Role of Homo Sapiens in Megafauna extinctions

Wherever man went, he destroyed. When it came to Nature, he played God too. Man has the distinction of being the greatest destroyer of Nature when compared to any other species that inhabited this earth. Wherever we go we decide what should live and what should not.

Ground  Sloth

 In America there were giant sloths, lions, mammoths and mastodons. Australia had eight foot long horned turtle, and a 25 foot lizard. All of them disappeared. What are the reasons for this recent megafauna extinctions? Paul Martin, a scientist at the University of Arizona developed the theory of "Pleistocene overkill", which held that as man spread out from Africa and colonized new continents, he killed off the great beasts that he found there. The dates seem to fit. Man arrived in Australia 48,000 to 50,000 years ago, the megafauna disappeared 46000 years ago. Man crossed into Tasmania from Australia through a land bridge 43000 years ago and the big animals in Tasmania disappeared 41000 years ago. In North America the megafauna seems to have disappeared around 13000 years ago at around the date of the first human settlements. Our earliest ancestors would, quite reasonably, have gone after the biggest animals they could to feed their families and kill the biggest predators to cut down on competition and attacks. Mix in human ingenuity, climatic changes, and hundreds and thousands of years and you soon get a land denuded of megafauna.

Glyptodons - enormous armored mammals 

Lets see what Man has done when he first set foot on some inhabited mass of land. Ever since the present Maoris ancestors arrived in New Zealand from some Polynesian islands somewhere in 1250-1300 it has lost 51 species of birds, three of frogs, three of lizards and one of freshwater fish. This was brought about by a combination of hunting, deforestation and the Polynesian rats that the Maoris brought with them.  Nearly all of the world's isolated islands could furnish similar examples of extinctions occurring shortly after the arrival of Homo sapiens. For some reason megafauna in Africa and Southern Asia was spared during the Pleistocene extinction. Some scientists have blamed climatic changes for such mass extinctions, but recent research has shown that climate change were minimal during this time.

Throughout earth's history extinctions have been the norm. Around 99% of all creatures that have ever lived have disappered from this planet. Hardly any of the species that are around now existed 100 m. years ago. It is also unlikely that many of today's species will be around in another 100m years.

What is the impact of humanity on biodiversity? In order to assess this fact, we need to know as to how many species there are on this planet. The most widely used estimate now is 8.7m species excluding bacteria and archaea. It is an established fact that species continue to die out naturally in the natural scheme of things. This is known as the "background rate of extinction" This rate has been calculated as one per million species years - if there were a million species on the planet, one would go extinct every year, and if there was one species on the planet, it would go extinct in a million years. There are 10000 species of birds. If the background extinction rate was the only force at work, one bird species would go extinct every century. A study of some Pacific islands inhabited by Polynesian migrants revealed that they wiped out 50% to 90% of the bird life. On an average these Polynesians were wiping out a species or two per year, that is at least a hundred times more than the background extinction rate.

In Australia, researchers argue that newly arrived humans hunted the animals to extinction, with the reduced grazing pressure causing an increase in the fuel load and fire intensity. This prompted the disappearance of rainforests and the expansion of eucalypt-dominated forests. Scientists suggest that protracted hunting by humans, perhaps over 10,000 years or more, was the probably number one extinction driver, but environmental changes happening at the time probably exacerbated the situation. This has led them to conclude that one-factor explanations for the Pleistocene extinctions are very likely overly simplistic in Australia.

Some scientists fear that unless people think that mass extinctions are imminent, they will not do anything about it. However, since the 1970's humanity has made far greater efforts to protect other species, mainly thanks to the change of attitudes brought about by greater awareness.

Source:

Extinction-Dead as a Moa, The Economist Sept 14th 2013.

The Plight And Flight Of The Amur Falcons

I found an interesting article about a fascinating bird called the Amur Falcon in the latest issue of 'Hornbill', a BNHS journal, and thought of sharing some interesting facts and its plight with you.

The Amur Falcon (Falco amurensis) is a small  raptor of the falcon  family. It breeds in south-eastern Siberia and Northern China before migrating in large flocks across India and over the Arabian Sea to winter in Southern Africa. It was earlier treated as a subspecies of the Red-footed Falcon (Falco vespertinus) and known as the Eastern Red-footed Falcon.

