February 1963 | Volume 14, Issue 2
In the spring of 1847 Thomas Woodcock, president of the Natural History Society of Brooklyn, New York, received from England a crate containing several pairs of small, dingy birds. He released them in a city park. None survived the following winter. Woodcock repeated his experiment with a similar lack of success each of the following three or four springs. In either 1851 or 1852 his persistence was rewarded, and Passer domesticus , the house sparrow, joined Rattus norvegicus , the house rat, Mus musculus , the house mouse, and Homo sapiens , the house builder, in the ranks of America’s major settlers.
All four of these immigrant species continue to prosper here despite the way the first three annoy the fourth. Many other varieties of once-foreign fauna and flora also thrive in the hospitable hemisphere to which they have come.
Many animal interchanges took place in the distant past between Siberia and Alaska via the land bridge which repeatedly has risen above and sunk below the waters of Bering Strait. Paleontologists have found that some animals that long seemed typically western hemisphere types—such as bison and black bears—actually may have done most of their evolving in the eastern hemisphere and crossed the bridge only a few million years ago. Others, such as horses and camels, were absent here when Columbus arrived but had originated here and traveled to the Old World late in the course of their development. In the last few hundred centuries the Indians have been the only notable new form of life to cross the bridge. (The dogs they brought with them from Siberia, apparently their only companions, were scarcely different from native wolves and coyotes.)
The Indians settled into inconspicuous niches throughout most of the hemisphere and provided minimum competition for native species. Ever since 1492, however, most immigrants have been the opposite of inconspicuous and uncompetitive. The hemispheric balance of nature still gyrates dizzily in response to them.
By far the most obvious in impact are the domesticated plants that now blanket millions of acres. With only a few notable exceptions all the cereals, fruits, and table vegetables commonly grown in this hemisphere originated in Asia, Africa, or Europe and have arrived here since Columbus. The Admiral himself brought along a wide variety of seeds on his second voyage, and most of the other explorers did the same. Jacques Cartier, for instance, reported that on his 1541 voyage up the St. Lawrence River, “We sowed seeds of our country, as cabbages, turnips, lettuces and others, which grew and sprung up out of the ground in eight days.”
Oddly, the better an immigrant plant has thrived here, the lower the U.S. human immigration quota is likely to be for the region from which the plant originated. Among non-native cereal grains, for instance, by far the most important is wheat, which originated in the Near East; only rye, a decidedly minor crop, may have originated in Europe, and probably low-quota southeastern Europe at that. Of fruits, apples are from the Caspian Sea region; peaches and apricots, from China; watermelons, from Africa; cherries, from the Near East; oranges, lemons, and grapefruit, from southeast Asia. Only such lesser ones as raspberries can claim any European ancestry. Of vegetables, peas are from Central Asia; radishes, from China; spinach, carrots, and lettuce, from western Asia; cabbage, from the eastern Mediterranean area. Only the likes of Brussels sprouts and rutabagas are from the high-quota lands of northern Europe.
Two of the most important plants used as human food in this country are wholly American in origin but had to go abroad in order to gain acceptance here. One of these, the white potato, was domesticated far back in prehistoric times by the Indians of the high Andes. So important was this vegetable there that Aymara, a language spoken by Indians of southern Peru, had 209 different terms for different kinds of potato. Hantha , for instance, meant “an old potato with black skin and white flesh.” Other terms indicated where the potato was to be grown or how well it resisted frost and so on.
To reach North America the potato had to travel first to Spain about the end of the sixteenth century. A few decades later it landed in the British Isles. What seem to have been the first potato plantings in this country were made by Irish immigrants to New Hampshire about 1720. The tomato took an even longer way round. Probably a native of either Mexico or the Andes, it apparently was never of much importance to (he pre-Columbian Indians who domesticated it, but when it arrived in southern Europe at the end of the sixteenth century, it caught on quickly, just possibly because some promoter had the bright idea of calling it la pomme d’amour . Two centuries later Thomas Jefferson, always ready to try something new, brought a few plants back from Europe. But here the hint of aphrodisiac qualities meant to many that the fruit was certainly sinful and possibly poisonous. Not until near the end of the last century did the love apple finally begin to attain general respectability in America.
