State of the World's Wildlife: Towards Mass Extinction?

[Lisbeth]

by Liz Kimbrough on 9 June 2020

- More than 500 vertebrate species are on the brink of extinction, with populations of fewer than a thousand individuals, a new study says.

- According to the authors, the Earth is experiencing its sixth mass extinction, extinction rates accelerating, and human activity is to blame.

- The authors call the ongoing extinction perhaps “the most serious environmental threat to the persistence of civilization, because it is irreversible.”

- “The conservation of endangered species should be elevated to a national and global emergency for governments and institutions, equal to climate disruption to which it is linked,” they say.

The giant panda, tiny tamaraw buffalo, riverine rabbit and Iberian lynx all have something in common: they join a growing list of animals on the brink of extinction.

A newly published study in the Proceedings of the National Academy of Sciences lists 515 animal species with fewer than a thousand individuals remaining. Overall, the report is grim: Earth is experiencing its sixth mass extinction; extinction rates are accelerating; and humans are to blame.

Researchers evaluated 29,374 land-based vertebrates using IUCN Red List and Birdlife International data. They identified 75 mammal, 335 bird, 41 reptile and 65 amphibian species “on the brink of extinction.” The majority of these critically endangered animals are concentrated in tropical and subtropical regions, where biodiversity is highest.

More than half of the species on the list have fewer than 250 individuals remaining.


A Javan rhino (Rhinoceros sondaicus), one of the rarest mammals in the world, in Ujung Kulon National Park. Fewer than 100 individuals remain in the wild. Image by Stephen Belcher/Dok. Balai Taman Nasional Ujung Kulon via International Rhino Foundation.


Fewer than 250 northern hairy-nosed wombats (Lasiorhinus krefftii) remain in the wild. Image by Fleshpiston via Creative Commons (CC BY-NC-ND 2.0).


Fewer than 200 mountain chicken frogs (Leptodactylus falla) remain in the Caribbean due to hunting and fungal pathogens. Photo by Tim Vickers via Wikimedia Commons Public Domain.


New Zealand’s flightless, nocturnal, kakapo (Strigops habroptilus) population has dwindled to around 200 individuals. Image by New Zealand Department of Conservation (CC BY 2.0).

“The ongoing sixth mass extinction may be the most serious environmental threat to the persistence of civilization, because it is irreversible,” the authors write.

Previous major extinctions, like the one that wiped out the dinosaurs, were caused by catastrophes such as volcanic eruptions, depletion of oxygen, and asteroid impact. Each of these events wiped out an estimated 70 to 90% of life on Earth at the time.

Our current extinction crisis is caused by humans, driven by activities such as habitat destruction, habitat fragmentation, poaching, illegal trade, overharvesting, the introduction of non-native and domesticated species into the wild, pathogens, pollution, and climate disruption.


Fewer than 400 tiny tamaraw buffalo (Bubalus mindorensis) remain on the island of Mindoro in the Philippines, where they are endemic. Image by Gregg Yan via Wikimedia Commons (CC BY-SA 3.0).

Many of the species on the brink of extinction will be extinct soon, according to the authors, and extinction rates will continue to increase sharply. By 2050, the extinction rate is expected to be 117 times higher than the background extinction rate of two out of every 10,000 species per century seen over the past 2 million years.

“Predictions that one-fifth of all species would be in danger of extinction by midcentury and half or more by the end of the century begin to make sense,” the paper says.

Since 1900, 543 species of vertebrates have gone extinct. And those are just the ones we know of. In the past century, we have witnessed the disappearance of the ivory-billed woodpecker (Campephilus principalis), the Round Island burrowing boa (Bolyeria multocarinata), the laughing owl (Ninox albifacies), the sea mink (Neovison macrodon), and the golden toad (Incilius periglenes), to name a few.


The Panama golden toad is classified as Extinct-in-the-Wild as a consequence of a combination of factors, including the pet trade. Photo by Rhett A. Butler

The case of the golden toad is emblematic of massive amphibian declines, triggered by chytrid fungus (Batrachochytrium dendrobatidis), a disease that eats away at an amphibian’s skin, ultimately killing it. More than 500 amphibian species have seen chytrid-related declines over the past decades. In many countries the spread of the fungus has been expedited by the amphibian pet trade.

Invertebrates are also declining. Reports of a great insect dying, monarch butterfly declines, and the loss of bees have been widely reported, in many cases linked to the widespread use of pesticides in agriculture.

The extinction of one species can set off a cascade, leading to a domino effect of extinctions to other, interconnected species. “Extinction breeds extinctions,” the authors write. As species disappear, so to do their unique ecosystem services such as pollination, nutrient cycling, or population control toward other animals.

