When rockets go wrong – protecting the environment from catastrophe
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Colorado group submits petition to ban hunting of bobcats, mountain lions, lynx
Human hunting played a decisive role in the extinction of large mammals
Humans were responsible for the extinction of large mammals.
7 Jul, 2024
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https://www.techexplorist.com/human-hunting-played-decisive-role-extinction-large-mammals/85977/
For decades, the question has loomed large: what caused the extinction of numerous species of large mammals, birds, and reptiles over the past 50,000 years? Defined as animals weighing at least 45 kilograms or megafauna, a minimum of 151 mammal species vanished during this period, based on the discovered remains.
The megaherbivores – land-dwelling herbivores weighing over a ton – suffered the most significant blows. Fifty thousand years ago, 57 species of megaherbivores existed, and today only 11 remain. The surviving 11 species have also experienced severe population declines, although not to the point of complete extinction.
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A research team from the Danish National Research Foundation’s Center for Ecological Dynamics (ECONOVO) at Aarhus University has now reached the conclusion that human hunting led to the extinction of many of these vanished species.
During the late Pleistocene period, spanning from 130,000 to 11,000 years ago, significant changes in climate had a profound impact on the global distribution of both large and small animals as well as plants. It is noteworthy that while these dramatic climate shifts led to the extinction of numerous large animals, particularly the largest ones, smaller animals and plants were not as significantly affected.
Interestingly, previous ice ages and interglacial periods occurring over the past few million years did not result in the same selective loss of large animals. Although the onset of glacial periods did lead to widespread extinctions in certain regions, such as trees in Europe, large animals did not experience selective extinctions during these periods.
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“The large and very selective loss of megafauna over the last 50,000 years is unique over the past 66 million years. Previous periods of climate change did not lead to large, selective extinctions, which argues against a major role for climate in the megafauna extinctions,” says Professor Jens-Christian Svenning. He leads ECONOVO and is the lead author of the article. He adds, “Another significant pattern that argues against a role for climate is that the recent megafauna extinctions hit just as hard in climatically stable areas as in unstable areas.”
Ancient humans were skillful hunters, capable of effectively targeting and consuming the largest mammal species. Their hunting activities resulted in a significant reduction in the populations of these large animals. Vulnerable due to their long gestation periods, low offspring production, and extended time to reach sexual maturity, these large animals were greatly affected by human activities.
The analysis further indicates that human hunting of mammoths, mastodons, and giant sloths was widespread across the globe. The extinction of these species occurred at varying times and rates globally but consistently followed the arrival of modern humans or cultural advancements among humans in Africa.
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The extinction of species has occurred on all continents except Antarctica and across various ecosystems. Even species capable of adapting to different environments have disappeared, indicating that their extinction cannot be solely attributed to climate changes.
The researchers point out that the loss of these megafauna species has significantly impacted ecosystems, leading to changes in vegetation, seed dispersal, and nutrient cycling. Their disappearance has resulted in significant changes in ecosystem structures and functions.
“Our results highlight the need for active conservation and restoration efforts. By reintroducing large mammals, we can help restore ecological balances and support biodiversity, which evolved in ecosystems rich in megafauna,” says Jens-Christian Svenning.
Journal reference:
- Jens-Christian Svenning et al. The late-Quaternary megafauna extinctions: Patterns, causes, ecological consequences and implications for ecosystem management in the Anthropocene. Cambridge Prisms: Extinction (2024). DOI: 10.1017/ext.2024.4
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3-year-old boy in Cambodia contracts H5N1 bird flu
Scientists have confirmed the spread of bird flu in Antarctica which has caused significant mortalities of wild birds and mammals on a global scale
Experts warn H5N1 bird flu strain ‘likely’ to arrive in Australia in spring and could put wild birds such as little penguins at risk
/ By James Tugwell
Posted Yesterday at 4:45pm, updated 23h ago23 hours ago
abc.net.au/news/h5n1-birdflu-strain-threat-australian-wildlife-barunguba-penguin/104050166Copy link
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In short:
The H5N1 bird flu variant — different to the H7 affecting eggs — has wreaked havoc on native wildlife on every other continent on Earth.
Ecologists say the virus could arrive in Australia with the spring migration of birds.
What’s next?
Experts and advocates say awareness and preparedness is key to preventing the spread of the virus.
As authorities work to restrict the spread of the deadly H7 strain of bird flu affecting chickens and eggs across Australia, ecologists and advocates warn a different strain of the virus could lead to an environmental disaster in some wild birds.
The H5N1 avian influenza has caused mass mortality events in wildlife on every other continent on Earth, particularly among birds and animals that eat infected birds.
As the yearly migration of birds to Australia in spring approaches, experts say more communication and planning is needed, with unique species most at risk.
Federation University ecologist Meagan Dewar has tracked the spread of H5N1 throughout Antarctica since February and witnessed mass casualties among many species including Adélie penguins and southern elephant seals.
“Unfortunately our wildlife is integrated and interconnected so [remote ecosystems] aren’t as safe as we think,” she said.