Although the proportion of immigrants among our domesticated plants is high, that among our domesticated animals is even higher. The only domesticated animal of much importance that is a native and faithful resident of this hemisphere is the turkey. (As noted, the horse and camel lived lengthily abroad.) Indeed, add two minor ones, the llama and the guinea pig, and you have about the whole list. Europe has been niggardly in this respect, too, having supplied only the domestic pigeon and the reindeer, and Africa has yielded only the donkey and the cat. All those of great economic importance in this country come from Asia-chickens from the southeastern jungles of that continent, and cattle, sheep, goats, and hogs from its arid southwestern areas. (Modern dogs probably have among their ancestors wolves and jackals of all the continents except Australia, which had no canines until men let doa;s run wild there and created the dingo.)
The colonial evaluation of domesticated animals was a good deal different from the modern in many ways. In early New England, for instance, goats were far more popular than sheep because they gave more milk and required less care. And throughout most of the North American colonies black cattle were worth ni least twice as much as red. The theory was that black cattle would fool the wolves, who were used to preying on reddish deer. Since wolves pay more attention to the news from their noses than to that from their eyes, this was pure nonsense, but that did not affect the theory’s status as an established verity for several generations. Some westering families even dragged it along step-by-step all the way across the continent.
All the farm animals from southwestern Asia found this hemisphere much to their liking, in 1591 Henry May, the first Englishman to write of Bermuda, reported that it was swarming with wild hogs probably descended from a few deliberately left there to multiply by sailors who thought they might be back that way some day. The Virginia colonists later took to sailing out to the island just to hunt the hogs. And in 1598 a group of French sailors left on Cape Sable Island, off Nova Scotia, found wild cattle, sheep, and goats, whose ancestors probably had been left for the same purpose as Bermuda’s hogs.
But by far the most remarkable reaction to this hemisphere of any domestic animal immigrant was that of the horse. As noted earlier, the horse family did much of its evolving here. From the time of the fox-sized Eohippus of the Eocene period, some sixty million years ago, until probably more than three thousand years ago, horses of one kind or another, and sometimes of several different kinds simultaneously, were standard features of the hemispheric fauna. The early Indians hunted a species much like the modern horse, though it had a heavier, deeper-jawed, zebra-like skull and a more compact body. In On the Origin of Species Charles Darwin puzzled over this animal’s extinction and could conclude only that some unknown factor or factors had been unfavorable to it. The reason for his puzzlement was the spectacular success in the wild of the modern horses that escaped from the herds brought in by Spanish colonizers.
When Hernando Cortes landed in Mexico in 1519 with seventeen horses, the animals terrified the Aztec soldiers. It took only a few exposures to change the reaction of the Aztecs and most other tribes of Indians from fear to covetousness. That covetousness led to the institutionalization of horse thievery, usually in the form of raids by one tribe on the herds of another. The raids were noisy affairs that often drove more horses into the wild than into the raiders’ corrals. Within a couple of centuries this process populated the range lands of Argentina, Uruguay, southern Brazil, Mexico, the United States, and Canada with what may well have been the greatest horse herds the world has ever known. It has been estimated that at their peak on the western U.S. prairies in the middle of the last century there may have roamed between two and five million horses.
While the stocking of the American wilderness with horses was accidental, another class of animal has been the subject of countless thousands of experiments in deliberate stocking—namely, game birds. Only a very few of the experiments have succeeded.
Formosan teal, European corn crakes, Norwegian willow ptarmigan, Finnish capercaillie, bamboo partridges, Cyprian francolin, West African guinea fowl, and scores of other species of shootable birds have been imported and turned loose repeatedly in every part of the country by state game commissions, local rod and gun clubs, and private individuals. A typical case of such involuntary immigration was that of the Egyptian quail. One spring some years ago, the game commissions of several eastern states joined to import thousands of pairs of these birds. All went well for several months, and the birds raised many broods. But in November they disappeared and were never seen again, except by a ship some hundreds of miles off Cape Hatteras. A few hundred exhausted quail settled briefly on the vessel before continuing their hopeless flight. It had not occurred to anyone to investigate the species’ migrating habits. Since they habitually took a southeasterly course, the start from our eastern seaboard meant that they must inevitably perish in the open sea.
