Posts Tagged ‘demographic effects’

The Pleistocene Massacres

The Pleistocene Massacres

by Ken Fischman, Ph.D.

History and pre-history are often best told in stories or narratives. There  are two alternative stories to explain the extinction of North American megafauna around 10,000 years ago.
In one story, it was the advent of a land bridge from Siberia to North America, created by the waning of the last ice age, that enabled Siberian hunters to enter and people the Americas. These selfsame hunters hunted the megafauna into extinction.(Martin, 1967).
In the other story, climate changes, transitioning from the last Ice Age, set in place complex ecological forces, which were responsible for the disappearance of mammoths, giant sloths, megabison, dire wolves, and other large mammals (Allen, 2010).
I believe that it matters greatly which of these stories you believe because they enter our cultural consciousness and are responsible, at least in part, in how we see the world. Our understanding of how the world has come to be, in turn influences how we react to and treat the Earth.
Therefore, it is my intention to examine each of these narratives, stating the evidence for them as fairly as I can, while recognizing that I, though a scientist, cannot be perfectly objective, and then to come to some conclusions about them.
In the interest of transparency, I want to state from the beginning that I have a bias toward the climate change theory, but I will endeavor to present both arguments as best I can. I cannot promise though, to present them with the same tone.
So, let us begin. In the first story, which I call the “Pleistocene Massacre” theory, there are two kinds of evidence, one chronological and the other material.
The end of the last ice age, the formation of a land bridge, called Beringia, between Siberia and North America, the movement of human beings into this continent, and the disappearance of megafauna all seem to have taken place at around the same time. This evidence forms the chief argument of the proponents of the massacre theory. This is impressive evidence, but is it sufficient to make definitive conclusions about what happened?
Let us examine this evidence, piece by piece. First, there is the statement that the migration of Siberian hunters to North America and the extinction  of large animals occurred simultaneously. When events occur concurrently, there are at least two possible explanations:
In one, there is cause and effect at work. For instance, if a blizzard were to hit your town and a number of automobile accidents ensued, you might fairly assume that the icy conditions made it more difficult to control vehicles, thus causing more accidents.
Sometimes two events occur at the same time and/or change at the same rate, but it is mere coincidence. For example, a recent scientific paper concluded that people who take large doses of vitamins have a greater mortality, thus showing cause and effect. However, another possibility remains. Did the vitamins cause these deaths or is it possible that people in poor health take more vitamins” How we distinguish between the two in our case is the challenge.
In the so-called hard sciences, like physics and chemistry, the way to distinguish between two such possibilities, is to search for a plausible, and hopefully testable, statistically significant mechanism. Alas, in anthropology and paleontology we usually have less evidence to go by and the opportunity to test these theories is much more limited.
My father used to tell me about the routine of a pair of old-time vaudeville comics. The first one would often recite an improbable story, a whopper, and the other would challenge him. The first would reply “Vas you dere Charley”? Well, we were not there 10, 000 years ago and under most circumstances cannot reproduce the conditions to test them.
I actually do know of one case however, in which a long ago occurrence was tested. Coincidently, it involved one of the animals whose disappearance we are examining here, so I may permit myself a slight divergence to tell you about it, both because of its relevance and because it illustrates the astounding potential of molecular biology to uncover long lost information.

Painting of a Woolly Mammoth

An Artistic Representation of a Wooly Mammoth

The animal in question was the woolly mammoth (Elaphas primigenius) . As most readers know, some of these animals have been recovered intact from Siberian ice, and carefully examined. One of things noted about them was the intense network of capillary beds in their feet. Scientists reasoned that oxygen, carried in blood, was released in their feet to protect the animals from frostbite at temperatures that sometimes dropped as low as – 60 degrees F. However, how could this occur when hemoglobin (Hb), the blood molecule that carries oxygen, releases it only grudgingly at low temperatures?
The scientists speculated that mammoth Hb was different from Hb of contemporary mammals. But, how could they prove this? First they tried the comparison method. They looked at Hb in the Indian elephant (Elaphus maximus indicus), a modern relative of mammoths. No luck. Elephants have the same Hb that we have. Then they had an outlandish idea. Why not attempt to reconstruct mammoth Hb, using DNA, which they obtained from mammoth tissue, samples? The DNA would contain the gene for constructing mammoth Hb.
They grew the Hb gene in bacterial plasmids, gave it the appropriate precursors of Hb and wondrously produced mammoth Hb. They then proceeded to test the oxygen-carrying capacity of mammoth Hb at low temperatures. They discovered that the mammoth version of Hb gave up its oxygen at much lower temperatures than ours does, and thus would have protected mammoths from frostbite. (Yuan et al., 2011). What shall we call this amazing feat? Molecular Paleontology, or the Lazarus method?
In the absence of an analogous method by which to reconstruct the post-Pleistocene environment, and thus prove or disprove the massacre theory, we are left to sift the evidence, little and conflicting as it is, and to speculate, a lot.

More Evidence for the Massacre Theory:

In addition to the chronological situation, the most convincing evidence for the massacre theory seems to be that there have been finds of enormous numbers of mammoth bones along Siberian rivers and on Arctic islands like Kotelnoi and Liakoff, off the north coast of Siberia. However, there are little or no signs of human activity associated with these bones. Nevertheless, these troves of mammoth bones are often cited as evidence of the destructive tendencies of Paleolithic man. It would seem more likely that some cataclysmic natural event, such as a flood or storm can better account for these phenomena (Vereshchagin, 1967).
As stated previously, the main evidence is the assumption that when man first came to North America, the megafauna disappeared. In order to bolster their case, the proponents of this theory also declare that the Aborigines accomplished the same kind of faunal exterminations in Australia shortly after they arrived there, some 30,000 years ago.
In addition, according to Jared Diamond in his book, “Collapse,” the Polynesians wiped out many native animal species when they colonized South Pacific islands between 400 – 1100 A.D. (Diamond, 2005).
One of the consequences of this line of evidence is that ideologically oriented scholars and media have used it to argue that mankind is inherently predisposed to damaging its environment and exterminating many animals.
With regard to the times that various animals went extinct in North America, there is actually a great difference. For example, Martin cites the demise of the giant short-faced bear (Arctodus sp.) in both North and South America at 20,000 BP (Before the Present). However, among several others, he also lists the American mastodon (6-8,00 BP). He also cites the horse (Equus sp.) as the most common bones associated with man, but states that it became extinct at 18,000 BP (Martin ,1967). Therefore, there is a spread of 14,000 years during which these extinctions may have occurred and some of them happened long before the 11,000 BP Clovis Horizon that supposedly marks the entrance of Siberian hunters on the North American continent.
There is yet another line of evidence, derived from eyewitness accounts of native behavior that appears to strengthen this line of reasoning.
There have been historic accounts from European explorers, traders, and travelers, recounting that they saw Indians set fire to prairies and drive bison off cliffs. According to many massacre proponents, these acts establish that Native Americans were bloodthirsty, wasted thousands of animals, were clearly capable of wiping out North America’s megafauna, and are therefore no better people than we are today. As this story goes, the only reason that they did not totally destroy this continent was that they had not perfected the sophisticated technology with which our society has quickly accomplished that sort of destruction, both in North America and elsewhere. This is what I call evidence by analogy.

Evidence Against the Massacre Theory:

Eiseley’s Rebuttal
Loren Eiseley, was a respected anthropologist and author of many popular science books, like “The Immense Journey” and “The Star Thrower.” At the time when he was the Chairman of the University of Pennsylvania Anthropology Department, he issued a rebuttal to the massacre proponents. (Eiseley, 1943). Here are some of his most persuasive points:
(1)  Not only megafauna died in these extinctions. Many smaller fauna, such as birds, mollusks, and frogs also perished. It is hard to conceive that fires, drives, spears, and atlatls could have killed off such animals. Eiseley emphasized, in particular, the 12-13 species of woodland songbirds that perished (cf.). That extinction certainly cannot be accounted for by the work of big-game hunters.

(2)      Eiseley also points out that many grazing animals survived, such as regular bison, antelopes, deer, elk, and moose.

(3)  Most tellingly, Eiseley states that that there is no evidence of any contemporary hunter gatherers, or even tribal people, using traditional means, significantly decreasing or extinguishing any species.

(4)  Predators and their prey almost always adjust to each other’s numbers, with one increasing while the other decreases and vice versa.  [Classic examples of this dynamic equilibrium are that of snowy owls and arctic hares, and also wolves and moose on Ile Royale National Park, isolated on Lake Superior. To this I  would add the population swings of wolves and elk in Yellowstone National Park which have been intensively studied by Mark Hebblewhite and Doug Smith head of the Yellowstone Wolf Project (Hebblewhite & Smith, 2010).] It is hard to understand why the Paleolithic hunters and their megafaunal prey would not also obey the age-old natural law that no predator can manage to kill off its prey because it depends on the prey for its own existence.

(5)  According to the Bering Straits land bridge story, the Siberian hunter gatherers migrated over it to the New World. Yet, there is no evidence that these Siberian hunters eliminated many of these same beasts where they came from, in Siberia. The same is true for the European Stone Age hunters, Why would they have been able to do so in North America, using the same technology as their Old World cousins?

(6)      It is hard to imagine how small bands of hunter gatherers, estimated at the present time to be less than 2,000 individuals at one point, could have accomplished this task. We know that these small groups existed because molecular biologists have detected bottlenecks in our own DNA (Amos & Hoffman, 2009).  It does not seem likely that the migrating hunters, using traditional weapons and methods, could have even made a dent in these extensive animal populations. It is hard to imagine that they would even attempt to tackle them as long as more vulnerable animals also abounded.)

(7)  When European explorers arrived in the North American continent, they described the land as teaming with game, and the rivers literally overflowing with fish. Just to read the Journals of Lewis & Clark is eye-opening and thrilling. [One explorer in the 17th century walked through what was later named Pennsylvania and described trees throughout his journey so huge that they shut out the sunlight and reduced the understory, making it easy to traverse the entire state. What he was describing was basically a temperate rain forest.]

(8)  The Bartram brothers were naturalists who travelled throughout the southeast of what was to become the United States. One particular episode struck Eiseley in such a fashion that he never forgot it. William Bartram in 1774 was crossing the Saint Johns River in Florida and described it as being so filled bank to bank with alligators that he could practically step on them (Van Doran, 1928).

(9)  In the West, explorers and mountain men found the prairies, forests and mountains were in great shape. Were they exaggerating, as they often did in their stories? The amazing amounts of furs, which they often brought back, testifies to the truthfulness of these statements. [How can this abundance of wildlife be accounted for? Did these Indians lose the skill and blood thirstiness of their predecessors?]

(10)     Large predators, such as saber toothed tigers, dire wolves, and spectacled bears (Tremarctos ornatos) also died during these extinctions. It is hard to imagine that the Pleistocene peoples would have hunted them down for sport, as some massacre advocates have speculated. For example, Steadman (PNAS, 2005), cites evidence on Caribbean islands that sloths went extinct at about the same time, around 11,000 years ago, that Pleistocene hunters entered the Americas as indicative that humans killed them off. Once again, was this cause and effect or association?

