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Thread: Large Mammal Extinction 10,000 years ago

  1. #101  
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    Quote Originally Posted by forrest noble View Post

    The saber tooth tiger, or Smiladon, was a more modern north American cat evolving about 2.5 million years ago, probably from the American panther. They became extinct only about 10,000 years ago when other large animals also became extinct. The American mountain lion/ cougar is related to the Asian variety, which was believed to first cross the Bearing straight about 8 million years ago. It shared much of the same territory as the saber toothed tiger but was smaller and generally hunted smaller animals. At the La Brea tar pits in southern California, both species were found about the same fossil age at this same location. Whether they competed often at the same time in the same location is a matter of conjecture, but most believe that when they did, they generally did not compete for the same prey. Saber cats generally hunted larger animals. Cougars would have been very leary of saber toothed cats not just because they were bigger, but because they were not solitary hunters like cougars but ran in packs more like African lions.
    May I ask where your assertion that Smilodon evolved from the genus Puma? Smilodon is one of the last members of the felid subfamily Machaiordontinae and not closly related to any of the modern Felinae members living in the America's or Asia.
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    skeptic,

    Quote Originally Posted by forrest noble View Post
    Therefore man, at that time, could not have been the cause of the Smilodon's extinction by the competition of over-hunting large game. Instead the most likely cause of these extinctions in South America (thought to be the origin of the Smiladons) at the end of the last ice age was changing climates.
    With the utmost respect, Forrest, that is bullsh!t.
    For a start, we actually do not know when humans first came to North America. It was probably (but not certainly) some time between 12,000 and 16,000 years ago, but closer than that, we do not know. Within that time range, humans causing saber tooth extinction fits perfectly.

    Saber tooth cats survived 9 other climate change events of similar severity. Yet they died out only when humans arrived. Simple logic says ......
    As to the world as a whole the human predation theory is the dominant theory, but as to South America there were accordingly a number of extinctions coincident with the first introduction of man. Even if man first entered South America earlier than present archeology indicates, their numbers would have been far too small to effect both plants and animals of the vast land areas of South America. There was at the same time extinctions of a number of long established plant species that lends credence to the climate kill hypothesis, at least for South America.

    An additional hypothesis involves man bringing in diseases. Just like modern man's diseases were known to have wiped out most of the native peoples of the Americas, the first men were thought to have brought dogs and poultry with them to the Americas from the old world. Both men and/or these domestic animals may have brought new diseases to the Americas which could have spread quickly and decimated native fauna, of which most of the mega-fauna of South America were unique in the world. Here is a listing and discussion of many of the alternative hypothesis.

    http://uwacadweb.uwyo.edu/SUROVELL/p...cyclopedia.pdf
    Last edited by forrest noble; March 28th, 2012 at 02:44 PM.
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    Quote Originally Posted by Paleoichneum View Post
    Quote Originally Posted by forrest noble View Post

    The saber tooth tiger, or Smiladon, was a more modern north American cat evolving about 2.5 million years ago, probably from the American panther. They became extinct only about 10,000 years ago when other large animals also became extinct. The American mountain lion/ cougar is related to the Asian variety, which was believed to first cross the Bearing straight about 8 million years ago. It shared much of the same territory as the saber toothed tiger but was smaller and generally hunted smaller animals. At the La Brea tar pits in southern California, both species were found about the same fossil age at this same location. Whether they competed often at the same time in the same location is a matter of conjecture, but most believe that when they did, they generally did not compete for the same prey. Saber cats generally hunted larger animals. Cougars would have been very leary of saber toothed cats not just because they were bigger, but because they were not solitary hunters like cougars but ran in packs more like African lions.
    May I ask where your assertion that Smilodon evolved from the genus Puma? Smilodon is one of the last members of the felid subfamily Machaiordontinae and not closly related to any of the modern Felinae members living in the America's or Asia.
    my quote
    The saber tooth tiger, or Smiladon, was a more modern north American cat evolving about 2.5 million years ago, probably from the American panther.
    from link: subfamily: Pantherinae; species: Smalodon gracilis

    Here is the classificaton of Smilodon's.

    Extinct Smilodon Fact Sheet

    (quote from above link)

    Smilodon gracilis, 2.5 million-500,000 years ago; the smallest and earliest species (estimated to have been only 55 to 100 kg (120 to 220 lbs.)) was the successor of Megantereon in North America, from which it probably evolved. The other Smilodon species probably derived from this species.
    Last edited by forrest noble; March 28th, 2012 at 11:43 PM.
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    Good to see that you, in post 102, recognise that over-hunting is the dominant theory. Climate change cannot be a major cause, since all those megafauna survived previous climate change periods, and some geographic regions (like New Zealand, Mauritius, and Australia) did not experience any climate change at all coincident with mass extinction.

    The disease theory suffers from the fact that no known disease introduction ever has caused mass extinctions. Generally, disease is reasonably specific to a few related species. Crossing the species boundary does happen, but not sufficiently to kill off dozens of unrelated large animals. For example : in Australia, the megafauna extinction event included birds, mammals and reptiles. No disease will attack all of them. So introduced disease would be a very minor factor, if it has any effect at all.
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    Quote Originally Posted by forrest noble View Post
    Quote Originally Posted by Paleoichneum View Post
    Quote Originally Posted by forrest noble View Post

    The saber tooth tiger, or Smiladon, was a more modern north American cat evolving about 2.5 million years ago, probably from the American panther. They became extinct only about 10,000 years ago when other large animals also became extinct. The American mountain lion/ cougar is related to the Asian variety, which was believed to first cross the Bearing straight about 8 million years ago. It shared much of the same territory as the saber toothed tiger but was smaller and generally hunted smaller animals. At the La Brea tar pits in southern California, both species were found about the same fossil age at this same location. Whether they competed often at the same time in the same location is a matter of conjecture, but most believe that when they did, they generally did not compete for the same prey. Saber cats generally hunted larger animals. Cougars would have been very leary of saber toothed cats not just because they were bigger, but because they were not solitary hunters like cougars but ran in packs more like African lions.
    May I ask where your assertion that Smilodon evolved from the genus Puma? Smilodon is one of the last members of the felid subfamily Machaiordontinae and not closly related to any of the modern Felinae members living in the America's or Asia.
    my quote
    The saber tooth tiger, or Smiladon, was a more modern north American cat evolving about 2.5 million years ago, probably from the American panther.
    from link: subfamily: Pantherinae; species: Smalodon gracilis

    Here is the classificaton of Smilodon's.

    Extinct Smilodon Fact Sheet

    (quote from above link)

    Smilodon gracilis, 2.5 million-500,000 years ago; the smallest and earliest species (estimated to have been only 55 to 100 kg (120 to 220 lbs.)) was the successor of Megantereon in North America, from which it probably evolved. The other Smilodon species

    probably derived from this species.
    I would recommend you reexamine the page in the link you provided. It shows Smilodon in the subfamily Machaiordontinae rather clearly listing the three subfmilies of Felidae at the same indentation and then the genus and species at larger indentations. The page goes on to explain that Smilodon is a decendent of the genus Megantereon which lived from about 6 million years ago to about 2.5 million years ago.
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    Quote Originally Posted by Paleoichneum View Post

    I would recommend you reexamine the page in the link you provided. It shows Smilodon in the subfamily Machaiordontinae rather clearly listing the three subfmilies of Felidae at the same indentation and then the genus and species at larger indentations. The page goes on to explain that Smilodon is a decendent of the genus Megantereon which lived from about 6 million years ago to about 2.5 million years ago.
    You are correct, I misread the link concerning the subfamily of Smilodons being Machairodontinae, however this subfamily lived until about 11,000 years ago in the genus of Smilodons.

    Machairodontinae is an extinct carnivoran mammal subfamily of (the family) Felidae (true cats) endemic to Asia, Africa, North America, South America, and Europe from the Miocene to Pleistocene living from c. 23 Ma until c. 11,000 years ago.
    (parenthesis added)

    Machairodontinae - Wikipedia, the free encyclopedia
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    May I ask what your point is?

    BTW genus names are supposed to be typed in italics, and the genus name is Smilodon not Smilodons
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    Quote Originally Posted by Paleoichneum View Post
    May I ask what your point is?
    I mentioned this subject in answer to barbi's question: were there other cats in the same locations as saber tooth tigers? That was my only reason for bringing up the subject other than it does fit nicely with the large-animal extinction subject

    BTW genus names are supposed to be typed in italics, and the genus name is Smilodon not Smilodons
    Since there was more than one species in the genus Smilodon, I called the collective of these species "Smilodons," like we call the collective of the human families hominids. I'll grant that this is not a formal classification but an informal collective description of saber-toothed cats for the purpose of this thread.
    Last edited by forrest noble; March 28th, 2012 at 11:25 PM.
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    The plural of a genus is the genus name eg Smilodon or Smilodon ​species
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    Quote Originally Posted by Paleoichneum View Post
    The plural of a genus is the genus name eg Smilodon or Smilodon ​species
    Smilodon for singular and smilodon for plural, makes sense to me
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    always caps on genus names
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    Quote Originally Posted by Paleoichneum View Post
    always caps on genus names
    Always caps, got it
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    i think that the two ideas occur in our mind that is:
    The first one has to do with climate. About 12,800 to 11,500 years ago, it became very cold, changing the environment in which these large mammals lived. Paleontologists think the cool weather may have reduced the amount of food available for these large animals.

    The second idea has to do with humans. Humans arrived in North America about 13,000 years ago. They were hunters and killed large mammals for food.
    Last edited by KALSTER; April 3rd, 2012 at 05:17 AM. Reason: Spam link
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    Out of curiosity was there a point to your post other then the spam link in the text that takes people off site to your "einfopedia"?
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    einfopedia, I suspected you would start a campaign of link spamming after a few posts. IS that what you are doing? No further links to your site please or your account will be suspended. Thanks
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    The problem I have in believing that those extinctions were globally human caused is that the assumption that we reproduced rapidly and were able to raise those offspring until they reached sexual maturity thus creating the numbers to justify the need to hunt all those to extinction or clearing of habitats with fire. It wasn't until recently that we were able to reduce mortality among newborns and children so I would imagine it was even tougher for those indviduals that were alive 13,000 years ago to expand their numbers.