Only three eastern hemisphere game birds have thus far settled in this country with any notable permanence. By far the most conspicuous success has been that of the ring-necked pheasant. A century of fruitless efforts to persuade this bird to settle here preceded the arrival of several pairs from Shanghai in Oregon’s Willamette Valley in 1881. Today, their descendants are scattered from coast to coast across the northern half of the country and number in the millions. A few decades later the Hungarian partridge found the northern Great Plains to its liking and became firmly established there, and since World War II the chukar partridge from Asia Minor has taken hold in the arid parts of the Northwest.
By coincidence, the big successes among the nongame bird immigrants also number three. The first of these to become established here was the common pigeon, or rock dove, a feral descendant of domesticated pigeons kept by Virginia colonists as early as 1621. Its wild ancestors nested in cliffs, but it has found the ledges and cornices of human dwellings far safer and more comfortable. The reason for its prospering appears to be that, unlike most native species, it can not only tolerate but actively profit from the changes wrought by man in the ecology of the continent.
The same is true of the other two—the house sparrow and the starling. The former is often called the English sparrow, presumably because that is where the Brooklyn Natural History Society’s President Woodcock got the ones he turned loose; actually it is neither a sparrow nor of English origin. It is an African weaverbird. And not only does it profit from human activities, but it also adapts itself with remarkable facility to changes in those activities.
During the bird’s first sixty years in this country, for instance, its chief and overwhelmingly plentiful food supply was the undigested grain in horse droppings. When that supply began to dwindle, it switched to a great variety of other food sources. Now some of the birds hang around filling stations to pick up the dead insects that fall off cars when they stop for gasoline. Others can be found dining on beach sea wrack and snatching bits of angleworms away from robins five times their size.
Today, however, the starling is by far the most successful of all immigrant birds, game or otherwise, in adaptation to the ecological revolution effected by humans on this continent. It also does better than native birds; some ornithologists think it may now be the most abundant bird in the hemisphere. And it has accomplished all this in little more than seventy years.
Shakespeare started the whole thing. In Henry IV , Part I, he made Henry Percy (Hotspur) say: “I’ll have a starling shall be taught to speak …” Three centuries after this was written, a German-born American drug manufacturer named Eugene Schieffelin, who doted on Shakespeare, decided that he wanted to do something for both his adopted land and his favorite dramatist and that the something should consist of transplanting to the former birds of every species mentioned in the plays of the latter. Shakespeare had a word to say about a great many birds, and Schieffielin had plenty of funds to devote to the enterprise. He devoted most of them to importing and releasing in and around New York City hundreds of pairs of skylarks, song thrushes, nightingales, and suchlike. None survived long enough to raise broods. On March 6, 1890, he finally got around to starlings and turned forty pairs loose in Central Park. The next spring he loosed another twenty pairs in the same place. At last he achieved success.
For millions of Americans the results of that success grow more annoying year by year. A discovery a few years ago by the custodian of the state capitol in Springfield, Illinois, added a frightening dimension to that annoyance. He noticed that the roof seemed to be sagging. He investigated. He found that it was covered by more than ten tons of starling droppings.
Only two immigrant mammals, other than man, have rivaled the starling’s proliferation in this hemisphere. Like the starling, both owe man a great deal, although he has never sought to be helpful to either. They are the house rat and the house mouse.
With man’s help the house rat has scored one of the more spectacular biological triumphs in the history of life on earth. Yet the first record we have of it goes back only 236 years. In 1727 a great horde of the creatures engulfed the city of Astrakhan on the northern shore of the Caspian Sea. They apparently had originated somewhere in eastern Siberia, and some unknown compulsion drove them westward. Within a few months they reached Germany and within a year, England. In 1775 their first known representatives landed in Boston. Others were resident in San Francisco in time to greet the forty-niners. Today the species is established all over both temperate zones.