(11)     He also failed to take into account that animals are more prone to go extinct on islands because there is little chance that their numbers could be reinforced by in-migrations from other areas as would be the case in mainland North America (c f Quammen, 1996).

(12)     Martin, in a fanciful tale, even went so far as to suggest that little Indian boys shot giant ground sloths, 8 -9 feet tall, for fun(Deloria, 1997). [This does not fit with the eyewitness descriptions I have read about contemporary hunter gatherers. For example, the children of South African Bushman were given toy bows and arrows (without arrowheads) and proceeded to use them on rabbits and other small game, with surprising accuracy] (Fischman, 2012). Needless to say, rabbits and squirrels make more likely game than giant ground sloths for eight year olds.

As stated previously, it is not even certain that man’s first appearance in North America and the disappearance of its megafauna were concurrent  events. It is quite possible that these two events occurred as much as several thousand years apart (cf.). Scholars argue over the dates incessantly and it is clear after examining the literature that methods for dating long-ago events are neither standardized nor agreed upon. We shall see however, that some dates can be established with more reliability than others and that the sequences of some occurrences can be accepted as true with some degree of certainty.
For example, the age of the first North American human migrations continues to be pushed further back into the past than the so-called “Clovis Horizon” hunters, indicted by massacre proponents, at 11,000 years ago. Signs of a pre-Clovis culture, at the Aucila River in North Florida at 14,000 years BP showed well-dated animal bones, and butcher marks. At Paisley Five Mile Park Caves in Oregon there are feces and seeds, demonstrating the existence of a foraging economy at 14,400 BP (Jenkins 2012). The Buttermilk Creek Complex in Texas contains pre-Clovis tools dated 15,500 years BP (Waters et al., 2011). The site at Monte Verde in Chile, (8,000 miles south of the Bering Straight), is now authoritatively dated at about 14,400 – 16,000 years BP (Wikipedia, 2012). There may be even older sites at Meadowcroft, PA, Saltville Valley, VA, etc., but their dates are still in dispute.
The significance of these earlier dates of human occupation is that it raises an important question of why these pre-Clovis hunters were unable to eradicate the megafauna, given their at least twenty five hundred year head start. On the other hand, it could be argued that their cruder lithics (blades, scrapers, and choppers) indicated that their culture was not as technologically (and perhaps strategically) as advanced as that of the Clovis people, and that this made them less proficient at hunting.

Hunting Large Animals:

To my knowledge, no one who claims that Siberian migrants killed off North American megafauna has ever attempted to kill a large and powerful animal, in the open, armed with nothing more than a stone-tipped wooden spear, stone clubs and stone knives.
It is important to realize that these Pleistocene hunters did not have bows and arrows or atlatls (spear throwers), and were not mounted on horses. On the contrary, according to the hypothesis, they were supposed to have also killed off these fleet stallions 18,000 years ago (Martin, 1967) while hunting them on foot.
As I previously pointed out, no contemporary observers were there while these events were supposedly taking place, so how do we know if this sort of hunting is possible, and if so, how efficient it is? Here we are on firmer ground because: (1) some hard evidence of ancient hunting methods does exist, and (2) we can also turn to present day surviving hunter gatherer and tribal cultures to see how they go about their hunting tasks.

A Bushman Hunting Grazing Animals with a Throwing Spear

Bushman, throwing a spear

Bushman Hunting With A Throwing SpeaThere are many eyewitness accounts in the one continent where large herds of grazing ungulates still exist, and smaller relatives of mastodons, woolly mammoths, and rhinoceroses still roam free. I am speaking of the savannas and rain forests of Africa.

There are many eyewitness accounts in the one continent where large herds of grazing ungulates still exist and smaller relatives of mastodons, woolly mammoths and rhinoceroses still roam free. I am speaking of the savannas and rain forests of Africa.Famous European explorers of Africa in the eighteenth century, like Burton and Speke, gave many accounts of the hunting of these animals by African natives, armed with much better weapons than Pleistocene man had at his disposal.
Africans used metallurgy as early as 2,000 B.C.E., and produced iron-tipped spears and knives by 500 B.C.E. They had invented bows and arrows long before European observers arrived on the scene. They coordinated their hunts, using hunting techniques, some of which were borrowed from their observations of jackals, hyenas, and other predators.
North American Pleistocene hunters probably borrowed techniques from wolf packs. Later on, Native Americans admired and definitely copied wolf tactics. For instance, the Pawnee Nation’s scouts were called the “wolf scouts” by other admiring tribes, due to their uncanny proficiency.
By all accounts, hunting large animals on the African plains was dangerous, frustrating, time consuming, and energy depleting. The majority of attempts met with failure. By the way, this is true for most predators, no matter who or where they are.
We have accounts of iKung (African Bushmen from  Botswana) hunters tracking prey wounded by their poisoned arrows for over a day until they literally ran them down (Van der Post and Taylor, 1984).
People who observe predators closely, whether wolves in Yellowstone or lions on the Serengeti, have noted that nine out of ten attacks on prey on the average meet with failure. That is an enormous expenditure of energy and time for rather poor results.
Stone age man might have been more successful than animal predators, due to his strategic abilities and weapons, but he too undoubtedly met with more failures than successes in such difficult undertakings.

 

An ABO had to be a jack-of-all-trades

Only a few animals were likely to be killed in such hunts, certainly not enough to even put a dent in large ungulate herds, which sometimes numbered in the tens of thousands. Such animals, in Africa, even when poached with rifles these days, restricted in territory by the fences and other obstructions of agriculture, and challenged by periodic droughts, have obviously managed to survive in large numbers.
This brings us to the subject of buffalo jumps. Some massacre proponents have cited these as examples of “primitive” people’s ability to employ systematic and efficient methods of killing large numbers of prey animals. These jumps were usually cliffs over which American Indians would attempt to stampede bison herds, in order to drive them to their deaths. Apparently, there were a good many such places in the American West, and we know of some of their locations. Using these tactics, hunters were able to kill large numbers of bison with less effort than hunting them from horseback, with bows and arrows, a method, which was at any rate, not available to Paleolithic hunters.
Some scholars also point out the waste of such a method, often leaving many more dead animals than the hunters could butcher and use for food. In this way, these critics get to make two anti-Pleistocene hunter criticisms at once, one, that these hunters were indeed capable of killing large numbers of animals and two, that they wasted resources.
An amusing story, derived from a Blackfoot legend by Joseph Campbell, illustrates both the difficulty of such endeavors and the reverence and respect in which the Native Americans held Bison, who are accused by some of indiscriminately slaughtering them. (J. Campbell, 1988).
The trouble with these accusations is that they do not appear to stand up to scrutiny. The critics state that these methods were widespread. If so, how successful were the Indians in wiping out the bison? By all accounts, enormous herds of bison, from a population which some have estimated at 50 million animals,(Nowak, 1983) still roamed the American West, even in the 1800s. Obviously, the Indians’ methods were insufficient at the least to eliminate the bison.
In addition, why should we assume that the Siberian Neolithic migrants to North America, who were the predecessors of American Indians, and who had a much smaller population than the Indians, perhaps as little as 2,000 at one point (cf.) , had been more successful in exterminating much larger, and presumably more dangerous, bison (Bison antiquus ) when their ancestors had been unable to do so in Siberia?
And, how did these Neolithic hunters accomplish the permanent demise of dozens of other megafauna? There is no evidence that other animals, such as wooly mammoths  and giant sloths, were susceptible to these stampede methods. How did the paleohunters, for instance, wipe out the large ungulates, such as Bison antiquus, when horse-mounted Indians were unable to do so with their smaller descendents, Bison bison ? Were their Pleistocene predecessors cleverer than they? Hardly likely. In fact, some scholars have argued that ancient Hunter Gatherers were intellectually inferior to us and lived in a sort of preconscious state ( James, 1976), although there exists considerable evidence to the contrary (Fischman & Johnson, 2010)
As for the charge of wasting the meat from animals killed at buffalo jumps, none of the critics have explained how the Indians could have limited the numbers of animals killed, using this crude but effective strategy. Needless to say, our European/American ancestors, shooting bison for sport from moving trains, could have easily limited the numbers killed by that method, but they did not. In fact, they left the corpses of thousands of bison to rot on the western plains as their trains moved on.
( Nature, 2011).

A Pile of Bison Skulls, Almost Twenty Feet High

This Pile Contains Probably Thousands of Bison Skulls

In addition to these senseless killings, it is well known that the wanton killing of American bison was a deliberate and overt tactic employed by our government to remove an animal absolutely essential to the lifestyle (and spiritual well being) of Plains Indians (IUCN, 2010). The loss of the bison forced them onto reservations and opened up the plains states to private property, ranching and agriculture. (Gates et al., 2010). No such motivation can be attributed to the paleohunters, who were just looking for meat.
Observations of native African hunters affords us another opportunity to evaluate these methods, this one of comparison: How did these hunters fare?
Prior to the advent of Bantu agriculturalists and white European explorers and colonists in the 19th and 20th centuries, the Bushmen inhabited the entire region of South Africa. There is recent genetic and archaeological evidence that the Bushmen are descended from the oldest line of human evolution (Gibbons, 2009; Henn et al., 2011). Therefore they have hunting experience in this region for tens of thousands of years.
As previously mentioned, Bushmen hunted large ungulates on foot and employed bows with poison-tipped arrows as early as 24,000 years ago (Zorich, 2012). (The poison used then was the deadly ricin, derived from castor beans). That would seem like a neat, efficient way to dispatch large ungulates, but as they say, the devil is in the details.
Bushmen first had to stalk near enough to edgy herds in order to use their weapons with any kind of accuracy. The poison, now usually made from toxic beetle grubs, worked slowly. The hunters, therefore had to follow or track the wounded animal for hours and sometimes even days before the animal died. I have seen a film of bushman actually running after these animals all day until they exhausted and cornered them (Foster. C. & Foster D.,2000) The stamina of Iron Man competitors and ultra marathoners pales in comparison to that of these hunters. They were then faced with the task of killing and butchering the animal on the spot, and thus heavily laden, had to carry the meat back to their extended families at their temporary encampments.
Keep in mind that the Bushmen are little fellows, most of them barely over five feet tall. Any elk hunter, who has ever shot an elk on top of the mountain or far off the road, can testify as to what a challenging task this is.
Congolese forest pygmies still hunt in their own unique traditional style. The Babenzele pygmies (Mbouti) of Zaire’s northeastern rainforests, have perfected a neat way to hunt in heavily forested areas. It is a cooperative hunt, using nets, made from nicusa vine (Manniophyton) cordage.  The entire group, which is actually an extended family, participates (Sarno, 1995). Each nuclear family is responsible for one section of net, about as high as a volleyball net, but much longer, which they must keep in good repair.
     They put the nets together end to end, the entire apparatus in the form of a horseshoe-shaped trap, covering several acres, by tying it to trees and bushes.

