Figure 2. Changes of Red List categories for bird species from to Numbers of taxa making each change are shown in the circles. Total birds in each category in are shown in parentheses; the total for extinctions is the number confirmed since CE. Recent studies of birds 12 and 13 and mammals 2 have used information like that shown in Figure 2 to estimate transition probabilities between IUCN Red List categories in both directions, for the better or worse and forecast rates of extinction over the coming decades.
These studies suggest that extinction rates for birds and mammals are about to increase by more than tenfold Figure 1. Similar accelerations in extinction are likely for other groups that are not as well-known; if anything, the increases could be even greater in many groups of organisms that are given less attention than birds and mammals and so are less likely to be helped by specific conservation actions.
The second reason to anticipate a steep rise in extinction is that the forces that caused recent extinctions are as strong as ever. The main direct causes of extinction are loss and degradation of habitats due to human use of land and sea; overexploitation of wild populations; and the impacts on populations and ecological communities of invasive alien species, pollution, and climate change 14, 16 and These direct causes are driven ultimately by demographic, economic and societal factors that increase the pressures that human populations place on biodiversity.
Most indicators of the direct and ultimate causes of biodiversity decline show that they are continuing to grow stronger 18 and There are several other reasons to think that the pressures that have caused extinction in the recent past will have worse effects in the future.
Populations of many species are becoming smaller and more geographically restricted, whether or not those species yet qualify as threatened This makes them more susceptible to threats they might have resisted when abundant and widespread, because for each population affected by some insult such as habitat loss or overexploitation there are fewer others to offset local declines and supply immigrants to replenish losses. Also, the general increase in human impact on nature makes it more likely that remaining natural areas are subject to several different threats at the same time, leading to compounding or synergistic effects with greater total impact The future will also bring an increasingly important overlay of global climate change to the long-standing forces of habitat loss, overexploitation, and so on.
The most significant effect of climate change may well be to increase the frequency or magnitude of extreme events. Extreme events that affect large areas can force large, abrupt and unexpected declines of many species at one time. The climate-driven fires that recently burned much of southern Australia supply an illustration of such an extreme event The fires caused extreme damage to habitats that typically experience recurrent fires of lower intensity and extent, while consuming other habitats that normally do not burn at all.
In the broad region affected by the fires, vertebrate species or subspecies are listed as threatened. At this stage there is less complete knowledge of impacts on other species, but rapid appraisals have identified invertebrate and plant species as potentially severely affected Roughly similar trends have occurred in most major regions of the world, in freshwater and dryland ecosystems, and in the oceans as well as on land 5, 15 and There is also growing evidence of widespread decline in the abundance of invertebrates, especially insects 15 and This is best studied in Europe, where it is becoming clear that the abundance and diversity of arthropods is declining even in relatively undisturbed habitats, evidently because of spill-over effects from agricultural land use So far, conservation action has had little success in reversing the general decline in abundance of wild species.
We have prevented some extinctions; for example, interventions between and prevented bird and mammal extinctions, such that extinction rates in both groups would otherwise have been 2. This is encouraging, but most improvements have been in moving species out of the Critically Endangered category into Endangered Figure 2 , that is, holding the line against extinction for some of the most severely threatened taxa.
Few threatened species have recovered their original distribution and abundance against the much stronger tide running in the other direction Figure 2. Image caption: the Critically Endangered orange-bellied parrot Neophema chrysogaster by Tiana Pirtle.
Not all species are being forced into decline; some are becoming more abundant as a result of human disturbance. In general, however, large-bodied and ecologically specialised species are more likely to decline 28 , being replaced by less diverse sets of species that either tolerate disturbance or benefit from it and are capable of invading new or altered habitats 29 and The result of this process is that a great part of the original diversity of nature is being lost from much of the planet.
As this happens, ecological communities are being made simpler and some important ecosystem functions are degrading. In the places that still have them, very large herbivores such as elephants and rhinos control the structure and pattern of vegetation, promote habitat heterogeneity, limit the extent of wildfire, transport nutrients, and disperse seeds. These various effects combine to promote diversity among smaller animal and plant species; megaherbivores could even influence the climate through alterations to land-surface albedo Another key point is that we have many species that are not far from extinction: species that are critically endangered or endangered.
If they did, extinction rates would increase massively. In another study published in Science , Michael Hoffman and colleagues estimated that 52 species of birds, mammals and amphibians move one category closer to extinction on the IUCN Red List every year.
Again, to times higher than the background rate. One way to answer this is to compare recent extinction rates with rates from previous mass extinctions. In the chart we see the comparison of non-dinosaur vertebrate extinction rates during the K-Pg mass extinction to recent rates.
This shows how many times faster species are now going extinct compared to then. We see clearly that rates since the year are estimated to be 24 to 81 times faster than the K-Pg event.
If we look at even more recent rates, from onwards, this increases to up to times faster. Again, this might even be understating the pace of current extinctions. We have many species that are threatened with extinction: there is a high probability that many of these species go extinct within the next century.
Recent rates of extinction, if they continued, would put us on course for a sixth mass extinction. A final way to check the numbers on this is to estimate how long it would take for us to get there. If this number is less than 2 million years, it would qualify as a mass extinction event.