Unintentionally, we human beings have been especially helpful to rat immigrants in this hemisphere. We have provided them transportation hither. We have cleared out the native rodents which might have resented and resisted their intrusion (the squirrel-like American wood rats, for instance, find civilized man and his works so distasteful that they long ago withdrew from all settled areas). And we have set for them a most magnificently bounteous table. Rodent control specialists of the U.S. Fish and Wildlife Service estimate that in this country alone we spend, albeit involuntarily, an annual average of three dollars per person on feeding our 100,000,000 house rats.
House mice probably outnumber house rats in this country by about three to one, but since they average only one-half ounce compared with the rat’s twelve ounces, they cost somewhat less than a third of a billion dollars a year to feed. Their debt to man is of somewhat longer standing, however. They seem to have originated in Central Asia at least several thousand years ago, and they moved in on humans way back in Neolithic, mud-hut times. The first ones to reach this hemisphere probably arrived with the early Spanish explorers. They now are comfortably domiciled in every part of it from Alaska to Tierra del Fuego.
A third immigrant rodent that arrived along with the house mouse was what now usually is called the roof, or black, rat. Smaller than the house rat, it too apparently originated in eastern Siberia. It reached the Near East by the time of the Crusades and voyaged to western Europe with returning Crusaders. It had the run of man’s world until the appearance of the modern house rat in the eighteenth century. This close cousin attacks the roof rat on sight, nearly always wins the battle, and has taken over most, though not quite all, the choicer rat quarters provided by man.
The roof rat received the specific formal name, Rattus rattus . The house rat’s formal name, Rattus norvegicus , is as inappropriate as the name of the English sparrow and is a slander on the people of Norway. When the rats first turned up in England in 1728, the Hanoverian dynasty was new and much despised by some Britons. A rumor got started that the new rodent had been seen swimming ashore from the very ship that brought the recently installed George II to the country. For a while the animal was informally known as the Hanoverian rat. But a naturalist named John Berkenhout heard a false rumor that the rat had actually arrived in England along with a shipment of lumber from Norway. He formally proposed the name Rattus norvegicus . The rule of the international system for agreeing on scientific names is that the first one formally proposed for a new species must be given precedence. Berkenhout’s was the first.
Another unadmired animal immigrant also bears the name of a European nation that resents the association, but in this case the country was the creature’s original home. This is Blatella germanica , the German cockroach. Today, a little carelessness in housekeeping in almost any part of the globe is likely to result, when someone suddenly turns on a light in a dark kitchen, in the sight of a number of half-inch-long creatures darting for the nearest crevices. (One of the few places where these creatures are not called German cockroaches is Germany. In the northern part of that land they are known as Swabian roaches. In the southern part they are Prussian; in the eastern part, Russian; and in the western part, French.)
Not nearly so widespread in this hemisphere as the German cockroach but much more damaging where they have appeared are two other immigrant insects—the Japanese beetle and the gypsy moth. In Japan the former is not a serious pest, but it has been very much so here since it established itself in New Jersey about 1910. It apparently arrived in the form of grubs in the roots of imported nursery stock and has gradually spread westward. The gypsy moth, specimens of which accidentally escaped from the custody of a French naturalist who brought them to Medford, Massachusetts, for experimental tests in 1869, is a native of Europe that feeds on the leaves of many kinds of trees.
Another European immigrant introduced by a naturalist a few years later was the carp. The naturalist was Spencer F. Baird, secretary of the Smithsonian Institution, and few secretaries of scientific organizations have earned more bitter denunciation for their efforts. In countless ponds and streams throughout the hemisphere the fertile and adaptable carp have blotted out the native fish favored by sport fishermen. But eventually Baird may be vindicated. If the hemisphere’s human population continues increasing at the anticipated rate, there will inevitably come about the kind of protein shortage that already afflicts much of the Old World, and carp are one of the most efficient organisms known for turning vegetation into protein.