    It is without question that we were causing many extinctions much more recent in time then between 13,000 and 10,000 years ago. Our success in lowering infant mortality and childhood deaths has currently created the biggest and fastest extinctions of many species globally today.
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    Human populations are known to be able to increase at about 4% per year under modern, far from ideal conditions. That would double a given population every twenty years. The early pioneers into the new territories would have left behind them most diseases, and all factors such as warfare or competition. They would have had unimpeded access to rich food and open land. The fastest physically possible rates of increase for any human population would be expected.

    That would mean about five doublings per century, or in absolute terms about 3 million people for every 100 initial pioneers within 300 years. That is unlikely, but only because they would have run short of resources and begun more normal human territorial disputation etc on a continental scale long before then.
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    Hmmm. I notice no one has even suggested the potential role of infectious diseases in animal specific extinctions, many of which could have been brought into geographic areas by migrating humans.

    This concept has come into more serious study within the past couple of decades as we have recently seen more populations of specific animals being threatened by disease. The introduction of hitherto absent life forms into a new areas has always had an impact on the area where they were introduced for various reasons, some of which have been mentioned in above posts. Sometimes this impact has been the introduction of new diseases for which the native fauna had no resistance. Other times the foreigner has either been a predator of a class of victims or has outcompeted the victims for a specific food source.

    But in the case of humans, one of the major impacts has been the introduction of new diseases or their own difficulty in adapting to local diseases to which they had not been previously introduced. Many diseases are carried by one animal in which they are harmless and passed to other animals to which they are deadly. Humanity has been a highly mobile lifeform and has had the greatest chance to spread disease -- even to other life forms. Perhaps this is a more significant factor than we previously considered.

    But the most enlightening thing in this thread is to learn that the religion forum is not the only place where iceaura ignores established facts while making up his own non-facts, twisting and spinning what others have said and presenting strawman arguments. I admire his consistency.
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    Quote Originally Posted by daytonturner View Post
    Hmmm. I notice no one has even suggested the potential role of infectious diseases in animal specific extinctions, many of which could have been brought into geographic areas by migrating humans.

    This concept has come into more serious study within the past couple of decades as we have recently seen more populations of specific animals being threatened by disease. The introduction of hitherto absent life forms into a new areas has always had an impact on the area where they were introduced for various reasons, some of which have been mentioned in above posts. Sometimes this impact has been the introduction of new diseases for which the native fauna had no resistance. Other times the foreigner has either been a predator of a class of victims or has outcompeted the victims for a specific food source.

    But in the case of humans, one of the major impacts has been the introduction of new diseases or their own difficulty in adapting to local diseases to which they had not been previously introduced. Many diseases are carried by one animal in which they are harmless and passed to other animals to which they are deadly. Humanity has been a highly mobile lifeform and has had the greatest chance to spread disease -- even to other life forms. Perhaps this is a more significant factor than we previously considered.

    But the most enlightening thing in this thread is to learn that the religion forum is not the only place where iceaura ignores established facts while making up his own non-facts, twisting and spinning what others have said and presenting strawman arguments. I admire his consistency.
    What diseases have Humans transmitted to other species? I am only aware of the diseases transmitted to other humans by migration.
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    What diseases have Humans transmitted to other species? I am only aware of the diseases transmitted to other humans by migration.
    It's entirely possible for humans to carry diseases which move easily, without much change, between species - influenza, tuberculosis, brucellosis. And thereby initiate such diseases into previously unexposed animal populations.

    But I expect the much bigger impact comes from the fact that humans rarely travel alone. Apart from the fleas, lice and other parasites they carry themselves, the animals they bring deliberately or inadvertently are also carrying passengers which function as disease vectors. Rats, dogs, cats, chooks and other food animals like goats, as well as pack animals can all be carrying disease themselves or parasites which carry disease to which the humans and animals have some resistance from previous exposure. The animals in the new area may have had no previous exposure at all or only to other variants of the disease. (Influenza is an obvious candidate here.)

    Just think of the sorts of things that get inspected at quarantine stations. Leather, fur, feathers, bone as well as food items like jerky can all carry disease into areas not previously host to particular diseases.
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    Not that it of much doubt, but it seems there's at least some direct evidence of sloth hunting.
    ""This research provides the first scientific evidence for hunting or scavenging of Ice Age sloth in North America," said Redmond. "The significant age of the remains makes them the oldest evidence of prehistoric human activity in Ohio, occurring in the Late Pleistocene period."
    First evidence of hunting by prehistoric people in what is now Ohio
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    Barbi asked:

    What diseases have Humans transmitted to other species? I am only aware of the diseases transmitted to other humans by migration.
    Probably a difficult question to track down answers for. If such a thing were fatal to an entire animal population all those years ago, it would be difficult to perform an autopsy today which is the only way we could determine if they had died from a human born disease. If the disease was not fatal, we probably wouldn't notice it. Other species pass diseases to us; reciprocity seems in order. One of the reasons we continue to speculate on the cause of their extinctions is because we don't know what killed them.

    It seems highly possible that we could have been "typhoid Marys," carriers of diseases that do not effect us but which we can pass on via mosquitoes and fleas and ticks or some other method. Such diseases need even not be human diseases but diseases to which we are immune.

    I will have to admit though, that I am not aware of a recorded case of this happening. Where was the Associated Press when we needed it? I don't really suppose deer are aware of when their ticks pass lyme disease to humans, either. I really don't think there has been a lot of published research in this area as it is not one to which we have paid much attention. Existing animals may well have developed immunities to diseases which we carry.

    I was just thinking about how the Europeans brought chicken pox to some of my distant partial relatives, although they were not non-human animals. That is human to human, but does show how suseptable to foreign diseases anything without immunity would have.

    It just seems possible that humans could have introduced or transmitted diseases to wild animals. Maybe it was not by coughing in their face or leaving our scat where they could get into it. We exterminated Bighorn sheep in the Snake River basin by trying to graze domesticated sheep in their territory. We did indirectly cause that.
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    While there is little doubt of Europeans bringing and returning devistating deseases to and back from to North America, did anything similar happen for the remaining fauna about 400 years ago? Also the long passage through high latitude would have filtered out a lot of deseases before getting to the new world. Do we have any evidence of desease spread 10,000 years ago? We certainly have evidence of hunting.
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    Currently there is no evidence of disease from Humans to the large megafauna mammals 10,000 yrs ago nor is there alot of evidence that humans hunted those creatures in N. America. Of course it doesn't mean that it could not have been a factor, we just don't have the evidence. Cats and dogs are native to Asia and my understanding of this is that we didn't begin domestication of them until 10,000 in Asia so it is highly unlikely that they came along with those early humans that made it to N. America. Those people became extinct anyway and it wasn't until much later that a second wave of humans came to N. America.
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    It seems to me that if we actually knew all the answers, there would be no need to continue to discuss it. I did see an article someplace (perhaps the local newspaper) recently speculating that human borne diseases may be more of a problem for some other species than we originally thought. This is not something I just made up on my own and pulled out of thin air.

    Personally, I have never understood why primitive man would want to hunt down the biggest and most dangerous animals of their environment. That seems kinda dumb to me. I think I would have wanted to hunt something with a little less ability to bring about my own demise. If you had a normal 10-20 person clan of cavemen, most of the meat of a wooly mammoth would have spoiled long before they could completely consume it. Although I can understand that it would look like a long-lasting food source.

    Some of the speculation earlier in this thread was that the extinctions of large animal populations seemed to conincide with the migration of humans into their territory. And it seems to have ocurred often enough to rule out coincidence. But I am not sure that predation by a limited number of human invaders can fully account for the complete collapse of a much larger pre-resident population of other larger animals.

    We do have examples of human predation wiping out a whole species -- the passenger pigeon for one. By this time, however, we had become far more efficient killers. It was only the much more efficient killing methods that threatened the extinction of Bison who had thrived in spite of predation by Native Americans.

    I think I would feel that the major cause would have been climate change causing food source and habitat depletion, aided and abetted by some of these other causes. Let's heat up Antarctica and see what happens to penguins.
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    "But I am not sure that predation by a limited number of human invaders can fully account for the complete collapse of a much larger pre-resident population of other larger animals.

    We do have examples of human predation wiping out a whole species -- the passenger pigeon for one. By this time, however, we had become far more efficient killers. It was only the much more efficient killing methods that threatened the extinction of Bison who had thrived in spite of predation by Native Americans.

    I think I would feel that the major cause would have been climate change causing food source and habitat depletion, aided and abetted by some of these other causes. "

    As pointed out though climate change is almost certainly not a "major factor"--these same animals had been through similar and more adbrupt climate change many times before. Also, your use of the term "limited numbers" is misleading--even a small human population can produce many millions over as short as a few thousand years--especially if there's many dumb and fearless animals to provide food. To my knowledge there didn't seem to be a similar extinction of flighted bird species.
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    Another thought where climate change could have been a big factor in the Neanderthal extinction or the clovis people of N. America is the colder temperature allowed their big kill to become frozen so it was preserved longer if they guarded it against other predation. Using fire to thaw and cook it would allow them to feed on it for awhile and sustand a growing population. When the climate changed to getting warmer it would increase their need to kill often and leave alot to waste or other predators. This could explain why so many went extinct relatively at the same time in a quick manner.
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    Quote Originally Posted by Lynx_Fox View Post
    "But I am not sure that predation by a limited number of human invaders can fully account for the complete collapse of a much larger pre-resident population of other larger animals.

    We do have examples of human predation wiping out a whole species -- the passenger pigeon for one. By this time, however, we had become far more efficient killers. It was only the much more efficient killing methods that threatened the extinction of Bison who had thrived in spite of predation by Native Americans.

    I think I would feel that the major cause would have been climate change causing food source and habitat depletion, aided and abetted by some of these other causes. "

    As pointed out though climate change is almost certainly not a "major factor"--these same animals had been through similar and more adbrupt climate change many times before. Also, your use of the term "limited numbers" is misleading--even a small human population can produce many millions over as short as a few thousand years--especially if there's many dumb and fearless animals to provide food. To my knowledge there didn't seem to be a similar extinction of flighted bird species.
    We probably would not have any other mammals left if we had not learned agriculture and domestication of food animals 10,000 years ago.
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    As a general rule, harmful outcomes from cross species disease transmissions require the species concerned to be closely related. So humans can cause great harm by passing human diseases to chimps. But not to dogs. Certainly not to woolly mammoths.

