A special thanks to Rosie for sharing with me an article from the Independent last Monday. The article focuses upon a paper published in the journal Nature at the beginning of this month on Mankind unleashing the sixth mass extinction.
Article available here:
http://www.independent.co.uk/environment/worlds-sixth-mass-extinction-may-be-underway--study-2234388.html
The article provides a brief overview of the Nature paper mentioning the previous mass extinctions, evidence for the sixth mass extinction, and what the future may hold. The article ends by stressing that there is hope if we act now.
The paper published in Nature will be the focus of my next post and provides a fantastic overview of the sixth mass extinction.
Available here:
http://www.nature.com.libproxy.ucl.ac.uk/nature/journal/v471/n7336/pdf/nature09678.pdf
Monday 14 March 2011
Sunday 6 March 2011
Interesting birds of prey article.
So far throughout this blog I have focused upon the diminishing populations of large numbers of species around the world. These doom and gloom case studies of disappearing species are numerous, so I was delighted to find an article on the BBC News website portraying a more positive story.
Here is the article:http://www.bbc.co.uk/news/magazine-12634698
The article states that a number of bird of prey populations have increased over the last 50 years. Humans had a negative impact upon populations in the first half of the 20th Century through rapid industrialisation and the wide use of organochlorine pesticides. Two examples of increased populations are the Red Kite which now has 1,800 breeding pairs in the United Kingdom, and the Buzzard with a population of around 40,000.
However, not all of the 15 species of birds of prey native to the United Kingdom are experiencing this increase in populations. A number of species are still at risk including the Golden Eagle, with only one breeding pair in the United Kingdom.
(Image of Golden Eagle with a lamb in its grasp. Images like this shown in the Daily Mail this week create negative views of birds of prey, often encouraging persecution.)
Food and territory are not the problem for birds of prey, it is persecution including poisoned bait that is limiting populations. Yet another case study of the negative impact of humans on a wide range of animal species.
References:
http://i.dailymail.co.uk/i/pix/2011/02/27/article-1361000-0D5D039E000005DC-275_634x689.jpg
http://www.bbc.co.uk/news/magazine-12634698
Here is the article:http://www.bbc.co.uk/news/magazine-12634698
The article states that a number of bird of prey populations have increased over the last 50 years. Humans had a negative impact upon populations in the first half of the 20th Century through rapid industrialisation and the wide use of organochlorine pesticides. Two examples of increased populations are the Red Kite which now has 1,800 breeding pairs in the United Kingdom, and the Buzzard with a population of around 40,000.
However, not all of the 15 species of birds of prey native to the United Kingdom are experiencing this increase in populations. A number of species are still at risk including the Golden Eagle, with only one breeding pair in the United Kingdom.
(Image of Golden Eagle with a lamb in its grasp. Images like this shown in the Daily Mail this week create negative views of birds of prey, often encouraging persecution.)
Food and territory are not the problem for birds of prey, it is persecution including poisoned bait that is limiting populations. Yet another case study of the negative impact of humans on a wide range of animal species.
References:
http://i.dailymail.co.uk/i/pix/2011/02/27/article-1361000-0D5D039E000005DC-275_634x689.jpg
http://www.bbc.co.uk/news/magazine-12634698
"Attenborough and the Giant Egg"
Just a quick post on this lazy Sunday. David Attenborough is my one of my favourite presenters and I am an avid fan of much of his work. I was particularly interested to see that his most recent documentary focuses upon a giant egg that he came across when he was in Madagascar in 1960. This giant egg belongs to no other species than the 'elephant bird' as featured in a previous post.
As well as focusing upon the existence of the 'elephant bird' and the causes and approximate time of its demise, the documentary also talk about other dwindling species on the island and the natives relations with these animals. The other main focus is the indri, a black and white lemur species who are particularly under threat as they are extremely intolerant to habitat disturbance and cannot survive in captivity.
