Monday, 30 December 2019
Saturday, 28 December 2019
Do every Species have its Niche?
Every species has its niche, its place in the grand scheme of things. Consider a wolf-spider as it hunts through the litter of leaves on the woodland floor. It must be a splendid hunter; that goes without saying for otherwise, its line would long since have died out. But it must be proficient at other things too. Even as it hunts, it must keep some of its eight eyes on the look-out for the things that hunt it; and when it sees an enemy it must do the right thing to save itself. It must know what to do when it rains. It must have a lifestyle that enables it to survive the winter.
It must rest safely when the time is not apt for hunting. And there comes a season of the year when the spiders, as it were, feel the sap rising in their eight legs. The male must respond by going to look for a female spider, and when he finds her, he must convince her that he is not merely something to eat—yet. And she, in the fullness of time, must carry an egg-sack as she goes about her hunting, and later must let the babies ride on her back. They, in turn, must learn the various forms of fending for themselves as they go through the different molt of the spider’s life until they, too, are swift- running, pouncing hunters of the woodland floor. Wolf-spidering is a complex job, not something to be undertaken by an amateur. We might say that there is a profession of wolf-spidering.
It is necessary to be good at all its manifold tasks to survive at it. What is more, the profession is possible only in very restricted circumstances. A woodland floor is necessary, for instance, and the right climate with a winter roughly like that your ancestors were used to; and enough of the right sorts of things to hunt; and the right shelter when you need it; and the numbers of natural enemies must be kept within reasonable bounds. For success, individual spiders must be superlatively good at their jobs and the right circumstances must prevail. Unless both the skills of spidering and the opportunity are present, there will not be any wolf-spiders. The “niche” of wolf-spidering will not be filled. “Niche” is a word ecologists have borrowed from church architecture. In a church, of course, “niche” means a recess in the wall in which a figurine may be placed; it is an address, a location, a physical place. But the ecologist’s “niche” is more than just a physical place: it is a place in the grand scheme of things. The niche is an animal's (or a plant's) profession.
The niche of the wolf-spider is everything it does to get its food and raise its babies. To be able to do these things it must relate properly to the place where it lives and to the other inhabitants of that place. Everything the species does to survive and stay “fit” in the Darwinian sense is its niche. The physical living place in an ecologist's jargon is called the habitat. The habitat is the “address” or “location” in which individuals of a species live. The woodland floor hunted by the wolf-spiders is the habitat, but wolf-spidering is their niche. It is the niche of wolf-spidering that has been fashioned by natural selection. The idea of niche gets at the numbers problem without any general questions that ecologists want to answer—the question of the constancy of numbers. The common stay common, and the rare stay rare, because the opportunities for each niche, or profession, are set by circumstance. Wolf-spidering needs the right sort of neighbors living in the right sort of wood, and the number of times that this combination comes up in any country is limited.
So, the number of wolf-spiders is limited also; the number was fixed when the niche was adopted. This number is likely to stay constant until something drastic happens to change the face of the country. Likening an animal’s niche to a human profession makes this idea of limits to number very clear. Let us take the profession of professing. There can only be as many professors in any city as there are teaching and scholarship jobs for professors to do. If the local university turns out more research scholars than there are professing jobs, then some of these hopeful young people will not be able to accept the scholar's tenure, however, cum laude their degrees. They will have to emigrate or take to honest work to make a living. Likewise, there cannot be more wolf-spiders than there are wolf-spider jobs, antelopes than there are antelope jobs, crabgrass than there are crabgrass jobs. Every species has its niche. And once its niche is fixed by natural selection, so also are its numbers fixed.
This idea of niche gets at the numbers problem without any discussion of breeding effort. Indeed, it shows that the way an animal breeds has very little to do with how many of it there are. This is a very strange idea to someone new to it, and it needs to be thought about carefully. The reproductive effort makes no differ ence to the eventual size of the population. Numerous eggs may increase numbers in the short term, following some disaster, but only for a while.
