounds, and consider how we might create soundscapes to enhance human and non-human well-being. This is easier said than done, given there’s no universal measure of what sounds give pleasure and what sounds are perceived as noise.

This aligns with the growing body of evidence on the need to reduce noise pollution and protect biodiversity when planning and managing our cities.

Like just about every other dimension of urban life, envisioning and creating an improved urban soundscape requires careful attention to spatial inequality and diversity – including of species – and a capacity to work through our differences in a fair and just way.

Kurt Iveson, Associate Professor of Urban Geography and Research Lead, Sydney Policy Lab, University of Sydney and Dieter Hochuli, Professor, School of Life and Environmental Sciences, University of Sydney

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

This shy little wallaby has a white moustache and shares its name with a pub meal. Yet it’s been overlooked for decades

Elliott Dooley, University of Newcastle and Matt Hayward, University of NewcastleAm I not pretty enough? This article is part of The Conversation’s new series introducing you to Australia’s unloved animals that need our help.

For many people, the term “wallaby” may describe a single species, or rather just a small kangaroo. So you may be surprised to learn there are actually more than 50 known species of wallaby in Australia.

The parma wallaby (Macropus parma) is one of Australia’s smallest. It’s no larger than a house cat, with a body length up to 55 centimetres and a tail about the same length again. It has thick, brownish-grey fur, and a defining white moustache.

But this is about as much as can be said for its appearance, as even its moustache is common to many other wallaby species, such as the yellow-footed rock-wallaby.

Here, we aim to defend the voiceless. The parma wallaby’s failure to charm with either its looks or charisma has condemned it to obscurity by the general public and wildlife researchers alike, potentially dooming it to extinction.

The parma’s resurrection

So overlooked is the parma wallaby that for more than 30 years, it was presumed extinct until 1966, when a feral population was discovered on Kawau Island, New Zealand.

The species was introduced there a century earlier by former Prime Minister of New Zealand, Sir George Grey, who’s zoological interests led to Kawau becoming home to a menagerie of exotic animals.

A parma wallaby with a joey — Parma wallaby was presumed extinct for 30 years.
Benjamint444/Wikimedia, CC BY-SA

This sudden rediscovery resurrected the parma from the pages of natural history books, prompting a reintroduction program to re-establish the Kawau Island population in Australia. This occurred on two occasions, once on Pulbah Island in Lake Macquarie, and near Robertson, NSW. But both attempts were considered abject failures, with all reintroduced, marked individuals found dead, mostly due to predation by dogs and foxes.

Despite this unsuccessful program, the sudden spotlight on the species led to its rediscovery on the mainland in 1972 near Gosford, NSW. Soon after, a state-wide parma survey was conducted.

An elusive species

But since then, its ecology has largely gone unstudied and, once again, the parma has faded to obscurity.

The IUCN Red List — the pre-eminent assessment of the conservation status of the world’s biodiversity — has relied on a guestimate of population size, placing it at under 10,000 individuals.

Despite little monitoring the species is still considered only “near threatened” on the Red List, but events like the Black Summer bushfires may have significantly reduced its population.

As a result of its cryptic nature and very recent rediscovery in the wild, there is scarce known about the ecology of the parma wallaby. We don’t even know the exact origins of its name.

We do know its preferred habitat is moist eucalyptus forest with thick, shrubby understory. It shelters there during the day, often with nearby grassy areas as, at night, they typically feed on grass and herbs. They’re also found in rainforest margins and drier eucalypt forest, but to a lesser extent.

Parma wallabies weigh just 5kg, making them vulnerable to dogs, foxes and cats.
Lachlan McRae, Author provided

The parma wallaby is under threat

We also know the parma wallaby’s range is in decline and has been since European colonisation.

The species once occurred from southern Queensland to the Bega area in the southeast of NSW. Now, its range is confined to the coast and ranges of central and northern NSW. It’s patchily distributed throughout cool, high-altitude forests along the Great Dividing Range.