    Human extinctions in the past appear to be mainly by two mechanisms.

    1. Over-hunting/fishing.
    2. Introduction of alien animals.

    As I have said before, I am most familiar with the extinctions of 800 years ago in my own country. The Maori wiped out 11 species of large flightless birds called moa in less than 150 years. We know they hunted these birds for food, since we have found numerous remains of their bones charred in cooking fires.

    Maori also introduced the polynesian rat which is undoubtedly responsible for the extinctions of small bird species, like several tiny flightless rock wrens.

    Climate change and habitat loss are often cited, but with little evidence and less logic.
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    Climate change and habitat loss are often cited, but with little evidence and less logic.
    I think the rabbit in Australia is a pretty good example of both invasive and habitat-destroying imports. Their burrowing displaces small burrowing native animals. More importantly, repeatedly eating the first early shoots of shrubs and small trees certainly wrecks the habitat for small animals and birds. It might have been idiotic agricultural practices that led to Australia's version of the dustbowl in mallee country, but rabbits denuding vast areas formerly covered by shrubs and small trees set the scene before people started ploughing vulnerable land 10 times between seasons. They'd have been much better employed ripping burrows and giving the cropland a rest..
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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    Of course, rabbits in Australia are a pretty good example of the destructiveness of my item 2 - the introduction of alien animals. As are foxes, and rats.

    Here in NZ, it is stoats, opossum, rats, rabbits, and a few others.
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    As pointed out though climate change is almost certainly not a "major factor"--these same animals had been through similar and more adbrupt climate change many times before.
    That does not exonerate climate change. They survived bottlenecks before, but bottlenecks still increase vulnerability - to everything.

    The Maori wiped out 11 species of large flightless birds called moa in less than 150 years. We know they hunted these birds for food, since we have found numerous remains of their bones charred in cooking fires.
    And of course they - and their dogs? - ate eggs. Is that hunting?

    We do have examples of human predation wiping out a whole species -- the passenger pigeon for one.
    The passenger pigeon suffered huge losses of habitat - the lowland eastern forest was extensively logged and plagued, greatly reduced in extent and altered in species mix.

    Witnesses at the time, from vantage points in nearby cleared fields and roads, report flocks of passenger pigeons roosting and nesting in such numbers that they broke the branches of the trees available - not enough trees available, any more, by the sound of that, no?

    As with the dodo, the closer we look the less preponderant hunting pressure seems to be - and the passenger pigeon was hunted for money, for sale, with none of the natural feedback curbs that tend to limit subsistence hunting.
    Last edited by iceaura; April 8th, 2012 at 04:51 PM.
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    none of the natural feedback curbs that tend to limit subsistence hunting.
    This notion is extremely variable. "Subsistence" hunters will destroy a resource unless something like a religious or dreaming or totem significance is attached to it. The classic example is turtles on Pacific islands. They were exterminated by both hunting and egg eating in places where they weren't attrributed with some kind of supernatural qualities that inhibited hunting to some extent.
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  34. #134  
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    Still pushing the taurine feces uphill, Iceaura?

    Habitat loss is one of many factors that may contribute, in a minor way, to extinctions. But as a major force driving extinctions, it is rare. I have asked, several times, for examples of species that have gone extinct solely due to habitat loss, and the positive responses are few and far between. On the other hand, I can name quite a large number of extinct species, driven that way by over-hunting, or by the introduction of alien animals, without even having to refer to any references.

    Professor Bjorn Lomborg, in his book, The Skeptical Environmentalist, describes Puerto Rico. Covered with rain forest. About 50 species of endemic rainforest birds. All the rain forest has been destroyed at one time or another. Yet only 3 species went extinct, and local biologists say this was due to the introduction of rats. One of the problems with the habitat loss hypothesis is that habitat has a habit of growing back. Total loss of a specific habitat is nowhere near as common as irrational environmentalists believe.

    Iceaura thinks that the extinction of the 11 species of moa cannot be ascribed to hunting because it may be partly due to harvesting of eggs. Is egg collecting the same as hunting? Of course it is. Just a specific kind of hunting.
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    Habitat loss is one of many factors that may contribute, in a minor way, to extinctions. But as a major force driving extinctions, it is rare.
    It is a very common major factor in the extinctions we do know about and have reasonably complete information on - the dodo, the passenger pigeon, the ivory billed woodpecker, and so forth. It appears to be rare mainly in the case of extinctions we have only sketchy information about, and extinctions brought about or nearly brought about by market forces and trade, and even in those habitat factors appear more often than not.

    Quote Originally Posted by skeptic
    I have asked, several times, for examples of species that have gone extinct solely due to habitat loss, and the positive responses are few and far between.
    No one is arguing for that.
    Quote Originally Posted by skeptic
    On the other hand, I can name quite a large number of extinct species, driven that way by over-hunting, or by the introduction of alien animals, without even having to refer to any references.
    Alien animals are not human hunting. Dogs that eat eggs are not human hunting. Rats that eat eggs are not human hunting. And your examples of known and established overhunting extinctions have been errors, so far. The moas in New Zealand are the most likely possibles, in my view, but they are also the ones I know least about: the close association of ignorance with hypothesized overhunting as sole major factor is something to keep in mind, eh?

    Quote Originally Posted by adelady
    none of the natural feedback curbs that tend to limit subsistence hunting. This notion is extremely variable. "Subsistence" hunters will destroy a resource unless something like a religious or dreaming or totem significance is attached to it.
    Or warfare. Or the existence of refugia otherwise - habitat factors. Larger expanses of habitat will more likely offer refugia.

    Subsistence hunters can destroy a resource, given certain circumstances - restricted habitat being the most general and obvious. Hence the prevalence of islands in these accounts. But "will"? They haven't, in many cases.
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    Quote Originally Posted by iceaura View Post
    It is a very common major factor in the extinctions we do know about and have reasonably complete information on - the dodo, the passenger pigeon, the ivory billed woodpecker, and so forth. It appears to be rare mainly in the case of extinctions we have only sketchy information about, and extinctions brought about or nearly brought about by market forces and trade, and even in those habitat factors appear more often than not.
    Iceaura

    You have no data on habitat loss as a contributor to the extinctions of the dodo, passenger pigeon etc. These are merely things you dream up. The dodo was killed off by a combination of over-hunting and by the introduction of alien animals. The passenger pigeon appears to have been wiped out by both commercial hunting and habitat loss. So again, not due to habitat loss alone.

    You said that alien animals are not the same as human hunting. True. But where do you think I said that? I have always stated that human-generated extinctions have two major causes.

    1. Over-hunting/fishing
    2. Introduction of aliens.

    These are separate causes. They can work together, of course. But they are not the same.

    These are also minor causes such as habitat loss, pollution, and climate change. These rarely act alone to cause an extinction, unlike the two causes above. Mostly they are just exacerbating factors.

    You claim that my examples of over-hunting extinctions are in error? Where?
    Do you think that rats wiped out the woolly mammoth? Or the marsupial lion?
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    Quote Originally Posted by skeptic
    You have no data on habitat loss as a contributor to the extinctions of the dodo, passenger pigeon etc. These are merely things you dream up.
    I linked you to info on the dodo, including the assertions of several experts and researchers who talked about the dramatic reduction of good dodo habitat on that island complex, the introduction of macaques, and other non-hunting factors.

    The deforestation of eastern North America between 1700 and 1900 is simply common knowledge, the dependence of forested country birds that nest in million bird rookeries on the presence of extensive expanses of suitable trees comes under the heading of "obvious".
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  38. #138  
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    About the dodo
    Dodo - Wikipedia, the free encyclopedia

    I quote :

    "As with many animals that have evolved in isolation from significant predators, the dodo was entirely fearless of people, and this, in combination with its flightlessness, made it easy prey for humans.[46] However, journals are full of reports regarding the bad taste and tough meat of the dodo, while other local species such as the Red Rail were praised for their taste. When humans first arrived on Mauritius, they also brought with them other animals that had not existed on the island before, including dogs, pigs, cats, rats, and Crab-eating Macaques, which plundered the dodo nests, while humans destroyed the forests where the birds made their homes;[47] the impact these animals—especially the pigs and macaques—had on the dodo population is currently considered to have been more severe than that of hunting. "

    Or as I said before. Two main causes. Over-hunting and alien animals. Habitat loss may have been a contributor, but only a minor one.
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    Quote Originally Posted by skeptic
    Or as I said before. Two main causes. Over-hunting and alien animals. Habitat loss may have been a contributor, but only a minor one.
    The Wiki is at some pains to discourage the notion of hunting as the - or even a - major factor: the quote you posted there asserts, as the major causes of dodo extinction (named in the position of greatest emphasis), human deforestation and nest plundering by macaques.

    In that it agrees with the other links I have posted for you on this topic.

    It also alludes to the influence of pigs, which competed sharply for food and destroyed good food habitat, and the usual rats, cats, etc. All of these more important than hunting.

    People didn't hunt dodos intensively for the same reason that - as you note - they didn't hunt koalas intensively : there were better things to hunt.

    Meanwhile, if you recall this is what I've been replying to - compare it with your Wiki quote:
    We know the dodo went extinct very rapidly because it did not fear humans, and would walk right up to those who were looking for a dodo dinner.

    What do you think removed the dodo? That is a matter of history and is documented in the ships logs and other reports of the time. It is hunting.

    But we do know what has happened more recently, in places like Mauritius and New Zealand. When humans move into a new, and previously untouched area, there is rapid extinction, caused by
    1. for larger animals - hunting
    2. for smaller animals - the introduction of animal aliens.
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  40. #140  
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    Iceaura

    That last quote from what I said earlier, was obviously incomplete. I admit I should have said hunting and alien animals.
    So there you go. I have admitted a small mistake. Have you any admissions to make?
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    Haven't reread everything here, but I think my memory's reasonably good for what we discussed and emphasised.

    We've been looking at this stuff all wrong. I was watching a wildlife program tonight. Unsurprisingly, there were a couple of sequences about predators. Light dawned.