(Image of Indri lemur from: http://www.african-pride.co.uk/images/madagascar-lemur.png)
Overall this programme is a fantastic easy watch full of interesting facts and very relevant to this blog:
Here is the link: http://www.bbc.co.uk/iplayer/episode/b00z6dsg/Attenborough_and_the_Giant_Egg/
Enjoy!
References:
http://www.african-pride.co.uk/images/madagascar-lemur.png
http://www.wildmadagascar.org/wildlife/lemurs-indri.html
As well as focusing upon the existence of the 'elephant bird' and the causes and approximate time of its demise, the documentary also talk about other dwindling species on the island and the natives relations with these animals. The other main focus is the indri, a black and white lemur species who are particularly under threat as they are extremely intolerant to habitat disturbance and cannot survive in captivity.
Overall this programme is a fantastic easy watch full of interesting facts and very relevant to this blog:
Here is the link: http://www.bbc.co.uk/iplayer/episode/b00z6dsg/Attenborough_and_the_Giant_Egg/
Enjoy!
References:
http://www.african-pride.co.uk/images/madagascar-lemur.png
http://www.wildmadagascar.org/wildlife/lemurs-indri.html
Friday 4 March 2011
"Call of Life: Facing the Mass Extinction".
Call of Life: Facing the Mass Extinction is the first feature length documentary investigating the growing threat to the Earth's life support systems from this unprecedented loss of biodiversity (www.calloflife.org 2011).
Through interviews with leading scientists, psychologists, anthropologists, philosophers and indigenous leaders the film explores the causes, the extent, and the potential effects of the mass extinction. The documentary also looks beyond the immediate causes of the crisis to consider how our cultural and economic systems, along with psychological and behavioural patterns have allowed this situation to develop, and determine our response to it.
The documentary opens with the shocking statement that "if current trends continue, scientists warn that within a few decades at least 50% of all plant and animal species will disappear forever" (Call of Life 2010).
Here is the trailer for the film (from Youtube):
The documentary gives a really good introduction into mass extinctions putting into perspective the vast amount of time that life has been on Earth without the influence of humans. All previous extinction events have occurred with a slow decline in species number over a period of many centuries, a brief period of time compared to the millions of years it took to recover diversity after each event. However, advocates of the sixth mass extinction believe that this event will not take centuries to unfold, it will take place over our lifetimes (Call of Life 2010).
Scientists in the documentary believe that half of all plant and animal species will disappear in the wild within the next 30-40 years including many of the most familiar and beloved large mammals such as polar bears, elephants, and chimpanzees. One example of this is the African lion, where populations have declined by 90% since the 1980s. (Call of Life 2010). Many bird species are similarly imperilled, with songbird populations having halved in the last 40 years (www.calloflife.org 2011). The oceans are not safe either, populations of large ocean fish have declined by 90% since the 1950s (Call of Life 2010).
(Image showing African lion. Only 10% of 1980s populations remain today, it would be devastating to lose such a beautiful animal forever. From: www.africanvoyages.com)
People tend to forget plants, however large losses of biodiversity are also being experienced amongst this group. 1 in 8 plant species of plant life worldwide face extinction, this is most shocking in the United States where the figure is as high as 1 in 3 (www.calloflife.org 2011).
For a look at some interesting endangered plant life click here: http://webecoist.com/2008/11/03/strange-rare-bizarre-endangered-flowers-plants-and-trees/
The documentary focuses upon the higher estimate that modern rate of extinction could be 10,000 times greater than the natural background rate, with tens of thousands of species vanishing every year including many that have yet to be discovered or named (Call of Life 2010). As well as highlighting attention that when species within an ecosystem becomes extinct species depending on that species are also threatened. This cascade effect can bring an entire ecosystem to breaking point.
Call of Life ends by attempting to find solutions by examining the collective and individual responses that will be needed to mitigate the impacts of the mass extinction, stating the critical choices we have before us. Before ending on a positive note emphasising that we still have time to avert the worst of the crisis and save much of the biosphere if we act now.