It weighs around 5 kilograms, placing it in the critical weight range category. This means it’s vulnerable to feral predators, such as dogs, cats and foxes.

Another major threat facing parma wallabies is habitat destruction from catastrophic bushfires.

The 2019-2020 Black Summer bushfires killed, injured or displaced an estimated three billion animals. Over half (55%) of the parma’s key habitat was severely burned. Coupled with the loss of those that would have perished in the flames, the species is now considered vulnerable in NSW.

Over half of the Parma wallaby’s habitat was burned in the Black Summer bushfires.
Elliott Dooley, Author provided

Saving the parma

The recent bushfire Royal Commission raised the issue that Australia doesn’t have a comprehensive, central source of information about its native flora and fauna. This is especially urgent, given seemingly “drab” species like the parma wallaby that have gone unnoticed for too long.

All species rely on interactions with a plethora of other species to survive in a complex system from which humans are not exempt. But with so little known about these interconnected relationships, we don’t know what the broader impacts to the ecosystem would be if one species disappeared.

Imagine a Jenga tower where each species is a wooden block. You can never really be certain which block you remove will cause the tower to collapse. Australia has an appalling extinction record, and we can’t afford to be playing Jenga with our biodiversity — whether it’s a boring bird, an ugly fish or just another wallaby.

Our ongoing research aims to help fill this conservation gap. We focus on a range of conservation actions the parma wallaby needs immediately.

These include carrying out field surveys to gauge the extent of their survival, and identifying the places that need refuge vegetation recovery. Refuge patches of bushland are important because they provide parma wallabies escape routes and places to hide, helping protect them from predation.

Parma wallaby sitting on a rock — If you want to help save parmas, keep your cat inside.
Lachlan McRae, Author provided

But you can help, too

Given the breadth of catastrophic fires is expected to increase under climate change, we can all help threatened species like the parma wallaby bounce back.

Come bushfire season, you can reduce the fire risk around your home by clearing anything that could fuel a fire — long grass, weeds and leaves on the ground and in guttering.

The parma wallaby, like many other little mammals, is vulnerable to introduced predators, especially cats. By keeping your cat indoors, you could be sparing the lives of 186 animals per year.

You can urge your politicians to value Australia’s unique and precious biodiversity. They are the ones who will ultimately determine whether our threatened species survive or go extinct.

Finally, you can volunteer. There are many volunteer-based conservation projects all over Australia, run by government agencies, charities, and universities.

With the ongoing pandemic travel restrictions, there’s no better time to experience the rich biodiversity this country has to offer, and discover less celebrated, but still fascinating, species like the parma wallaby.

Elliott Dooley, PhD Candidate, University of Newcastle and Matt Hayward, Professor of Conservation Science, University of Newcastle

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

Flies like yellow, bees like blue: how flower colours cater to the taste of pollinating insects

Hoverfly (*Eristalis tenax*) feeding on marigold.
Fir0002/Flagstaffotos, CC BY-NC

Jair Garcia, RMIT University; Adrian Dyer, RMIT University, and Mani Shrestha, Bayreuth UniversityWe all know the birds and the bees are important for pollination, and we often notice them in gardens and parks. But what about flies?

Flies are the second most common type of pollinator, so perhaps we should all be taught about the bees, the flies and then the birds. While we know animals may see colour differently, little was known about how fly pollination shapes the types of flowers we can find in nature.

In our new study we address this gap in our knowledge by evaluating how important fly pollinators sense and use colour, and how fly pollinated flowers have evolved colour signals.

Specialed flower visiting flies: a hoverfly (*Eristalis tenax*) (left panel), and a bee-fly (*Poecilanthrax apache*) (right panel)
Michael Becker, Pdeley

The way we see influences what we choose

We know that different humans often have preferences for certain colours, and in a similar way bees prefer blue hues.

Our colleague Lea Hannah has observed that hoverflies (Eristalis tenax) are much better at distinguishing between different shades of yellow than between different blues. Other research has also reported hoverflies have innate responses to yellow colours.