    When lions, baboons, wolves, crocodiles take down prey what are they most likely to end up with? They're most likely to get the weakest, slowest, stupidest or smallest of any group, apart from the just plain unlucky. Humans aren't strong or powerful like your average top predator. We also would go for slow, weak, small especially when we are dealing with a large mammal like a mammoth or a giant kangaroo. We wouldn't tackle something big, strong, clever or aggressive enough to attack us right back. Let's face it, a 'small' baby mammoth is a pretty good feed for several days for a group of twenty or less. Even for a group of up to 50.

    And that's where the extinction effect comes in. These are large mammals we're talking about going extinct. What sort of litter size and reproduction rate are we likely to be dealing with? Large or small, fast or slow? If we're talking from bigger than a bear up to the same size as your average elephant, I'd expect females to be producing between 1 or 2 a year (eg bears), through to less than 2 every 5 years or so (elephants).

    A smallish number of groups of humans knocking off the slowest and weakest every chance they get means they'll usually be getting the youngsters along with the occasional older, sicker animal. If the game is plentiful, these humans are unlikely to move on to new areas with unknown resources. So they'll stay in that area for a while. Wouldn't take long to reduce the local population of whatever to below replacement rate. When the easy pickings are gone, they have the choice of taking on the bigger, stronger adult animals or moving to a different tatget animal or to an area where the hunting is easier.

    Keep doing that area by area, and all the other little bands of human hunters do the same, pretty soon the slower reproducing animals will die out. Not because humans killed large, intimidating animals, but because they picked off the new, 'small' targets of each population each season.

    Until the new generations stopped coming.
    skeptic and forrest noble like this.
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  42. #142  
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    Very good analysis, Adelady.

    Nice to see someone thinking.
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  43. #143  
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    Quote Originally Posted by adelady View Post
    Haven't reread everything here, but I think my memory's reasonably good for what we discussed and emphasised.

    We've been looking at this stuff all wrong. I was watching a wildlife program tonight. Unsurprisingly, there were a couple of sequences about predators. Light dawned.

    When lions, baboons, wolves, crocodiles take down prey what are they most likely to end up with? They're most likely to get the weakest, slowest, stupidest or smallest of any group, apart from the just plain unlucky. Humans aren't strong or powerful like your average top predator. We also would go for slow, weak, small especially when we are dealing with a large mammal like a mammoth or a giant kangaroo. We wouldn't tackle something big, strong, clever or aggressive enough to attack us right back. Let's face it, a 'small' baby mammoth is a pretty good feed for several days for a group of twenty or less. Even for a group of up to 50.

    And that's where the extinction effect comes in. These are large mammals we're talking about going extinct. What sort of litter size and reproduction rate are we likely to be dealing with? Large or small, fast or slow? If we're talking from bigger than a bear up to the same size as your average elephant, I'd expect females to be producing between 1 or 2 a year (eg bears), through to less than 2 every 5 years or so (elephants).

    A smallish number of groups of humans knocking off the slowest and weakest every chance they get means they'll usually be getting the youngsters along with the occasional older, sicker animal. If the game is plentiful, these humans are unlikely to move on to new areas with unknown resources. So they'll stay in that area for a while. Wouldn't take long to reduce the local population of whatever to below replacement rate. When the easy pickings are gone, they have the choice of taking on the bigger, stronger adult animals or moving to a different tatget animal or to an area where the hunting is easier.

    Keep doing that area by area, and all the other little bands of human hunters do the same, pretty soon the slower reproducing animals will die out. Not because humans killed large, intimidating animals, but because they picked off the new, 'small' targets of each population each season.

    Until the new generations stopped coming.
    Easier pickings is how the natural environment works for predators so what made us the exception to this rule?
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    Adelady:

    In order for your hypothesis to have validity, it would be important to show that in those instances where large numbers of fossil remains have been found together close in proximity and time, there was a disproportionate number of adult to young remains. Your hypothesis sounds reasonable, but lacks any substantiating data. Thus, I see no science involve here even those skeptic seems more than willing to blindly accept it.

    Expressing an hypothesis is easy. Real research goes out to find confirming or refuting data and someone who is really "thinking" looks for both. I

    n a quick look around, I am unable to find any actual data which would confirm or refute your hypothesis. However, since it is your hypothesis, I think the onus is on you to figure out what kinds of information would substantiate your claim and then going out to find some. That is what science is about -- not just positing hypotheses which are a dime a dozen.
    Science without religion is lame, religion without science is blind. -- Albert Einstein

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  45. #145 humans in americas 60,000ybp 
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    evidence for human activity in the americas seriously predates the 14-16000ybp belief --- perhaps by another 50,000 years
    (see the work of albert goodyear, the preda furada site, and mtdna comparisons of indiginous populations suggest a primary wave of migration of @30,000ybp)
    the trouble with archaeology for that time frame is that the coastlines during the glaciation are now under hundreds of feet of ocean, and deep water archaeology is prohibitively expensive
    so, if we find a handfull of sites at heigher elevations that can be dated to those times, we may readily assume that we have a very small sampling

    if, as is currently postulated the earliest arrivals came by boat along the edge of the ice, and then the edge of the continent, then they would most likely have settled near the coasts, (as do a majority of us today)
    and,
    as the ice melted and sea levels rose, the evidence of their existence was obscured by water, waves, and silt
    -------
    tieing humans of that time to a singular causality of extinction of the megafauna seems to be an extraordinary claim requiring extraordinary evidence to support that theory

    which
    we ain't got

    (wild guess)
    if, indeed there was an ice free corridor through berengia into north america
    diseases carried by the heard animals that the migrants were following found new hosts in the new world that had no imunity to them
    add in the stressors of climate change, and voila
    corpses of the megafauna littering the landscape
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    Dayton, if you read the earlier discussion, several of us were arguing how humans might have managed to kill off such large mammals and others were saying it couldn't have been done at all. They were too big. You couldn't eat what you'd killed. All that stuff.

    All I'm saying is that the "couldn't be done" argument ignores a glaringly obvious reality about the observed behaviour of modern predators. And that if, if, IF, humans were directly responsible for large mammal extinctions on every continent they moved to, it really wouldn't have been that hard to wipe them out if their reproduction rates were slow.
    "Courage is what it takes to stand up and speak; courage is also what it takes to sit down and listen." Winston Churchill
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  47. #147  
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    Quote Originally Posted by daytonturner View Post
    it would be important to show that in those instances where large numbers of fossil remains have been found together close in proximity and time, there was a disproportionate number of adult to young remains. Your hypothesis sounds reasonable, but lacks any substantiating data. .
    On the face of it, Dayton, that is correct. Adelady was applying good logic rather than good science, though I am entirely happy to accept that her logical conclusion is probably correct.

    The problem with your suggestion of comparing fossil bones, young versus old, is that finding a disproportionate number of young bones such as woolly mammoth, will be almost impossible, and of problematic conclusion, even if so discovered. If Adelady is correct, and I strongly suspect she is, then the disproportion would only happen for short time periods, and only in a few localised places. It is also worth remembering that mortality among the young is always higher than among older animals, and the disproportion will always be there. To pick up a scattering of bones and conclude that the disproportion is out of whack would be difficult in the extreme - possibly impossible.
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    Quote Originally Posted by adelady
    Dayton, if you read the earlier discussion, several of us were arguing how humans might have managed to kill off such large mammals and others were saying it couldn't have been done at all. They were too big. You couldn't eat what you'd killed. All that stuff.
    Nobody has been arguing that it couldn't have been done at all, they were too big, etc.

    The only person here who has even been implying that modern (stone age or better) humans were incapable of hunting and killing essentially any animal they encountered has been skeptic, who introduced the concept of the genetically naive and unwary large mammal and bird - one incapable of learning the danger of humans by the example of their young and herdmates or their experience with bears, wolves, big cats, etc - to explain people being able to kill mammoths and moas.

    Quote Originally Posted by adelady
    All I'm saying is that the "couldn't be done" argument ignores a glaringly obvious reality about the observed behaviour of modern predators. And that if, if, IF, humans were directly responsible for large mammal extinctions on every continent they moved to, it really wouldn't have been that hard to wipe them out if their reproduction rates were slow.
    Moose reproduce more slowly than cheetahs and horses, grizzly bears more slowly than any known big cat or camel. The basic problem with confining the proposed influence of humans to hunting predation, hunting and hunting alone as it was put, is that so many of the extinguished animals were such unlikely hunting targets compared with so many of the surviving ones.

    Slow reproduction of course intensifies the pressure from all of the standard extinction risks - especially habitat destruction, which tends to reduce the refugia available for replenishment of extermination zones. Refugia are valuable specifically because they are (almost by definition) protected areas of reproduction.
    Quote Originally Posted by skeptic
    I admit I should have said hunting and alien animals.
    You should have said hunting, alien animals, and habitat destruction - as well as possibly disease, etc.

    In particular, you should have said that immediately after you were supplied with information and argument, rather than repeating yourself and shifting the same essential error to multiple other geographical locations and examples.
    Last edited by iceaura; April 26th, 2012 at 09:03 PM.
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    Quote Originally Posted by iceaura View Post
    skeptic, who introduced the concept of the genetically naive and unwary large mammal and bird - one incapable of learning the danger of humans by the example of their young and herdmates or their experience with bears, wolves, big cats, etc - to explain people being able to kill mammoths and moas.
    Actually, it is not my idea. That concept has been around for a long time and is quite real. In places where humans have not been predators, it is very common for the wild life to be quite naive and trusting towards humans. Here in New Zealand, we lost the moas, but we still have very tame flightless birds, that humans can approach, including Takahe, Kakapo, and weka.

    This tameness is not lost easily, since it is the result of evolution, not learning. For example : the Takahe was hunted almost to extinction by the NZ Maori. The sole remaining population was a tiny one in very inaccessible mountain terrain. And yet, when discovered, they were found to be very tame also.

    The Takahe is a special bird to me, since there is now a small population on Tititiri Matangi Island, which I have visited many times. The Takahe on this island are so tame that they walk up to people. I once, while lying in the sun on the beach, had one walk up to me, onto my bare chest, and peck me on the nose.
    http://www.tiritirimatangi.org.nz/takahe-on-tiri



    In Antarctica, anyone who wishes can walk right up to various species of penguin. Indeed, if you stand still, they will walk up to you.

