How to reverse global wildlife declines by 2050


Wouter Taljaard/Shutterstock

Michael Obersteiner, University of Oxford; David Leclère, International Institute for Applied Systems Analysis (IIASA), and Piero Visconti, International Institute for Applied Systems Analysis (IIASA)

Species are going extinct at an unprecedented rate. Wildlife populations have fallen by more than two-thirds over the last 50 years, according to a new report from the World Wildlife Fund. The sharpest declines have occurred throughout the world’s rivers and lakes, where freshwater wildlife has plummeted by 84% since 1970 – about 4% per year.

But why should we care? Because the health of nature is intimately linked to the health of humans. The emergence of new infectious diseases like COVID-19 tend to be related to the destruction of forests and wilderness. Healthy ecosystems are the foundation of today’s global economies and societies, and the ones we aspire to build. As more and more species are drawn towards extinction, the very life support systems on which civilisation depends are eroded.

Even for hard-nosed observers like the World Economic Forum, biodiversity loss is a disturbing threat with few parallels. Of the nine greatest threats to the world ranked by the organisation, six relate to the ongoing destruction of nature.

A digger tears down trees in a Malaysian rainforest.
New infectious diseases tend to emerge in places at the forefront of environmental destruction.
Rich Carey/Shutterstock

Economic systems and lifestyles which take the world’s generous stocks of natural resources for granted will need to be abandoned, but resisting the catastrophic declines of wildlife that have occurred over the last few decades might seem hopeless. For the first time, we’ve completed a science-based assessment to figure out how to slow and even reverse these trends.

Our new paper in Nature featured the work of 60 co-authors and built on efforts steered by the Intergovernmental Panel on Biodiversity and Ecosystem Services. We considered ambitious targets for rescuing global biodiversity trends and produced pathways for the international community to follow that could allow us to meet these goals.




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Bending the curve

The targets of the UN Convention on Biological Diversity call for global trends of terrestrial wildlife to stop declining and start recovering by 2050 or earlier. Changes in how land is used – from pristine forest to cropland or pasture – rank among the greatest threats to biodiversity on land worldwide. So what are the necessary conditions for biodiversity to recover during the 21st century while still supporting growing and affluent human societies?

Two key areas of action stand out from the rest. First, there must be renewed ambition from the world’s governments to establish large-scale conservation areas, placed in the most valuable hotspots for biodiversity worldwide, such as small islands with species found nowhere else. These reserves, in which wildlife will live and roam freely, will need to cover at least 40% of the world’s land surface to help bend the curve from decline to recovery for species and entire ecosystems.

The location of these areas, and how well they are managed, is often more important than how big they are. Habitat restoration and conservation efforts need to be targeted where they are needed most – for species and habitats on the verge of extinction.

A downward sloping line showing wildlife declines splits into three alternative trajectories, where biodiversity increases, plateaus and crashes by 2050.
The next 30 years will prove pivotal for Earth’s biodiversity.
Leclère et al. (2020), Author provided

Second, we must transform our food systems to produce more on less land. If every farmer on Earth used the best available farming practices, only half of the total area of cropland would be needed to feed the world. There are lots of other inefficiencies that could be ironed out too, by reducing the amount of waste produced during transport and food processing, for example. Society at large can help in this effort by shifting towards healthier and more sustainable diets, and reducing food waste.

This should happen alongside efforts to restore degraded land, such as farmland that’s becoming unproductive as a result of soil erosion, and land that’s no longer needed as agriculture becomes more efficient and diets shift. This could return 8% of the world’s land to nature by 2050. It will be necessary to plan how the remaining land is used, to balance food production and other uses with the conservation of wild spaces.

Without a similar level of ambition for reducing greenhouse gas emissions, climate change will ensure the world’s wildlife fares badly this century. Only a comprehensive set of policy measures that transform our relationship with the land and rapidly scale down pollution can build the necessary momentum. Our report concludes that transformative changes in our food systems and how we plan and use land will have the biggest benefits for biodiversity.

But the benefits wouldn’t end there. While giving back to nature, these measures would simultaneously slow climate change, reduce pressure on water, limit nitrogen pollution in the world’s waterways and boost human health. When the world works together to halt and eventually reverse biodiversity loss, it’s not only wildlife that will thrive.The Conversation

Michael Obersteiner, Director, Environmental Change Institute, University of Oxford; David Leclère, Researcher in Ecosystem Services and Management (ESM) Program, International Institute for Applied Systems Analysis (IIASA), and Piero Visconti, Research Scholar, Ecosystem Services and Management Programme, International Institute for Applied Systems Analysis (IIASA)

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

‘Like trying to find the door in a dark room while hearing your relatives scream for help’: Tasmania’s whale stranding tragedy explained


Olaf Meynecke, Griffith University

A desperate rescue effort is underway after hundreds of long-finned pilot whales (Globicephala melas) became stranded in Macquarie Harbour on Tasmania’s west coast.

Yesterday, more than 250 pilot whales were reported to have stranded, with one-third presumed dead. And this morning, rescuers found another 200 pilot whales stranded up to ten kilometres away from the first group — most are likely dead.