The numbers that may live are set by the number of niche-spaces (jobs) in the environment, and these are quite independent of how fast a species makes babies. But all the same, everyone must try to breed as fast as it can. It is in a race with its neighbors of the same kind, a race that will decide whose babies will fill the niche-space jobs of the next generation. The actual number of those who will be able to live in that next generation has been fixed by the environment; we may say that the population will be a function of the carrying capacity of the land for animals of this kind in that time and place. But the issue of whose babies will take up those limited places is open. It is here that natural selection operates. A “fit” individual is, by definition, one that successfully takes up one of the niche-spaces from the limited pool, and the fitness of a parent is measured by how many futures niche-spaces her or his offspring take up. “Survival of the fittest** means survival of those who leave the most living descendants.
A massive breeding effort makes no difference to the future population, but it is vital for the hereditary future of one’s own line. Therefore, everything that lives has the capacity for large families. Yet these are degrees of largeness in wild families, and these degrees of largeness make sense when looked at with an ecologist’s eye. The intuitively obvious consequence of a law that says, “Have the largest possible family or face hereditary oblivion,’* is the family based on thousands of tiny eggs or seeds. This seems to be the commonest breeding strategy. Houseflies, mosquitoes, salmon, and dandelions all do it. I call it “the small-egg gambit.’’
It has obvious advantages, but there are also costs, which the clever ones with big babies avoid. For users of the small-egg gambit, natural selection starts doing the obvious sums. If an egg is made just a little bit smaller, the parent might be able to make an extra egg for the same amount of food eaten, and this will give it a slight edge in the evolutionary race. It is enough. Natural selection will, therefore, choose families that make more and more smaller and smaller eggs until a point of optimum smallness is reached. If the eggs are any smaller than this, the young may all die; if they are any larger, one’s neighbor will swamp one’s posterity with her mass-production. The largest number of the smallest possible eggs makes simple Darwinian sense. But the costs of the small-egg gambit are grim. An inevitable consequence is that babies are thrown out into the world naked and tiny. Most of them as a result die, and early death is a common lot of baby salmon, dandelions, and the rest.
In the days before Darwin, people used to say that the vast families of salmon, dandelions, and insects were compensations for the slaughter of the young. So terrible was the life of a baby fish that Providence provided a salmon with thousands of eggs to give it a chance that one or two might get through. It seems a natural assumption and one that still confuses even some biologists. But the argument is the wrong way around. A high death rate for the tiny, helpless young is a consequence of the thousands of tiny eggs, not a cause. A selfish race of neighbor against neighbor leads to those thousands of tiny eggs, and the early deaths of the babies are the cost of this selfishness.
There is this to be said for the small-egg gambit, though; once you have been forced into it, there are the gambler’s compensations. Many young scattered far and wide mean an intensive search for opportunity, and this may pay off when the opportunity is thinly scattered in space. Weed and plague species win this advantage, as when the parachute seed of a dandelion is wafted between the trunks of the trees of a forest to alight on the fresh-turned earth of a rabbit burrow. The small-egg gambits of weeds may be likened to the tactics of a gambler at a casino who covers every number with a low-value chip. If he has enough chips, he is bound to win, particularly if big payoffs are possible. He does have to have very many chips to waste, though.
Therefore economists do not approve of gamblers. To the person with an economic turn of mind, the small-egg gambit, for all its crazy logic, does not seem a proper way to manage affairs. The adherents of this gambit spend all their lives at their professions, winning as many resources as possible from their living places, and then they invest these resources in tiny babies, most of whom are going to die. What a ridiculously low return on capital. What economic folly. Any economist could tell these animals and plants that the real way to win in the hereditary stakes is to put all your capital into a lesser number of big strong babies, all of which are going to survive. Several animals in fact do this.
I call it “the large-young gambit.'* In the large-young gambit one either makes a few huge eggs out of the food available, or the babies grow inside their mother, where they are safe. Either way, each baby has a very good chance of living to grow up. It is big to start with and it is fed or defended by parents until it can look after itself. Most of the food the parents collect goes into babies who live. There is little waste. Natural selection approves of this as much as do economists. Big babies who have a very good chance of long life mean more surviving offspring for food-investment in the end. This prudent outlay of resources is arranged by birds, viviparous snakes, great white sharks, goats, tigers, and people. Having a few, largely young, and then nursing them until they are big and strong, is the surest existing method of populating the future. Yet the success of this gambit assumes one essential condition.