The Americas’ contributions to the rest of the world have been far fewer, but some emigrants have made big impressions. Among the few native North American animals that have taken to life in other lands are whitetailed deer and gray squirrels. A number of the former were turned loose in New Zealand in the hope that they would provide good hunting. Now the New Zealand government provides free ammunition to anyone who will shoot them and keeps a small army of hired hunters in the field in an effort to hold down the deer’s numbers. In South Africa the North American gray squirrel similarly astonished and horrified its sponsors by passing up the local oaks and acorns in favor of orchards, where it has debudded thousands of trees.
Even more unwelcome abroad has been a little native American beetle with bright yellow and black stripes down its back. When first noticed early in the last century, it was a species of some rarity, apparently confined to the eastern slopes of the Rockies and to a diet of the leaves of such weeds as the beaked nightshade. White potatoes belong to the nightshade family. The first taste of leaves of potato plants put out by settlers persuaded the bugs to abandon the weeds, and the location of their first enthusiastic attack on potatoes in the early 1860’s won them the popular name, Colorado potato bug. The nutritious new diet fed a population explosion among the beetles; by 1865 the first hordes had reached Illinois, and by 1874 others were on the Atlantic coast and seeking new frontiers.
Their first foray into Europe was in 1877, when a small number were found in Belgium. That advance party was wiped out. For half a century stringent measures similarly destroyed every other beetle beachhead. World War I weakened these defenses and gave the creatures a foothold in France. They slowly fought their way eastward, and their successful invasion of Polish and Russian potato fields after World War II led to Russian charges that the United States was waging underhanded biological warfare.
A number of western hemisphere plant emigrants have been received more enthusiastically. North American tobacco, Central American sweet potatoes, and pineapples from South America were early successful emigrants to the Old World. Many kinds of beans—lima beans, string beans, pea beans, kidney beans—were under cultivation from Peru to New England when Columbus arrived, and they quickly caught on in one place or another abroad.
Next in importance to potatoes among western hemisphere gifts to the rest of the world is corn. Columbus took seeds to the eastern hemisphere on his first trip back, but corn was a long time winning acceptance there. The Elizabethan historian of exploration, Samuel Purchas, quoted an early traveler in Africa who had described seeing corn growing in a Portuguese colony there and remarked: “They make no account of it for they give it to their Hogs.” The observer was hasty with his no-account. Corn’s great virtue is precisely as a livestock feed. About eighty-five per cent of the crop in this country usually goes to hogs, cattle, and chickens, and our enormous corn harvests are among the chief reasons for our plenitude of meat. In the last few decades the rest of the world has come to understand this, and corn acreages have been increasing everywhere.
But cases like that of the starling in this country and the white-tailed deer in New Zealand have shown that a good thing in one place is not necessarily a boon somewhere else. Nowadays men tend to be far more cautious than they once were in helping other species migrate from one part of the globe to another. Some authorities argue vehemently in favor of the most rigid international quarantines of all forms of life, and a number of laws aiming at this goal have been passed by the United States Congress and other legislatures.
The difficulty about such laws is that few would-be migrants take the trouble to find out whether the trip they have in mind is legal. The most rigid exclusionists admit that it is scarcely possible to make absolutely certain that bacteria, fungi spores, and other microscopic forms of life will stay where they belong or go back where they came from. Realistically speaking, it is only the larger, more readily noticeable species of insects, crustaceans, fish, birds, and mammals that they can hope to keep put. Even this hope is often vain.
Ten years ago a Florida bird-watcher took pictures of some strange birds that had landed in his pasture. It took him a long time to get them identified. They were African cattle egrets. Their ancestors a generation or two back had in some unknown way crossed the Atlantic and settled down. They still are multiplying rapidly and now range all along our Atlantic coast.
Advocates of stringent quarantine darkly insist that it is too early to be sure that these birds will not have a disastrous effect on the balance of nature here. Others admire the egrets’ enterprise and take comfort in the evidence that the effect of Homo sapiens and his fellow immigrants on this hemisphere has not yet rendered it utterly repugnant to all other forms of life.