Ituri Forest Pygmy with a Hunting Net

Pygmy with NeThe rest of their families then drive the animals into the open end of the trap, shouting, pounding trees with sticks and altogether making as much noise as possible. In this manner they can trap and kill small animals, such as pygmy deer and duikers, in an efficient manner (Sarno,1995). You could consider this method as a rain forest equivalent of a buffalo jump, but it is certainly no way to wipe out the entire forest fauna, and obviously, hunting in this way for millennia  if not longer, they have not done so.

Pygmies are genetically related to Bushmen, and like them, are  also descendants of the longest human lineage in the world (Wade, 2012).
It should be mentioned in this regard, that Anthropologists had long suspected pygmy ethnic antiquity from examining their language and culture. In addition, DNA studies have lately confirmed the ancient lineage and racial interrelationships of the various pygmy groups, such as the Baka and Mbouti, even though these aforementioned groups are separated by more than a thousand miles of forest. (Verdu et al., 2009). This is a testimony to the cohesiveness and relative exclusivity of their cultures and lineage.
Pygmies are also reputed to be efficient and courageous hunters of forest elephants (Loxodonta cyclodis ), which they hunt with spears. These animals are a smaller version of those in large herds ( Loxodonta africana ), which roam the African Savannah.
Australia: Massacre proponents recite virtually the same scenario for the continent of Australia as they do for North America. That is, when humans arrived in Australia, they wiped out the widespread and varied marsupial megafauna. They cite the demise of animals such as the giant wombat, Diprotodon, the largest marsupial to ever exist (Martin, 1967).
However, there is a good deal of evidence accumulating that these two events, the marsupial extinctions and the arrival of Australian aborigines, did not even come close to occurring simultaneously. These megafauna became extinct around 46 – 51,000 BP. However, by some accounts, man has inhabited Australia as far back as 61,000 BP (Brook, 2002,). That would make 10-15,000 years of overlap before these animals went extinct.  It is hard to understand why the Aborigines were able to coexist with the megafauna for such a long time and then suddenly developed methods and desire to wipe them out in a relatively short time. There is no evidence of a change in aboriginal technology.
It is important to note, that like the Bushmen and Pygmies, the Australian Aborigines were hunter-gatherers, who wandered on foot, in small groups of related people, over a landscape, which is mostly a desert, with a fragile ecology. Note, for example, how a recent and continuing drought (Chancellor, 2012) has wrecked havoc with the agricultural and herding economies of that land, despite the availability of modern technology. Australia is almost the size of the USA.
No one knows for sure what the Aboriginal population was before the arrival of Europeans on that continent. The best estimate at the time of first contact was 318,000. (Wikipedia, 2012)
The area of Australia is 2,967,892 square miles. This would have averaged out to one Aborigine/9.3 square miles. For comparison purposes, the least populous state in the US is Wyoming, which has 13 persons/square mile. In other words, it would have taken 121 Aboriginal Australias to match Wyoming’s present population density.
Even assuming that Australia’s population near the coast was much greater than in its desert interior, it is hard to believe that such a tiny population, using Middle Paleolithic technology, could have killed off all of these large animals.
Polynesia: Here the massacre proponents, at first glance, appear to be on firmer ground. The accounts of Polynesian islanders wiping out many species on the islands they colonized are probably true. Nevertheless, this situation may not be relevant to the North American and Australian experiences. It is necessary to put these events in context by examining the special circumstances in which they occurred.
Perhaps the difference that most distinguishes the Polynesian experience, is that these people were agriculturalists, not hunter-gatherers. Their ancestors had migrated down into the Pacific islands from mainland South East Asia (Kumar et al., in press, Kayser, 2008).
They produced large amounts of food and stored it, thus enabling their populations to become much more dense than those of hunter-gatherers. They were prone to population explosions, which put a strain on the carrying capacities of the islands they colonized (Diamond, 2005). It was indeed, their propensity to outgrow their islands’ biological carrying capacities that impelled their long voyages of discovery.
The unique circumstance effecting the Polynesians were their finite resources. They lived on islands, many of them quite small, and when they had used up the local resources, they could not just pick up a few belongings and move to a more promising region as do contemporary hunter-gatherers, like the Hadza in Tanzania and the iKung of the Kalahari Desert. In fact, most of Polynesia was probably colonized from other overcrowded, over-taxed islands. Thus, the impressive, long Polynesian voyages of discovery were probably voyages of necessity.
For example, Easter Island is 3,000 miles from most Polynesian-populated archipelagoes, and despite the romantic notion that these were voyages of exploration and adventure, it is not likely that such arduous and potentially dangerous voyages would be undertaken except in a desperate search for new territory to exploit.
In fact, these overcrowded conditions leading to heavy exploitation of their natural resources were among the primary factors in stimulating new voyages of discovery, as groups of marginalized or land-poor islanders searched for new islands to exploit. Islands have finite resources.
One of the main reasons that many extinctions occur on islands is that once a faunal or floral population drops below a certain level, there is not much likelihood that they will be “rescued” by in-migration. In fact, there is a well-known phenomenon of island dwarfism, by which many species, isolated on islands have a tendency to become much smaller than their mainland relatives (Quammen, 1996). This may be due, in part to the evolutionary pressures brought on by limited resources. Obviously, a smaller version of a rhinoceros or deer would have an advantage in needing less energy. This would be especially true of those living on islands in which their natural predators were never present or had been eliminated, so that their need to grow to a size large enough to defend themselves or flee predators was eliminated.
An extreme example of this principle is the development of flightless birds on many islands., like the Dodo (Raphus cuculatus) of Mauritius Island and the Guam rail (Rallus owstoni). Both of these birds are now extinct due to human activities.
On the other hand, the island of Guam is literally crawling with an introduced predator, the brown tree snake. These snakes originated in New Guinea, and probably got to Guam as non-paying passengers in freighters. The lack of natural enemies allowed this snake population to explode, much the same way as did Yellowstone’s elks after the last member of its original wolf population was killed in 1926.
Human population pressures resulted in a kind of hopscotch invasion of more islands as the Polynesians pressed ever onward towards the Eastern Pacific, until they reached  islands like Easter and Mangareva, which were distant from most of the other islands. The Polynesian’s profligate ways led to starvation and sometimes their extinction when they continued them on such isolated, hard-to-get-to islands (Diamond, 2005).
It is important to compare the Polynesian’s ever-increasing populations with those of Hunter Gatherers, Although we cannot be certain about the life styles of North America’s Pleistocene hunters, we know from geographical, archaeological, and DNA studies that their numbers were relatively small and sometimes led to population bottlenecks of only a few thousand souls. (Amos and Hoffman, 2010). For example, the “Out of Africa “ migration of Homo sapiens to the Near East and Eurasia was calculated to contain only about 2,000 persons.
In fact, Hellenthal et al. (2008), found genetic evidence of at least two migrations, both small, from Siberia to America, the earlier one eventually reaching South America and the later, larger one, arriving in the northwest corner of the continent.
We can also examine the populations and reproductive behavior of these North American migrants’ present day equivalents. Although they are scattered all over the world, and usually have been forced into challenging and impoverished environments by tribal and western technological cultures, hunter-gatherer cultures are remarkably similar in many respects. Their populations, in contrast to those of agriculturalists, like the African Bantus, horticulturists, such as the New Guinea highlanders, and migratory herders like Mosaic and Fulani in Africa, are remarkably stable, both between areas and down through the centuries during the time in which they have been studied.
Their groups usually consist of basically extended families of 10 – 30 persons, who move from one area to another and back again, depending on season and availability of resources such as water, edible plants, and game.
Their numbers are self-limiting, due to biological constraints and their use of a variety of birth control techniques. For example, in ways similar to the game they hunt, they reproduce more abundantly under ideal conditions, and much less so under conditions of stress, such as lack of food and water resources. They also practice late marriage. For instance, among the iKung (Namibian Bushmen), girls do not usually reach menarche and marry until their late teens, while those of tribal agriculturists often do so even prior to puberty.
Pygmies and Bushmen also breast feed their children up to the ages of four or even later. Breast-feeding liberates hormones, such as oxytocin, which block ovulation. This is a natural method of birth control, which has the effect of spacing children so widely that few hunter-gatherer mothers have more than three or four offspring. Contrast this with the families of agriculturalists, who often have as many as ten children. The more the merrier. It takes lots of hands to run a farm, or at least it did until the advent of modern technology. This trend toward large families has persisted even in our culture, into the twentieth century. Witness all the older, large Victorian houses you see, with four, five, even six bedrooms, in rural towns as well as farms.
Hunter-gatherers use other techniques to limit families, which are less savory to our western moralities. They use particular plants for their abortifacent qualities, and have been known to leave newborns to die of exposure, when conditions are particularly desperate for them, choosing to try to save their other children and not add to the stress on them.
So many other, non-game animals disappeared at the end of the Pleistocene that it is hard to argue that the Siberian migrants wiped them out. The extinction of many predators, like the dire wolf and the Miracinonyx, a cheetah-like animal, which relied on its speed to run down its prey, is hard to understand, especially with many herds of smaller ungulates still extant at the time.

The Climate Hypothesis:

The alternative explanation for the disappearance of these large and small animals, interestingly enough, is one that many people today still have difficulty in wrapping their minds around – climate change. In the present case, the reasons for denying the realty of these changes are clear enough. They are first, that these have been mostly predictions of things to come and secondly, accounts of some things that are happening now, but to other people.
In an infamous remark, while he was talking to the chief climate scientist in the world, James Hansen, the renowned TV interviewer, Larry King, asked Hansen when some of these changes would occur. When Hansen told him that some would happen as soon as fifty years from then, King snorted “No one gives a damn about what will happen fifty years from now.” Lamentably, he was undoubtedly right. Humans have apparently evolved to react to present dangers, such as an attack from a saber-toothed tiger, or an algebra test tomorrow morning, and not from future dangers that they may not be around to encounter.

In the case of the Pleistocene, at least no one challenges the reality of these past climate changes, but frustratingly enough, the power of their effects are downgraded in the estimation of the massacre proponents.

Are the Beliefs of Earth-Based Peoples a Valid Guide to Their Behavior?