You must start with just the right number of young. If you lay too many monster hen’s eggs or drop too many bawling brats, you may not be able to supply them with enough food, and some or all will die. You have then committed the economic wastefulness of those of the tiny eggs. So, you must not be too ambitious in your breeding. But the abstemious will also lose out, because its neighbor may raise one more baby, may populate the future just that little bit better, and start your line on a one-way ride to hereditary oblivion. You must get it just right; not too many young, and not too few. Natural selection will preserve those family strains which are programmed to “choose” the best or optimum size of the family.
Many ecologists have studied birds with these ideas in mind, and they have found that there is often a very good correlation between the number of eggs in a clutch and the food supply. In a year when food is plentiful, a bird may lay, on the average, one or two eggs more than in a lean season. The trend may be slight but sometimes is obvious. Snowy owls, which are big white birds of the arctic tundra, build vast nests on the ground. They feed their chicks on lemmings, the small brown arctic mice. When lemmings are scarce, there may be only one or two eggs in each owl’s nest, but when the tundra is crawling with lemmings, the nests may well have ten eggs each.
The owls are evidently clever at assessing how many chicks they can afford each year. But people are cleverer than snowy owls and have brought the large-young gambit to its perfection. They can read the environment, guess the future, and plan their families according to what their intelligence tells them they can afford. Even the infanticide practiced by various peoples at various times serves the cause of Darwinian fitness, rather than acting as a curb on population. There is no point in keeping alive babies who could not be supported for long.
Killing babies who could not be safely reared gives a better chance of survival to those who are left, and infanticide in hard times can mean that more children grow up in the end. Thus, every species has its niche, its place in the grand scheme of things; and every species has a breeding strategy refined by natural selection to leave the largest possible number of surviving offspring. The requirement for a definite niche implies a limit to the size of the population because of the numbers of the animal or plant are set by the opportunities for carrying on life in that niche.
The kind of breeding strategy, on the other hand, has no effect on the size of the usual population, and the drive to breed is a struggle to decide which family strains have the privilege of taking up the limited number of opportunities for life. Every family tries to outbreed every other, though the total numbers of their kind remain the same. These are the principles on which an ecologist can base his efforts to answer the major questions of his discipline.
Yohimbine (Corynanthe yohimbe)
Brief Descriptions
Yohimbine (Corynanthe yohimbe), Schizandra fruit (Schizandra chenensis), and Ginkgo (Ginkgo biloba), these three are included together because of their remarkable sexual rejuvenating properties. Particularly when used in conjunction with each other.
Yohimbine is the popularized name of a real tongue-twisting chemical known officially as 17 alpha-hydroxyyohimban-16 alpha-carboxylic acid methyl ester. Yet it has clinically verified aphrodisiac effects to it and is obtained from the bark of an African evergreen by the same name and growing in Cameroon, West Africa.
Schizandra is an aromatic, woody vine with alternate, petiolate and oblong-obovoid leaves. The flowers adorning it may be either pink or white. The nourishing fruit is a collection of berry-like, ripened carpels in a short, spike-like, drooping head that's fleshy but not splitting open when ripened.
Ginkgo happens to be the only living representative left of a once vast order of tall, resinous trees widely distributed throughout the Mesozoic Era. The drupe-like fruit yields yellow seeds when it matures and acquires a rather foul-smelling odor to it.
The outer fleshy a portion of the fruit provokes a very warm sensation to the skin when brought in contact with it. The leaves also are used as well. Both schizandra and Ginko are very popular in Chinese folk medicine for a wide variety of health complaints, especially sexual frigidity.
Ultimate Sexual Rejuvenators
During the stopover visit, one of the experts made a stay at Singapore to Indonesia. He said I had the good fortune of being introduced to an old Chinese herb doctor by the name of Hsii Chingtso. Through an acquaintance who spoke both languages well, I was able to obtain a very old sexual rejuvenating formula that had been in this man's family for at least 17 generations.
What had attracted me to this old gent were the wide number of claims. I had heard from many others (especially men) concerning the amazing effectiveness of his simple formula. I learned that his only three ingredients were yohimbine bark, dried schizandra berries, and ginkgo leaves and seeds.
Now about the medical success of yohimbine as reported in Science. Therein scientists from Stanford University discovered to their astonishment that when impotent male rats were given yohimbine. They went wild and mounted female rodents up to 45 times in less than 15 minutes about twice as often as they normally would. Even when castrated rats were given a shot of the stuff, they climbed longingly on females.