Amur  Falcon

The Amur Falcon breeds in east Asia from the Transbaikalia, Amurland and northern Mongolian region to parts of North Korea. They migrate in a broad front through India, to reach southern Africa. Birds going over India are thought to be aided by strong winds blowing westward. These winds are strong at an altitude of about 3000m and the birds are thought to fly at a height of above 1000m during migration. The route taken to return to their breeding grounds is not clear but they avoid the long ocean crossing and possibly take an overland route northward through Africa and to the west of the Himalayas. Vagrants have been recorded as far west as in Italy, Sweden, St. Helena and the United Kingdom. They cover an amazing 22,000 kms. round trip, with 4000 kms. of sea crossing (Indian Ocean) between India and South Africa twice a year!

Doyang Reservoir swarming with amur falcons

Doyang reservoir in Nagaland, a north-eastern state of India, is the product of a dam on the Doyang river. The water body formed in 2000, has been attracting Amur Falcons in lakhs ever since. The sharp-eyed falcons dart above the water, catching insects.

In 2012, Shashank Dalvi and Ramki Sreenivasan documented the shocking massacre of tens of thousands of migrating falcons along the banks of the Doyang reservoir in Wokha district of Nagaland.

Massacred  birds

Everyday thousands of these beautiful Amur falcons were being caught in mist nets, plucked alive, skewered, and then smoked before transport to market for sale as a cheap source of protein. An estimated 120,000 – 140,000 Amur falcons (Falco amurensis) were being slaughtered each year. The numbers are too much to comprehend.

Conservation India (CI) approached Bombay Natural History Society (BNHS) with a shocking video showing this massacre. It was an issue of hunting on a scale that was unsustainable. An active conservation plan had to be drawn up to save these falcons from extinction. Birdlife International put out an emergency fund appeal for the species. The response was overwhelming.

BNHS along with Nagaland Wildlife and Biodiversity Conservation Trust (NWBCT) set up ecoclubs in several villages to educate the villagers about the uniqueness of the avian visitor. With the help of Birdlife International's help under the Preventing Extinction Programme, and working with several creative people, a range of educational material was created for the children. For the first time children were also a part of the conservation program, by being made aware of the migratory falcons. The success of the NWBCT’s initiative was the development of a teaching manual for Amur falcon conservation. They held an intensive 4-day ‘Under the Canopy’ programme that trained around 20 teachers about how amazing the falcon migration really was. These teachers, have created and today run four EcoClubs in Sungro, Pangti and Doyang, where children are taught about these extraordinary falcons. The children make up songs, learn about conservation, and take this information home to their families. This is the only way to support the long-term sustainability of community conservation projects such as ”Friends of the Amur Falcon”. Result? children who ate Amur Falcons last year did not do so this year! Church leaders and village councils too appealed to villagers not to hunt these birds. The turnaround is heartening. Unless this effort is continued over the years, and unless other alternatives to earn money are not offered to the villagers, hunting will resume. A villager used to earn anywhere between Rs. 30,0000 to Rs. 80,000 per season, which is a lot for an average villager.

Shashank Dalvi of Wildlife Conservation Society (WCS – India), Bangalore, is leading a survey team of volunteers across locations in North-East India where the falcons have been seen in the past, recording their numbers, routes, and roosts, as well as potential hunting pressures.

On November 7th, 2013 three Amur falcons were satellite-tagged with 5g transmitters in Nagaland as part of a collaboration between scientists from the Wildlife Institute of India, Ministry of Environment and Forests, Convention on Migratory Species, United Nations Environment Programme, Environment Agency-Abu Dhabi, and the Nagaland Forest Department.

“The three satellite-tagged birds were named Naga, Wokha and Pangti on November 9. With the help of satellites, they were tracked as they flew across Bangladesh, India and finally across the Arabian Sea to reach Africa in one month. For the next four weeks, they flew slowly southwards from Somalia to Kenya, Tanzania, Malawi, Mozambique, Zimbabwe, till they reached South Africa on January 9.

Satellite transmitter fitted falcon

The male bird named Naga flew over Senapati and Churachandpur (Manipur) to Aizawl (Mizoram), entered Bangladesh, Bay of Bengal, Andhra Pradesh, Karnataka and Goa, after which it flew non-stop across the Arabian Sea to reach the Coast of Somalia on November 20. It then stayed at the Tsavo National Park in Kenya for a few days, before crossing to Tanzania, Zimbabwe and Botswana to finally enter South Africa on January 9.