    However, to qive a visual idea, I will pick the Providence Petrel, which nests on Mount Gower, Lord Howe Island. I climbed this high hill myself and called the petrels to me with loud calls. See how tame they are.
    Providence Petrel @ Mt. Gower, Lord Howe Island - YouTube
    The Providence Petrels have, in fact, been preyed upon by humans. They were easy food for shipwrecked sailors. Yet they are still tame.

    Iceaura said :
    "You should have said hunting, alien animals, and habitat destruction - as well as possibly disease"

    I have seen precisely zero evidence that the other factors are more than relatively minor influences. There is heaps of evidence that hunting and introduction of alien animals are major factors in causing extinctions.

    Habitat destruction is not good, but its influence in causing extinctions, regardless of the divinely inspired off the cuff conclusions of irrational environmentalists, has never been shown to be anything but an "also ran".
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    [quote="skeptic"] I have seen precisely zero evidence that the other factors are more than relatively minor influences. [quote] Try reading the links I and other supply.

    Quote Originally Posted by skeptic
    In places where humans have not been predators, it is very common for the wild life to be quite naive and trusting towards humans. Here in New Zealand, we lost the moas, but we still have very tame flightless birds, that humans can approach, including Takahe, Kakapo, and weka.
    And then you explained the non-extinction of the ones that didn't go extinct by assuming they were not so afflicted by tameness - emus, cassowaries, etc.

    And you overlook the evidence that even with the very tame and very helpless, such as the dodo, hunting was not the overwhelming factor in the cases we know a lot about. The common pattern is that hunting recedes in perceived importance as more detailed information comes to light.

    All the examples of genetic tameness are in situations that lacked large mammalian predators altogether. No genetically trusting, unwary mammal could have survived the bears of North America, and the tameness we see in unpredated mammals (deer in the subuirbs, a coyote I watched last week stroll down the middle of the street in Minneapolis) is learned and unlearned rapidly.

    Mammoths in NA were predated by bears, wolves, lions, tigers, etc. - at least the young. The assumption that mammoths and similar NA animals allowed repeated human killing for generations requires a great deal of evidence to be remotely plausible. That all 50 or so large animals driven extinct in NA at the advent of human populations were genetically tame, and the others not, is not reasonable without serious argument and evidence.

    Why would you presume that large scale habitat modifications of human settlement - fire, etc - would have no major influence?
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  51. #151  
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    Quote Originally Posted by iceaura View Post
    Why would you presume that large scale habitat modifications of human settlement - fire, etc - would have no major influence?
    I have answered this query many times.
    Simply because there is no strong evidence of that.
    There is substantial evidence of extinctions caused by human over-hunting, and also substantial evidence of extinctions caused by introduction of alien animals. However, there is very little evidence of extinctions caused by habitat change. Not zero evidence. There are a few, relatively rare cases, such as a lake drained, and a unique fish species dying out. But those are few and far between.

    I could name 20 species made extinct by human hunting as a sole cause, and another 20 made extinct by introduced aliens as a sole cause, without having to look at any references. I could not name a single species made extinct by habitat loss, unless it is just a small part of many causes, and I have asked many times on this and other forums for examples.

    There are, however, numerous examples of so-called 'authorities' declaring, ex-cathedra, that habitat loss is the main cause of extinctions. They are not inconvenienced by lack of evidence when disciples like yourself, Iceaura, simply believe what they say, based purely on faith.

    The following comment by Mark Twain about religion and politics also applies to that very modern of faiths, extreme environmentalism.

    "In religion and politics people's beliefs and convictions are in almost every case gotten at second-hand, and without examination, from authorities who have not themselves examined the questions at issue but have taken them at second-hand from other non-examiners, whose opinions about them were not worth a brass farthing."
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    It really comes down to what the numbers were in Human population 10,000 years ago and nobody knows this answer. Also the fact we are ominivores and are not strictly carnivores that could possibly wipe them out if there were alot of us alive at that time.
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  53. #153  
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    Quote Originally Posted by skeptic View Post

    I could name 20 species made extinct by human hunting as a sole cause, and another 20 made extinct by introduced aliens as a sole cause, without having to look at any references. I could not name a single species made extinct by habitat loss, unless it is just a small part of many causes, and I have asked many times on this and other forums for examples.


    "In religion and politics people's beliefs and convictions are in almost every case gotten at second-hand, and without examination, from authorities who have not themselves examined the questions at issue but have taken them at second-hand from other non-examiners, whose opinions about them were not worth a brass farthing."
    as/re habitat loss, may I suggest:
    "The Irish elk" as a likely candidate for extinction due to habitat loss(when the tundra/grasslands turned into dense forest)
    but
    we didn't do it
    likewise there are many examples from earts's past---from vulcanism, ice, etc
    sometimes, the changes were so radical, and extinctions so massive, that we date certain era's of the earth's past by the change in species.

    excellent marktwain quote
    thanx
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    When it comes to habitat loss and extinctions, there are really 2 separate issues. One is the issue of local extinction. I'm pretty sure that the Greeks cutting down pretty well every tree they could see in order to make their ships when they did caused the loss of lots of little creatures in their area along with their soil. But Greece is part of a larger land mass and extensive coastline. Anything that could no longer survive there had plenty of refuges to move to or stay in. And we were certainly capable of wiping out any animals too slow - either in escape speed or in reproduction or both - if they hadn't a large enough population or range to withstand that impact.

    And that's where the other issue comes in. Back when the total world population of humans was counted in millions rather than billions, everything we did was on a fairly small scale. Even when it had a big impact on a confined area or a specific river or island or species, there weren't enough of us to extend or prolong that impact to whole environments or whole biota. Animals and plants always had somewhere to go, or somewhere they could stay, away from that impact unless they were too specific or confined in the first place.

    Once we hit the 2 billion mark, that all changed. Even then, we managed to wipe out almost all the large whales when we were at not much more than that level. They still haven't recovered to even 30% of their pre-whaling industry populations. And that effect was only from direct predation, no cascading effects there. Now that we're forcing rivers to salt up and silt up by preventing them from reaching the sea and all the similar large scale effects, we can't ensure that plants and animals won't be driven to extinction by our agricultural and engineering activities.
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    Could it be a gamma ray event that is the culprit?

    'LaViolette has advanced his theory that the melting of the polar ice caps and the mass extinction of large animals ("megafauna") around 12,000-16,000 years ago was caused by a cyclical Gamma Ray Burst from a pulsar near the core of the Galaxy.

    The results of this Gamma Ray Burst (GRB) was a nuclear winter of darkness, freezing cold, severe solar storms, periodic heat and cataclysmic flooding that plagued all life on Earth for several generations. He reckons that these "Galactic Superwaves" occur in 10,000-year cycles.'
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    To Adelady

    Sorry, but the answer is no.
    We do not have to number in the billions to cause extinctions. The biggest human caused extinction event ever, is the migration by Polynesians across the Pacific Ocean. This began about 12,000 years ago, and ended about 800 years ago. It was caused by small numbers of stone age peoples.

    We know this due to studies of the sub-fossil record of bird bones. Some 2,000 species of birds have been found in this record, now extinct, and which died out with the coming of the Polynesians. The cause is a combination of hunting by Polynesians for food, and the introduction of the polynesian rat, which killed off the smaller bird species.
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  57. #157  
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    Quote Originally Posted by adelady
    And that's where the other issue comes in. Back when the total world population of humans was counted in millions rather than billions, everything we did was on a fairly small scale. Even when it had a big impact on a confined area or a specific river or island or species, there weren't enough of us to extend or prolong that impact to whole environments or whole biota.
    That is almost certainly a misperception. The colonizers of at least two entire continents - North America and Australia - made large changes in the landscape on a continental scale. The entire prairie system east of the Mississippi River (the "buffalo commons" extending up the Ohio River, etc) appears to have been created by humans setting fires, for example; much of the landscape of the entire continent of Australia similarly but even more dramatically, to the point that it is now (40 thousand years later) ecologically dependent on unusually frequent fires.

    Quote Originally Posted by skeptic
    I could name 20 species made extinct by human hunting as a sole cause, and another 20 made extinct by introduced aliens as a sole cause, without having to look at any references. I could not name a single species made extinct by habitat loss, unless it is just a small part of many causes, and I have asked many times on this and other forums for examples.
    The ones you have named so far have been, with the possible exception of the moas if egg predation is reclassified as "hunting", in error: The dodo, the passenger pigeon, the cats and condors of North America, etc. Links have been posted for your edification, in vain.

    Rat predation, macaque egg predation, etc, are not human hunting

    Neither is industrial exploitation, actually, in this context:
    Once we hit the 2 billion mark, that all changed. Even then, we managed to wipe out almost all the large whales when we were at not much more than that level. They still haven't recovered to even 30% of their pre-whaling industry populations.
    Exploitation for money is a new factor, not present ten thousand years ago. It has some properties much different from what is normally called hunting - scarcity increases effort and reward, for one, so there is less natural feedback reducing the kill pressure. Even so, even the most heavily pressured whales are not actually extinct yet - for which we can give some credit to the size and resistance of the ocean to degradation. We did not destroy large areas of their habitat, wipe out their food supply, etc. If we had (and we may be now doing that, including such factors as noise pollution and ship strike in their travel and feeding bottlenecks) quick extinction would have been much more likely, perhaps inevitable, for several major species frequenting near shore habitats.
    Last edited by iceaura; April 29th, 2012 at 05:30 PM.
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  58. #158  
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    Iceaura

    You are operating on religious faith. Your religion states that humans caused extinctions due to destroying habitat, and because it is your religion, you seem unable to perceive how little real evidence exists for that faith-based belief.

    The dodo died out as a result of hunting and introduction of alien animals. Habitat destruction on Mauritius was never total. Even to the present moment, there remains enough forest to support a dodo population. The passenger pigeon is an even more clear cut case, since it ranged North America and was able to exploit any remaining suitable habitat, of which there was plenty.

    Habitat loss is undesirable, of course. And, of course, substantial habitat loss, when it happens, is a contributor to extinctions. But it is not the major cause. Except in rare and specific cases. You have not managed to give me even one single example of an extinction which was caused entirely or primarily by habitat loss.