For more information please visit: http://www.calloflife.org/
References:
Call of Life: facing the mass extinction. Monte Thompson. 2010
www.africanvoyages.com
www.calloflife.org
www.webecoist.com
www.youtube.com
Through interviews with leading scientists, psychologists, anthropologists, philosophers and indigenous leaders the film explores the causes, the extent, and the potential effects of the mass extinction. The documentary also looks beyond the immediate causes of the crisis to consider how our cultural and economic systems, along with psychological and behavioural patterns have allowed this situation to develop, and determine our response to it.
Here is the trailer for the film (from Youtube):
The documentary gives a really good introduction into mass extinctions putting into perspective the vast amount of time that life has been on Earth without the influence of humans. All previous extinction events have occurred with a slow decline in species number over a period of many centuries, a brief period of time compared to the millions of years it took to recover diversity after each event. However, advocates of the sixth mass extinction believe that this event will not take centuries to unfold, it will take place over our lifetimes (Call of Life 2010).
Scientists in the documentary believe that half of all plant and animal species will disappear in the wild within the next 30-40 years including many of the most familiar and beloved large mammals such as polar bears, elephants, and chimpanzees. One example of this is the African lion, where populations have declined by 90% since the 1980s. (Call of Life 2010). Many bird species are similarly imperilled, with songbird populations having halved in the last 40 years (www.calloflife.org 2011). The oceans are not safe either, populations of large ocean fish have declined by 90% since the 1950s (Call of Life 2010).
(Image showing African lion. Only 10% of 1980s populations remain today, it would be devastating to lose such a beautiful animal forever. From: www.africanvoyages.com)
People tend to forget plants, however large losses of biodiversity are also being experienced amongst this group. 1 in 8 plant species of plant life worldwide face extinction, this is most shocking in the United States where the figure is as high as 1 in 3 (www.calloflife.org 2011).
For a look at some interesting endangered plant life click here: http://webecoist.com/2008/11/03/strange-rare-bizarre-endangered-flowers-plants-and-trees/
The documentary focuses upon the higher estimate that modern rate of extinction could be 10,000 times greater than the natural background rate, with tens of thousands of species vanishing every year including many that have yet to be discovered or named (Call of Life 2010). As well as highlighting attention that when species within an ecosystem becomes extinct species depending on that species are also threatened. This cascade effect can bring an entire ecosystem to breaking point.
Call of Life ends by attempting to find solutions by examining the collective and individual responses that will be needed to mitigate the impacts of the mass extinction, stating the critical choices we have before us. Before ending on a positive note emphasising that we still have time to avert the worst of the crisis and save much of the biosphere if we act now.
For more information please visit: http://www.calloflife.org/
References:
Call of Life: facing the mass extinction. Monte Thompson. 2010
www.africanvoyages.com
www.calloflife.org
www.webecoist.com
www.youtube.com
Thursday 3 March 2011
Evidence for the 'Sixth Mass Extinction'.
Species are currently disappearing at a faster rate than ever before with the exception of cataclysmic events such as asteroid impacts or unusual volcanic activity (IUCN 2000). This time it appears that humans may be the cause.
Actual species extinction rates are extremely difficult to quantify with different scientists having different opinions. Most conservative estimates place the current rate at 1000 times the background rate as derived from the fossil record, but some estimates place it as high as 10,000 times greater (Call of Life 2009).
(Graph showing species extinction rates since 1800 from: http://www.whole-systems.org/extinctions.html)
This graph is based on a mathematical model linking species to habitat and was developed by a group of scientists led by Edward Wilson. The graph assumes that there is a total number of 10 million species on the Earth today. Background extinction rate from the fossil record is one extinction per million species per year, suggesting that the natural background extinction rate is 10 species per year.