Many flowering plants depend on attracting pollinators to reproduce, so the appearance of their flowers has evolved to cater to the preferences of the pollinators. We wanted to find out what this might mean for how different insects like bees or flies shape flower colours in a complex natural environment where both types of insect are present.

The Australian case study

Australia is a natural laboratory for understanding flower evolution due to its geological isolation. On the mainland Australian continent, flowers have predominately evolved colours to suit animal pollination.

Around Australia there are plant communities with different pollinators. For example, Macquarie Island has no bees, and flies are the only animal pollinator.

We assembled data from different locations, including a native habitat in mainland Australia where both bees and flies forage, to model how different insects influence flower colour signal evolution.

Measuring flower colours

Since we know different animals sense colour in different ways, we recorded the spectrum of different wavelengths of light reflected from the flowers with a spectrometer. We subsequently modelled these spectral signatures of plant flowers considering animal perception, allowing us to objectively quantify how signals have evolved. These analyses included mapping the evolutionary ancestry of the plants.

Generalisation or specialisation?

According to one school of thought, flower evolution is driven by competition between flowering plants. In this scenario, different species might have very different colours from one another, to increase their chances of being reliably identified and pollinated. This is a bit like how exclusive brands seek customers by having readily identifiable branding.

An alternative hypothesis to competition is facilitation. Plants may share preferred colour signals to attract a higher number of specific insects. This explanation is like how some competing businesses can do better by being physically close together to attract many customers.

Our results demonstrate how flower colour signalling has dynamically evolved depending on the availability of insect pollinators, as happens in marketplaces.

In Victoria, flowers have converged to evolve colour signals preferred by their pollinators. The flowers of fly-pollinated orchids are typically yellowish-green, while closely related orchids pollinated by bees have more bluish and purple colours. The flowers appeared to share the preferred colours of their main pollinator, consistent with a facilitation hypothesis.

Typical flowers preferred by bees (*Lobelia rhombifolia*, left panel) and flies (*Pterostylis melagramma*, right panel) encountered in our study sites. Inserts show the spectral profile for each species as measured by a spectrometer.
Mani Shrestha

Our research showed flies can see differences between flowers of different species in response to the pollinator local “market”.

On Macquarie Island, where flies are the only pollinators, flower colours diverge from each other – but still stay within the range of the flies’ preferred colours. This is consistent with a competition strategy, where differences between plant species allow flies to more easily identify the colour of recently visited flowers.

When both fly and bee pollinators are present, flowers pollinated by flies appear to “filter out” bees to reduce the number of ineffective and opportunistic visitors. For example, in the Himalayas specialised plants require flies with long tongues to access floral rewards. This is similar to when a store wants to exclusively attract customers specifically interested in their product range.

Our findings on fly colour vision, along with novel precision agriculture techniques, can help using flies as alternative pollinators of crops. It also allows us to understand that if we want to see a full range of pollinating insects including beautiful hoverflies in our parks and gardens, we need to plant a range of flower types and colours.

Jair Garcia, Research fellow, RMIT University; Adrian Dyer, Associate Professor, RMIT University, and Mani Shrestha, Postdoc & International Fellow, Disturbance Ecology, Bayreuth University

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

Sydney’s Platypuses

Australia has failed greater gliders: since they were listed as ‘vulnerable’ we’ve destroyed more of their habitat

Darcy Watchorn, Deakin University and Kita Ashman, Deakin UniversityIn just five years, greater gliders — fluffy-eared, tree-dwelling marsupials — could go from vulnerable to endangered, because Australia’s environmental laws have failed to protect them and other threatened native species.

Our new research found that after the greater glider was listed as vulnerable to extinction under national environment law in 2016, habitat destruction actually increased in some states, driving the species closer to the brink. Now, they meet the criteria to be listed as endangered.

Despite this, the federal government has put forward a bill that would further weaken Australia’s environment laws.

If Australia wants to ditch its shameful reputation as a global extinction leader, our environmental laws must be significantly strengthened, not weakened.