    I know that asking this is futile, since religious people cannot be persuaded away from the tenets of their religion by mere data and logic, but please try to use your brains, and think things through. Please try to respect data, rather than just dogma.
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  59. #159  
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    Quote Originally Posted by Chrisgorlitz View Post
    Could it be a gamma ray event that is the culprit?

    'LaViolette has advanced his theory that the melting of the polar ice caps and the mass extinction of large animals ("megafauna") around 12,000-16,000 years ago was caused by a cyclical Gamma Ray Burst from a pulsar near the core of the Galaxy.

    The results of this Gamma Ray Burst (GRB) was a nuclear winter of darkness, freezing cold, severe solar storms, periodic heat and cataclysmic flooding that plagued all life on Earth for several generations. He reckons that these "Galactic Superwaves" occur in 10,000-year cycles.'

    I once did the calculations on gamma ray bursts for somebody who was writing a doomsday movie script. Our galaxy is about 50,000 light years concerning its radius, and our position is about 27,000 light years out from the center of the galaxy. For a gamma ray repeater to effect wildlife/ human life, my estimate was that it needed to be no more than 5,000 light years away. For it to be devastating conceivably causing major extinctions it would accordingly need to be maybe 1,000 light years away. These are called soft gamma ray bursts lasting only a few seconds but less than a minute. These are theoretically caused by neutron stars or magnetars having less than 1 solar mass. There are no known Gamma Ray repeaters that are thought to be close enough to us to cause plant or animal deaths, and statistically they are very rare.

    http://en.wikipedia.org/wiki/Soft_gamma_repeater

    Gamma radiation from supernovas have been observed to also last only seconds but their magnitude is far greater. This kind of type II supernova produces gamma radiation in a one time stellar explosion event that can involve a star of 100 solar masses or more. If a type II supernova like this were to explode 10,000 light years away, by my calculations it could cause a major extinction, my guess being 20% of larger animal life (maybe 100 pounds or greater) on one side of the Earth, which would be the side facing the burst. This would destroy life mechanisms like an over-exposed X-Ray negative. Another maybe 20% of animals would eventually die of starvation because they would be partially or totally blind and many plants would also wither and die, not a pretty picture. But the other side of the Earth would by relatively intact. There would be no nuclear radiation or fallout from such an event other than man-made. My recollection is that there are a lot of stars within that distance from us that could one day "pop," but none are thought to be near enough to be a major problem in the foreseeable future. Of course there always could be a rogue star that could seem to come from nowhere, and within maybe a dozen years might be close enough to do harm.

    Gamma Radiation from active galactic nuclei can even be more powerful and some have lasted for more than a years duration, but all such galaxies are seemingly too far away to cause us harm.

    The scenario chosen for the doomsday movie script mentioned above, was a rogue star of maybe 50 solar masses that we on Earth spotted one day but were unaware of its existence before then. Because of its great relative motion it was calculated to make its closest approach to our solar system at a distance of about 10,000 light years. It was thought to still be too young to explode based upon observations but according to the script it gravitationally interacted with a binary star system, its mass shifted and then BOOOOOM! I think he exaggerated the human devastation as being almost total on one side of the Earth and disease via the winds according to script, wiped out more than half of the other side of the Earth. He didn't tell me how he managed to find redemption and a new beginning from this event.

    As far as mass extinctions on Earth are concerned, I think that such a Gamma Ray or other supernova type extinction event might be more uncommon than a Yucatan sized asteroid hitting the Earth roughly every 30 million years.

    Skeptic,

    My educated guess before on this thread concerning large animal extinctions by around 10,000 years ago, was a combination of changing weather patterns of rain, wind, aridity, humidity, some areas being colder, hotter, etc. There were greatly changing weather conditions in many locations. This would first effect the vegetation as not being adapted to the climate changes which would then effect the largest animals, and so on. This process had its peak roughly 12,000 years ago as the last ice age was ending and the ocean and lake levels greatly rising. And of course there were carnivores and human predation that would have taken advantage of more animals with less food and ability to cope, or just that humans were increasing in numbers. In such a scenario one would expect the largest and slowest animal species to die out first followed by the largest predators. Humans individually or in groups, could still hunt and trap animals of all sizes.

    Some, or most human groups then had control of fire so they could burn out a habitat to provide food if they wanted to. Even man's accidental fires could have been a problem in some environments like today. If meat was scarce some men could become more adaptable by eating small animals, grubs, insects, spear fish, etc. as well as eating wild fruit, nuts, roots, grain, and vegetation. This was also thought to be the beginning time of the domestication of dogs for protection, partners in hunting, and for consumption in hard times. Whether hard times or not, probably some groups of humans were also part or full-time cannibals. Some predators of all sizes in bad times will also eat smaller predators, different species of predators, especially the young and feeble of all species including their own.
    Last edited by forrest noble; May 1st, 2012 at 10:42 PM.
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    Sorry, but the answer is no.
    We do not have to number in the billions to cause extinctions.
    That's what I said. Island by island, river by river, species by species, mountain by mountain, small numbers of people were able to wreak real havoc and destruction - including driving many susceptible species to extinction - more than we'll ever know locally, far too many entirely.

    My view is that our much larger numbers, and our much larger and wider agricultural and engineering impacts on landscapes and water resources can lead us into uncharted territory. I know the Greek example was only a couple of thousand years ago, not the 10,000+ we've been talking about, but I'm sure I recollect reading about earlier such examples from the Middle East during the early periods of organised agriculture. Large scale water storages and diversions, land clearing and forest encroachments and soil 'management' practices desertified several regions which were previously fertile. It's hard to believe that plants and critters originally in such areas didn't suffer major impacts, up to and including local, if not entire, extinction.

    Might look a few things up now.
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    Quote Originally Posted by skeptic
    The dodo died out as a result of hunting and introduction of alien animals.
    And loss of habitat. The links, evidence, facts, remember them?
    Quote Originally Posted by akeptic
    Habitat destruction on Mauritius was never total.
    No one ever said it was. So? You're giving the impression that you have no idea how living beings need and use habitat.
    Quote Originally Posted by skeptic
    The passenger pigeon is an even more clear cut case, since it ranged North America and was able to exploit any remaining suitable habitat, of which there was plenty.
    Yet more ignorance of fact and argument on display. Google is your friend. Compare the effects of logging the eastern NA forest in the 1800s with the behavior and habitat needs of the Passenger pigeon.

    Clue: it was named for its wandering, traveling, nomadic behavior - this fast and far traveling done in huge flocks, from one Chestnut studded wide expanse of deciduous forest to another. Its habitat needs were specific and significant in scale.

    Quote Originally Posted by skeptic
    And, of course, substantial habitat loss, when it happens, is a contributor to extinctions. But it is not the major cause.
    You need to drop the notion of "the major cause". It's confusing you. We are interested in how and why these animals went extinct - for example, the last woodland bison in the US, a few hundred animals in one herd, were "hunted" and wiped out in a deliberate, dedicated, one time military operation with that as its goal. But that doesn't make hunting "the major cause", or "the major factor", or even "a major factor" (although it seems to have been) in their demise.

    Quote Originally Posted by skeptic
    I know that asking this is futile, since religious people cannot be persuaded away from the tenets of their religion by mere data and logic, but please try to use your brains, and think things through. Please try to respect data, rather than just dogma
    You can post like that, despite your lack of acquaintance with even basic facts and theory, despite your inability to follow the simplest of arguments or paraphrase a single one of my posts accurately, because you have moderator support here. But you should once in a while attempt to post three consecutive times without personal attack and shitheaded playground insult, just to see if you can do it.
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    Iceaura

    You have not given evidence. You have not given data.
    Your arguments are made by assertion, and assertion only. I have asked for examples of species wiped out by habitat loss and what do I get.

    1. The dodo. Tame and trusting as they come. Killed off by hunters for food and by alien predators.
    2. The passenger pigeon. The mass hunting and drop in numbers that went with the mass hunting is recorded in history. Yet you claim it is all habitat loss.
    3. Bison that are shot dead.

    Now, you are not alone in asserting that habitat loss is the main killer. But it is an assertion unsupported by evidence. I have called your views a form of religious faith. They meet the definition. To believe something without evidence, just because someone else tells you that it is so - that is religious-type faith.

    On the passenger pigeon, Wiki suggests habitat loss as one factor, but goes on to say :
    Passenger Pigeon - Wikipedia, the free encyclopedia

    and I quote :

    "The primary factor emerged when pigeon meat was commercialized as a cheap food for slaves and the poor in the 19th century, resulting in hunting on a massive and mechanized scale. There was a slow decline in their numbers between about 1800 and 1870, followed by a catastrophic decline between 1870 and 1890.[5] Martha, thought to be the world's last Passenger Pigeon, died on September 1, 1914, at the Cincinnati Zoo.


    Wiki on the dodo


    "The dodo was first mentioned by Dutch sailors in 1598. By 1681, all dodos had been killed by hungry sailors or their domesticated animals. """"
    Give up, Iceaura.
    There is little or no data to prove that habitat loss is the major factor in extinctions. Hunting and alien introductions are the two most potent forces in human generated extinctions. Other things like habitat loss, global warming, pollution etc, have an effect but a much more minor effect.
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    Quote Originally Posted by skeptic
    I have asked for examples of species wiped out by habitat loss and what do I get.
    You get me once again pointing out that such a question indicates a failure to follow the argument.

    As repeated to you several times now, you are the only person here arguing for a single major "cause" of the human associated extinction waves.

    Quote Originally Posted by skeptic
    "The primary factor emerged when pigeon meat was commercialized as a cheap food for slaves and the poor in the 19th century, resulting in hunting on a massive and mechanized scale.
    1) That kind of exploitation, similar to the commercial whaling industry, was a new factor not relevant to the thread topic. In the passenger pigeon case, it was made much worse in its effects by the habitat destruction of logging - the pigeons had nowhere to flee to, and huge flocks carried over from the forest days were confined to small and easily accessible woodlots etc near roads and tracks.

    We have no accounts of the remnants of the pigeon flocks being killed by hunters, or secluded areas not easily hunted where pigeons hid out. Other animals and birds have recovered from quite low populations - if suitable habitat is ready to hand.

    Along about that time a couple of other birds that needed large and continuous tracts of forest - two varieties of Carolina parakeet, the Ivorybill woodpecker, etc - also went extinct, without being hunted much at all in their last years.