When we study past cultures, we usually take only so-called hard evidence, such as bones, implements, and ruins seriously. We even define whether a people had something called a “civilization” in such a way as to discount any people unless they had monumental ruins, a written (and decipherable) language, hierarchical social orders with separable skills and duties, and whether or not they made war.
Nevertheless there is additional evidence, which indicates that North American hunters did not exterminate the megafauna. This might be considered “soft” evidence, but I am impressed by it. It takes the form of the spiritual beliefs and lifestyles of contemporary hunter gatherers all around the world, about which we have collected considerable knowledge. As previously stated, I do not think that we attach sufficient significance to the beliefs and observed behavior of Earth-based peoples.
Laurens Van Der Post wrote several books, such as “The Lost World of the Kalahari “and “The Heart of the Hunter,” describing his interactions with the San Bushmen in the Kalahari desert in the 1960s. (Van Der Post; 1958, 1961). Anthropologist Elizabeth Marshall Thomas wrote of her early adventures with these people in “The Harmless People,” and her recollections of her life with them in “The Old Way.”(Thomas, 1958, 2006).
David Abram has written “The Spell of the Sensuous” about the traditional Balinese people (Abram. 1997). James Cowen spoke of the lives and beliefs of Australian Aborigines in “Letters From A Wild State” and “Messengers of the Gods” (Cowen, 1991, 1993), as did Bruce Chatwin(1987) in “Songlines.”
Anthropologist Colin Turnbull turned his attention to the Congo Pygmies in “The Forest People,”and Robert Wolff (2001) wrote movingly of his experiences with the Sng’oi of Malaysia and other aboriginal hunter gatherers in that part of the world, in “Original Wisdom.”
This is only a partial list, and I only have space to summarize a few stories and legends to give you an idea about people who found a way to tread softly upon the Earth and  to live in communion with the world.
I will begin with an Australian aboriginal legend called “The Kadimakara,”as retold by Cowen (1991)
“According to the Aborigines, the desert they must cross to reach the oasis at Cullymurra water hole was once a vast region of fertile plains and forests. traversed by rivers flowing into lakes. The bones of ancient animals which we call Diprotodons scattered en route  were the surest proof that conditions had changed since that primordial moment …
The present clear sky above had once been filled with dense clouds of dust, which perpetrated tropical downpours at regular intervals. Great Gum trees reached high into the sky, supporting a complex interlace of green life which shut out all sunlight.  From this arboreal vault a group of monsters known as the Kadimakara descended in order to feed on the fruits below. Once these creatures had tasted the fruits of the Earth their appetites became insatiable.  In time they had eaten all the shrubs, trampled the Earth hard, and finally had resorted to eating the giant trees down which they had come. In an ironic twist of fate they had destroyed their one escape route to the heavens!
As a result, the Kadimakara were forced to remain on Earth.  They wallowed in the lakes, drinking up the water.  They ate everything before them.  Soon the canopy of trees overhead had been destroyed, revealing one continuous hole of blue sky.  The tribesmen named it Pura Walpinina, or the great hole. Meanwhile, the Kadimakara began to die of starvation  now that they had eaten every shrub and bush.  In the heaving marshlands of putrefying earth which had once been rivers and lakes the monsters lay down to die.  One by one they expired, their bodies slowly petrifying in the relentless sun, which their destruction of the natural environment had released upon the Earth.  Their bones, the bones of the Kadimakara, littered the dry earth as somber reminders to the surviving tribesmen of what can happen when the natural environment is treated as an inexhaustible larder The Kadimakaras’ insatiable appetites had been the direct cause of their own extinction.
Perhaps the aborigines were warning themselves that if they exceeded the carrying capacity of this fragile, barely livable area, they would suffer the fate of the Kadimakara.
On the other hand, perhaps this cautionary tale is meant for ears other than those of aborigines who have lived in harmony with the Earth for so long.  Perhaps this myth is of more recent origin, say since the days of first contact with Europeans and observation of their peculiar appetites.”
Here is another story, from a very different place. This legend was told to James Cowen by an islander, living in the Torres Strait, between New Guinea and Australia. His family was reputed by other natives to “own” the Pleiades (Seven Sisters) constellation (Cowen, 1993). How can one own a constellation? Read on and find out.
“Tagai was a man.  He owned a canoe, along with his friend, Kareg.  One day they were out fishing with a crew made up of Usiam and Seg people.  To you these people are the Seven Sisters and the stars in the belt of Orion.  Anyway, while Tagai and Kareg were paddling along, the Usiam and Seg people decided to eat all the food and drink all the water on board.  Kareg saw this happening and called out to Tagai, who was in the bow of the boat.  So Tagai strung the Usiam together and tossed them in the sea.  He did the same to the Seg people.  Only Tareg, his friend, remained with him in the boat,”
“Yeah, the story of the stars belongs to me. I must interpret it for others, to remind them that all of us must take care not to act like the Usiam and Seg people.  By drinking too much, by eating too much, we forget to leave some over for others.  The food and water on Tagai’s boat represents nature. If we use it up without thinking, we run the risk of exhausting our food supplies on the voyage.”
I have trouble with people who tell me that the only reason that Native Americans and other indigenous peoples did not destroy their environments just as thoroughly as we seem on our way to doing, is that they lacked bulldozers and insecticides.
I find it hard to believe that people who regarded the rivers as their sisters, would have raped them by pouring toxic waste into them, or their forests as brothers, would have clear-cut them. Explain to me how people who looked at wolves as older brothers and whose scouts emulated them, like the Pawnee and Cheyenne did, would have turned around and shot them from helicopters if only they had they possessed such equipment
Every one of these sources, without exception, tell the same story. These hunter gatherers are remarkably like ourselves. In fact, they are us. Biologically, we are still living in the Pleistocene. They are not Rousseau’s “noble savages”. They were capable of anger, envy, voraciousness, and all the other dark emotions  that people of our society exhibit. However, by both happenstance and planning, they created a lifestyle that discouraged those darker behaviors and valued the best human qualities, like cooperation, egalitarianism, and community.  These qualities enabled them to tread lightly upon the Earth and to live lives of integrety. We have much to learn from them.

The Tale of The Blind Men and the Mammoth:

Some respected researchers, like William Ripple of Oregon State University, who first opened our eyes to the dynamics of wolf/elk interaction in Yellowstone, believe that human predators may have been involved in the extinction of the wooly mammoth. Ripple and Van Valkenburgh (2010), presented evidence that mammoths may have fallen victim to trophic cascades some 10,000 years ago.

Trophic cascades are ever-widening, usually top-down effects brought about by interactions between living organisms in ecosystems, particularly originating with predator/prey relationships. Interestingly, we are at present witnessing damaging cascades which are caused by a world-wide loss of predators. This, in turn, is mostly due to human disruption of ecosystems, such as the effects of shark slaughter on fisheries.
Ripple and his co-workers examined wear and fracture rates of fossil carnivore teeth and from growth rates of their prey, Heavily worn and fractured teeth are an indication of bone consumption, which predators avoid except when there is prey scarcity. There was little indication of such wear. Their evidence suggests that there were no serious food shortages in northern America 10-15,000 years ago.
They believe that a range of predators, such as the dire wolf, lions, and saber toothed cats (Smilodon sp.) reduced the number of fauna. This system was balanced but dominated by the predators. When humans arrived however, they provided increased competition for these predators.         Giving an example of a modern equivalent of this situation, these authors state that in contemporary Alaska, human hunting of moose caused wolves to switch to sheep, which in turn, resulted in a precipitous decline, not only of sheep, but eventually of wolves and moose. [Ripple et al. make it clear that this trophic cascade started with that apex predator, man].
The Pleistocene predators, now desperate for food, may have finally driven their prey to extinction. This conclusion, however, goes against one of the primary dicta of wildlife biologists, which is that predators never cause extinction of their prey.  Before that could happen, the predators themselves would decrease in number from lack of sufficient prey to sustain themselves (cf.).
The authors argue by analogy that human whale hunts have resulted in Orcas switching to seals and sea otters. This, in turn has led to an explosion in sea urchin populations and a decline in kelp forest ecosystems, in another contemporary trophic cascade.

Dwindling green Pastures:

Allen and his colleagues, however, recently reported that a massive reduction in grasslands and the spread of northern forests may have been the cause of the Pleistocene decline in mammals. This occurred during  and after the height of the Ice Age, 21,000 years ago, and dramatically reduced available food.
It resulted in the reduction of large mammals across northern Eurasia and North America by 11,400 years ago, although some held on for several thousand years longer in limited localities, termed “refugias,” in which both climate and food supplies were more amenable to their survival. Migratory hunters were also restricted to these areas by availability of these mammals for their own food supply. Several refugias have been identified, strung along the coast of what is now called Alaska and British Columbia.
These researchers have reconstructed the environment from ancient pollen records and noted which major megafauna became extinct and which survived. The wooly mammoth, cave lion, giant deer, wooly rhino and cave bear went extinct. The brown bear, elk, moose, reindeer, saiga antelope, and musk ox survived (Allen et al., 2010).

We are all connected:

Another group of scientists, (Nogues-Bravo et al.,2008) have accomplished what amounts to a synthesis of the last two views. They used climate models and examined fossil distribution, concluding that change in global climate was exacerbated by human pressures to drive the mammoths and other megafauna to extinction.
These researchers used a number of climate models, ranging from 6,000 to 126,000 years ago. Clearly, the environment was much worse for mammoths 126,000 years ago, yet the animals survived. They showed though that there was a catastrophic loss of habitat 6,000 years ago so that only 10% of the former habitat remained.
They also considered the effects of temperature changes and rainfall. They then compared these parameters with age and distribution of fossils.
Nogues-Bravo and his colleagues say that mammoths faced rising temperatures and increased hunting pressure at the same time. They argue that that these animals had faced previous temperature increases without going extinct and that the only difference was that this time there was human influence.
They came to the conclusion that  it was a combination of climate change and human hunting that was responsible for these megafaunal extinctions.

Conclusions:

Well, I have come to the place where I need to sum up the evidence and tell you of my conclusions. However, it is not as easy to do as I first thought. I started out on this journey pretty sure of myself. I was on the side of the angels – at least they were my angels. I was pretty sure that the massacre proponents had at best exaggerated their case and at worst had become prisoners of their ideological propensities. .
The last few papers I have cited impressed me, both with their approach and their reasoned arguments. I was most impressed with the work of with Ripple and his co-workers because they had a novel approach to this difficult subject, and due to my respect for Ripple’s past work.
Perhaps you will be surprised that when I evaluated  the worth of these publications, I took into account who wrote it. At first sight that does not seem to be objective, so I will let you into a little secret of science. It matters who did the investigation. In over 30 years of scientific research I found out that not all the facts are published and that the devil is often in the details. I that learned that I could trust the intelligence, thoroughness, and integrety of some researchers more than others.
Ripple is one of these. As I mentioned previously, his salient work was accomplished by tracing trophic cascades in Yellowstone National Park from wolves to elk and to their widespread and important effects on the rest of the ecosystem. Ripple showed that the elk population explosion, that occurred after the last wolves were exterminated in 1927, had deleterious effects that ranged from the disappearance of riparian flora to decreases in bird, fish, and scavenger populations, and that the wolves, reintroduced in 1996, have been an important factor in restoring balance to the entire system.
Nogues-Bravo and his colleagues seem to have nicely combined the ideas of Ripple with those of Allen et al., who emphasized the important role of climate change.
Nevertheless, despite Ripple’s analysis, I think that the preponderant evidence supports the idea that humans were not responsible, or played only a small roll in the demise of these animals.