Earlier we came up with a crude estimate for this number. If these species did go extinct soon, our extinction rates would be much higher than the average over the last years. To be clear: these are not predictions of the future. The results are shown in the chart.
If only our critically endangered animals went extinct in the next century, this would increase to a few thousand years. In any scenario, this would happen much faster than the million year timescale of previous mass extinctions.
This makes two points very clear. Current rates do point towards a sixth mass extinction. Second, these are scenarios of what could happen. There is one thing that sets the sixth mass extinction apart from the previous five. It can be stopped. We can stop it. There was no one or nothing to hit the brakes and turn things around. We are the primary driver of these environmental changes: deforestation, climate change, ocean acidification, hunting, and pollution of ecosystems. But is also the best news we could hope for.
It means we have the opportunity and some would argue, the responsibility to stop it. There are a number of examples of where we have been successful in preventing these extinctions [see our article on species conservation].
Or, worse, that they will accelerate. Nothing about that is inevitable. This is the first step to understanding what we can do to turn things around. This is what our work on Biodiversity aims to achieve. The world missed all of them. Perhaps, then, the loss of biodiversity is unavoidable. Maybe there is nothing we can do to turn things around. Thankfully there are signs of hope. As we will see, conservation action might have been insufficient to meet our Aichi targets, but it did make a difference.
Tens of species were saved through these interventions. We need to make sure these stories of success are heard. In fact, the risk here is asymmetric: growth in one wildlife population does not offset a species getting pushed to extinction. A species lost to extinction is a species lost forever. But we can make sure two messages are communicated at the same time. If there was no hope of the second one being true, what would be the point of trying?
If our actions really made no difference then why would governments support anymore conservation efforts? No, we need to be vocal about the positives as well as the negatives to make clear that progress is possible. And, importantly, understand what we did right so that we can do more of it. In this article I want to take a look at some of these positive trends, and better understand how we achieved them.
For anyone interested in wildlife conservation, losing a species to extinction is a tragedy. Conservation efforts might have saved tens of beautiful species over the last few decades. We might have missed this, but efforts have not been completely in vain. In a recent study published in Conservation Letters , researchers estimate that between 28 and 48 bird and mammal species would have gone extinct without the conservation efforts implemented when the Convention on Biological Diversity came into force in In the last decade alone from to , 9 to 18 bird, and 2 to 7 mammal extinctions were prevented.
This has preserved hundreds of millions of years of evolutionary history. It prevented the loss of million years of evolutionary history of birds, and 26 million years for mammals. What this means is that extinction rates over the last two decades would have been at least three to four times faster without conservation efforts.
This does not mean that these species are out-of-danger. In fact, the populations of some of these species is still decreasing. We see this in the chart, which shows how the populations of these bird and mammal species that were expected to have gone extinct are changing.
This is positive, but makes clear that many of these species are still in decline. Conservation has only been able to slow these losses down. This only looks at species on the brink of extinction. Many species in serious but less-threatened categories have been prevented from moving closer to extinction.
Around 52 species of mammals, birds and amphibians move one category closer to extinction every year. There are more examples. Studies have shown that protected areas have had a positive impact on preserving bird species in tropical forests. We will look at more European success stories later.
Friederike Bolam et al. Protected areas are not perfect — there are countless examples of poorly managed areas where populations continue to shrink. We will look at how effective protected areas are in a follow-up article. But, on average, they do make a difference. Clearly these efforts were critical for species that had gone extinct in the wild. Other important factors were controlling the spread of invasive species into new environments; reintroducing old species into environments where they had been previously lost; and restoring natural habitats, such as wetlands and forests.
The European Bison might steal the headlines, but there are many good news stories across Europe. Many of the drivers of biodiversity loss — deforestation, overhunting, and habitat loss — are happening in the tropics today. But these same changes also happened across Europe and North America. Only, they happened earlier — centuries ago. Europe is now trying to restore its lost wildlife and habitats through rewilding programmes.
Most had seen an overwhelming recovery. Brown bear populations more than doubled over these 50 years. Wolverine populations doubled in the s alone. My European ancestors had already hunted many species to extinction; expanded agricultural land into existing forest; and built cities, roads and other infrastructure that fragments natural habitats.
Only in our very recent past have European countries been able to reverse these trends: reforesting; raising livestock instead of hunting; and now reducing the amount of land we use for agriculture through improved productivity. But there have also been a number of proactive interventions to restore populations.
In the chart here we see the main drivers of recovery across European bird species. At the top of the list is habitat restoration — the re-establishment of wetlands, grasslands, forests and other national habitats. Reintroduction of species has also been key. But protecting existing habitats and species has been equally important. Legal site protections and bans on shooting have been the main recovery drivers of almost as many species.
After millennia of habitat loss and exploitation by humans, wildlife is coming back to Europe. Somewhat ironically, humans have played an important role in this. With continuing deforestation and climate change adding to the loss of species, the study questions whether humans will be involved in the next one. The authors write, however, that there is hope. Technology, such as satellite imagery, allows scientists to track these species and take action.
In addition, the public can aid by using smartphone applications that allow them to update data on where to find endangered species and habitats. Once identified, efforts can be made to save them and provide a chance to live on. Support Provided By: Learn more. Thursday, Nov The Latest. World Agents for Change.
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