This brings the total number of stranded pilot whales in Tasmania to more than 450, and it’s believed to be the biggest ever recorded in the state. The Greens are calling on federal Environment Minister Sussan Ley to launch a national response.

The rescue mission aims to refloat the pilot whales that appear to still be in reasonable health. But their behaviour hampers rescue efforts: many pilot whales re-strand themselves to be with their family. This event likely means a number of generations of the local population will be lost.




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How did they become stranded?

Despite its name, the long-finned pilot whale is actually a large oceanic dolphin. They cover vast areas of the Southern (Antarctic) Ocean, reaching between four and six metres in length and weighing up to one tonne.

They are well adapted to deeper oceans where they hunt for various species of squid in depths of between 600-1,000m, using echolocation to find their prey. Echolocation is a way of using sound to navigate in complete darkness.

They generally spend most of their lives offshore and it’s not well understood what conditions drive them close to shore, and to enter shallow embayments.

Some theories suggest food shortages are to blame, or changes in electromagnetic fields that disorient them. They may also be following a sick or distressed pod leader. And in some past cases strandings were related back to active sonar from ships and naval sonar interrupting their echolocation.




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What causes whale mass strandings?


But once in shallow waters, it’s difficult to swim back out. As these whales mostly navigate with echolocation it’s not possible for them to use sonar effectively in shallow and muddy embayments.

It’s extremely distressing for the whales, a lot like trying to find the door in a dark room while hearing your relatives scream for help.

In fact, the stress is what many die from in the end. Other causes of death are overheating from sun exposure and drowning if they can’t move their bodies up to breach the surface in shallow water.

The rescue efforts

There are a number of strategies to refloat whales. In Macquarie Harbour, rescuers are using slings to tow the whales to deeper water, before releasing them.

Other options include multiple people pushing them off the beach during high tide into deeper water.

In this case, albeit potentially dangerous for the helpers, people power can make a big difference. After all, time is of immense importance for success, and to stop more whales beaching.

However, chances of survival plummet with long exposure to sun and extended periods of stress. What’s more, Macquarie Harbour is relatively remote and difficult to access, further complicating rescue efforts.

Dying together

But the biggest obstacle rescuers face is the whales’ social bonding. Long-finned pilot whales are highly intelligent and live in strong social units.

So when dealing with mass strandings, it’s important to realise the emotions and bonding between the whales are very likely beyond what humans can feel. One well-documented example of their emotional depth is the pilot whale seen carrying its dead calf for many days.

Mother pilot whale grieves over her dead calf.

This makes the stranding process extremely complex, as it unfolds over several hours to several days — the whales don’t all strand at the same time.

We know from killer whales, which also have strong social bonding, that if a close member of the group strands, others will attempt to join to die together.




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The situation for pilot whale pods can be similar, but more complex as a result of having much larger pods. Pilot whale pods have multiple sub-units, which can consist of friends as well as family and they don’t have to be genetically related.

Social units get mixed up when they’re in shallow bays. This means individuals can become disconnected from their social units before the actual stranding occurs, causing stress and confusion prior the beaching.

Fewer pilot whales in the gene pool

There are an estimated 200,000 long-finned pilot whales in the Southern Ocean and Antarctica, but mass strandings like this can have a profound impact on sub-populations.

In Tasmania alone, 1,568 long-finned pilot whales have stranded between 1990 and 2008 in 30 stranding events.

Many similar sad events occured in New Zealand: hundreds of long-finned pilot whales stranded in 2018 and 2017, and the majority died.

To make matters worse, studies suggest the long-finned pilot whales in the Southeastern Pacific have low genetic diversity. There are similarities between this species found in Chile and New Zealand, but with surprisingly distinct differences between New Zealand and Tasmania.

Considering they can live up to 50 years and the fact only few survive when multiple generations strand, such events not only destroy entire generations but also remove them from the gene pool.

This puts local populations at further risk. Inbreeding is one consequence, but the biggest problem is their decreasing general fitness and ability to adapt to changes.

How to help

In the past, significant numbers of stranded whales have been successfully released, making it worth the effort. For example, in one of largest mass strandings in New Zealand in 2017, volunteers helped about 100 whales refloat, and made a human chain to try to stop them restranding.




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Still, such events are likely to be more frequent in the future due to changing ocean conditions and increasing human activity such a noise pollution, commercial squid fisheries and deep sea mining.

Climate change shifts ocean currents as sea temperature rises. And with this, squid availability will change. A lack of food offshore can cause stress and drive them closer to shore.

We can help the whales not only by actively supporting rescue organisations such as ORRCA, but also by helping reduce carbon emissions, foster sustainable fisheries, reduce plastic pollution and advocate for marine sanctuaries.The Conversation

Olaf Meynecke, Research Fellow in Marine Science, Griffith University

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

Swimming with whales: you must know the risks and when it’s best to keep your distance



Shutterstock/anna sanfeliu gozalvez

Chantal Denise Pagel, Auckland University of Technology; Mark Orams, Auckland University of Technology, and Michael Lueck, Auckland University of Technology

Three people were injured last month in separate humpback whale encounters off the Western Australia coast.