But Dr Dewar said it would be migrating birds from Asia that would “most likely” bring H5N1 to Australia in spring.
“The virus is coming closer, and it is on our doorstep,” she said.
Global mass mortalities
More than 650,000 seabirds are known to have died from H5N1 in South America since 2022, Dr Dewar said.
Animals that prey on dead infected birds also contract the virus. It killed 95 per cent of southern elephant seal pups in Argentina in 2023.
It has killed more than 30,000 South American sea lions. Australia’s population is only 12,000.
Dr Dewar said Australia’s unique ecosystems with small animal populations were most at risk of collateral damage.
“If it gets into our highly endangered or critically endangered bird species that could have very severe consequences for them and their survival,” she said.
“We can get alterations in our ecosystems because we are losing large proportions of animals and birds.”
Dr Dewar said her greatest concern was animals like threatened sea lions or vulnerable little penguin colonies with “small population numbers that really can’t afford to be hit by a large-scale virus”.
Fears for unique ecosystems
On the NSW south coast, Barunguba Montague Island (Barunguba) is culturally significant for the Yuin people and an ecological epicentre for almost 100 bird species.
It is the northernmost breeding colony for Australian fur seals, long nose fur seals and sea lions and is home to NSW’s largest little penguin colony during breeding season.
According to a study published in the journal Genome Biology, the H5N1 virus could make the black swan, a culturally significant species to the Yuin people, locally extinct.
However, Dr Dewar said species such as seals, sea lions, seabirds and little penguins could also be at threat if susceptible to the virus.
Narooma-based seal-diving and tourism operator Francois Van Zyl said the effects of the virus on the island would be horrific.
“The seals play a big part in our small-town community,” Mr Van Zyl said.
“Yes it will have catastrophic financial issues on small coastal towns, however I think the larger concern is: ‘What’s going to happen to the wildlife?'”
Need for rapid response
While there are reports of mammal-to-mammal transmission in North American cattle and South American sea mammals, virus ecologist Michelle Wille said those were two context-specific cases and those strains were unlikely to threaten Australia.
“This is still very much an avian virus,” she said.
But like any virus, Dr Wille said managing the spread would reduce the risk of mammal-to-mammal variations occurring because there would be less chance of mutations developing.
“It’s important we focus on what’s happening in birds because that’s where everything jumps out of,” she said.
“The more dead birds there are in the landscape, the higher the likelihood that some mammal is going to be infected over and over until you get that right combination of the exactly right genetic make up and exactly the right mammal that allows for [mammal to mammal transmission].”
Protecting the home front
In the Netherlands and Belgium, collecting dead birds before predators can feed on them reduced mammal fatalities by 80 per cent.
It is one strategy in Phillip Island Nature Parks’ site-specific contingency plan for the virus. However not all similar ecosystems across the country have such a plan.
Invasive Species Council advocacy director Jack Gough wants the federal government to establish a national task force and help develop similar, localised strategies for ecosystems right across Australia.
“Right now, Australia is not prepared in terms of our wildlife if the deadly H5 strain turns up,” he said.
“If it turns up here, it will cause damage and that there are opportunities with isolated populations to make sure that we can respond quickly.”
Early detection critical
Biosecurity PhD candidate at UNSW Hayley Stone said the virus arriving in Australia was inevitable and early detection was critical to managing its spread.
“You want to catch it as quickly as possible,” she said.
“It needs to be on a federal level. There needs to be federal policy that everyone can follow.
“America didn’t realise they were having an outbreak until it had already hit poultry.”
She said there could be more testing under the National Avian Influenza Wild Bird surveillance program, which tests sick wild birds for diseases.
The Department of Agriculture, Fisheries and Forestry (DAFF) declined an interview, but in a statement, said the department would coordinate a national approach in the event of a large outbreak.
In April 2024, DAFF and Wildlife Health Australia published guidelines helping wildlife managers to deal with high-risk bird flu virus, such as the H5N1 strain.
It includes prevention measures, and tips for creating a site-specific plan, which it says is the responsibility of individual jurisdictions.
The guidelines recommend dead birds be reported to the Emergency Animal Disease Hotline (1800 675 888).
“There is no way to prevent new strains of avian influenza viruses — including this H5 strain — entering Australia through migratory birds,” a department spokesperson said in a statement.
Mr Gough said part of the solution was improving local awareness that dead birds washing up on a beach in Tasmania or Far North Queensland, for example, was a sign the virus had arrived.
He said the federal government had more to do in bringing people together and creating localised plans to manage the virus.
“That involves tourism operators, local fishers – people who are out seeing these environments – that they know what bird flu is, that they’re checking for it and that if they see any signs of it, they’re able to really quickly notify the authorities and get on top of it,” he said.
“Bring wildlife carers, zoos, veterinarians, tourism operators, fishers — everyone — together. Make sure that everyone is aware, knows what to look for if this turns up and that we can respond quickly.”
Exposing the Big Game 