Migratory flight path of the falcon

Similarly, the female bird named Pangti flew over Silchar (Assam), Agartala (Tripura), Bangladesh, Sundarbans, Bay of Bengal, Andhra Pradesh, Karnataka and Maharashtra before crossing the Arabian Sea. It then crossed the Coast of Somalia, entered Kenya and rested at the Tsavo National Park for a few days before flying across Tanzania, Zambia and Botswana to enter South Africa.

The third falcon, Wokha, flew over Silchar (Assam), Chittagong (Bangladesh), Bay of Bengal, Andhra Pradesh, Karnataka and Goa before crossing the Arabian Sea to reach Somalia through the Gulf of Aden.

Lets pray that this amazing brave bird survives human greed and cruelty to  fly unhindered across the vast oceans and continents.

https://www.youtube.com/watch?v=QfEXLGUIdYk

                                           (Cruel massacre of Amur Falcons in  Nagaland)

https://www.youtube.com/watch?v=06jrs1WDBoA

                                            (Video of Amur Falcons)

Yellow Stone National Park- The next supervolcano?

In 1971, a young geologist named Mike Voorhies came across a perfectly preserved.skull of a young rhinocerous in eastern Nebraska.  It turned out that he had just dicovered the most extraordinary fossil beds of North  America, which is known today as the Ashfall Fossil Beds State Park.  It was a dried up water hole around  which was a mass grave for many animals. All had died due to a sudden event which occured two million years ago in the Miocene period.  The animals were found to be buried under volcanic ash 3 meters deep. It was intriguing that there were no volcanos nor have there been any volcanoes in Nebraska.  At  first they thought that the animals were buried alive, but soon realized that the animals hadnt died  suddenly.  They were all found to be suffering from hypertrophic pulmonary osteodystrophy, which you contract when you breathe a lot of abrasive ash..  Such ash is found for hundreds of  miles around this area. The ash at that time would have buried the grass and turned the water in the watering hole into an undrinkable sludge.   The million dollar question was where did all this ash come from?  Voorhies sent ash samples to colleagues in the western United States asking if anybody could help.  Bill Bonnichsen from Idaho Geological Survey informed him that the ash samples matched a volcanic deposit from a place called Bruneau-Jarbidge in southwest Idaho, which is located 1600 kms. away.  It is a known fact that there is a huge cauldron of magma under the western United States, which erupted cataclysmically every 6,00,000 years. The last eruption in this region also occured six hundred thousand  years ago!  The hotspot is still there in what is known today as the Yellowstone National  Park.

In 1960, Bob Christiansen of the United States Geological Survey tried looking for the Yellowstone volcano, but strangely enough, couldnt find it.  He was particularly looking for a caldera (Latin for cauldron), which is a vast subsided pit which occurs after a single mighty rupture.  Christiansen happened to accidentally glance at some high altitude  pictures taken by NASA of the Yellowstone park.  It suddenly dawned on him that the whole park 9000 square kilometers of it was the caldera.  The explosion had left a crater 65 kilometers wide. That is why he couldnt spot it from the ground.   At some point in the past Yellowstone must have blown up with a violence, the magnitude of which cannot  just be imagined.  Prof Bill McGuire of University College, London says that when it erupted one wouldn't be able to get within one thousand kilometers of it!

Yellowstone  sits  on  top of an enormous hotspot.  Beneath the surface lies a magma chamber which  is about 72 kms.  across.  The pressure from  the magma chamber on its crust is what  has lifted the park and sorrounding areas half a kilometer higher. The heat from the hotspot is what powers all the park's geysers, vents and hotsprings.  Since its first  eruption 16.5 million years ago, it has blown up about a hundred  times.  The last eruption was atleast a  thousand tiimes bigger than St. Helens, and the one before that was atleast 2500 times bigger.  The yellowstone eruption which occured 2 million years ago, threw up enough ash to bury New York state to  a depth of 20 meters and California to a debth of 6 meters. The ashfall from the last eruption coverd all or parts of 19 western states.

                                         Volcano Eruption Mount St. Helens May 18, 1980 USGS
                                 
The last supervolcano erupted in Toba, Northern  Sumatra 74000 years ago. Greenland ice cores reveal that the Toba eruption was followed by 6 years of volcanic winter.  The event might have carried humans to the brink of extinction,  reducing the global population to a few thousand individuals.  For the next 20.000 years the population remained at the few  thousand level.  That is a long time to recover from a single  blast. A supervolcanic eruption like Yellowstone could wipe out mankind from the face of  this earth.

                                       TIME BOMB: YELLOWSTONE'S SUPER-CALDERA READY TO BLOW?