And when I was aware of the in-depth study on yohimbine published in Pharmacological Reviews concerning its fantastic erection-promoting ability when sexual desires were present in men. But when their penile veins weren't up to much contracting.
So, the old fellow's inclusion of one-third yohimbine bark in his powerful sexual stimulant obviously made sense. Therefore, I also knew about the warm, sexual energies attributed to schizandra berries by ancient Chinese herbalists.
But I couldn't for the life of me figure out why he included one-third ginkgo leaves and seeds along with his other one-third schizandra fruit. It was explained to this patient, the old fellow that ginkgo helped to increase the vital "life energies" passing through the brain.
He said it wasn't enough to lift a man's copulating organ holding up a drooping, bony finger that quickly became firm and elevated. As he spoke, but it was also necessary to raise his mental powers of sex as well. This, he believed, is what ginkgo essentially accomplished with the mind, while the other two ingredients worked on the reproductive organs themselves.
He made and sold this the concoction in tablet form, instructing those who purchased the same to take 6-8 tablets at a time at least 30 minutes before sexual activities commenced. In recommending this same formula to different men here in the states who were unable to buy it directly from him.
Then, I soon found that an alcoholic tincture of the yohimbine worked better than when taken in capsule form with the other two ingredients. Mix 6 ounces of powdered yohimbine bark with 4 of a pint of brandy. Shake daily, allowing the mixture to sit for about 12 days.
Strain and bottle. Then when taking approximately 5 capsules of Nature's Way Ginkgold and Nature's Way Schizandra Fruit with adequate water, follow taking these capsules by squirting about a dozen drops of the mixture beneath the tongue and allowing it to enter the bloodstream sublingually. All these herbs may be obtained at most local health food stores or nutrition centers.
Wednesday, 25 December 2019
What Hunting Animals Do?
What Hunting Animals Do? Probably the first man who ever kept sheep lost some to wolves, and cursed the wolves accordingly, passing on his opinions to his offspring so that wolves finally became ogres in fairy tales. In Europe one of the duties of feudal lords was to hunt wolves, and they did it so well that no wolves are left. In Alaska, agents of the the government are still killing wolves from airplanes, with the declared belief that it must be “good” for the “game” to do this.
No doubt part of this attitude stems from fear of the wolf, one of the few animals capable of attacking a man who does not hold a firearm. But our belief in the killing power of predators extends even to those that cannot hurt people. We tell preschool children that cats are necessary to “control” mice; while spiders are “good” because they eat “flies.” In western American states, comic cowboys have been shooting bald eagles from helicopters, giving that age-old excuse of the wolf-killer that the birds were taking their sheep.
Naturalists tend to frown on shooting wolves from airplanes or birds from helicopters, but they find it hard to escape from the underlying philosophy. Predators kill prey, but if they kill it all, they will themselves starve. On the other hand, they will obviously kill as much as they can get. There must be a “balance” between their efforts to kill and the efforts of the prey to escape, a balance that controls the numbers of both predators and prey.
We have learned that the supposed struggle between species is a decidedly muted affair that leads to peaceful coexistence; might not the struggle between predators and their prey be decisive in providing that general balance we see in nature? We are inclined to like this simple idea, but the truth is not so simple.
It is easy to think of a fierce hunting animal such as a tiger or a lion, or the even fiercer combination of wolves hunting together in a pack, as a fearsome scourge for their timid prey. The meek may escape by flight, but it is certain that the hunter must manage to fill its belly at regular intervals, or the big cats and wolves would not exist. We can easily think of their hunting as depredations, as shepherds have always thought of the activities of wolves.
And yet the few careful studies that we have of the last big cats and wolves tell a very different tale. Adolph Murie long ago watched the wolves on Mount McKinley, living for years in the wilderness, recording what the wolves did, and giving us our first impartial study of what big predators really do. A very important part of the wolves’ food supply was wild sheep, and Murie watched the wolves as they hunted. So here was the shepherd’s curse truly at work on sheep that were without the protection of a shepherd. And Murie, in his painstaking way, deciphered a very special record of what the wolves killed.