“What we do to deal with the current extinction crisis in the next two decades will define the fate of millions of species,” study lead author Gerardo Ceballos, a senior researcher at the National Autonomous University of Mexico’s Institute of Ecology said in a statement. “We are facing our final opportunity to ensure that the many services nature provides us do not get irretrievably sabotaged.”


An Iberian lynx (Lynx pardinus) cub. Less than 100 individuals remained in 2002. Now there are around 400. Image by Ex-Situ Conservation Program of the Iberian Lynx via Wikimedia Commons (CC BY 3.0 ES).

The Convention on International Trade in Endangered Species (CITES) regulates the global trade of some of the world’s most endangered and threatened animals. Many animals, including endangered species like pangolins and the tigers, are traded for use as food, ornaments, pets, in traditional medicine, and as a status symbol.

In the U.S., the Endangered Species Act (ESA) has helped protect local wildlife since it was enacted in 1969. The ESA is credited with playing an instrumental role in the recovery of bald eagles, gray whales, grizzly bears and a number of other species. The ESA is also a wide-ranging international tool that governs and restricts the trade of hundreds of other endangered species abroad such as rhinos, elephants and tigers. Marine mammals and sea turtles have also been given a boost, according to more recent reports.

In 2019, the Trump administration weakened the ESA, tipping the scales to favor industry with fewer regulations. In early June, Trump signed an executive order waiving the requirements of a suite of environmental regulations including the Clean Water Act and the ESA. The order allows agencies to use the emergency provisions of environmental laws to expedite projects such as highways, pipelines and construction.


The riverine rabbit (Bunolagus monticularis) in South Africa is the only rabbit known to make an underground shelter for its young. Fewer than 500 adult individuals remain. Image by Tony Camacho via Wikimedia Commons (CC BY-SA 4.0).

“When humanity exterminates populations and species of other creatures, it is sawing off the limb on which it is sitting, destroying working parts of our own life-support system,” said Paul Ehrlich, professor emeritus at Stanford and co-author of the new study.

“The conservation of endangered species should be elevated to a national and global emergency for governments and institutions, equal to climate disruption to which it is linked.”

See the full list of 515 species on the brink of extinction here.

[Klipspringer]

The extinction of one species can set off a cascade, leading to a domino effect of extinctions to other, interconnected species. “Extinction breeds extinctions,” the authors write. As species disappear, so to do their unique ecosystem services such as pollination, nutrient cycling, or population control toward other animals.

This is the summary and a lot of people don't think that way.

[Lisbeth]

IMO all is connected like a very long chain or maybe several long chains and if a link disappears the next link and the one before will be missing something

[Peter Betts]

The only problem ...Too many Humans

[Lisbeth]

The sixth mass extinction is happening now, and it doesn’t look good for us


(Image: Adobe Stock)

By Corey Bradshaw | 09 Mar 2022

Species are going extinct at an unusually high rate. Our efforts now will prevent a future too ghastly to contemplate.
___________________________________________________________________________________________________________________________
Mounting evidence is pointing to the world having entered a sixth mass extinction. If the current rate of extinction continues we could lose most species by 2200. The implication for human health and wellbeing is dire, but not inevitable.

In the timeline of fossil evidence going right back to the first inkling of any life on Earth — more than 3.5 billion years ago — almost 99% of all species that have ever existed are now extinct. That means that as species evolve over time — a process known as speciation — they replace other species that go extinct.

Extinctions and speciations do not happen at uniform rates through time; instead, they tend to occur in large pulses interspersed by long periods of relative stability. Scientists refer to these extinction pulses as mass extinction events.

The Cambrian explosion was a burst of speciation about 540 million years ago. Since then, at least five mass extinction events have been identified in the fossil record (and probably scores of smaller ones). Arguably the most infamous of these occurred when a giant asteroid smashed into Earth about 66 million years ago in what is now the Gulf of Mexico.

The collision vaporised species immediately within the blast zone. Later, species were killed off by climate change arising from pulverised particulates suspended in the atmosphere, as well as intense volcano activity stimulated by the buckling of the Earth’s crust from the asteroid’s impact. Together, about 76% of all species around at the time went extinct, of which the disappearance of the dinosaurs is most well known. But dinosaurs didn’t disappear altogether — the survivors just evolved into birds.

To be classified as a mass extinction, at least 75% of all the species on Earth must go extinct within a “short” geological period of fewer than 2.8 million years. That timeframe seems long to us because modern humans have only existed for about 200,000 years so far.

As a species, humans have been implicated in smaller extinction events going back to the late Pleistocene (about 50,000 years ago) to the early Holocene (about 12,000 years ago) when most of the “megafauna”, such as woolly mammoths, giant sloths, diprotodons and cave bears disappeared from nearly every continent over a few thousand years.