Why is the greater glider losing its home?

At about the size of a cat, greater gliders are the largest gliding marsupial in the world, and can glide up to 100 metres through the forest canopy. They nest in the hollows of big old trees and, just like koalas, they mostly eat eucalypt leaves.

A dark morph greater glider in a patch of old growth forest in Munruben, Logan City, south of Brisbane.
Josh Bowell

Greater gliders were once common throughout the forests of Queensland, New South Wales, and Victoria. However, destructive practices, such as logging and urban development, have cut down the trees they call home. The rapidly warming climate and increasingly frequent and severe bushfires are also a major threat.

Together, these threats are causing the greater glider to rapidly disappear.

For our new study, we calculated the amount of greater glider habitat destroyed in the two years before the species was listed as vulnerable under Australia’s environment law, the Environment Protection and Biodiversity Conservation Act (EPBC) Act. We then compared this to the amount of habitat destroyed in the two years after listing.

In Victoria, we measured the amount of habitat that was logged. In Queensland and NSW, we measured the amount of habitat cleared for all purposes, including logging, agriculture, and development projects.

What we found

The amount of greater glider habitat logged in Victoria remained consistently high, with a total of 4,917 hectares logged before listing compared to 4,759 hectares after listing. And of all forest logged in Victoria after listing, more than 45% was mapped as greater glider habitat by the federal government, according to our research paper.

State-owned forestry company VicForests is responsible for the lion’s share of native forest logging in Victoria. The Conversation contacted VicForests to respond to the arguments in this article. A spokesperson said:

There are 3.7 million hectares of potential Greater Glider habitat in Victoria under the official habitat model. The most valuable areas of this habitat are set aside in conservation reserves that can never be harvested.

The total area harvested by VicForests in any year is around 0.04% of this total potential habitat.

A small bulldozer used for tree ‘thinning’ in Queensland, May 2017.
WWF-Australia

In Queensland, habitat clearing increased by almost 300%, from a total of 3,002 hectares before listing compared to 11,838 hectares after listing. The amount of habitat cleared in NSW increased by about 5%, from a total of 15,204 hectares to 15,890 hectares.

We also quantified how much greater glider habitat was affected by the 2019-2020 Black Summer bushfires, and found approximately 29% of greater glider habitat was burnt. Almost 40% of this burnt at high severity, which means few gliders are likely to persist in, or rapidly return to, these areas.

As a result, earlier this year — just five years after listing — an assessment by the Threatened Species Scientific Committee found the greater glider is potentially eligible for up-listing from vulnerable to endangered.

A greater glider found in burnt bushland, Meroo National Park, NSW, December 2019.
George Lemann, WWF-Australia

Why was habitat allowed to be cleared?

Development projects can take decades to be implemented after they’ve been approved under the EPBC Act. Therefore, a lot of the habitat cleared in NSW and Queensland was likely to have been approved before the greater glider was listed as vulnerable, and before the 2019-2020 bushfires.

Once a project is approved, it is not reassessed, even if a species becomes vulnerable and a wildfire burns much of its habitat.

This means the impact of clearing native vegetation can be far greater than when initially approved. It also means it can take many years after a species is listed until its habitat is finally safe.

This young greater glider was displaced by clearing near Chinchilla on the Darling Downs, Queensland. It was rescued by a fauna spotter/catcher who was present.
Briano, WWF-Australia

In Victoria and parts of NSW, the forestry industry is allowed to log greater glider habitat under “regional forest agreements”. These agreements allow logging to operate under a special set of rules that bypasses federal environmental scrutiny under the EPBC Act.

The logging industry is required to comply only with state regulations for threatened species protection, which are are often inadequate.

In 2019, the Victorian government updated the protection measures for greater gliders in logged forests. However, these still allow logging of up to 60% of a forested area authorised for harvest, even when greater gliders are present at high densities.