The modern day extinction rate estimates that this model takes into consideration are (from: http://www.whole-systems.org/extinctions.html):
Historically man-made extinctions were primarily due to hunting such as the predation of slow-moving species e.g the wooly mammoth and the moa. Another factor may have also been the human introduction of new diseases by man or domesticated animals. The loss of these species led to the extinction of other dependent species such as giant vultures.
The cascade of current extinctions is mostly related to the destruction of habitat and displacement by introduced species. In the last 500 years human activity has forced 816 species into extinction, with 103 bird species extinctions since 1800 (IUCN 2000).
In September 2000 the World Conservation Union released a 'Threatened Species Survey' also known as the Red List, with shocking results. 11,046 species of plants and animals are considered threatened. This means that they are considered vulnerable, endangered or critically endangered. These species are considered to face high risk of extinction in the near future, in almost all cases this is seen as a result of human activities. This accounts for 24% of mammals and 12% of birds (IUCN 2000).
Since 2000 the Red List has been updated numerous times, with the number of threatened species increasing each time (IUCN 2009).
Here is the IUCN Red List website which may be of interest: http://www.iucnredlist.org/
Rates of species loss are not globally consistent, here are some of the worst affected places (IUCN 2000):
Actual species extinction rates are extremely difficult to quantify with different scientists having different opinions. Most conservative estimates place the current rate at 1000 times the background rate as derived from the fossil record, but some estimates place it as high as 10,000 times greater (Call of Life 2009).
(Graph showing species extinction rates since 1800 from: http://www.whole-systems.org/extinctions.html)
This graph is based on a mathematical model linking species to habitat and was developed by a group of scientists led by Edward Wilson. The graph assumes that there is a total number of 10 million species on the Earth today. Background extinction rate from the fossil record is one extinction per million species per year, suggesting that the natural background extinction rate is 10 species per year.
The modern day extinction rate estimates that this model takes into consideration are (from: http://www.whole-systems.org/extinctions.html):
- Edward Wilson - 27,000 species lost per year.
- Niles Eldridge - 30,000 species lost per year.
- Georgina Mace - 14-22% of loss of species and subspecies over the next 100 years.
- Paul Erlich - Based on total energy use estimates extinction rates at 7,000-13,000 times the natural rate - 70,000 to 130,000 species lost per year.
This graph clearly shows that since 1920 there has been a dramatic rise in the number of extinctions. Of course as with all models there will be inaccuracies, but the increase is so dramatic that one cannot deny that the losses are abnormal compared to the natural extinction rate.
The cascade of current extinctions is mostly related to the destruction of habitat and displacement by introduced species. In the last 500 years human activity has forced 816 species into extinction, with 103 bird species extinctions since 1800 (IUCN 2000).
In September 2000 the World Conservation Union released a 'Threatened Species Survey' also known as the Red List, with shocking results. 11,046 species of plants and animals are considered threatened. This means that they are considered vulnerable, endangered or critically endangered. These species are considered to face high risk of extinction in the near future, in almost all cases this is seen as a result of human activities. This accounts for 24% of mammals and 12% of birds (IUCN 2000).
Since 2000 the Red List has been updated numerous times, with the number of threatened species increasing each time (IUCN 2009).
Here is the IUCN Red List website which may be of interest: http://www.iucnredlist.org/
Rates of species loss are not globally consistent, here are some of the worst affected places (IUCN 2000):
- Madagascar - Which is home to more critically endangered primates than anywhere in the world. The island is a biodiversity hotspot with high levels of endemism (home to species that cannot be found anywhere else in the world). The island has already lost over 90% of its original vegetation.
- Philippines - Another biodiversity hotspot which has lost 97% of its original vegetation and is home to more critically endangered birds than any other country.
- Indonesia - Home to 135 threatened mammals, more than anywhere else in the world.
These shocking figures show that species extinction rates do appear to be occurring at a rate far above the natural baseline rate. It also appears that a large proportion of these losses are due to human influence. Something which I will continue to investigate throughout this blog.