Much later, the expansion of European colonists throughout the world from about the 14th century precipitated an extinction cascade first on islands, and then to areas of continental mainland as the drive to exploit natural resources accelerated. Over the past 500 years, there have been more than 700 documented extinctions of vertebrates and 600 plant species. These extinctions come nowhere near the 75% threshold to include the modern era among the previous mass extinction events.

But those are just the extinctions humans have recorded. In fact, many species go extinct before they are even discovered — perhaps as many as 25% of total extinctions are never noticed by humans. Even accounting for undetected extinctions, the modern era still cannot be classified as a mass extinction event.

But it’s not the total number of extinctions we should focus on — it’s the extinction rate. If past mass extinctions took nearly three million years to ensue, then we should instead examine how many species go extinct per unit of time relative to the “background” extinction rate that occurs between mass extinction events.

According to the fossil record, the average “lifespan” of a species is about one million years, which equates to a background rate of about 0.1 to 2.0 extinctions per million “species-years”. This makes the number of observed extinctions in the modern era 10 to 10,000 times higher than the background rate. Even the most conservative estimates that ignore undetected extinctions firmly place the modern era well within the expected range to qualify as a mass extinction.

An optimist might contend that surely the rate of loss will decline with time, such that we’d be unlikely to meet the 75% threshold. However, the outlook is not at all rosy. The devastation wrought to date means the extinction rate is only likely to accelerate.

Most of the damage to the Earth’s life-support system has happened over the past century. The global human population has tripled since 1950, and there are now about one million species threatened with imminent extinction due to massive population declines, representing about 10% to 15% of all complex life on Earth. Since the start of agriculture about 11,000 years ago, the total amount of vegetation on Earth has halved. Less than 15% of all wetlands recorded 300 years ago are still present today, and more than two thirds of the world’s oceans are compromised to some extent by human activity. Not to mention climate change. Recent evidence suggests global warming causes up to 10 times more extinctions than we might expect by looking only at a species’ upper temperature limit. In fact, when we take the relationships between species into account — such as predators depending on their prey, parasites depending on their hosts, or flowering plants depending on their pollinators — near-future extinctions are expected to skyrocket.


The IUCN Red List tracks the species most under threat. But it also shows just how little we know about species extinction.

A truly indifferent person might also claim that as long as the species that provide resources for modern societies survive, there’s no reason to consider extinction a problem. The evidence suggests otherwise.

Species loss also erodes the services biodiversity provides us. These include reduced carbon sequestration that exacerbates climate change, reduced pollination and increased soil degradation that compromise our food production, poorer water and air quality, more frequent and intense flooding and fires, and poorer human health. Even human diseases like HIV/Aids, Ebola, and Covid-19 are the result of our collective indifference to the integrity of natural ecosystems.

You could be forgiven for thinking that in the presence of overwhelming scientific evidence supporting the necessity to change our course, human societies and their leaders would prioritise damage control. In fact, the opposite is occurring.

Short-term interests, an economic system that concentrates wealth among a few individuals, the rise of right-wing populism with anti-environment agendas, and financed disinformation campaigns designed to protect short-term profits, mean it’s unlikely we’ll be able to make changes at sufficient scale to avoid environmental catastrophe. A ghastly future seems almost assured.

However, the grim outlook does not justify inaction. On the contrary, we could potentially limit the damage if societies around the globe embraced certain fundamental, yet achievable, changes.

We could abolish the goal of perpetual economic growth, and force companies to restore the environment using established mechanisms such as carbon pricing. We could limit undue corporate influence on political decision-making, and end corporate lobbying of politicians. Educating and empowering women, including providing greater self-determination in family planning, would help stem environmental destruction.

With a little effort and longer-term planning, we could make our future just that little bit less ghastly. DM/OBP

Corey Bradshaw is the Matthew Flinders Professor of Global Ecology at Flinders University, Adelaide. This research was funded by the Australian Research Council.

This story is part of Covering Climate Now, a global journalism collaboration strengthening coverage of the climate story.

[Lisbeth]

Mass animal extinctions: our new tool can show why large mammals – like the topi – are in decline

Published: September 23, 2024 - Joseph Ogutu, Senior Researcher and Statistician, University of Hohenheim


Topis are under threat in eastern Africa. Marc Guitard/Getty Images

We could be witnessing the sixth mass extinction at an alarming rate worldwide. It’s marked by the rapid loss of species due to human activities like habitat destruction, pollution and climate change. Unlike previous mass extinctions, which were caused by natural events, this one is driven by human impact – like growing populations, pollution, invasive plant species and human-wildlife conflict.