In the Arctic, before finally decomposing, bones lie about on the frozen ground for years, particularly the hardest parts such as the tops of skulls, and on Mount McKinley there were many whitening skulls of sheep. Murie collected all he found, 608 of them. His years of careful watching told him that the only important cause of death for a Mount McKinley sheep (other than by a human hunter who would take the head) was being killed and eaten by wolves.
So, these 608 skulls represented a large sample of the wolves’ victims. This would not be very informative, but Murie was able to tell the age of each sheep when it was killed by the wolves from growth-rings on the horns. There were only two age classes in the collection of skulls, the very old and the very young. Apparently, these were the only sheep the marauding wolf-packs caught, the infirm old and the feeble young.
Mount McKinley wolves did not kill sheep in the years of their prime; the skull collection showed this very clearly, and it was also quite consistent with Murie’s personal observations of the wolf pack at work. If a pack of hungry wolves is the terrible instrument for destruction described by folklore and fable, this is not what common sense would expect. The wolves did not kill sheep in their prime, which leads us inexorably to the conclusion that they could not. Apparently, natural selection has so fashioned sheep that they can outrun, outclimb, or outwit their formidable adversary.
More recently another pack of wolves has been watched at their hunting, this time on Isle Royale, an island forty miles long in Lake Superior. The only big game on the island that can feed the wolves through the winter are moose, and it is the powerful moose that the sixteen or so wolves of the Isle Royale pack hunt down through the winter snows.
The pack has an appetite that requires one moose every week. From the air David Mech watched to see how they got this moose, picking up the clear trail the wolves left through the deep snow in the early morning, then winging overhead as they went about their hunting. Sixty-nine times he followed them thus. Nine times he was up with the hunt all the way from the find to the check from the check to the view to the kill.
Twice he saw the kill near where he could land his plane, came running at the pack waving his arms to drive the hungry wolves from their meal, and had a look at the carcass himself. Studying chewed-over remains of many more kills, he saw very clearly what happened when the wolf pack closed with a moose.
In the chase itself the wolves were superb. When they had once hit on the trail of a moose there was very little chance of the moose avoiding them as a fox so often avoids fox-hounds. Perhaps this is not surprising, for the trail of a moose running in thick snow would not need much trail-craft in the following, but most of the moose escaped with their lives all the same.
The wolf pack either gave up early or after a short skirmish with a moose that had turned and stood to confront its persecutors. Whenever a prime moose chose its place and stood to fight, the wolves gave up and went away. The moose they closed with and dragged down were always youngsters in their first two years of life, old senile moose, or the sick.
Both Mech’s observations of the hunting and his examination of the remains showed very clearly that the Isle Royale wolves never took prime moose. Like the Mount McKinley wolves, they took only the easy meat from the herd: the old, the young, and the sick.
It is easy to see why the wolves leave prime moose alone; they are too dangerous. There can be little doubt that if sixteen wolves really closed with any moose, they would overcome it, however strong and fit it might be. But some of the wolves would get hurt, and a hurt wolf can hunt no more. The natural selection sees to it that the strain of brave aggressiveness in wolves is purged from the wolf gene pool because such individuals would incur more than an average share of being fatally hurt and thus would leave fewer descendants.
The wolves that have survived the winnowing of natural selection are those that make do with the the prey they can kill without danger to themselves. Since packs of wolves habitually kill neither prime moose nor prime sheep (obviously for different reasons) our preconception that they might regulate the numbers of their prey is bound to develop doubts.
The wolves certainly have some effect on the populations of their victims because they kill some of the young, but this is much less than the depredations that folklore and intuition would lead us to expect. And for other big predators, which hunt alone, the difficulties of severely culling the numbers of their prey are even greater.
The American mountain lion, sometimes called a puma, a cougar, or even a catamount, is small as big cats go, but it is still a powerful animal and it is known to hunt white-tailed and mule deer. The accounts of mountain lions in popular mythology might make it seem as terrible a scourge to the “defenseless” deer as wolves were supposed to be to sheep, yet the reality is again very different.
We still have no good eyewitness accounts of much mountain-lion hunting, partly because the lions are secretive but also because our philosophy of killing them has made them nearly extinct over most of their old haunts. But there are some left in Idaho, and M. G. Homocker recently won a Ph.D. with some remarkable tracking and woodlore in the haunts of the mountain lions.