The incidents happened during snorkelling tours on Ningaloo Reef when swimmers came too close to a mother and her calf.

Swim encounters with humpback whales are relatively new in the Australian wildlife tourism portfolio. The WA tours are part of a trial that ends in 2023. A few tour options have also been available in Queensland since 2014.

But last month’s injuries have raised concerns about the safety of swimming with such giant creatures in the wild.

Close encounters

Until recently, you had to travel to Tonga, Niue or French Polynesia for similar humpback whale encounters in Oceania. Or you could swim with other species, such as dwarf minke whales on the Great Barrier Reef.




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But when we interact with wild animals there is always a risk to safety, especially in challenging environments such as open water.

Whales, like other wildlife, may behave unpredictably. Active surface behaviours such as breaching, tail and fin slaps present a significant risk for swimmers and whale watchers.

Four drawings of a humpback whale.
A humpback whale (1) breaching, (2) head lunge, (3) tail slap and (4) pectoral fin slap can all be a danger to people close by.
Chantal Denise Pagel, Author provided

In one of the WA encounters, the nursing female was reported to display pectoral fin and tail slaps. These are potentially threatening due to the size (up to 16 metres long) and power of humpback whales.

These behaviours are frequently observed in social interactions between humpback whales and can present a severe risk of injury to anyone close by, with potentially life-threatening results.

A recent study of the impacts of swimmer presence on humpback whales off Réunion Island (on Madagascar’s east coast in the Indian Ocean) confirmed a high occurrence of aggressive and/or defensive whale behaviour.

The researchers observed flipper and tail fluke swipes and thrashes – sudden movements of a whale’s extremities – especially in mother-and-calf pairs.

A humpback whale slaps its pectoral flipper and splashes the water
Active whale behaviour is exciting to observe, but that flipper can pack a powerful punch.
Flickr/Michael Dawes, CC BY-NC

Keep your distance

While the reasons for the Australian incidents are still unclear, a possible explanation could be that the swimming groups approached the whales too closely and ignored the signs the whales did not welcome visitors.

Maintaining a safe distance should be required of any tourists interested in seeing or getting close to unpredictable wildlife, especially in unfamiliar environments.

We cannot expect tourists, who are often first-time whale swim participants, to be able to read and interpret whale behaviour. So it is vital that crew members are skilled and experienced and can end an encounter if it needs to be.

Knowledgeable in-water guides are indispensable in commercial swim-with-whales programs. Yet this is often not a requirement by organisations issuing licenses for such activities.

For example, permits in New Zealand require “knowledgeable operators and staff”, but there is no requirement to have guides in the water during the encounter. People interested in swim-with-whale encounters should choose tour companies that provide in-water guides who join them in their adventure.

We should also question whether interactions with female whales caring for newborn calves should be allowed. Best-practice guidelines advise against interactions where calves are present.

A mother humpback whale underwater with her calf.
We need to be extra careful when near a mother humpback whale with her calf.
Shutterstock/Lewis Burnett

Recent research in the popular whale-swim destination Tonga showed mother-and-calf pairs avoid about one-third of tour vessel approaches by diving for longer periods.

Yet surface resting times are critical for calves. Any decrease in time spent resting for mother-and-calf pairs can affect a calf’s growth rate, overall fitness and chances of survival.

Similar observations were made in Réunion. Three out of four (74%) mother-calf-pairs changed their behaviour to avoid swimmers.

Safety first: for whales and swimmers

The Pacific Whale Foundation is undertaking a study to assess the impact of swimming with humpback whales in Hervey Bay, Queensland, Australia.

This research is to monitor the behaviour of humpback whales, providing critical insights into whether tourism activities add stress to this recovering population.




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But research into the suitability of wildlife species used for commercial tourism operations and their health and safety provisions still lacks fundamental depth.

In highly interactive tourism activities such as swim-with-wildlife programmes, tourists should receive education about the risks involved in these “bucket list” experiences. This should include information on animal behaviour and the potential consequences for swimmers.

Furthermore, training tour operators to identify behaviours that may indicate disturbance or have the potential to be harmful to clients is an important additional step towards safer interactions.The Conversation

Two images of a humpback whale breaching the water and one of a whale tail raised above the water.
Humpback whale breaching and tail slap.
Flickr/Grant Matthews, CC BY-NC-ND

Chantal Denise Pagel, Doctoral student | Marine Wildlife Tourism Professional, Auckland University of Technology; Mark Orams, Acting Dean, Health and Environmental Sciences, Auckland University of Technology, and Michael Lueck, Professor of Tourism, Auckland University of Technology

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

Banning trophy hunting can put wildlife at risk: a case study from Botswana



Before the trophy hunting ban, Botswana specialised in big game such as elephants, buffalos and leopards.
Shutterstock

Peet Van Der Merwe, North-West University and Lelokwane Lockie Mokgalo, Botswana Accountancy College

Wildlife tourism is an important segment of Botswana’s tourism industry, representing 80% of the total annual revenue of trips to Botswana. Key to this are protected areas which have led to the growth of the country’s wildlife tourism.