The following points sum up the basis for my conclusion:

• Human signs were usually not associated with the massive troves of mammoth bones found on Siberian islands.
• The extinctions took place over a very long period, some of that including times when man was apparently not present on the continents of North and South America.
• It was not only the charismatic megafauna that became extinct during this period, but so were other animals, that were unlikely to have been eliminated by hunters. One example of this is the dozen or so species of woodland song birds that went extinct.
• The direct ancestors of these hunters did not eliminate many of the same animals in Siberia.
• It is hard to believe that such a small number of people, around 2,000 at one point caused by genetic bottlenecks, could have killed off so many animals.
• Later on, Native Americans, with much more advanced technology available to them, put hardly a dent in the populations of megafauna, especially the immense herds of bison, whose numbers may have reached as high as fifty million animals.
• North America was occupied by these Siberian migrants over a much longer time than previously thought, at least 14,000 years, and so the question arises over why it took them such a long time to eliminate the megafauna.
• African megafauna have survived native hunters, who had much more advanced technologies than the North American migrants did.
• Australian aborigines were also few in numbers. They entered that continent much earlier than massacre proponents thought, and coexisted with the marsupial megafauna there for 15 – 20,000 years.
• The Polynesians, who exterminated many native fauna, were islanders and agriculturalists, two factors that make extinctions much more possible.
• Hunter gatherer beliefs and spirituality make it improbable that they would treat their environment in as ruthless a fashion as our culture does.

In conclusion, I do not think that that the last word has been said in this controversy by any means, but the idea that the demise of the megafauna was due, not to one, but to a combination of factors, including climate change and perhaps anthropogenic action, seems like a more likely answer to this vexing question.

Trophic Downgrading or Where Have All the Predators Gone?

THE TROPHIC DOWNGRADING OF PLANET EARTH

(Or, where have all the predators gone?)

  J.A. Estes, et al. (2011) The Trophic Downgrading of Planet Earth (2011) Science, 15 July, 333(6040) 301-306.

Summary and Comments by Ken Fischman, Ph.D.

This is a paper that is worth your diving into because the information it contains is important to the health of our planet. I will help you get through it by summarizing and commenting on it. You can either read the summary or skip directly to my comments on it at the end of this post. What is it about? It deals with the recent and rapid disappearance of top predators, such as wolves, lions, & sharks, mostly brought about by the actions of that top predator of all – mankind, and the surprisingly profound effects their loss is having on ecosystems worldwide.  It was the feature article in the July, 2011 issue of Science, one of the most prestigious scientific journals in the world. Among its 23 authors are: John Terborgh, Joel Berger, Michael Soule, and William Ripple. The former three are considered to be among the founders of the field of Conservation Biology, and Ripple is our foremost researcher into the effects of top predators on the ecosystems of North America. Simply put, a trophic cascade (TC) is the effect that the absence or abundance of a top or apex predator has on succeeding levels of the rest of the ecosystem. The authors have gathered a vast array of evidence showing that these losses lead to ever-increasing and widespread effects on other living creatures, on ecosystems, and on the Earth itself. Terborgh pioneered this type of study by showing the profound effects of the presence or absence of predators on the fauna and flora of isolated islands in the Barro Colorado, a recently flooded region near the Panama Canal. Soule, in a classic paper, neatly demonstrated how the presence or absence of coyotes effected the bird and cat populations within the urban canyons of San Diego. Ripple has shown the profound influence that the reintroduction of wolves in Yellowstoneand loss of mountain lions in Zion National Park  have had on the animals and plants in those areas. In this paper, these scientists turn their attention to the effects of predators on ecosystems worldwide and warn us of the present and impending dangers that our  steady & seemingly inexorable extermination of predators is having on the Earth

Summary of the Paper

 The loss of apex predators all over the world is having a pervasive influence on nature. There are cascading effects of the disappearance of predators. These “top-down forcings” (causes of variability) are having unanticipated effects, such as increase in disease, wildfires, losses in carbon sequestration, appearance of invasive species, and disruption of biogeochemical cycles. In its 4.5 billion years of existence, our planet has undergone several mass extinctions, with huge loss of biodiversity, followed by novel changes. We are now in the early to middle stages of a sixth mass extinction. Man has mostly caused these recent extinctions. Many of them are started by the removal of apex predators. These extinctions may be mankind’s most pervasive effect on the natural world. Extinction obviously means a permanent loss of these animals, which in turn often has a ripple effect, causing many other changes throughout the ecosystem. These widespread changes are what are referred to by scientists as “trophic cascades” (TCs). Some of the ultimate outcomes of TCs are: fires, disease, climate change, habitat loss, and pollution. Theory behind concept of TCs: (1)  An ecosystem is shaped by its top consumers (usually apex predators). (2)  Alternative stable states. TCs push a system, and it reaches tipping points. These are thresholds or breakpoints, and when they are reached, significant phase shifts occur. (3)  Connectivity – this is built around connection webs and through the mechanics of predation, competition and mutualism (organisms that have a supportive effect on each other), biologically, and through physicochemical processes. Cryptic nature of TCs: Species interactions are usually invisible under stable conditions. They may require years to become evident due to the long generation times of some species.  The effects usually do not become evident until after the loss. The scales of TC s can be much more vast than most feasible scientific studies can handle. Most field biology studies concentrate on small, discrete areas, and on non-motile species, with short generation times, making them easy to  manipulate. This results in an incomplete and distorted picture of apex predator influence. Hence, the authors have written what is called a mega study, which brings together the results of many other similar studies, using similar protocols & subjects. This enables them to combine the studies & to note general principles and draw important conclusions with more certainty. Widespread Occurrence of TCs: TCs have been documented throughout the world. When apex predators are reduced or removed, and sufficient time and space are accounted for, their influence becomes obvious. “Natural experiments” showing these effects are pervasive: e.g. loss of: killer whales, lions, wolves, cougars, sharks, sea otters.

These interactions are often complex. e.g. apex predators have little influence on megaherbivores:  Elephants, hippos, rhinoceroses, etc. in Africa are basically invulnerable to predation. Mostly, therefore effects are seen in the increase in smaller herbivores: e.g. Thompson’s gazelle, impala. Influence of apex predators on autotrophs (An organism capable of synthesizing its own food from inorganic substances, using light or chemical energy. Most plants are autotrophs): (a)  Increase of autotrophs – by suppression of herbivory (any animal that feeds mostly on plants), e. g. the loss of sea otters, which prey on shellfish,  have diminished the health of kelp forests. The extirpation of wolves from forests has resulted in a corresponding increase of ungulates adversely effecting other animals and plants in various ecosystems. e.g. the removal of wolves from what has become Rocky Mountain NP in Colorado has resulted in the overgrowth of elk, which in turn have devastated much of the plant life. (b) Decrease of autotrophs – e. g. large mouth bass by feeding on smaller fish, which feed on 200 kinds of plankton (microscopic aquatic plants & animals)  have decreased their numbers to such an extent in many mid western US lakes, that this has resulted in a loss of oxygen, leading to the demise of other life forms in these lakes. Herbivory and Wildlife: Increase in herbivory (mostly domestic animals that eat plants) has resulted in a change from grass lands to scrub lands, & the burning up to 500 million hectares (ha) in the global landscape and has released over 4,000 metric tons (Tg) of CO2 into the atmosphere. Diseases: e.g. Rinderpest (an infectious viral disease) in East Africa decimated ungulates. (animals like wildebeests & buffalos that chew their cud). This led to an increase in plant biomass, which in turn led to wildfires. Vaccination and control eliminated Rinderpest and this led to the recovery of the wildebeests and buffalos. Because of this, shrub lands became grass lands, which reduced the frequency and intensity of wild fires.

e.g. Impacts of predatory fish on mosquito larvae: effects the incidence of Malaria. Physical & Chemical Influences: There is a linkage between apex predators & atmospheric CO2. e.g.  presence or absence of predatory fish in lakes can effect the production & uptake of CO2. e.g. whaling transferred 105 million tons of carbon from whales to the atmosphere. e.g. Extinction of Pleistocene herbivores reduced atmospheric methane & contributed to a drop of 9° C. temperature drop in the Younger-Dryas period, some 12,900 years ago. Soils: e.g. Herbivores profoundly influence soils. e.g. introduction of rats & arctic foxes in high latitude (mostly arctic) islands reduces soil nitrogen by disturbing nesting birds. Water: e.g. collapse of large demersal (bottom feeders) fish in the Baltic Sea led to a 20% decrease of silica in pelagic diatoms (one-celled organisms that make up the majority of plants found in the open sea). e.g. Yellowstone wolves protect riparian vegetation from over-browsing herbivores. This leads to more shade & cooling of streams, which in turn decreases streambed erosion & increases cover for fish & other aquatic organisms & leads to an increase in songbirds.

Invasive Species: Lack of top-down predators allows invasive species to spread. e.g. spread of the brown tree snake, originally from the Solomon Islands, on Guam, which has exterminated most of its birds, was due to lack of other predators, which could have held the snake population in check. e.g. reduced fish predation in the Mississippi River led to the invasion of zebra mussels. Biodiversity (Abundance of & diversification in living creatures): Biodiversity(BD) is now largely confined to protected areas (e.g. national parks, designated wildernesses). Loss of BD has been mostly caused by over-exploitation (hunting, fishing, increase of areas reserved to domestic & other ungulates, etc.) has led to habitat loss & fragmentation of ecosystems. e.g. over browsing by an increasing population of elk in Rocky Mountain NP is due to lack of natural predators,(i.e. wolves). The same situation occurred in: the Kaibab Plateau, adjacent to the Grand Canyon in Arizona, which was overrun with deer. Minnesota has a serious problem with areas overrun by more than 1 million deer. Princeton NJ had to employ sharpshooters to kill deer, which were overrunning suburban gardens. Deer (ironically) starved on Deer Island in San Francisco Bay due to their burgeoning population, which was unchecked by predators.  Mesopredators (coyotes) in San Diego canyons strikingly changed populations of songbirds and cats.

e.g. Sea Stars in intertidal areas interact with mussels, wiping out many species. e.g. loss of small vertebrates after the extirpation of wolves, cougars & bears in temperate & boreal North American forests changed the ecology of these forests. Effects of Tree Longevity: e.g. wolves & other megapredators were almost entirely eliminated in the US by the 20th century. At that time there began to be recruitment failure & reduced tree growth rate in many places (most obvious in national parks). e.g. wolves were eliminated 100 yrs. ago on Anticosti Island in mouth of the St Lawrence River. This led to a decrease in the number of saplings & an increase in graminoids (grasses), e.g. wolves were extirpated from the Scottish island of Rum 250 -500 years ago, resulting in total loss of its forest. It is now treeless.