Homocker found that the Idaho mountain lions in winter are complete loners; each has a tract of wilderness through which it hunts alone. Tracks in the snow showed that this loneliness is from choice because a lion will turn away from the tracks or the presence of another. Even powerful males in their prime will turn aside from a weaker or younger animal. There is no social dominance in this, no expulsion of a weak animal from a superior’s preserves.
Homocker concluded that the lions habit of each keeping to itself had been preserved by natural selection because of the difficult task of hunting. The big cats could only kill deer if the deer were quite unsuspecting. Deer that were nervous because a marauding lion had been through the country were virtually unattackable by another.
Although there were plenty of deer in the wilderness, the mountain lions had to keep a very low profile, or they could not catch deer. This does not sound as if mountain lions kill easily or that they have much influence on the numbers of deer in a wild population.
The big cats are less than impersonal killing machines too. George Schaller relates the killing methods of tigers as they take tethered domestic buffaloes and his account does not suggest that killing is safe or easy for a tiger even with these advantages. The Tigers ran at their prey, half-climbed on their backs, wrestled them to the ground, then dodged the flailing hooves to seize the buffalo by the neck.
It always took several minutes for the buffalo to die. This was not at all the quick surgical operation of killing that nature-story accounts of the big cats would lead us to expect. If it has that much trouble with a tethered domestic buffalo, it is not improbable that a lurking tiger might normally let the formidable animals pass unmolested and look for something more out of sorts.
It is probably generally true that large vertebrate predators go about their killing cautiously. Whether it is a lion or tiger stalking a game herd on the plains, or wolves running down their quarry through a northern winter, the predator always faces the reality that it must kill again and again if it is to survive. Fifty-two desperate encounters a year would be likely to result in hereditary oblivion.
Neither big cats nor pack-hunting canines have the firepower to pull off fifty-two safe butchering’s a year if they attack the fit and the strong. They avoid desperate encounters, unless extreme hunger drives them. Usually, they feed by culling the old, the sick, and the young.
There is no doubt that all these big fierce predators have some effect on the numbers of their prey because they kill the young. But they cannot usually kill a very large proportion of the young because the number of predators is relatively small. The young typically make their appearance at only one time of the year, and the predators must live the rest of it too. The numbers of big cats and wolves that a herbivore mother must look out for in the spring is mercifully low because it will be the number that has been kept alive through the winter by the supply of old and sick animals.
It thus seems very likely that the larger and fiercer predators are not nearly so important in regulating the numbers of animals in nature as common sense suggests. They are really to be looked upon as scavengers without the patience to wait for their meat to die. They cheat the bacteria who would have got the bodies otherwise.
Two rather pleasing thoughts come from this discovery. One is that the lives of big game animals are lived in a large measure of freedom from the awful world of tooth and claw that we can conjure up by a careless reading of Darwin. Not only do these animals live in that peaceful coexistence with their neighbors, which the mathematical ecologists discovered, but they also may live with less fear of being killed than we had supposed, except as a sort of euthanasia.
The second pleasing thought is that those who like to shoot big game themselves no longer have a pretext for killing off the wolves and cats before they start on the deer. But if the firepower of a big cat is insufficient to devastate a herd of game, the firepower of the smaller predators may be truly awful. A spider or a wasp is a deadly efficient engine of destruction.
Perhaps most of the species of hymenopteran insect that we loosely call wasps are in the business of hunting caterpillars and grubs of other insects, piercing them and laying their eggs under the skin, letting the maggots feed and grow on the living flesh of their victims, and eventually flying away from the empty carcass as mature wasps themselves.
Although the victim thus takes longer to die, the crucial predatory act is the initial attack by the female wasp on the caterpillar, and in this encounter the caterpillar stands no chance. When a wasp strikes, it is not like a tiger striking a buffalo; the issue is never in doubt; the chance of the wasps being wounded is zero. The same must be true when a web-spider closes with a fly struggling in it meshes.
It must also be true when a spider-hunting hornet plunges like a dive-bomber, with its armor-plated body and its poison-loaded stinger, on a spider, sighted in the open. It must also be true when a tiger-beetle pounces, when a praying mantis reaches out with its dreadful arms, and when a large carnivorous diving beetle finds a small tadpole.