The spokesperson for VicForests said the company prioritises live, hollow-bearing trees wherever there are five or more greater gliders per spotlight kilometre (a 1 kilometre stretch of forest surveyed with torches). But this level of protection is limited and is unlikely to halt greater glider decline, as the species is highly sensitive to disturbance.

Recently logged native forest from the Central Highlands, Victoria.
Darcy Watchorn

In May 2020 the Federal Court found VicForests breached state environmental laws when they failed to implement protection measures and destroyed critically endangered Leadbeater’s possum and greater glider habitat.

Despite this, earlier this year, the Federal Court upheld an appeal by VicForests to retain their exemption from the EPBC Act. This ruling means VicForests will not be held accountable for destroying threatened species habitat, even when it is found in breach of state requirements.

The spokesperson for VicForests said the company takes sustainable harvesting seriously.

VicForests operations are subject to Victorian laws, and enforced by the Office of the Conservation Regulator (OCR) and Victorian courts when necessary. The recent federal court appeal decision has not changed that fact.

They add that VicForests surveys show greater gliders continue to persist in recently harvested areas, under its current practices.

VicForests has not seen any evidence that even a single Greater Glider has died as a result of our new harvesting approach.

The government isn’t learning its lesson

The EPBC Act is currently undergoing a once in a decade assessment that considers how well it’s operating, with a recent independent review criticising the EPBC Act for no longer being fit for purpose. Our new research reinforces this, by showing the act has failed to protect one of Australia’s most iconic and unique animals.

And yet, the federal government wants to weaken the act further by implementing a streamlined model, which would rely on state governments to approve actions that would impact threatened species.

There’s a raft of reasons why this would be problematic.

For one, state environmental laws operate independently, and don’t consider what developments have been approved in other states. Cutting down trees may seem insignificant in certain areas, but without considering the broader impacts, many small losses can accumulate into massive declines, like a death by a thousand cuts.

As a case in point, despite the devastation of greater glider habitat from the Black Summer fires in NSW, the Queensland government have recently approved a new coal mine, which will destroy over 5,500 hectares of greater glider and koala habitat.

What needs to change?

The greater glider is edging towards extinction, but there is still no recovery plan for this iconic marsupial. Adding to this, new research suggests there are actually three species of greater glider we could be losing, rather than just one as was previously thought. Significant effort must be invested to create a clear plan for their recovery.

Because Australia has such a rich diversity of wildlife, we have a great responsibility to protect it. Australia must make important changes now to strengthen — not weaken — its environmental laws, before greater gliders, and many other species, are gone forever.

Darcy Watchorn, PhD Candidate, Deakin University and Kita Ashman, Threatened Species & Climate Adaptation Ecologist, Deakin University

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

Monarch butterflies raised in captivity can still join the migration

Migrating monarch butterflies rest at Pismo Beach, Calif. on their way to Mexico.
(Shutterstock)

Alana Wilcox, University of Guelph and Ryan Norris, University of GuelphEach year, thousands of hobbyists and educators across North America collect monarch eggs or caterpillars from the wild to raise indoors and patiently wait for butterflies to emerge. Raising monarch butterflies indoors has become an increasingly popular activity that can have numerous benefits.

Captively reared monarchs provide a unique opportunity for people to learn about the complex life cycle of butterflies and, at the same time, help raise awareness about monarch conservation. However, rearing monarchs (and other butterflies) must be done responsibly and in moderation to make sure that it does not have a negative effect on the population.

Monarch butterflies undergo a multi-generational migration in spring and summer that will bring them as far north as Canada and then, in the fall, a new generation of monarchs undergo a unique transformation that prepares them for a single-bout long-distance migration south. These larger, stronger monarch butterflies will travel more than 4,500 kilometres to congregate and overwinter by the millions in the tree canopies high in the Sierra Madre Mountains of Mexico.

A PBS Nature special on overwintering monarch butterflies in Mexico.