Wildlife tourism can take place either in the animals’ natural environments such as national parks, game reserves or other protected areas or in captivity, such as zoos or rehabilitation centres. Activities during these tours can be classified into two main groups; non-consumptive (viewing and photographing of wild animals) and consumptive which refers to activities such as trophy hunting and fishing.

Since the start of trophy hunting operations in 1996 in Botswana, trophy hunting has grown steadily. The industry employed an estimated 1,000 people, received 350 hunters annually and sold more then 5,500 hunting days per year. In 2011, a year before the trophy hunting ban was announced in the country, the industry netted Botswana US$20 million in revenue annually from 2,500 animals sold to trophy hunters. Botswana specialised in big game such as elephants, buffalo and leopard which generated higher hunting fees from few animals.

The main reason given by the Botswana government for the trophy hunting ban was the decline in the number of wildlife due to trophy hunting – a reason that was widely questioned by trophy hunting operators.

The ban on trophy hunting had an adverse impact as highlighted by various data sources. We therefore set out in 2018 to study the impact of the ban of trophy hunting on local communities. We chose two communities, Sankuyo (400 inhabitants in Northern Botswana) and Mmadinare (12,000 inhabitants in Eastern Botswana). The two communities that were selected for the study, had prior involvement in hunting.

We collected data through interviews with community members and leaders of the community-based organisations trusts. These are legal entities established to represent interests of communities and are often made up of multiple villages of close geographical proximity.

We also interviewed former employees from the hunting sector and small business owners. Some of the questions asked were: how did hunting tourism benefit the community? Was hunting seen as a positive impact on the community? What are the current challenges that the community face since the ban of trophy hunting? Have attitudes toward wildlife changed from the times of trophy hunting?

Human-wildflife conflict

Participants said they’d lost income as a result of the trophy hunting ban. The study didn’t focus on determining how much or what percentage was lost. Participants said the ban also led to more instances of human-wildlife conflict.

In addition, community members said wild animals were a risk to their livelihoods as they were a danger to livestock and crop production. The 2016 Review of Community Based Natural Resources Management in Botswana, indicated that the top three most important livelihood sources for communities were livestock, social welfare and crops. This can undermine conservation efforts, especially if the benefits of co-existing with wildlife are minimal.

Another finding was that both communities were outraged that they weren’t consulted on the trophy hunting ban in 2014. One of the participants, a business owner, said:

Aah, I don’t know I just heard them saying it will be the last hunting season and they didn’t explain why.

Another participant, former hunting employee, reiterated the business owner’s sentiments:

What I remember is them informing us that hunting is being stopped. As for asking for our opinions, I don’t remember them coming to do that.

The results of the study also showed that the two communities experienced the benefits of trophy hunting differently. Community tourism benefits from trophy hunting are more pronounced in smaller communities.

In Sankuyo community members, former hunting employees and small business operators all said that they benefited through employment contribution, the sale of meat, as well as financial contribution to community development. But in Mmadinare, the larger community, the members felt they didn’t benefit that much from trophy hunting. Although some former hunting employees did mention benefits such as sale of meat, employment and skills development.

The study found that both communities experienced challenges as a result of the ban on trophy hunting. The participants decry an increase in the number of wildlife in the areas and expressed that this has led to an escalation of human-wildlife conflict. This conflict involve mostly elephants, kudus, antelopes and buffaloes which invaded people’s farms.

A former hunting employee in Sankuyo said:

In the past because of trophy hunting it was not easy to see animals around. Nowadays, they are everywhere, sometimes we see them in our yards.

The result was that almost half of the participants (47.8%) of in both communities expressed that their attitudes were negative towards wildlife as a result of escalation in such conflicts. This puts the sustainability of wildlife resources in jeopardy.

Last year Botswana’s parliament passed a motion to lift a ban on elephant hunting, which had been in place since 2014. This will only allow the hunting of elephants and hunting licenses were auctioned in February 2020 as elephants were seen as the main contributors to animal and conflicts with in certain areas.

Our research supports this, and further recommends the lifting of the ban on the remaining animals listed under the ban. This can help to alleviate challenges experienced by households in communities like Sankuyo, where trophy hunting was a key source of income. The lifting of the ban will also reverse the negative attitudes within communities that threaten conservation efforts.The Conversation

Peet Van Der Merwe, Professor in Tourism, North-West University and Lelokwane Lockie Mokgalo, Lecturer, Botswana Accountancy College

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

Predators, prey and moonlight singing: how phases of the Moon affect native wildlife



Wes Mountain/The Conversation, CC BY-ND

Euan Ritchie, Deakin University; Courtney Marneweck, Clemson University , and Grant Linley, Charles Sturt University

Humans have long been inspired and transfixed by the Moon, and as we’re discovering, moonlight can also change the behaviour of Australian wildlife.

A collection of recently published research has illuminated how certain behaviours of animals – including potoroos, wallabies and quolls – change with variation in ambient light, phases of the Moon and cloud cover.




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One study found small mammals were more active on cloudy nights. Another found variation in moonlight led to differing amounts of species captured in non-lethal traps. And a study on willie wagtails found males just love singing on a full moon.