    There is little or no data to prove that habitat loss is the major factor in extinctions
    It's a striking coincidence then - which is more than can be said for hunting, since so many extinctions seem to involve little hunting at all, and hunting seems to involve so few extinctions that we have good information about.
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  64. #164  
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    Quote Originally Posted by iceaura View Post
    As repeated to you several times now, you are the only person here arguing for a single major "cause" of the human associated extinction waves.
    Wrong (yet again).
    I have said, repeatedly, that there are two major causes for human generated extinctions (over-hunting and introduction of alien animals), plus several minor causes.

    On your latest examples, let us see what Wiki says.

    Carolina parakeet.

    "To make space for more agricultural land, large areas of forest were cut down, taking away its habitat. The bird's colorful feathers (green body, yellow head, and red around the bill) were in demand as decorations in ladies' hats. The birds were also kept as pets and could be bred easily in captivity. However, little was done by owners to increase the population of tamed birds. Finally, they were killed in large numbers because farmers considered them a pest, although many farmers valued them for controlling invasive cockleburs. It has also been hypothesized that the introduced honeybee helped contribute to its extinction by taking many of the bird's nesting sites.[5]
    A factor that contributed to their extinction was the unfortunate flocking behavior that led them to return immediately to a location where some of the birds had just been killed. This led to even more being shot by hunters as they gathered about the wounded and dead members of the flock."

    and

    "The final extinction of the species is somewhat of a mystery, but the most likely cause seems to be that the birds succumbed to poultry disease"


    the extinction was caused by four factors
    1. Over-hunting
    2. An alien introduction (honey-bee)
    3. An alien pathogen
    4. habitat loss

    On the ivorybill woodpecker

    "Heavy logging activity exacerbated by hunting by collectors devastated the population of Ivory-billed Woodpeckers in the late 19th century. It was generally considered extinct in the 1920s when a pair turned up in Florida, only to be shot for specimens."



    So once again, several factors are implied.

    Habitat loss is important here, but by itself was insufficient to cause the extinction. Over-hunting made the difference, creating an extinction.

    So, even with your self chosen examples, Iceaura, you cannot demonstrate that habitat loss is the major cause of human generated extinctions.

    You said : "which is more than can be said for hunting, since so many extinctions seem to involve little hunting at all, and hunting seems to involve so few extinctions that we have good information about."


    Demonstrated to be wrong even in the examples you choose yourself, Iceaura.
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    Quote Originally Posted by skeptic
    I have said, repeatedly, that there are two major causes for human generated extinctions (over-hunting and introduction of alien animals), plus several minor causes.
    You started out claiming "hunting, and hunting alone". Then after I objected you brought in alien animals (we may as well include diseases here, which are implicated in the Carolina parakeet's disappearance among other major losses). So far so good. We are almost half way to my original and still running assertion, and a reasonable evaluation of the role of hunting in the extinctions of the OP.

    Meanwhile, you have failed to provide any reasoning or evidence to justify your classification of the various factors into "major" and "minor". By the evidence, in the cases we know a lot about, hunting was occasionally but not always likely to have been important in the extinctions that followed new human colonization.
    Quote Originally Posted by skeptic
    So once again, several factors are implied.
    Yes. My point throughout. Habitat loss being a nearly universal one.

    We should notice resource loss as well, in the this "habitat" approach - humans outcompete most animals for mutually desired resources of all kinds.

    Quote Originally Posted by skeptic
    Habitat loss is important here, but by itself was insufficient to cause the extinction. Over-hunting made the difference, creating an extinction.
    As hunting did not have such effects on animals not subject to severe loss of habitat, I don't see where you have any reason to claim that hunting made "the difference". We see many animals intensively hunted without even being reduced much. We see no animals tolerating serious habitat loss without serious population reduction.

    Quote Originally Posted by skeptic
    Carolina parakeet
    - - - - -
    the extinction was caused by four factors
    1. Over-hunting
    2. An alien introduction (honey-bee)
    3. An alien pathogen
    4. habitat loss
    In the quote, the order of importance is 1) habitat loss (the hypothesized honeybee takeover of the few remaining nest sites goes here, btw) 2) hunting 3) disease.

    The importance of the hunting is questionable, btw: it provided neither the major reduction of population or the final wipeout, in this case. That is true even if you include the farmer destruction of pests as "hunting", which would be irrelevant to the thread topic.

    And the importance of habitat loss is of course my continual point. We seem to be agreed, then?
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    Iceaura

    You still miss the point.
    On rare occasions habitat loss may be the primary cause of an extinction. For example : if a small freshwater fish is found in one single pond and that pond is drained. But such situations are rare indeed. The thing about habitat loss is that it is very rarely complete. Normally havens are left in which threatened species can survive.

    The classic example, as described in the book : The Skeptical Environmentalist - is Puerto Rico, which had about 50 endemic rain forest birds. Every last part of that rainforest habitat has been destroyed at one time or other over the past 200 odd years. However, only 3 species of rainforest bird have gone extinct, and those 3 are ascribed by naturalists studying the situation as dying off due to predation by rats.

    So why did the other rainforest bird species survive? Because rainforest grows back. While all the rainforest was destroyed at one time or other, there always was at least some rainforest - often young and growing, but always some.

    Sure, total habitat destruction (like my freshwater fish example) can render a species extinct. But total habitat destruction is rare. In none of the examples you gave was habitat destruction total.

    But as I keep telling you, and you keep ignoring, extinctions due to over-hunting, and extinctions due to introduction of alien animals, are common, and well documented. The reason is that these causes happen everywhere. People range over whole countries and over-hunt everywhere. If an alien predator is introduced, it spread to all areas.

    Habitat loss is very rarely that complete. Extinctions due to habitat loss as the primary cause, are rare indeed. You have not been able to give me even one single example so far. Habitat loss as one factor, sure. But not as the major.

    During the 600 years that Polynesians lived in New Zealand, before the arrival of Europeans, 36 species of native bird went extinct. The only loss of habitat was 25% of the rain forest. All 36 that went extinct can be shown to be the result of over-hunting, or of alien predator (polynesian rat) introduction.
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  67. #167  
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    Quote Originally Posted by skeptic
    On rare occasions habitat loss may be the primary cause of an extinction. For example : if a small freshwater fish is found in one single pond and that pond is drained. But such situations are rare indeed.
    You have no idea how influential habitat loss is, because you don't understand how it works.

    It boosts the risks of extinction - multiplies them manyfold - from all other factors.
    Quote Originally Posted by skeptic
    The thing about habitat loss is that it is very rarely complete. Normally havens are left in which threatened species can survive.
    They can survive if they are lucky enough to not meet rats at the wrong time, get a disease in their small remaining population, have the last small herd shot by vengeful farmers one winter's day, take a direct hit from a hurricane, get found by a wandering band of hunters who take out the fertile females, get trapped in a fire, have bad luck with the genetic bottleneck, etc. But it doesn't take much to wipe them out if they are confined to a small haven or two.

    Quote Originally Posted by skeptic
    But as I keep telling you, and you keep ignoring, extinctions due to over-hunting, and extinctions due to introduction of alien animals, are common, and well documented.
    Alien animals, especially combined with habitat restrictions (loss, island, etc), sure. Hunting, without habitat loss or disease or alien animals to make it critical, not so much - your examples that I know about have all been errors, the ones I can't check are suspect because you seem oblivious to the issues and objections involved. There are no such "documented" cases from my continent, and the mass extinction here followed a pattern indicating some other important pressures were likely involved.
    Quote Originally Posted by skeptic
    The reason is that these causes happen everywhere. People range over whole countries and over-hunt everywhere. If an alien predator is introduced, it spread to all areas
    That isn't generally true. Usually, if the habitat is extensive enough, there are refugia from hunters, often even from rats and snakes. If there has been significant loss of habitat then the effects of the aliens are intensified, of course.
    Quote Originally Posted by skeptic
    During the 600 years that Polynesians lived in New Zealand, before the arrival of Europeans, 36 species of native bird went extinct. The only loss of habitat was 25% of the rain forest. All 36 that went extinct can be shown to be the result of over-hunting, or of alien predator (polynesian rat) introduction.
    How was the significance of a 25% permanent loss of critical habitat dismissed as a major factor?
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  68. #168  
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    Iceaura

    A species can survive when most of its habitat is lost, if there is no hunting by humans or new predators/competitors/pathogens.

    Here in NZ, i can think of several examples. The native stormy petrel was thought extinct for 50 years.
    http://en.wikipedia.org/wiki/New_Zealand_Storm_Petrel

    No hunting habitat loss at all, since it fished over the open ocean. However it nested on rocky islands, and there was an effective loss of nesting habitat due to introduced rats, that ate eggs and chicks. The only rat free islands left were a few tiny pinnacles of rock. Yet they were sufficient. The native stormy petrel was rediscovered about 15 years ago, and its numbers are now on the increase. The reason for the increase is human effort to kill off rats. There are now a number of mammalian predator-free islands. It appears that it now nest on Little Barrier Island, which had all cats and rats removed several decades back.

    A truly tiny amount of suitable habitat for nesting permitted survival.

    Another example is the Takahe - a flightless bird that was hunted by Polynesians almost to extinction. Gone from 99% of New Zealand. However, a small population was found, after 600 years of Maori hunting effort, high in mountains, where the Maori did not go due to the cold.
    Man who rediscovered the takahe, nonagenarian « O\’Folks
    Human effort is now operating to re-introduce this species in many other parts of the country, and its numbers are increasing.

    A tiny remnant of suitable, though harsh, habitat was enough to save the species.

    I have yet to see any 'expert' claiming that the 25% loss of native rain forest in NZ during the Maori occupation of the land had any impact whatever on extinctions. That amount of loss is just too small.