Conclusion: “Best management solution is likely restoration of effective predator regimes.” [English translation: Bring back the predators] Paradigm Shift in Ecology: There is clearly a top-down forcing in ecosystem dynamics.  [We argue that ] “burden of proof be shifted to show for any ecosystem, that consumers do (or did) not exert strong cascading effects.” Conclusions: Unanticipated changes in the distribution & abundance of key species, as well as pandemics, population collapses, eruptions of unwanted species, major shifts in ecosystem states, are caused by altered top down forcing , brought about by loss of native apex consumers. Repeated failures to anticipate & moderate such events arise through  fundamental misunderstandings of their causes. Resource managers usually base their actions on the expectation that physical causes are the ultimate drivers of ecological change. “Top-down forcing must be included if there is to be any real hope of understanding & managing the workings of nature.”

 COMMENTS – Ken Fischman, Ph.D.

 I find it helpful in understanding TDG to picture a pyramid, with the predator at the peak or top & prey animals at several successive & increasingly wider levels, (indicating larger populations) underneath. For example, sharks are the top predators in our oceans & they prey on smaller fish such as tuna, which in turn prey on smaller fish like anchovies, etc. until the lowest & most fundamental layer is reached, which consists of microscopic plankton (autotrophs) & is effected in a profound way.

Along this line, I recently read a paper published in Nature by Daniel Boyce of Dalhousie University in which the author utilized hundreds of thousands of historical records to show that the clarity of most of our oceans has been greatly increasing in the past few years. This is an indirect but powerful method, showing that plankton populations are decreasing rapidly. Because plankton are the base prey in our oceans, their scarcity would adversely effect all fish populations & since they are the ultimate autotrophs (think of what would happen if their dry land equivalent, grasses, were to decrease considerably) tend to increase CO2. Such a profound worldwide change undoubtedly has more than one cause, but the disruption of world fisheries through the loss of top predators is probably a contributing factor.

It is easy to overlook the effects of some predators, either because they are not charismatic megafauna, like “lions & tigers & bears oh my!” or are out of sight much of the time. For instance, who would even thought of sea stars as predators? I know that I had not until recently despite my background in Zoology.  Yet it has been shown that their loss can have profound effects on shellfish.  And those cute little sea otters. Who would have thought that they have an important effect on kelp beds? The film, “Jaws,” which came out in 1975, gave sharks a bad name that they have yet to overcome. That, together with the insatiable appetite of Chinese & other Orientals for shark fin soup (Talk about waste. They cut off the fins & throw the shark carcass away) & the dislike of commercial fishermen for sharks, who they view as competitors, in the same way that many elk hunters view wolves, has led to their wholesale destruction. No thought was given to the sharks’ role as the ultimate apex predator in the sea & the  effect their demise is having on other fish lower in the TC pyramid. It is quite possible, even probable, that the loss of many commercial fish species is linked not only to overfishing but also to the destruction of sharks, which has upset the ecological balance in oceans. In this connection, commercial fishermen may be doubly responsible for the serious depletion of fisheries worldwide, through their overfishing & destruction of apex predators.

My own studies on wolves and as an advocate for them has given me a fresh perspective on their importance in maintaining healthy forests. In this respect, the authors’ citing of studies showing that the eradication of wolves changed the flora of Anticosti Island in the St. Lawrence estuary & deforested the Scottish island of Rum, is instructive & worrying.

We do not however, need to go to the ends of the earth to find examples of TDG. In my own little part of northern Idaho, we have seen the results of overfishing in Lake Penderay, invasive species like spotted knapweed & the infamous zebra mussels, and loss of biodiversity caused by overpopulation of elk in the Clearwater NF. There are a substantial number of elk hunters in the state of Idaho, whose idea of heaven seems to be forests containing only elk & hunters. One of their leaders recently stated that he would only be satisfied when hunters success rates reached 90% Success rates throughout the Northwest have been historically at around 18 -20% (Spokesman Review 2/22/08). Idaho already contains over 100,000 elk. He apparently wants to turn Idaho into an elk farm, where hunters do not even have to get off their ATVs to kill elk. I doubt that many other Idahoans would agree with that vision. These hunters & the politicians who support them are responsible for the present vendetta against wolves, which in the last year has resulted in the killing of around 429 out of only 760 wolves in this state & the extension of the wolf hunt to year around, a hitherto unheard of strategy for “managing” wildlife.

I hope that this publication on the importance of top predators, like wolves, will be brought to the attention of state wildlife organizations like IDF&G and will result in a change of their policy toward a greater respect for these animals. For those of you who are interested in finding out more about this fascinating & important subject of how the loss of top predators is effecting the earth, I recommend the following books:

Monster of God – by David Quammen A very readable account of how our fear & killing of predators is changing the world.

Where The Wild Things Were – by William Stolzenberg A journalist writes about the research that been revealing the key role that predators play in ecosystems.

Song of the Dodo – by David Quammen One of our best scientific & nature writers chronicles the researchers & their studies who have created the new field of Conservation Biology.

Of Wolves and Men – by Barry Lopez A brilliant examination of wolf biology & the often-searing history of mankind’s relationship to these fascinating & badly misunderstood animals.

Wolf Country – by John B. Theberge. The results and conclusions of wolf biologist from an eleven year study of wolves in Algonquin Park, Canada. This book includes a lot of valuable information, written in a readable and popular format.

The Case of the Missing Predator, or Please Pass the Shark Fin Soup

The Case of the Missing Predator, or Please Pass the Shark Fin Soup

THE PREDATOR/PREY RELATIONSHIP. WHY IS IT SO IMPORTANT?        

From time to time in this website, we examine important scientific papers in light of what they show us about subjects of interest to ourselves and our readers.

         The following paper (Crooks and Soule, Nature, 1999) has become a classic because it vividly shows how the presence or absence of a predator can have unexpected and important effects on an ecosystem.

(I regret that I cannot reprint the entire paper, and can show you only the abstract. Copywrite policies prevent me from doing so, even if I were to purchase it. This is detrimental to the free flow of scientific information, but I have no control over the situation.)


Mesopredator release and avifaunal extinctions in a fragmented system

Kevin R. Crooks1 & Michael E. Soulé2

  1. Department of Biology, University of California, Santa Cruz, California 95064, USA
  2. The Wildlands Project, PO Box 1302 2010, Hotchkiss, Colorado 81419, USA

Correspondence to: Kevin R. Crooks1 Correspondence and requests for materials should be addressed to K.R.C. 
(e-mail: Email: krcrooks@earthlink.net.).

Mammalian carnivores are particularly vulnerable to extinction in fragmented landscapes1, and their disappearance may lead to increased numbers of smaller carnivores that are principle predators of birds and other small vertebrates. Such 'mesopredator release'2 has been implicated in the decline and extinction of prey species2, 3, 4, 5, 6. Because experimental manipulation of carnivores is logistically, financially and ethically problematic6,7, however, few studies have evaluated how trophic cascades generated by the decline of dominant predators combine with other fragmentation effects to influence species diversity in terrestrial systems. Although the mesopredator release hypothesis has received only limited critical evaluation8 and remains controversial9, it has become the basis for conservation programmes justifying the protection of carnivores6. Here we describe a study that exploits spatial and temporal variation in the distribution and abundance of an apex predator, the coyote, in a landscape fragmented by development. It appears that the decline and disappearance of the coyote, in conjunction with the effects of habitat fragmentation, affect the distribution and abundance of smaller carnivores and the persistence of their avian prey.

Letters to Nature

Nature 400, 563-566 (5 August 1999) | doi:10.1038/23028; Received 22 February 1999; Accepted 5 July 1999


The Soule paper was a sort of scientific detective story.

Michael Soule, who is considered to be the dean of the field of Conservation Biology, if not its creator, examined a puzzling situation in his home city of San Diego, California. The city, although it is highly urban, is transected by many deep and mostly wild ravines that extend out to the ocean front. The ravines contain animal populations and are basically isolated from each other by houses, streets, etc. One can think of them therefore as islands of life, the denizens of which can enter and leave only with great difficulty.

When Soule surveyed the animal populations in these ravines, he noted a strange situation. In some of the ravines there were dense populations of song birds, whereas in others, there were hardly any at all.

The mystery was clarified when Soule examined the other animal populations in these “urban islands.” He found cats in some ravines, and coyotes in others, but never cats and coyotes together. He also noted that in those ravines where there were coyotes but no cats, there were plentiful populations of song birds, but in others where there were no coyotes, but many cats, song birds were missing.

This is partially a big fish, little fish story, with intriguing consequences and implications. The picture that Soule put together was the following: Coyotes and cats are both predators. We call coyotes mesopredators because they themselves are the prey of others, such as mountain lions and wolves. Coyotes, in turn prey on cats and cats eat birds as well as their eggs and young.  Did you ever think of your kitty as a predator when it brought a dead creature home? Well, domestic as well as feral cats are responsible for the deaths of millions of song birds every year!

In those ravines where the only predators were cats, the cats decimated the bird populations. However in those ravines where there were urban coyotes, they preyed on the cats, keeping their numbers way down, thus allowing the bird populations to flourish. Mystery solved.

So, what has this to do with our interests? Just this.  Wolves are keystone predators, meaning that they sit on top of the food chain (if humans are ignored), and due to this situation, their behavior and eating habits result in a cascade of effects to the rest of the ecosystem.

Yellowstone National Park, like those San Diego canyons, is a sort of island of wildlife, surrounded by ranches, highways, houses and other accoutrements of human habitation. Animals do not easily get in or out. When a few wolves were reintroduced there in 1995, some of the effects were anticipated, but others were not.

 The effects of these predators have been widespread and profound. First, they reduced the number of coyotes in the park considerably as the wolves took their place as the top predators in Yellowstone. Then they reduced the elk population from roughly 15-17 thousand to around 4,500 – 5,000 at present. Lest you think that this drop in elk population is the nightmare hunters fear it is in other locales, it all depends on whose ox is gored.

In fact, the elks, themselves an introduced species in the 1930s, had increased greatly in numbers, due mainly to the lack of predators. They overran and overgrazed the park, considerably  changing the ecosystem. How profound these effects were became apparent when the wolves reduced elk numbers and changed their behavior, by chasing them from the river bottoms into the hills.

Aspens, willows and other water–loving plants began to grow in riperian areas, resulting in the stabilization of crumbling creek banks and increasing the amount of shade. Cold water fish, like trout, returned to shaded, cooler waters. Other animal species also benefitted. Animals that depended on the availability of carrion left by the wolves, such as vultures, crows, and foxes made a strong comeback.

These changes have been examined in many studies of the Yellowstone ecosystem by Ripple as well as Creel, W.D. Smith, and Hebblewhite. The documentary film, Lords of Nature, dramatically shows the effects of these changes, both in Yellowstone and in Zion National Park, where extirpation of mountain lions in the main valley has resulted in its being highly degraded by the ever-increasing deer population. In side canyons, where mountain lions still live, the riperian plant and animal life remains lush.

In Yellowstone, the elk and wolves have alternated in population bursts. When wolf numbers increased, the elk numbers diminished. Then the wolf population, stressed by lack of prey, dropped in turn, enabling the elk to make a comeback. These cycles have been observed a number of times during the wolve's 16 year sojurne in Yellowstone, as the wolves and elk repeated their predator/prey dance.