These findings are interesting from a natural history perspective. But they’ll also help ecologists and conservation scientists better locate and study nocturnal animals, and learn how artificial light pollution is likely changing where animals can live and how they behave.

Moonlit predator-prey games of hide and seek

Most of Australia’s mammals are nocturnal, and some smaller species are thought to use the cover of darkness to avoid the attention of hungry predators. However, there’s much we don’t know about such relationships, especially because it can be difficult to study these interactions in the wild.

Eastern barred bandicoots became more active on darker nights.
Simon Gorta

In the relatively diverse mammal community at Mt Rothwell, Victoria, we examined how variation in ambient light affected species’ activity, and how this might influence species interactions. Mt Rothwell is a fenced conservation reserve free of feral cats and foxes, and with minimal light pollution.

Over two years, we surveyed the responses of predator and prey species to different light levels from full, half and new moon phases.




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Potential prey species in our study included eastern barred and southern brown bandicoots, long-nosed potoroos, brushtailed rock-wallabies, and brushtail and common ringtail possums. Eastern and spotted-tailed quolls are their potential predators.

Just as we predicted, we found that while there does appear to be relationships between cloud cover, Moon phase and mammal activity, these interactions depend on the sizes and types of mammals involved.

Spotted tail quoll
The spotted-tailed quoll, a meat-eating marsupial, hunts smaller prey at night.
Shutterstock

Both predators and prey generally increased their activity in darker conditions.
Smaller, prey species increased their activity when cloud cover was higher, and predators increased their activity during the half and new moon phases.

This suggests their deadly game of hide and seek might intensify on darker nights. And prey might have to trade off foraging time to reduce their chances of becoming the evening meal.

What happens in the wild?

It’s important to acknowledge that studies in sanctuaries such as Mt Rothwell might not always reflect well what goes on in the wild, including in areas where introduced predators, such as feral cats and red foxes, are found.

Another recent study, this time of small mammals in the wilds of Victoria’s Mallee region, sheds further light on the situation. The authors tested if variation in weather and Moon phase affected the numbers of five small mammal species – Bolam’s mouse, common dunnart, house mouse, southern ningaui, and western pygmy possum – captured in pitfall traps.

Ningauis are less likely to be caught in ecological surveys with increasing moonlight.
Kristian Bell

Pitfall traps are long fences small animals can’t climb over or through, so follow along the side until they fall into a bucket dug in the ground. Ecologists typically use these traps to capture and measure animals and then return them to the wild, unharmed.




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At more than 260 sites and over more than 50,000 trap nights, they found wind speed, temperature and moonlight influenced which species were caught and in what numbers.

For example, captures of a small native rodent, Bolam’s mouse, and carnivorous marsupial, southern ningaui, decreased with more moonlight, whereas captures of pygmy possums were higher with more moonlight.

Variation in the moon phase and associated light can change how active mammals are.
Aaron Greenville

Moonlight songbird serenades

Research from last month has shown even species normally active by day may change their behaviour and activity by night.

It’s not uncommon to hear bird song by night, including the quintessentially Aussie warbling of magpies. Using bioacoustic recorders and song detection software, these researchers show the willie wagtail – another of Australia’s most recogisable and loved birds – is also a nighttime singer, particularly during the breeding season.

While both male and female wagtails sing by day, it is the males that are most vocal by night. And it seems the males aren’t afraid of a little stage-lighting either, singing more with increasing moonlight, with performances peaking during full moons.

While characteristically playful by day, male willie wagtails can really turn on a vocal performance by night.
Jim Bendon/Flickr

This work provides insight into the importance and potential role of nocturnal song for birds, such as mate attraction or territory defence, and helps us to better understand these behaviours more generally.

Moonlight affects wildlife conservation

These studies, and others, can help inform wildlife conservation, as practically speaking, ecological surveys must consider the relative brightness of nights during which work occurred.

Depending on when and where we venture out to collect information about species, and what methods we use (camera traps, spotlighting, and non-lethal trapping) we might have higher or lower chances of detecting certain species. And this might affect our insights into species and ecosystems, and how we manage them.

Artificial lighting can change the behaviour of wildlife.
Kenny Louie

As dark skies become rarer in many places around the world, it also begs a big question. To what extent is all the artificial light pollution in our cities and peri-urban areas affecting wildlife and ecosystems?




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Pipistrelle bats, for example, will be roughly half as active around well-lit bridges than unlit bridges. They’ll also keep further away from well-lit bridges, and fly faster when near them.

This means artificial light might reduce the amount and connectivity of habitat available to some bat species in urban areas. This, in turn could affect their populations.

Research is underway around the world, examining the conservation significance of such issues in more detail, but it’s another timely reminder of the profound ways in which we influence the environments we share with other species.