In all these, the only hopes for the hunted are to escape detection or timely flight. We might expect, therefore, that small predators can have more potent effects on their prey than do large predators. That these small predators can truly be devastating has been shown by the success stories of entomologists when they have ridded farmlands of an agricultural pest by introducing a suitable natural enemy, so-called biological control.
Celebrated among these successes is that of the Californians who rode the orange groves of the little, white, flightless insect called the cottony- cushion scale, which had appeared in plague-like proportions in the 1880s, threatening to destroy the entire citrus industry. The cottony-cushion scale was an Australian insect that must have come to California by the sea in a cargo of fruit, so a Californian entomologist went to Australia to look for enemies of the scale.
He had wasps in mind, and he found some, but they turned out to be ineffective. Then he found an Australian ladybird beetle called the vedalia. A little red ladybird with black spots like those common in Europe and North America. He sent to California a total of 129 live vedalias.
In January the few vedalias were put on an orange tree heavily infested with the cottony-cushion scales and the tree were covered with a muslin tent. By April the tented orange tree was free from scales but rich in ladybirds, and they opened the tent to let the beetles out. By July the whole orchard of 75 trees was free from the pest. The news spread, and planters journeyed far to collect the precious beetles for their own estates. Within a year the whole of southern California was rid of the plague of cotton scales.
This pretty ladybird, the vedalia, has proved itself to be a far more deadly predator than any wolf or tiger. It searches with diligence and kills with utter certainty. It processes the calories from the bodies of its victims into its own babies with such dispatch that the next generation is ready to carry on the killing in just twenty-six days. As we have seen, this ferocious attack can exterminate the prey in an entire country within a season. But what can the ladybirds do then?
Only part of the success of the vedalias was due to their deadliness and mobility; the rest came about because they were given a concentrated target. In the wild Australian home of both the vedalia and the scales, there were no citrus orchards, and the food base of both must have been scattered trees in the forest. Life in a colony of cottony-cushion scales on an isolated forest tree might well go on for generations before a flying beetle found the colony to begin its killing.
And life for vedalia beetles who must hunt them would involve sending out the next generation in pioneering searches for new and distant trees bearing colonies of their food. The scales escaped their enemies by living scattered across the land, and their ladybird hunters got their livelihood by arduous and unremitting searches.
After the first slaughter in California it seems that something like the ancestral Australian the pattern was established between the vedalia beetles and their prey. In later years the infestation was gone, but if you looked hard enough you could find a colony of scales somewhere in the orchards, but they were so few they were no longer a nuisance.
Chance had let a few escapes the attack of the vedalias and they served to found new colonies after the scourge of beetles had passed them by. Each colony would live until a wandering beetle found it when it would be rapidly wiped out. But meanwhile, another colony started up somewhere else. Life for both vedalias and scales became a game of hiding and seek across the spaces of California.
It is likely that games of hiding and seek between predators and prey run on indefinitely for many small species of animals. The outcome is a consequence of devastating killing power, and it can be expected on common-sense grounds as well as predicted by formal mathematics. Scientists make equations that show the numbers of prey growing in the classic geometric way, but which are cut back by the attacks of predators.
In this formal scheme each attack results in a kill, as it will for small animals, and each predator turns its victims into more predators after a suitable time lag for the business of reproduction. The result is a model that predicts the absolute wiping out of the prey as the predator numbers build-up, perhaps after some oscillations. This is what we see in nature.
Locally the prey is wiped out as the model of efficient hunting says it must be, but the game has been started all over again somewhere else by refugees from the first game. The result is a scattered population of prey animals living many generations in security, but occasionally faced with local annihilation. This pattern results even when the game is started on so uniform aboard as was provided by the ranks of citrus trees in the equable Californian climate, but in nature there are many other forces at work to frustrate the hunters.
The plant food of the prey is itself scattered, there are various physical barriers to both search and escape, and the fluctuating seasons, to say nothing of vagaries of the weather, influence the outcome.
In places of seasonal climate both predator and prey must endure a hostile time, perhaps a winter through which they must persist in some quiescent state, as seeds, eggs, or dormant adults. It often happens that only small numbers survive this lean time. With every growing season, therefore, a new game starts, and this game has some of the qualities of a race.