In recent years, the roles of predators in keeping an equilibrium in other species have been intensively studied in many ecosystems. Their value more appreciated by biologists than by the general public. Who knew for example what profound effects the loss of sharks, who are top marine predators, would have on the world’s fisheries. Shark fin soup anybody?

Scientists debate number of wolves needed for species’ survival

 

Scientists debate ‘magic number’ of wolves needed for species' survival

[To my knowledge, this is the first article in the media to address from a scientific point of view the important issue of how many wolves are needed for a viable population. Chaney points out that according to the Conservation Biology 50/500 rule, from 2,000 - 5,000 wolves are needed in the Northern Rockies to insure a population with sufficient genetic diversity.

He also points out that the areas chosen for reintroduction, Idaho, Montana, and Wyoming, are artificial, ignoring the fact that wolves regularly move back and forth between these states and Canada. 

He looks at the much cited 1987 restoration goal of 150 wolves per state, and bluntly labels it as a dishonest political, and not a scientific number. Ed Bangs, the retiring Wolf Coordinator for USFW has admitted as much in a recent interview.

Finally, I would be remiss in not stating that Chaney's enlightening article appears to have come too late to save Northern Rockies wolves. As most readers know, they have been removed from the protection of the ESA. Idaho's and Wyoming's stated plans for them, will basically lead to either their total extermination or to their reduction to a few struggling packs and lone wolf wanderers, that will have little or no effect on the ecosystem and will be seldom even glimpsed in our forests.]

by Ken Fischman

By ROB CHANEY of the Missoulian | Posted: Sunday, May 22, 2011 7:00 am 

Conservation groups and the federal government continue to disagree how many gray wolves are needed in the Northern Rockies to ensure the species’ survival. National Park Service photo

One of the biggest arguments left unresolved by last year's wolf lawsuit was the most obvious: How many wolves are enough?

The U.S. Fish and Wildlife Service took the gray wolf off the endangered species list in 2009, with the caveat that at least 150 wolves and 15 breeding pairs endure in each of the three states in the northern Rocky Mountain population (Montana, Idaho and Wyoming).

Recent surveys found at least 1,700 wolves in that area – more than enough to justify delisting.

But a coalition of environmental groups sued the government, claiming those numbers were wrong. To survive and thrive, they argued, the population needed at least 2,000 and preferably 5,000 wolves.

FWS biologists said they used the best available science to pick their number. Coalition members cited the well-established rules of conservation biology to justify their threshold. While the scientists dueled, U.S. District Judge Donald Molloy decided the case on a technicality and Congress reversed him with a budget rider. Wolves in the Northern Rockies are now delisted, but almost nobody's happy.

*****

Over the past decade, biologists have sought a "magic number" that would simplify endangered species debates. In 2010, an Australian team led by Lochran Traill of the University of Adelaide published a study declaring 5,000 was the population size required to prevent any species' extinction.

"We don't have the time and resources to attend to finding thresholds for all threatened species," Traill told Science Observer Magazine. "(T)hus the need for a generalization that can be implemented across taxa (classes of animals and plants) to prevent extinction."

But another group of U.S. Forest Service researchers along with American and British professors warn that a simple tool may be a flawed tool. While they agree that an easily understood standard helps persuade judges or members of Congress of the need for action, the 5,000 figure doesn't add up. Their paper will be published in the journal Trends in Ecology and Evolution.

"It's natural for any policy maker and practitioner to look for ways of simplifying the overwhelming process of endangered species management," said Greg Hayward of the Forest Service's Alaska Region Office. "If that worked, it would be a delightful world to live in. But if you're really going to do anything positive, in terms of turning around the situation for these species, going for that simple rule of thumb isn't going to help."

Both sides use a lot of math to make their points. Traill and company looked at 1,198 species with a computer model that calculated how many of each would be needed for the plant or animal to survive in the long term. In particular, the study looked at how many are needed to ensure a species doesn't in-breed itself into extinction.

That's key because one requirement to getting off the endangered species list is a population big enough to guarantee genetic diversity. Earthjustice attorney Doug Honnold relied on that in his argument to Molloy, to show why the wolf should remain a listed species.

"If you're talking about genetics, then there are some basic genetic principles that apply across all species," Honnold said. "It's been documented with every species that's been studied."

Honnold referred to what's called the "50-500 rule" which states you need at least 50 breeding-age females of a species for short-term survival or 500 for the long term. In the case of wolves, there's usually only one breeding female in a pack of four to 10 wolves, so the total population number balloons to 2,000-5,000.

*****

The "magic number opponents" respond that genetics isn't everything. In the case of wolves, where might that 2,000-5,000 figure apply? Do we need a minimum viable population in the three states where wolves were reintroduced back in 1995? Or should the figure be spread across the six-state area now delisted by congressional fiat (adding Utah, Washington and Oregon to Montana, Idaho and Wyoming)? Does it count the Canadian wolves that have relations with American packs along the international border?

"Under the Endangered Species Act, we sort of ignore other segments of populations that are outside the United States," said Hayward's colleague, Steven Beissinger of the University of California-Berkeley. "In the case of the paper we did, one thing we found was, the particular technique people used to come up with this minimum number was very context-specific."

In other words, each animal needs its own formula. Passenger pigeons had different lifespans and breeding rates than wolves. They could fly across continents at will, while wolves may be stymied by freeways. Passenger pigeons were, in fact, the most abundant land bird in the continental United States – 3 billion to 5 billion individuals – before the population crashed between 1870 and 1890. [ note: Here I disagree with the reporter. The passenger pigeon population did not crash. It was deliberately exterminated, using the most atrocious means imaginable.]

Science rarely gets to be just science. Lots of scientific reasons justify the wolf's presence on the landscape: It reduces elk populations, which in turn improves the plant communities along streams, which brings back songbirds and beavers.

But reduced elk numbers aggravate a hunting community that's invested millions of dollars to improve elk habitat. Wolves also have proved a poster target for politicians who want to leash the Endangered Species Act.

Natural Resources Defense Council staff scientist Sylvia Fallon said the U.S. Fish and Wildlife Service knew it would face public resistance if it proposed reintroducing lots of wolves, so it picked a deliberately low 150-per-state figure to get the reintroduction in play.

"They (FWS biologists) say they came up with that number in consultation with scientists, but they never said who they were," Fallon said. "It was some guesswork factoring in social and political considerations at the time, what would be acceptable to the states and the public."

FWS attorneys rejected that claim in their court briefs, but they never got to have the argument in Molloy's courtroom. Without ever discussing what an appropriate number should be, the judge only said the federal government illegally used state boundaries to divide a natural population.

*****

Beissinger suggested a better target in the search for the elusive magic number. Instead of a unified field theory of how many of a species is needed to survive, we humans should settle on what risk factor we're willing to work with, he said.

"In my profession, we don't have a single standard that's been set for what degree of risk we're willing to accept for a species to go extinct," he said. "I could make a calculation for a species and say nine times out of 10, it would be viable there, for 50 years. Would that be good enough, or would you want a 95 percent chance, or an 80 percent chance? But it's too naive to use just measures of population size and come up with some rule of thumb whether a population is safe or not."

Reporter Rob Chaney can be reached at 523-5382 or at rchaney@missoulian.com.

Note: some passages were bolded by KF for emphasis

 

Biogeographic And Genetic Factors In Northern Rockies Wolf Populations

 

       Biogeographic and Genetic Factors in Northern Rockies Wolf Populations

Ken Fischman, Ph.D.(Genetics)   April 9, 2008

 

         As we all know, Fish & Wildlife (USFW) has proposed delisting the wolf populations of Idaho, Montana, and Wyoming. They have recently estimated total wolf populations in these three states to be 1,242, with 92 breeding pairs.  Wolf population in Idaho is currently estimated at 672 ( Nadeau et al., 2007), with 42 breeding pairs (Bangs, Personal Communication, 3/8/07).

         Idaho Fish & Game proposes maintaining a minimum of 100 wolves in their state, with a minimum of 15 breeding pairs (IDFG, 10/07). 

         This paper examines these two population targets, some recent thinking about the genetics and biology of wild animal species, and finally the possible biogeographic and genetic consequences of the minimum number of wolves projected by the Idaho authorities.

          First, let’s look at the effects of population size on the viability of a species. The Hardy-Weinberg Principle states that allele frequencies (that is different forms of a gene) will not vary over time in a population. However, this principle only holds for a population sufficiently large to overcome the tendency for Genetic Drift to change gene frequencies. 

         Genetic Drift refers to the tendency for genes to become more common or more rare in successive generations.  It has no preferred direction, and it tends to sweep genetic variants out of the population with time.  It thus opposes Mutation, which introduces novel variants into the population, thus increasing species resiliency.  i.e. the ability to resist demographic shocks and adapt to changed conditions.

         Small populations often show a Founder Effect, in which one or more gene variants increasingly predominate as inbreeding increases. Inbreeding Depression, results from an increase in homozygosity. That is the state in which there are two identical copies of genes.  Homozygosity increases the possibility of recessive alleles expressing themselves. Some of these will turn out to be valuable, but most will be deleterious, thus weakening the genetic fitness of the population.

         Wolf packs, due to their size, and if they are effectively isolated from other wolf populations, also may show a Founder Effect, thus adversely effecting the long-term survival of the population. The increase in homozygosity would in turn be responsible for high frequencies inherited diseases.  This is something that wolf biologists should be on the watch for.

          What counts in small populations is not their census size, but the Effective Population size or number of breeding individuals in the population. The literature on wolves indicates that most packs have only two Effective Breeders.  However, the latest data on Yellowstone packs show multiple breeders within some packs (Smith, 2006).  I am curious as to whether this is also true for other northern Rockies wolf populations.  On the other hand, can this situation be attributed to something unique about Yellowstone wolves, such as access to large prey populations or lack of stress?  An answer to this question would be important for calculating viable population numbers.

         Let’s examine some of the other possible consequences of small population size.  Small populations in particular are prone to large fluctuations in size. Therefore, it is important to consider this in some detail.  Why does this occur?

           Inbreeding is one source of changes in population size.  The smaller the population, the more likely it is that related individuals will breed with each other, and their offspring will have a far higher number of homozygous genes.

         That is hard to detect, but its consequences, although sometimes subtle, can be severe.  Michael Soule showed that inbreeding of Poland Swine lead to deleterious effects in as soon as the second generation.  The inbreeding resulted in decrease in piglets/litter, decreased survival of newborns, and skewed sex ratios.  As we shall see, this last may be of particular importance for wolves.

         As I previously stated, inbreeding leads to lack of genetic diversity, which in turn may result in inability to adapt and evolve under changing conditions.

         There are also Demographic effects.  One such effect would be fluctuations in the size of small populations. Another is possibility of imbalance of sexes, and increasing chances of a same sex generation. For example, 3 offspring’s chance of being the same sex is 0.25 or 1/4.  If a population remains at a low level for several generations, then a same sex generation becomes almost inevitable.