The next post will focus upon the feature documentary "Call of life: Facing the mass extinction", which investigates the growing threat to Earths life support systems from the unprecedented loss of biodiversity (Call of Life 2009).
References:
Call of Life: Facing the mass extinction. Monte Thompson (2009).
IUCN. (2000). Compiled by C. Hilton-Taylor. 2000 IUCN Red List of threatened species. Thanet Press Ltd.: Margate.
IUCN. (2009). The IUCN Red List of threatened species 2009 update.
Wilson, E. O. (1992). The diversity of Life, The Belknap Press of Harvard university press: Cambridge.
www.whole-systems.org/extinctions.html.
Warmup for next post
I thought that this may be of interest, and a nice warm up for my next post which will be on recent extinction rates.
The article states that each stone block will be carved to depict the 850 species lost since 1662. This is a truly shocking figure considering the background extinction rate is 0.1-1 extinctions per thousand species per thousand years (Milennium Assessment 2000).
http://www.bbc.co.uk/news/10503222
Enjoy!
References:
http://www.millenniumassessment.org/
The article states that each stone block will be carved to depict the 850 species lost since 1662. This is a truly shocking figure considering the background extinction rate is 0.1-1 extinctions per thousand species per thousand years (Milennium Assessment 2000).
http://www.bbc.co.uk/news/10503222
Enjoy!
References:
http://www.millenniumassessment.org/
Wednesday 2 March 2011
Introduction to the Sixth Mass Exctinction.
This Blog attempts to determine whether we have entered the 'Sixth Mass Extinction', or whether the species losses experienced are just natural fluctuations. The factor that would set this mass extinction apart from the other is the fact that this would be the first mass extinction with a biotic cause.
This entry will give a small introduction into why many scientists feel that we have entered the 'Sixth Mass Extinction'.
Within the last 2,000 years a large number of species have become extinct in ways clearly linked to human dispersal or activity. Here are some examples:
The report states that after the emergence of modern humans few known extinctions occur in the areas of longest occupancy (Africa and Eurasia), and those that do occur are spread out. However, the migration of human beings into other areas is linked to the loss of a large number of large vertebrate species, as shown in the below map.
(Map showing human migration patterns, and extinction events over the last 100,000 years. From http://www.amnh.org/science/biodiversity/extinction/IntroFourteenFS.html)
The most shocking loss of species was in North and South America where some 135 mammal species were lost, representing 70% of North Americas large mammals when humans migrated from Asia between 12,500 and 10,000 years ago. Other examples where human settlement has coincided with extinction episodes include Hawaii (1,600 to 1,400 years ago), the West Indies (7,000 years ago), and the Mediterranean Islands (10,000 years ago). Notably all terrestrial vertebrates outside of Africa and Asia that weighed more than 1,000 kg have become extinct.
Human activities that are believed to impact extinctions include: overhunting, introduction of infectious diseases, increased interspecific competition, habitat destruction, and the introduction of exotic species.
It is this evidence that has led many scientists to believe that we have entered a period of accelerated anthropogenic mass extinction. Here are a couple of quotes to enjoy:
References:
Centre for Biodiversity and Conservation Conference. Humans and other catastrophes: perspectives on extinction. New York. American Museum of Natural History. Available at: http://www.amnh.org/science/biodiversity/extinction/IntroSymposiumFS.html
Eldredge, N. (1999). Cretaceous meteor showers, the human ecological niche and the sixth extinction. Centre for Biodiversity and Conservation Conference. Humans and other catastrophes: perspectives on extinction. New
York. American Museum of Natural History.
http://hoopermuseum.earthsci.carleton.ca/flightless/aepyorn.jpg
http://www.copyrightexpired.com/earlyimage/bones/large/large_extinctanimals_moa.jpg
Leakey, R. (1996) The Sixth Extinction. Weidenfield and Nicolson: London.