Population decline

The overwintering population of eastern monarch butterflies, however, has been dwindling from an occupancy level of 44.95 hectares in 1997 to 14.95 hectares in 2019 to five hectares this year. Some causes of this decline are thought to be loss of milkweed on which caterpillars feed, long-term changes in climate and deforestation at their overwintering sites. This has caused concern about the likelihood of extinction and the loss of the migratory phenomenon.

Rearing monarchs indoors has been touted as a way to help bolster population numbers and mitigate declines. In reality, indoor rearing probably does little to supplement the wild population, but arguably goes a long way towards awareness and education.

The practice of indoor rearing is not without controversy and has been considered potentially harmful due to the negative impact it could have on butterfly health and the risk it could pose to the butterflies’ ability to migrate to Mexico.

However, our recent research provides some evidence that monarchs raised indoors may still be able to migrate south to their overwintering grounds.

Monarch butterfly with a radio-tracking tag.
(Wilcox), Author provided

Disoriented butterflies

Our team at the University of Guelph raised monarch caterpillars on milkweed indoors in controlled environmental conditions that approximated what monarchs would experience naturally in the wild. Once butterflies emerged from their cocoons, they were tested in a flight simulator, a large open vessel with a digital sensor that recorded which direction the monarchs attempted to fly.

The results from this experiment were consistent with previous research showing that indoor-reared monarchs, on average, did not orient in the proper direction for migration to Mexico.

Monarch butterflies’ inability to orient in the flight simulator could be the result of a lack of exposure to natural and direct sunlight during development. Many animals are equipped with an internal clock that tells the animal when to perform certain activities. For monarch butterflies, this internal clock is located in their antennae and, when coupled with visual information on the sun’s position, tells the monarch which direction it should fly each fall.

an infographic showing the results of the experiment — monarchs released in the wild could re-orient themselves — Monarch butterflies hatched in captivity but released in the wild were found to join the southward migration.
(Wilcox, Newman, Raine, Mitchell and Norris), Author provided

Recalibration in natural light

Given this, our research team went one step further to determine if indoor-reared monarchs exposed to natural environmental conditions and sunlight after they were released could calibrate their internal compass and fly south.

To do so, our team attached tiny radio transmitters to a second group of indoor-reared monarchs and released the butterflies into the wild. The radio transmitters emit a signal during migration and, if a monarch flies close enough, can be received at one of several hundred automatic radio receiving towers scattered across North America, called the Motus telemetry array.

We detected 29 butterflies at the beginning of migration and found that, given some time outdoors, these butterflies were able to get their bearings and fly southward. This suggests that under certain controlled conditions, raising monarchs indoors may not affect their orientation and ability to start migration.

Indoor rearing offers a valuable tool for learning and fostering a connection to nature. Our results help curb concern that indoor rearing negatively impacts monarch orientation.

While more research needs to be conducted to determine how monarchs perform under different indoor conditions and at different rearing locations in North America, our research suggests that monarch enthusiasts may be able to continue enjoying the wonderful experience of raising these butterflies at home.

Alana Wilcox, Researcher, Conservation biology, University of Guelph and Ryan Norris, Associate Professor, Member of the Royal Society of Canada’s College of New Scholars, Artists and Scientists, University of Guelph

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

Pacific Island bats are utterly fascinating, yet under threat and overlooked. Meet 4 species

Artwork by Arison Kul from Lae Papua New Guinea.

John Martin, University of Sydney; David L. Waldien, Christopher Newport University; Junior Novera, The University of Queensland; Justin A. Welbergen, Western Sydney University; Malik OEDIN, Université de Nouvelle Calédonie; Nicola Hanrahan, Charles Darwin University; Tigga Kingston, Texas Tech University, and Tyrone Lavery, Australian National UniversityAm I not pretty enough? This article is part of The Conversation’s new series introducing you to unloved animals that need our help.

A whopping 191 different bat species live in the Pacific Islands across Micronesia, Melanesia, and Polynesia — but these are, collectively, the most imperilled in the world. In fact, five of the nine bat species that have gone extinct in the last 160 years have come from this region.