We would like to acknowledge Yvette Pauligk, who contributed to our published work at Mt Rothwell, and that the traditional custodians of this land are the Wathaurong people of the Kulin nation.The Conversation

Euan Ritchie, Associate Professor in Wildlife Ecology and Conservation, Centre for Integrative Ecology, School of Life & Environmental Sciences, Deakin University; Courtney Marneweck, Postdoctoral Researcher in Carnivore Ecology, Clemson University , and Grant Linley, PhD Candidate, Charles Sturt University

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

The Tasmanian tiger was hunted to extinction as a ‘large predator’ – but it was only half as heavy as we thought



Smithsonian Institution/colourised by D.S. Rovinsky

Douglass Rovinsky, Monash University; Alistair Evans, Monash University, and Justin W. Adams, Monash University

Until it was hunted to extinction, the thylacine – also known as the Tasmanian tiger or Tasmanian wolf – was the world’s largest marsupial predator. However, our new research shows it was in fact only about half as large as previously thought. So perhaps it wasn’t such a big bad wolf after all.

Although the thylacine is widely known as an example of human-caused extinction, there is a lot we still don’t know about this fascinating animal. This even includes one of the most basic details: how much did the thylacine weigh?

An animal’s body mass is one of the most fundamental aspects of its biology. It affects nearly every facet of its biology, from biochemical and metabolic processes, reproduction, growth, and development, through to where the animal can live and how it moves.

For meat-eating predators, body mass also determines what the animal eats – or more specifically, how much it has to eat at each meal.

Catching and eating other animals is hard work, so a predator has to weigh the costs carefully against the benefits. Small predators have low hunting costs – moving around, hunting, and killing small prey doesn’t cost much energy, so they can afford to nibble on small animals here and there. But for bigger predators, the stakes are higher.

Almost all large predators – those weighing at least 21  kilograms – focus their efforts on prey at least half their own body size, getting more bang for the buck. In contrast, small predators below 14.5 kg almost always catch prey much smaller than half their own size. Those in between typically take prey less than half their size, but sometimes switch to a larger meal if some easy prey is there for the taking – or if the predator is getting desperate.

The mismeasure of the thylacine

Scan of article from Launceston Examiner
The March 14, 1868 edition of the Launceston Examiner featured tales of a ‘hyena’ that managed to kill 25 sheep.
trove.nla.gov.au

Few accurately recorded weights exist for thylacines – only four, in fact. This lack of information has made estimating their average size difficult. The most commonly used average body mass is 29.5kg, based on 19th-century newspaper accounts.

This suggests the thylacine would probably have taken relatively large prey such as wallabies, kangaroos and perhaps sheep. However, studies of thylacine skulls suggest they didn’t have strong enough skulls to capture and kill large prey, and that they would have hunted smaller animals instead.

This presented a problem: if the thylacine was as big as we thought, it shouldn’t be able to live solely on small prey. But what if we’ve had the weight wrong the whole time?




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Weighing an extinct animal

Man taking a scan of a stuffed thylacine
Ben Myers of Thinglab scans a Museums Victoria thylacine.
CREDIT, Author provided

Our new research, published today in Proceedings of the Royal Society B, addresses this weighty issue. Our team travelled throughout the world to museums in Australia, the United States, the United Kingdom and Europe, and 3D-scanned 93 thylacines, including whole mounted skeletons, taxidermy mounts, and the only whole-body ethanol-preserved thylacine in the world, in Sweden.

Based on these scans, we created new equations to estimate a thylacine’s mass, based on how thick their limbs were – because their legs would have had to support their entire weight.

We also compared the results of these equations with a new method of digitally weighing 3D specimens. Based on a 3D scan of a mounted skeleton, we digitally “filled in the spaces” to estimate how much soft tissue would have been present, and then used our new formula to calculate how much this would weigh. Taxidermy mounts were easier as there was no need to infer the amount of soft tissue. The most artistic member of our team digitally sculpted lifelike thylacines around the scanned skeletons, and we weighed them, too.

Building and weighing a thylacine. Scanned skeletons (lop left) were surrounded by digital ‘convex hulls’ (top right), which then had their volume and mass calculated. The skeletons were then used in digitally sculpting lifelife models (bottom left), each with their own unique stripes (bottom right).
Rovinsky et al.

Our calculations unanimously told a very different story from the 19th-century periodicals, and from the commonly used estimate. The average thylacine weighed only about 16.7 kg – not 29.5 kg.




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Friday essay: on the trail of the London thylacines


Tall tales on the tiger trail

This means the previous estimate, based on taking 19th-century periodicals at face value, was nearly 80% too large. Looking back at those old newspaper reports, many of them in retrospect have the hallmarks of “tall tales”, told to make a captured thylacine seem bigger, more impressive and more dangerous.

It was based on this suspected danger that the thylacine was hunted and trapped to extinction, with private bounties already placed on them by 1840, and government-sponsored extermination by the 1880s.

Graphic showing the size of thylacines relative to a woman
Thylacines were much smaller in stature than humans or grey wolves.
Rovinsky et al., Author provided

The thylacine was much smaller than previously thought, and this aligns with the smaller prey size suggested by the earlier studies. Predators below 21 kg – in which we should now include the thylacine – all tend to hunt prey smaller than half their size. The “Tasmanian wolf” probably wasn’t such a danger to Tasmanian farmers’ sheep after all.