If the Samalas volcano which occured in 13th century was the mother of volcanoes, the yellow stone volcano will easily qualify to be the great  great grand  mother of volcanoes.  All the experts agree  on one thing, the yellowstone volcano is certain to erupt, and if and when it does heaven help us.  The worst  part  is that it is due anytime now.

Source:
Bill Bryson: A short history of  nearly everything

Supervolcanoes- Samalas Volcano, The Mother Of All Volcanoes

I first came across the term "Supervalcanoes" in Bill Bryson's 'A short history of nearly everything'. It was a really fascinating book, which lists out the possible scenarios which could bring about the end of Homo sapiens, one of which happens to be a "Super volcano". Yesterday, I came across an article in the 'Hindu' about a 13th century eruption in Indonesia, which by all accounts could be called the mother of all volcanoes in the last 3700 years. I followed up on that story and came across some very interesting and scary facts.

Scientists had always suspected that a massive catastrophic event had triggered of what is known as the Little Ice Age, sometime after 1250. The Little Ice Age has been abundantly depicted in contemporary accounts of advancing mountain glaciers that destroyed villages and paintings of ice-skating on frozen Dutch canals or on London’s River Thames. Chilling of the Northern Hemisphere was pronounced: cold summers, incessant rains, floods, and resulting poor harvests, according to medieval records. A volcano in Indonesia may be the location of a massive “mystery eruption” that has perplexed volcanologists for decades, according to a new study. The Indonesia’s Samalas volcano, is part of the Rinjani Volcanic Complex on Lombok Island.



Segara Anak Crater Lake formed after the eruption


The eruption occurred in 1257, and it could have been one of the events that started a 600-year cold period called the Little Ice Age. The previously unattributed eruption was an estimated eight times as large as the famed Krakatau explosion (1883) and twice as large as Tambora in 1815,

Volcanic eruptions release sulfur into the atmosphere. After cooling the Earth by reflecting sunlight, this material eventually falls back on Earth and gets deposited on ice sheets. These sulfur samples can be identified in ice cores obtained from polar regions. From the records, Clive Oppenheimer, a volcanologist at the University of Cambridge, found that an eruption in 1257 could have been responsible for the largest release of sulfur in the past 7,000 years.

But locating the volcanic source can be tricky. For the 1257 eruption, there were many candidates: Okataina in New Zealand, El Chichón in Mexico, Quilotoa in Ecuador, and Samalas in Indonesia.

To narrow down their choice, Franck Lavigne at the Pantheon-Sorbonne University and his colleagues had to consider many types of data, as they describe in a paper just published in the PNAS. They combined historical data, geochemistry evidence, carbon dating, and physical data to arrive at the conclusion.

The cataclysm blasted 10 cubic miles (40 cubic kilometers) of debris up to 27 miles (43 kilometers) high into the sky, producing fallout that settled around the world. Near the volcano itself, it settled into thick deposits that the team sampled in over 130 places to produce a stratigraphic and sedimentologic picture of the way the eruption unfolded. Further afield, the volcanic sulfate and tephra became locked in ice core samples taken from both Greenland and Antarctica.

Volcanic eruptions can have a large impact on the climate, which will then have social, economic, and environmental knock-on effects. Though the eruption was equatorial, its impact was felt and noted around the world. "The climate was disturbed for at least two years after the eruption, Medieval chronicles, for example, describe the summer of 1258 as unseasonably cold, with poor harvests and incessant rains that triggered destructive floods—a "year without a summer." The winter immediately following the eruption was warmer in western Europe, however, as would be expected from high-sulfur eruptions in the tropics. The team cites historical records from Arras (northern France) that speak of a winter so mild "that frost barely lasted for more than two days," and even in January 1258 "violets could be observed, and strawberries and apple trees were in blossom. In Indonesia records describe a catastrophe of a far more destructive and immediate sort. Found written on palm leaves, the Old Javanese texts of theBabad Lombok describe a massive volcanic blast that formed a caldera at Mount Samalas, on Lombok Island. The writing describes the deaths of thousands of people due to deadly ashfall and pyroclastic flows that destroyed Pamatan, capital of the kingdom, and surrounding lands. Archaeologists recently put a date of 1258 on the skeletons of thousands of people who were buried in mass graves in London. "We cannot say for sure these two events are linked but the populations would definitely have been stressed," Prof Lavigne told BBC News.

Source:

BBC news

National Geographic News

IBT Times