         Here is an example of a problem resulting from such a situation. One of the last populations of Kakapo, an extremely rare, flightless parrot, was found on an island off the coast of New Zealand.  There were 18 of them. Unfortunately, they were all male.

         A small population is also susceptible to  Environmental effects, such as forest fires, disease, climate change, etc

         Anthropogenic effects loom large for small populations.  These are events such as: accidents, hunting, killing of so-called problem Wolves, and illegal takings. This last is of particular importance in Idaho.  Since wolf reintroduction, 59 cases of illegal hunting/killing have been documented by ID F&G.  Due to its furtive nature, this is probably only a portion of such deaths. 

         Also, last year, 45 Wolves were deliberately killed by ID F&G, USFW, and ranchers. These deaths add up to more than 6% of the Idaho Wolf population.

         All of these effects contribute to population decrease, both directly and indirectly by damaging the social structure of a pack.  Most anthropogenic effects are indiscriminate acts with unforeseen consequences.  For instance one of the pack members killed might be the Alpha female.

         There are of course important Genetic consequences, resulting from the decreases in population size brought about by these demographic, environmental, and anthropogenic effects. As previously stated, inbreeding and small population size will increase the degree of Homozygosity. Recessive genes only express themselves when there is a double dose of them. And, because most harmful genes are recessive, this will result in a larger number of unfit animals and a greater number of deaths.

         Homozygosity also results in an increase of Monomorphisms and an associated  decrease of Polymorphisms, which are multiple functional alleles in a population. This can be damaging, especially if genes effecting the Immune system are involved.  The situation can also lead to a continuous and therefore increasing fixation of deleterious genes. We give this the fanciful name of “Muller’s Ratchet,” which is the continual loss of individuals with the smallest number of deleterious genes because there are so few such individuals.  Due to the elimination of these individuals, generation by generation, the population’s genetic load of damaging genes increases, thus decreasing its adaptive fitness, and leading to its eventual extinction.

         As the expression of recessive alleles become more common due to increase in homozygosity, a species becomes less fit because they are less diverse and therefore more subject to mass die-offs due to disease, etc.  Heterozygosity, in contrast, is increased by outbreeding, leading to improved adaptive fitness of the animals.                

          I would like to put the 673 wolves in Idaho in demographic and geographical perspective.  The size of Idaho is 82,751 square miles. That works out as one wolf for every 123 square miles.  The Human population is more than 1,240,000, which means one wolf for every 1,842 people.

         The chief prey of Idaho wolves are Elk. Their 2006 numbers were estimated  by IDFG as 102,706. The Wolf population of Idaho is actually very small in comparison.  There are 153 Elk for every wolf. 

         Geneticists and Biogeographers find it useful to employ the term Minimum Viable Population or MVP.  This is defined as the smallest population size likely to persist indefinitely in a particular area.

         Here is a little history lesson.  Main and Yadov(1971) examined marsupial populations on several Australian offshore islands and came to the conclusion that a minimum of 200 – 300 animals was necessary to maintain those populations.  However, they also concluded that MVP differs from one species to another, and according to conditions.

          Conservation Geneticists usually consider that a population of less than 500 individuals is endangered, Keep in mind however, that what is important to species preservation is not total population, but the number of Effective Breeders, and many Conservation geneticists recommend a minimum of 50  breeder pairs.

          If we assume an average of ten wolves/pack, with one breeding pair, this would extrapolate to a population of 500 wolves.

         It is of course self-evident that larger populations are usually safer for the viability of a species or sub-population of a species. The key question remains as to what is the minimum number of individuals that would put a population at risk of extinction. 

         All of the factors I have previously mentioned are involved in such a determination, but perhaps another factor is more important in this situation. That is whether or not there is such a thing as a megapopulation of wolves in the northern Rockies.

         USFW speaks of a northern Rocky wolf megapopulation, connected by wolves dispersing from packs.  The megapopulation they describe extends from Canada, western Wyoming and Montana to central Idaho, and from there to northern Utah, a distance of approximately 800 miles.

         Such a connection is particularly problematical between central Idaho and Northern Utah, yet the US FW has conflated what appear to be two distinct areas. I do not know of any data that supports this idea. Lets examine the evidence for the existence of such corridors:

         Since wolf reintroduction, and through the winter of 2006, eight wolves traversed between northwest Montana and central Idaho. Of those, only three have successfully bred. Attempts made by wolves to move between the central Idaho and Yellowstone populations have fared even worse. Only one wolf completed the journey in eleven years since reintroduction (Robinson, 2006)

         These numbers of dispersing wolves are so small that they are likely to have little or no effect on gene flow between these populations.  Additionally, the fact that in such a long time, span, only three of the nine dispersing wolves bred, makes it likely that a larger number of wolves would be necessary if their movement between these regions could be successfully translated into significant gene pool effects.

         To settle the question as to whether these so-called corridors have a real effect, it would be best to do comparative genetics studies between populations rather than to continue to track lone wolves.        

         Much has been made of the rapid increase in wolf numbers since the initiation of wolf recovery in the 1990s. This increase has been cited by the USFW as a sufficient reason to remove them from the Endangered Species list.

         Is this population increase truly remarkable, or is it due to the rapid filling of an ecological niche for a keystone predator that had been nearly empty for well over a century?  Only time will tell, but I suspect that as these niches fill, rates of increase in wolf population will slow down. This is especially liable to occur because many of the conditions that led to wolf extinction in the lower 48 in the first place, are recurring. Hunting, culling of so-called problem wolves, and illegal takings may result in destruction of the intricate social fabric of wolf packs, putting them at an even greater risk of a second extinction.  Just the other day, someone in eastern Idaho shot two wolves because they “were near his ranch.”  (KPBX radio, 4/3/08).

         It is a frequent mistake to assume that current trends will persist indefinitely into the future.  To assume that wolf populations will continue to increase at present rates is as biologically naive as were the assumptions of homeowners and Wall Street investors who have lately discovered that ever-increasing housing values are an illusion.  No one escapes the laws of Nature indefinitely.

                  So we turn to the key question of what is the Minimum Viable Population for Canis lupis?  It is important to realize that MVP has two corollaries, having to do with population size and time: (1) The smaller the population, the more likely it will go extinct within a certain time period.  (2) The longer the time period, the more likely extinction is for a population of any size.

         Mark Shaffer, in his studies of Grizzly populations in national parks, suggested that a 95% chance of persistence for 100 years would be a reasonable goal.

         Conservation Geneticists have recently set more stringent parameters of a 99% chance of persistence for 1,000 years.

         In reality, viability is too complex an issue to be reduced to a single number.  A population of some specified size might be viable under one set of circumstances, but not under another set, or viable for one species, but not for another.

         Soule and Gilpin (1987) came to the conclusion that theoretical numbers cannot be relied on, only real data, analyzed in complex ways and checked against real-life situations can be relied upon.  They called this method Population Viability Analysis (PVA).

         So, how large a population is sufficient to insure viability?  Soule stated that arguing from theory, several lines of analysis produce estimates of several thousand or larger. He said “ I am assuming a 95% expectation of persistence, without loss of fitness, for several centuries.  My guess is that it would be in the low thousands.  …estimates below this range should be an automatic signal for scrutiny.” (Soule. 1987)

         However he leaves us with the following warning:  “…anyone who applies the few thousand estimate to a given species, citing this author as an authority, deserves all the contempt that will be heaped on him or her.”

Considering all the evidence accumulated, it is clear that the wolf management plans of the federal and state agencies are not based on sound scientific and genetic data or theory.  If they are carried out as presently planned, they will undoubtedly lead to genetic impoverishment and possibly to a second extinction of wolves in the Rocky Mountain region.

Delisting isn’t based on sound science

 

April 15, 2009

Idaho Statesman

Delisting isn’t based on sound science

BY KEN FISCHMAN, Ph.D. AND NANCY GILLIAM, Ph.D. 

Secretary of the Interior Ken Salazar recently ruled that wolves be removed from the Endangered Species Act protected list.

We do not understand how he could have given this complex issue the thorough review it deserved in six weeks. Sadly, we suspect that this is yet another in a long history of political decisions about wolves, and not the scientific one that we had hoped for from this new administration.

The U.S. Fish and Wildlife Service claims that the wolves have made a significant comeback, and that a population of 1,500 wolves in Idaho, Wyoming and Montana will ensure their continued viability. Their number is not a biological reality, but a bureaucratic concept. In reality, there are three distinct populations, each numbering in the hundreds.

Ed Bangs, the wildlife service wolf coordinator, claimed that he had new evidence of genetic connection between distant wolf populations because, in 11 years, a few wolves have wandered between Yellowstone and Central Idaho. What counts biologically is not that a few lone wolves have made long journeys, but whether they have contributed genes to the other populations.

Bridgett vonHoldt from UCLA and her colleagues, in their recent study of the genetics of 500 wolves, has demonstrated that there is no gene flow between these three geographically distinct populations.

Scientists tell us that by 2050, from one third to one half of all species will go extinct due to climate change and habitat loss. Those already on the brink are likely to disappear first.

The low number of wolves living in the Rockies now leaves them vulnerable to inbreeding and environmental challenges.

With populations segregated, predicted habitat changes from warming temperatures are a further threat. We already are seeing habitat loss because of increased acreage burned in forest fires, increased tree mortality caused by disease and increased severe weather patterns.

The principles of conservation biology, the science that deals with extinction and viability of wild animals, also indicate that present numbers of wolves in the Rockies are too low. Michael Soule, the dean of conservation biology, has estimated that biologically viable populations would be “several thousand or larger.”

Our point is not that the wolves should never be delisted, but that doing so at this time would be premature. In a manner of speaking, the wolves are not yet out of the woods.

We do not have to guess at the consequences of premature delisting. In January, when the Bush administration attempted to delist wolves, they were left unprotected for three months until a federal judge issued an injunction. During that time, 132 wolves were killed. At that rate, the entire Northern Rockies wolf population could go extinct in three years.

The big, unanswered questions are what is the minimum biologically viable population for wolves, and how many wolves are necessary to ensure gene flow between the various populations and to avoid the consequences of inbreeding, such as loss of vigor, birth defects and decreased survivability of pups.

President Obama has been promising us a science-based approach to such issues. In fact, the president stated recently during his stem-cell research signing, “É We make scientific decisions based on facts, not ideology.” This is what we would like to happen with respect to wolves.

We were signatories of a letter to Salazar from Northern Rockies groups urging him to convene an expert panel of non-governmental scientists, who would examine the wolf issues.

Wolves have been a matter of bitter contention in the West. Science-based conclusions of a panel of experts may offer a way out of this dilemma, if both sides could be persuaded to accept its conclusions. If the Salazar decision is left to stand, it is certain that these issues will be dragged into court again.

Ken Fischman is spokesman for the Northern Rockies Wolf Group and Nancy Gilliam is director, Model Forest Policy Program. Both are from Sandpoint.