Steadman, D. W. (1995). Prehistoric extinctiond of Pacific island birds: biodiversity meets zoo archaeology. Science. 267: 1123-1131.
Wilson, E. O. (2002). The future of life. Vintage.
This entry will give a small introduction into why many scientists feel that we have entered the 'Sixth Mass Extinction'.
Within the last 2,000 years a large number of species have become extinct in ways clearly linked to human dispersal or activity. Here are some examples:
- In the 1500s several species became extinct in New Zealand after Polynesian settlers arrived. This included ten species of Moa (giant flightless ratite birds).
- Over 2,000 Pacific bird species have become extinct since the arrival of humans over the last 500 years (Steadman 1995).
- The arrival of humans 2000 years ago in Madagascar led to the majority of the islands megafauna becoming extinct. This includes the Aepyomism or 'Elephant Bird' (a giant flightless bird), 17 of 50 species of lemur and a giant tortoise.
- Around 500 years ago a number of species became extinct upon human settlement on islands in the Indian Ocean. This included several species of giant tortoise on the Seychelles and Mascarene islands.
- Other notable examples of modern extinctions include the Tasmanian Tiger, the Quagga, the Dodo, and the passenger pigeon of North America which became extinct as late as 1914.
(Picture showing the large size of a Moa compared to an Ostrich. From http://www.copyrightexpired.com/earlyimage/bones/large/large_extinctanimals_moa.jpg )
(Drawing of the Aepyomism which stood at over 3m tall and weighed approximately 450kg. From http://hoopermuseum.earthsci.carleton.ca/flightless/aepyorn.jpg )
The report states that after the emergence of modern humans few known extinctions occur in the areas of longest occupancy (Africa and Eurasia), and those that do occur are spread out. However, the migration of human beings into other areas is linked to the loss of a large number of large vertebrate species, as shown in the below map.
The most shocking loss of species was in North and South America where some 135 mammal species were lost, representing 70% of North Americas large mammals when humans migrated from Asia between 12,500 and 10,000 years ago. Other examples where human settlement has coincided with extinction episodes include Hawaii (1,600 to 1,400 years ago), the West Indies (7,000 years ago), and the Mediterranean Islands (10,000 years ago). Notably all terrestrial vertebrates outside of Africa and Asia that weighed more than 1,000 kg have become extinct.
Human activities that are believed to impact extinctions include: overhunting, introduction of infectious diseases, increased interspecific competition, habitat destruction, and the introduction of exotic species.
It is this evidence that has led many scientists to believe that we have entered a period of accelerated anthropogenic mass extinction. Here are a couple of quotes to enjoy:
- Niles Eldredge (1999): "It is well established that the Earth is undergoing yet another mass extinction event, and is clear that the major agent for this current event is homo sapiens".
- Edward Wilson (2002): "At current rates of human destruction of the biosphere, half of all species will be extinct in 100 years".
- Richard Leakey (1996): "It's the next annihilation of vast numbers of species. It is happening now and we, the human race, are its cause".
References:
Centre for Biodiversity and Conservation Conference. Humans and other catastrophes: perspectives on extinction. New York. American Museum of Natural History. Available at: http://www.amnh.org/science/biodiversity/extinction/IntroSymposiumFS.html
Eldredge, N. (1999). Cretaceous meteor showers, the human ecological niche and the sixth extinction. Centre for Biodiversity and Conservation Conference. Humans and other catastrophes: perspectives on extinction. New
York. American Museum of Natural History.
http://hoopermuseum.earthsci.carleton.ca/flightless/aepyorn.jpg
http://www.copyrightexpired.com/earlyimage/bones/large/large_extinctanimals_moa.jpg
Leakey, R. (1996) The Sixth Extinction. Weidenfield and Nicolson: London.
Steadman, D. W. (1995). Prehistoric extinctiond of Pacific island birds: biodiversity meets zoo archaeology. Science. 267: 1123-1131.
Wilson, E. O. (2002). The future of life. Vintage.
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