For too long, the conservation of Pacific Island bats has been largely overlooked in science. Of the 191 existing species, 25% are threatened with extinction, and we lack information to assess the status of a further 15%.

Just as these bats are rare and far-flung across the Pacific islands, so is the expertise and research needed to conserve them along with the vital ecosystem services they provide, such as pollination, seed dispersal, and insect control.

The first-ever Pacific Islands Bat Forum, held earlier this month, sought to change this, bringing together a new network of researchers, conservationists, and community members — 380 people from 40 countries and territories — dedicated to their survival.

So, why should we care about these bats anyway?

Conserving Pacific Island bats is paramount for preserving the region’s diverse human cultures and for safeguarding the healthy functioning of island ecosystems.

In many Pacific Island nations, bats have great cultural significance as totems, food, and traditional currency.

Bats are the largest land animals on many of the Pacific islands, and are vital “keystone species”, maintaining the structure of ecological communities.

Yet, Pacific Island bats are increasingly under threat, including from intensifying land use (farming, housing, roads) invasive species (rats, cats, snakes, ants), and human harvesting. They’re also vulnerable to climate change, which heightens sea levels and increases the intensity of cyclones and heatwaves.

So let’s meet four fascinating — but threatened — Pacific Island bats that deserve more attention.

1. Pacific sheath-tailed bat

Conservation status: endangered

Distribution: American Samoa, Federated States of Micronesia, Fiji, Guam, Northern Mariana Islands, Palau, Samoa, Tonga

Pacific Sheath tailed Bat (*Emballonura semicaudata*)
Ron Leidich

The Pacific sheath-tailed bat (Emballonura semicaudata) weighs just five-grams and has a weak, fluttering flight. Yet somehow, it has colonised some of the smaller and more isolated islands across the Pacific, from Samoa to Palau. That’s across 6,000 kilometres of ocean!

Over the past decade, this insect-eating, cave-roosting bat has disappeared from around 50% of islands where it has been recorded. The reasons for this are unclear. Disturbance of cave roosts, introduced species such as lantana and goats, and increasing use of pesticides, may all have played a part.

Unfortunately, the Pacific sheath-tailed bat is now presumed extinct in many former parts of its range, including American Samoa, Tonga, and several islands of the Northern Mariana Islands. This leaves Palau, the Federated States of Micronesia, and Fiji as remaining strongholds for the species, though data is limited.

2. Montane monkey-faced bat

Conservation status: critically endangered

Distribution: Solomon Islands

New Georgian monkey-faced bat *Pteralopex taki* — no picture exists of the Montane monkey-faced bat.
Tyrone Lavery

There are six species of monkey-faced bat — all are threatened, and all are limited to islands across the Solomon Islands, Bougainville, and Fiji.

The montane monkey-faced bat (Pteralopex pulchra) is one species, and weighs around 280 grams, eats fruit and nectar, and has incredibly robust teeth. But perhaps most startling is its ruby-red eyes and wing membranes that are marbled with white and black.

The montane monkey-faced bat has been recorded only once by scientists on a single mountain (Mt Makarakomburu) above the altitude of 1,250 metres, on Guadalcanal Island. This tiny range makes it vulnerable to rare, extreme events such as cyclones, which could wipe out a whole population in one swoop. And being limited to mountain-top cloud forests could place it at greater risk from climate change.

It’s an extreme example of both the endemism (species living in a small, defined area) and inadequacies of scientific knowledge that challenge Pacific island bat conservation.

3. Ornate flying-fox

Conservation status: vulnerable

Distribution: New Caledonia

Ornate flying-fox (*Pteropus ornatus*)‘
Malik Oedin, IAC

Like many fruit bats across the Pacific, New Caledonia’s endemic ornate flying-fox (Pteropus ornatus) is an emblematic species. Flying-foxes are hunted for bush meat, used as part of cultural practices by the Kanaks (Melanesian first settlers), are totems for some clans, and feature as a side dish during the “New Yam celebration” each year. Their bones and hair are also used to make traditional money.