By rewriting this fundamental aspect of their biology, we are closer to understanding the role of the thylacine in the ecosystem – and to seeing exactly what was lost when we deliberately hunted it to extinction.The Conversation

Douglass Rovinsky, PhD Candidate, Monash University; Alistair Evans, Associate Professor, Monash University, and Justin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash University

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

In a land of ancient giants, these small oddball seals once called Australia home


Artwork by Peter Trusler, Author provided

James Patrick Rule, Monash University; Erich Fitzgerald, Museums Victoria, and Justin W. Adams, Monash University

When most of us think of the prehistoric past, we envision a world of bizarre, often fearsome giants. From dinosaurs to mammoths and even penguins, life then seemed larger than life today.

Millions of years ago in Australia, giant goannas, kangaroos and diprotodontids (wombat relatives) roamed the landscape. The seas teemed with gargantuan predators such as the infamous “megalodon” shark and so-called giant killer sperm whales.

Fossils from this lost world can be found in sandstone rocks, between five million and six million years old, at Beaumaris – a bayside suburb in Melbourne and one of Australia’s most significant urban fossil sites. Here, fossils of ancient marine animals often wash ashore, eroded out of rocks by the tides.

However, some of these fossils are now revealing “jumbo” was not the only size for extinct animals. Our team’s research, published today in the Zoological Journal of the Linnean Society, reports nine new seal fossils from Beaumaris, which we suspect came from nine different individuals.

The findings paint a picture of a relatively small animal, making its way through a world of giants.




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Meet the giant wombat relative that scratched out a living in Australia 25 million years ago


More than doubling the seal fossil record

Melburnians have been collecting fossils from Beaumaris for more than 100 years. Yet it continues to produce remarkable and scientifically important finds.

A beach foreshore in Melbourne.
The fossils we studied were found on the foreshore of Beaumaris, Melbourne.
Erich Fitzgerald, Author provided

This includes extremely rare fossils of animals such as seals. Previously, scientists had studied only one seal fossil from this site.

The nine new fossils detailed in our research were collected and donated to Museums Victoria by local scientists and citizen scientists over the past 88 years. They have more than doubled the known fossil record of seals in Australia.

These fossils represent the oldest evidence of seals in Australia and were identified as “true seals”, a group mostly known from the Arctic and Antarctic. True seals belong to a different group to Australia’s fur seals and sea lions (eared seals), which only arrived in the region about 500,000 years ago.

Seal fossil specimens
In total, we found nine seal fossil specimens from Beaumaris, from potentially nine different individuals.
Erich Fitzgerald and James Rule, Author provided

In particular, one of the fossils we identified is a monachine (a southern true seal). Today, these are represented by animals such as leopard or elephant seals in the Southern Ocean surrounding the Antarctic, to which they are related.

Size estimates found the Beaumaris monachines to have been quite small, at only 1.7 metres long. This is similar to the size of today’s Northern Hemisphere seals such as the harbour seal.

However, the Beaumaris seal’s living relatives are much larger – usually 3m long or more. Modern leopard seals can grow to more than 3m long, while elephant seals can reach up to a gigantic 5m in length.

Most fossil whales found at Beaumaris are also smaller than their living counterparts.

This is the opposite trend to many other animal groups with fossils found there, including some sharks and seabirds, wherein the extinct animals were much larger than those alive today.

The extinct Beaumaris seal was much smaller than its living relatives today.
Art by Peter Trusler, Author provided

An uncertain future for marine life

Why is finding small seals at Beaumaris important?

Five million years ago, before the ice ages, the average annual temperature in southeast Australia was about 2–4°C warmer than it is today, with sea levels up to 25m higher.

These warmer oceans supported a greater diversity of marine megafauna than today, with longer but less energy-efficient food chains. These chains only had room for a few large top predators, such as megalodon sharks. And this may have limited the size of other top predators, including seals.

This chart shows the history of seals’ size evolution in Australia, compared to large sharks.
Peter Trusler and James Rule, Author provided

This is important. It suggests the large size of Antarctic seals living in the Southern Ocean today is due to colder oceans with more energy-efficient food chains, in which more food is available for marine animals.

If climate change continues to warm the oceans, food chains may once again start to become less energy efficient, resulting in a loss of the resources today’s large seals rely on for survival.

The discovery of seal fossils at Beaumaris has implications for not only unlocking the past, but also for contextualising the future.

It shows the biodiversity and ecology of marine megafauna off southern Australia originated during the long-term transition from a warmer to colder world – a process that only recently began changing trajectory.

To this day, the fossil site at Beaumaris continues to reveal scientifically important finds, thanks to members of the public working with scientists from Museums Victoria.




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The Conversation


James Patrick Rule, Palaeontology PhD Candidate, Monash University; Erich Fitzgerald, Senior Curator, Vertebrate Palaeontology, Museums Victoria, and Justin W. Adams, Senior Lecturer, Department of Anatomy and Developmental Biology, Monash University

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

What ‘The Birdman of Wahroonga’ and other historic birdwatchers can teach us about cherishing wildlife



Shutterstock

Russell McGregor, James Cook University

Under the first coronavirus lockdowns, birdwatching increased tenfold in Australia, with much of it done in and near the watchers’ own backyards. And as Melbourne settles into stage 4 restrictions, we’ll likely see this rise again.