    Still, I am pleased to see you admit that habitat loss by itself is not enough, and alien animals or other factor is needed along with habitat loss to cause an extinction, most of the time. Maybe you are learning regardless, and are not a lost cause, as I thought you were.
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    Quote Originally Posted by skeptic
    A species can survive when most of its habitat is lost, if there is no hunting by humans or new predators/competitors/pathogens.
    Or genetic inbreeding, misfortune from weather or geological event, loss of some key food source or water supply or breeding requirement, etc etc etc.
    Quote Originally Posted by skeptic
    A tiny remnant of suitable, though harsh, habitat was enough to save the species.
    That is called good luck. And it probably depended (depends) on human intervention after discovery - the odds of those birds still being around after a thousand years of restriction to such inadequate corners of their former habitat, without careful attention and protection, would be poor. That would be true regardless of whether anyone ever hunted any of them.
    Quote Originally Posted by skeptic
    Still, I am pleased to see you admit that habitat loss by itself is not enough,
    To repeat, once again, from the very earliest posts on this topic: the "hunting, and hunting alone" proposers are the only ones here who have ever claimed that any one factor is "enough" to explain the mass extinctions so often coincident with human arrival in new lands. Nobody else is arguing any such notion, or ever has argued any such notion. This has been clearly and explicitly explained to you several times now.
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    Iceaura.

    I speak the truth when I say that hunting alone has been enough to render many species extinct. 11 species of moa here in NZ for a start.
    New Zealand Birds | Birds | Gallery | Extinct bird | Moa, Dinornithiformes

    In the same way, alien animals are enough on their own to cause many other extinctions.
    eg. Stephens Island Wren.
    Stephen

    It is habitat loss that rarely acts alone to cause extinctions. I am arguing against the faith based belief of the irrational green movement that habitat loss is the major cause of human generated extinctions. It is just not true. It is a factor, but very rarely the sole, or even major factor.
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    Quote Originally Posted by skeptic
    I speak the truth when I say that hunting alone has been enough to render many species extinct. 11 species of moa here in NZ for a start.
    New Zealand Birds | Birds | Gallery | Extinct bird | Moa, Dinornithiformes
    Once again, we are to assume that the 25% rain forest loss (mostly the flatland forest, especially where the larger moa lived) and other landscape changes had no significant effects, that egg predation and the like are "hunting", that alien animals (such as the packs of feral dogs that the Maori introduced) and diseases had no effect, and so forth.

    Why would we make these assumptions? Because you did?

    You are the guy who told me passenger pigeons and dodos went extinct by "hunting, and hunting alone". Those I knew something about, so I could simply dismiss the assertion as ignorant. The moa I don't know about, but stuff like this keeps turning up whenever I look into them:
    Quote Originally Posted by skeptic link
    At around the same time as hunting was at it peak, the forests of South Island were burned off.
    The moa under discussion in that link suffered severe habitat loss coincident with their extinction. As usual, with human associated extinctions (at least, the ones we have detailed info about).

    Quote Originally Posted by skeptic
    I am arguing against the faith based belief of the irrational green movement that habitat loss is the major cause of human generated extinctions
    Since no one around here (and few people anywhere) has such "faith based belief", that obsession would be strange. Fortunately, you aren't. You haven't been dealing with that issue at all. You've been arguing that "hunting, and hunting alone" is the - the, not a - major cause of the wave of extinctions associated with humans, and that it usually and frequently acts on its own, with sole responsibility for much of the extinction wave on all continents and at all times.

    Quote Originally Posted by skeptic
    In the same way, alien animals are enough on their own to cause many other extinctions.
    eg. Stephens Island Wren.
    Another example of the vulnerability of animals restricted to small areas, especially small remnants of their former adapted habitat. Your point?

    And if it is only that there is an animal, or more likely an island bird, somewhere, that has been driven to extinction by human hunting and hunting alone, then consider it made and agreed - it would hardly surprise anyone, least of all me - and we can get back to the topic.
    Last edited by iceaura; May 2nd, 2012 at 07:39 PM.
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    Iceaura

    As you said yourself, you lack knowledge of NZ. For example, there were never packs of Maori dogs. There were only a very few. They did not adapt well to NZ. We know this extended back to the beginning due to a small number of dog bones. Also, they were very small. Not the big and vicious dogs we know from European breeding, or from wolf genes. There is no evidence they had any part to play in moa extinctions.

    And no. Moa did not suffer extensive habitat loss. The moa was a forest creature that browsed on leaves. The forest cover was depleted only by 25% in the time of the Maori. Some was burned off in the South Island, but never more than 25%.

    On 'faith based belief'.
    This takes the form of believing what you are told, without objective, empirical evidence. I have been trying to get such evidence from you throughout this debate, without success. You simply keep telling me that habitat loss is the major cause of extinctions, without such evidence. You cannot even give me examples of species killed off by habitat loss, even though I know that a few such examples do, in fact, exist. Not many, but a few.

    If your beliefs are there because you choose to believe something you are told, then that is a faith based belief. If there is more to your belief, then you will be able to supply evidence, which so far, you have not.

    And please.
    I have not been asserting that hunting alone is the cause of all extinctions. I assert that hunting and alien animal introduction are the two primary causes of human generated extinctions. Other causes are of lesser importance, but still exist. This is what I have said from the beginning.

    In some cases, hunting is the cause (eg moa). In some cases, it is alien animal introductions ( eg NZ native thrush). In some cases it is both (eg dodo). In some cases it is a combination of more than those 2.

    On the vulnerability of animals restricted to small areas - OK, you cannot be faulted for wrongly jumping to that conclusion for the Stephen Island Wren, since I did not go into further details. For your information, this wren was once widespread, but killed off in most places by the polynesian rat (shown by finding wren bones with rat gnaw marks). By the time Europeans arrived, it was confined to one small, rat-free island. Its extinction was entirely due to alien predators, but two kinds. The rat and the cat.
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  73. #173  
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    Here's an interesting article. By a new method of age dating (rare-earth elements) they are suggesting that man was in the Amercas maybe a thousand years sooner than the general concensus.

    University of Florida News – New UF study shows early North Americans lived with extinct giant beasts
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    Between 15, 000 and 10,000 years ago global temperature rose by 6 degrees and I would think that this effected many of the large mammals that were built for much colder climates to decrease in numbers. Humans were able to migrate easier into these areas that were warming up and obviously had their share in killing these mammals but I still do not believe that they were totally responsible for their demise.

    Increase in temperature allowed the vegetation to change and evolve while also weakening those large mammals that were optimal for colder temperatures. In other words, the large mammals were already in decline before we migrated into their territory and perhaps finishing them off to extinction.
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    Of course not all large mammals could not adapt since the giant coyote that lived 38,000 years ago shrunk in size to adapt to the warmer temperatures. Most likely several species adapted by downsizing in their physical size which is evident in that so many of them looked like many of the mammals that are alive today.
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  76. #176  
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    It is unlikely that the giant coyote shrank due to temperature change. More likely due to a change in prey species. From killing the calves of mega-fauna to dealing with such things as rabbits. A smaller size permitted survival on smaller game.
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    Quote Originally Posted by skeptic
    And no. Moa did not suffer extensive habitat loss. The moa was a forest creature that browsed on leaves. The forest cover was depleted only by 25% in the time of the Maori. Some was burned off in the South Island, but never more than 25%.
    Which 25%? According to your link the moa habitat part, and coincident with the extinction being discussed. That would normally be highly significant, perhaps dominant - you would need evidence of its lack of effect, to counteract the obvious physical situation your links describe, before dismissing it.
    Quote Originally Posted by skeptic
    I have not been asserting that hunting alone is the cause of all extinctions.
    So? Nobody has said any different.
    Quote Originally Posted by skeptic
    For example, there were never packs of Maori dogs. There were only a very few
    According to your link the Maori hunted moa with packs of dogs, and all dogs everywhere else ever used this way have formed feral packs to some extent. It's just another factor to consider, by those attempting a rational or scientific approach to this matter - introduced alien animals – available to be intensified by the hunting pressure and the loss of habitat and so forth.
    Quote Originally Posted by skeptic
    On the vulnerability of animals restricted to small areas - OK, you cannot be faulted for wrongly jumping to that conclusion for the Stephen Island Wren, since I did not go into further details. For your information, this wren was once widespread, but killed off in most places by the polynesian rat (shown by finding wren bones with rat gnaw marks)
    Your link told me that. Your example demonstrated the vulnerability of animals that have been confined to shrunken habitat. The same principle would apply to the extinctions from the other islands, where the effects of alien animals (rats, cats, snakes, whatever) would be of course intensified by any loss of habitat.

    You have yet to propose a definite example of an extinction in which habitat loss played anything less than a major role.

    And if you did, we would still have the situations described for NZ moa, NA megafauna of many kinds, Australian megafauna of many kinds, and so forth - habitat loss apparently, at least indicated or suggested by the physical facts, a major factor in most if not all of them.

    It's perfectly reasonable, rational, scientific, and all that, to provisionally accept the apparent situation, described in all your examples and links and so forth as well as mine: habitat loss played a large role in many - perhaps most, possibly all - of the extinctions in the waves associated with human colonization of new lands.
    The real question is: supposing that continues to hold as more and better information comes in, why would that be a problem?
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    The statement that Maori hunted moa with large packs of dogs is nonsense. No-one knows how Maori hunted moa. The Maori who were met by Captain Cook had no idea that moa had even existed. This ignorance of what their ancestors knew 500 years earlier comes from the fact that Maori had no writing, and no records. Word of mouth does not reach down 20 generations.

    Everything we know about them comes from analysis of moa bones. We know that moa were very common till the Maori arrived, from the vast number sof older moa bones. We know Maori hunted them and ate them, from the charred bones in Maori middens. Some of those charred bones were broken open, presumably to get the marrow out. There are no bones of moa younger than 150 years after the arrival of Maori in NZ.

    The Maori dog, the kuri, was present in small numbers when Europeans arrived, and was regarded by the Maori as something to be eaten when times were tough. Kuri bones are not present in large amounts at any time. Anyone who claims kuri were used to hunt moa is just engaging in wild guesswork.

    And why the hell, Iceaura, do you think that 25% habitat loss is going to be anything other than a tiny effect in the extinction of the moa? We have hundreds of examples elsewhere of massively greater habitat loss with no extinctions. Such tiny habitat loss is not an extinction issue. I think you are grasping at straws.
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    Iceaura, please provide supporting references for you assertions re the Moa
    If more of us valued food and cheer and song above hoarded gold, it would be a merrier world. -Thorin Oakenshield

    The needs of the many outweigh the need of the few - Spock of Vulcan & Sentinel Prime of Cybertron ---proof that "the needs" are in the eye of the beholder.
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