Large mammals are especially at risk, in Africa as elsewhere. For instance, nearly 60% of wild herbivores – such as elephants and hippos – are already threatened with extinction.

Effective conservation and recovery strategies are needed. To develop them, you need to know how the population of a certain animal is doing and, if it is in decline, what’s causing it.

One tool that’s useful here is a model, using biology, maths, statistics and computer software.

The problem is that there aren’t enough of these realistic, effective models for large mammals. There’s a shortage of appropriate data and the models are complex to build.

I was part of a team that developed a model to help fill that void. It’s the first to account for how large mammal populations interact with each other and their environment while also incorporating their detailed biology. It draws on valuable existing data and can be adapted for various wildlife species.

We tested the model on populations of east Africa’s topi (a large antelope). From the results we’re able to deduce that the drivers of the topi’s massive population decline were habitat loss, poaching and killing by predators.

Knowing what’s driving population declines is extremely valuable. Large mammals play a critical role in ecosystems. Changes to their populations will also affect many other species and could cause the extinction of connected species.

How the model works

Our model combines different types of data, like total population size from aerial surveys and ground vehicle counts, with predicted data on population figures. This allows us to estimate and track population trends that can’t be captured by just one data type. It considers factors like animal age, sex, gestation length, weaning period, calves per birth per year, birth rates, survival, and environmental influences like rainfall and temperature.

Essentially, the model starts with educated guesses, then updates these guesses as it processes more observed data.

The model can tell what causes a decline in two ways.

First, it finds out which factors (such as rainfall) have a strong negative impact on things like birth rates, survival or recruitment, and shows exactly how they affect each other.

Second, it lets us use simulations to see how changing one of these factors, while keeping others unchanged, changes the population by influencing its key characteristics (such as birth rate).

Testing the model on topi

We tested our model on the topi population found in Kenya, Tanzania and other African countries. We chose the topi because it’s a large herbivore in decline.

The topi is an elegant antelope weighing between 91kg and 147kg, with a long face and uniquely twisted horns. One of the largest remaining topi populations in east Africa occurs in the Greater Mara-Serengeti Ecosystem, which straddles the border between Kenya and Tanzania.

Kenya’s Directorate of Resource Surveys and Remote Sensing has, since 1977, monitored numbers and distribution of topi, and other large wild herbivores and livestock, using aerial surveys in the country’s rangelands, covering 88% of Kenya.

Based on this data, we can see that topi numbers have declined persistently and strikingly (by 84.5%) in Kenya’s Masai Mara ecosystem between 1977 and 2022, even those in protected conservation areas.

This decline indicates a high risk of extinction if the trend persists. This is a serious concern, since other antelope species, such as the roan, have gone extinct in the Mara in recent decades.

But the causes haven’t been fully established.

We ran the aerial and ground survey data into the model in a computer on a monthly interval. This approach allows the model to capture patterns in trends and dynamics on a monthly scale. It allows us to see the distribution of births per month, the timing of births, the degree to which multiple females in a population give birth around the same time, the proportion of females in a population that give birth, the total number of individuals of each age and sex in each month, and the proportion of young that survive to adulthood.

The model starts with initial guesses based on existing knowledge, and refines the guesses as it processes more actual data.

It produces results that match the observed patterns of population decline, seasonality of births and how many animals survive to become juveniles or to adulthood.

Based on these findings, we see that the decline in the topi population is driven by a combination of low adult female numbers, low newborn survival and low recruitment into the adult class because most young (over 95%) die before they become adults.

Based on the model, we attribute these changes to impacts from environmental changes, human activities and predation. For instance, since adult animals are the least sensitive to climatic changes, this suggests other factors – such as habitat loss or deterioration, poaching or high predation rates – are likely contributing to the decline.

The new model enhances our understanding of large herbivore population dynamics besides confirming existing knowledge.

By combining different kinds of data from different sources, the model helps estimate and track important population details that one type of data alone can’t show. For example, for the first time data is captured that can track the total number of topi of each age and sex in each month, how many adult female topi are ready to conceive and the various stages of pregnancy. This method also estimates changes in the total topi population by age and sex in all four zones of the Mara, even in zones without direct ground age and sex data.

Refining and enhancing the model

The team is now extending the model to include more features (like the influence of livestock numbers), make it user friendly, apply it to more wildlife species and assess the effectiveness of ongoing and planned management actions.

Improving our understanding of the drivers of large mammal losses will ensure that the right conservation actions are taken. It’ll also ensure resources aren’t wasted because solutions could include investing in major infrastructure, changing wildlife conservation and livestock production policies, changing law enforcement and rehabilitation of wildlife habitats – all of which are costly.