The increase in backyard birding is good news for conservation and can help birds recover from bushfires and other environmental catastrophes. But backyard birding isn’t new, nor is its alliance with conservation.




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Birdwatching increased tenfold last lockdown. Don’t stop, it’s a huge help for bushfire recovery


Since the turn of the 20th century, when birdwatching as a hobby began in Australia, birders have cherished the birds in their backyards as much as those in outback wilds. Birdwatchers admired wild birds anywhere, for one of their big motivations was — and is — to experience and conserve the wild near home.

Harry Wolstenholme holding a bird in front of him in his garden in Sydney
Pioneering birder Harry Wolstenholme recorded 21 native species nesting in his garden.
Alec Chisholm/National Library of Australia, Author provided

This wasn’t an abstract ambition, but a heartfelt commitment. Birdwatchers have long known that if we are to conserve nature, we need not only the intellectual expertise of science but also an emotional affinity with the living things around us. Birders in Sydney in the 1920s and ‘30s knew this well.

The Birdman of Wahroonga

Harry Wolstenholme, son of the feminist Maybanke Anderson, was an office-bearer in the Royal Australasian Ornithologists’ Union and a keen amateur birdwatcher. In the 1920s, his usual birding site was his own garden in the northern Sydney suburb of Wahroonga.

There, bird life was prolific. Harry recorded 21 native and five introduced species nesting in or near his garden, plus many more avian visitors.

His garden drew a stream of notable birders from the Sydney branch of the ornithologists’ union, such as wildlife photographer Norman Chaffer, naturalist and journalist Alec Chisholm, and businessman Keith Hindwood. (The union members were predominantly male, though with a liberal sprinkling of women, including Perrine Moncrieff who became its first female president in 1932.)

Keith Hindwood in black and white, with a White-eared Honeyeater on his head
Keith Hindwood, with a White-eared Honeyeater on his head, 1929.
Mitchell Library, Author provided

For his closeness to the birds, Harry earned the nickname “The Birdman of Wahroonga”. That suburb still hosts a good range of species, although the bird life is no longer as prolific as in Harry’s day.

Many others birded in city environs and, like Harry, published their suburban ornithological studies in the union journal, The Emu.

In 1932, Alec Chisholm devoted a whole book, Nature Fantasy in Australia, to birding in Sydney and surrounds. Featured on its early pages is a painting by celebrated bird artist Neville Cayley captioned “The Spirit of Sydney: Scarlet Honeyeater at nest in suburban garden”.

Scarlet honeyeater feeding on grevillia nectar
Scarlet honeyeaters can still be spotted in urban parts of Australia.
Shutterstock

The fact this gorgeous little bird was common in Sydney’s gardens exemplifies Chisholm’s theme of urban Australians’ ready access to the wonders of nature. Scarlet Honeyeaters can still be found in Sydney though they are no longer common there.

Mateship with Birds

Like all Chisholm’s nature writings, Nature Fantasy promoted conservation.

Conservation then differed from conservation now, having a stronger aesthetic orientation and less ecological content. Nonetheless, these pioneer conservationists, among whom birdwatchers were prominent, laid the foundations on which environmentalists later built.

Chisholm urged people not merely to observe birds but also, more importantly, to love and cherish them. In his first book in 1922, Mateship with Birds, he urged readers to open their hearts to their avian compatriots and embrace them as friends and fellow Australians.

Jacky winter, a small, pale-coloured bird is perched on a white log.
Early birders believed names of birds like ‘Jacky Winter’ would help us embrace birds as fellow Australians.
Shutterstock

One way of fostering this feeling, Chisholm and his birding contemporaries believed, was to give birds attractive names. For example, “Jacky Winter” struck the right note, and as Chisholm wrote:

it would be a healthy thing if we had more of these familiar names for our birds, bringing as they do, a feeling or sense of intimacy.

While those birders urged people to cultivate an emotional connection with nature, and while most were amateur rather than professional ornithologists, they nonetheless made major contributions to the scientific study of birds.

Science was needed, they realised, but so was feeling. As one reviewer of Nature Fantasy enthused, Chisholm was a naturalist “who in his writings combines with the exact research of a scientist the sensibility of a poet”.




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Birders today

Our city birdscapes have since changed. Some species have dwindled; some have increased. But suburbia still holds a remarkable degree of biodiversity, if only we’re prepared to look.

A woman holds binoculars to her eyes among trees
Lockdown is a great time to try backyard birdwatching.
Shutterstock

The world of the birders of the 1920s and ’30s is gone. Our attitudes toward nature are cluttered with fears unknown in their day, such as climate change. Yet those early birders still have something worthwhile to tell us today: the need to connect emotionally and tangibly with nature.

To hear that message, we need not, and should not, jettison today’s environmental fears. But fear needs complementing with more positive emotions, like love.

Despite — or because of — the prominence of environmental alarms in today’s world, the need to admire and love living things remains as pressing as ever. As birdwatchers have long known, the birds fluttering in our own backyards are adept at fostering those feelings.




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For whom the bell tolls: cats kill more than a million Australian birds every day


The Conversation


Russell McGregor, Adjunct Professor of History, James Cook University

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