Because they’re so highly prized, flying-foxes can be subject to illegal trafficking. Despite the Northern and Southern Provinces of New Caledonia having regulated hunting, flying-fox populations continue to decline. Recent studies predict 80% of the population will be gone in the next 30 years if hunting continues at current levels.

On a positive note, earlier this year the Northern Province launched a conservation management program to protect flying-fox populations while incorporating cultural values and practices.

4. Fijian free-tailed bat

Conservation status: endangered

Distribution: Fiji, Vanuatu

Fijian free tailed bat (*Chaerophon bregullae*)
Dave Waldien

In many ways, the Fijian free-tailed bat (Chaerephon bregullae) has become the face of proactive bat conservation in the Pacific Islands. This insect-eating bat requires caves to roost during the day and is threatened when these caves are disturbed by humans as it interrupts their daytime roosting. The loss of foraging habitat is another major threat.

The only known colony of reproducing females lives in Nakanacagi Cave in Fiji, with around 7,000 bats. In 2014, an international consortium with Fijian conservationists and community members came together to protect Nakanacagi Cave. As a result, it became recognised as a protected area in 2018.

But this species shares many characteristics with three of the nine bat species that have gone extinct globally. This includes being a habitat specialist, its unknown cause of decline, and its potential exposure to chemicals through insect foraging. It’s important we continue to pay close attention to its well-being.

Where do we go from here?

The perspectives of local knowledge from individual islands aren’t always captured in global scientific assessments of wildlife.

In many Pacific Islands, bats aren’t protected by national laws. Instead, in many countries, most land is under customary ownership, which means it’s owned by Indigenous peoples. This includes land in Papua New Guinea, Solomon Islands, and Vanuatu. Consequently, community landowners have the power to enact their own conservation actions.

The emerging Pacific Bat Network, inspired by the recent forum, aims to foster collaborative relationships between scientific conservationists and local leaders for species protection, while respecting cultural practices.

As the Baru Conservation Alliance — a locally-led, not-for-profit group from Malaita, Solomon Islands — put it in their talk at the forum:

conservation is not a new thing for Kwaio.

Now the forum has ended, the diverse network of people passionate about bat conservation is primed to work together to strengthen the conservation of these unique and treasured bats of the Pacific.

John Martin, Research Scientist, Taronga Conservation Society Australia & Adjunct lecturer, University of Sydney; David L. Waldien, Adjunct assistant professor, Christopher Newport University; Junior Novera, PhD Candidate, School of Biological Sciences, The University of Queensland; Justin A. Welbergen, President of the Australasian Bat Society | Associate Professor of Animal Ecology, Western Sydney University; Malik OEDIN, PhD Population Biology and Ecology, Université de Nouvelle Calédonie; Nicola Hanrahan, Terrestrial Ecologist, Department of Environment, Parks and Water Security, Northern Territory Government & Visiting Fellow, Charles Darwin University; Tigga Kingston, Professor, Department of Biological Sciences, Texas Tech University, and Tyrone Lavery, Postdoctoral Research Fellow, Australian National University

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

Protecting a lucrative industry

Piercing the ocean silence

Shining a light

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Small breaks in habitat can have big impacts

Disastrous clearing laws

The code should be amended

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When sounds become ‘noise’

A new quiet?

Rethinking post-pandemic soundscapes

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The parma’s resurrection

An elusive species

The parma wallaby is under threat

Saving the parma

But you can help, too

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The way we see influences what we choose

The Australian case study

Measuring flower colours

Generalisation or specialisation?

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Why is the greater glider losing its home?

What we found

Why was habitat allowed to be cleared?

The government isn’t learning its lesson

What needs to change?

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Population decline

Disoriented butterflies

Recalibration in natural light

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So, why should we care about these bats anyway?

1. Pacific sheath-tailed bat

2. Montane monkey-faced bat

3. Ornate flying-fox

4. Fijian free-tailed bat

Where do we go from here?

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