The few prey animals that have got through the winter set about the business of reproduction, probably helped by the lush spring growth of their food plants. But the predators will find little to eat and will not be able to produce many young until later in the summer when the population of its prey will have built up. The predators may not have time to build up devastating populations before the coming of the next winter clears the game board once more for a fresh start.
The lives of small predators and their prey are thus different in fundamental ways from the lives of large animals. Large predators live alongside and within sight of their prey, like a pride of lions lying in the sun as the herds of African game wander by them. This is essential because the weapons of the big hunters are not good enough for the safe pursuit of indiscriminate slaughter.
But this peaceful coexistence is not possible for small predators and their prey, so they must live scattered, the one fleeing and hiding, the other searching and destroying. Moreover, the large animals live through many different seasons, which lets them smooth out the effects of weather. Short-lived insects and their kind pass through several generations a year so that they meet the different seasons with different generations.
The numbers of predators and prey can be differently hit by such adversities as winter. This means that the effective power of the predators is often nullified by the further scattering or reduction of populations. Large predators and prey persist in harmony which owes much to a certain lack of weaponry. Small predators and prey coexist, if not in harmony then in relative safety, because the very deadliness of the weapons combines with chance and their short lives to keep the antagonists scattered and apart.
What Hunting Animals Do? Probably the first man who ever kept sheep lost some to wolves, and cursed the wolves accordingly, passing on his opinions to his offspring so that wolves finally became ogres in fairy tales.Read More – Taq-e-Kasra The Arch of Ctesiphon
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Sunday, 1 December 2019
TIPS FOR ATTRACTING BUTTERFLIES TO YOUR WILDLIFE HABITAT
Trying to attract more butterflies to your garden? It’s easy when you include host plants! Adult butterflies lay their eggs on specific plants, called “host plants,” which serve as food sources for their larvae.
Once consumed, these plants often re-sprout their leaves within the same growing season. Seemingly as payment for services rendered, butterflies (and other insects) pollinate the plants, as they take breaks from egg-laying to sip upon nectar. Witness this cycle in your own garden.
- Locate the garden in a sunny area
- Butterflies and most butterfly-attracting plants require bright sunshine.
- Plant nectar-producing flowers.
- Butterflies visit flowers in search of nectar, a sugary fluid, to eat. Many native butterflies seem to prefer purple, yellow, orange, and re-colored blossoms. Clusters of short, tubular flowers or flat-topped blossoms provide the ideal shapes for butterflies to easily land and feed.
- Select single flowers rather than double flowers.
- The nectar of single flowers is more accessible and easier for butterflies to extract than the nectar of double flowers which have more petals per flower.
- Use large splashes of color in your landscape design.
- Butterflies are first attracted to flowers by their color. Groups of flowers are easier for butterflies to locate than isolated plants.
- Plan for continuous bloom throughout the growing season.
- Butterflies are active from early spring until late fall. Plant a selection of flowers that will provide nectar throughout the entire growing season (e.g. spring: blue-berries, clover, wild cherry; summer: milkweeds, cone flowers, thistle; fall: goldenrod, Joey weeds).
- Include host plants in the garden design.
- Host plants provide food for caterpillars and lure female butterflies into the garden to lay eggs.
- Include damp areas or shallow puddles in the garden.
- Some butterflies drink and extract salts from moist soil. Occasionally large numbers of male butterflies congregate around a moist area to drink, forming a "puddle club."
- Place flat stones in the garden.
- Butterflies often perch on stones, bare soil or vegetation, spread their wings and bask in the sun. Basking raises their body temperature so they are able to fly and remain active.
- Do not use pesticides in or near a butterfly garden.
- Most traditional garden pesticides are toxic to butterflies. Use predatory insects, insecticidal soap or hand remove the pests if problems occur.
Also Read: Lilac Breasted Roller, Most Attractive Bird / Indian Roller Bird / Yellow Cardinal – One in Million Birds
Affiliates Links:
How One Woman Discovered the Female Fat-Loss Code Missed by Modern Medicine And Lost 84lbs Using a Simple 2-Step Ritual That 100% Guarantees Shocking Daily Weight Loss
60 Seconds Habit ! That Reversed Type 2 Diabetes and Melted 56 lbs of Fat
Boost Your Energy, Immune System, Sexual Function, Strength & Athletic Performance
Diabetes Remedy # 1 Mega Offer for 2019
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