Zoogeography

“ It is not, therefore, possible to divide the world into realms and regions which shall express the facts of distribution of the entire animal kingdom. Such divisions, which are common in text-books of zoology having but a small section devoted to zoogeography, are at best mere approximations and averages; no good is gained by taking such a comprehensive view of the matter, as the essential object of subdividing the earth's surface is thereby lost sight of. ”

“ Canada, West, Central, and South Africa, India, Ceylon, Burma, Australia, and Tasmania have alike furnished zoological records. We hope that our pages may be still more informative of the great fauna to be found by colonists and travellers in a region over which the sun never sets, that exhibits the extremes of temperature, and comprises great districts still awaiting the visit of a naturalist.
Our contributors have ably maintained the position of 'The Zoologist' as the journal for animal bionomics, and in this work the ornithologists are again far in front. ”

“ It may nevertheless be advantageous to point to some existing anomalies in the geographical development of distinct classes of vertebrata which may be comparable to former conditions of the animal creation brought to light by geology. Thus in the arctic regions, at present, reptiles are small, and sometimes wholly wanting, where birds, large land quadrupeds, and cetacea abound. We meet with bears, wolves, 141 foxes, musk oxen, and deer, walruses, seals, whales, and narwals, in regions of ice and snow, where the smallest snakes, efts, and frogs are rarely, if ever, seen. ”

“ By the collection of great series of specimens in North America and elsewhere in the world it has been proved that it is common for a single species of mammal to occupy a great area, including such diverse climatic conditions as humid forested districts near the sea-level, sections of arid desert plains in the interior, and high rugged mountain slopes. In each area of differing conditions it is ordinarily found that representatives of a species, under certain conditions, vary from those in other areas mainly in shades of color and in proportions. ”

“ If we examine more closely the distribution of animals in any extensive region, we find that different, though closely allied species, are often found on the opposite sides of any considerable barrier to their migration. Thus, on the two sides of the Andes and Rocky Mountains in America, almost all the mammalia, birds, and insects are of distinct species. To a less extent, the Alps and Pyrenees form a similar barrier, and even great rivers and river plains, as those of the Amazon and Ganges, separate more or less distinct groups of animals. ”

“ Geographical Distribution and Migrations of Birds.
I shall now offer a few observations on some of the other divisions of 643 the animal kingdom. Birds, notwithstanding their great locomotive powers, form no exception to the general rules already laid down; but, in this class, as in plants and terrestrial quadrupeds, different groups of species are circumscribed within definite limits. We find, for example, one assemblage in the Brazils, another in the same latitudes in Central Africa, another in India, and a fourth in New Holland. ”

“ Linnæus held, early in the last century, that all creatures which now inhabit the globe had proceeded originally from some such common centre as the ark might have furnished; but no zoologist acquainted with the distribution of species can acquiesce in any such conclusion now. We now know that every great continent has its own peculiar fauna; that the original centres of distribution must have been, not one, but many; further, that the areas or circles around these centres must have been occupied by their pristine animals in ages long anterior to that of the Noachian Deluge ”

“ An intractable and obstinate animal soon becomes a nuisance.
The following, named in the order of their importance, are the species whose zoological park training is a matter of necessity: Elephants, bears, apes, hippopotami, rhinoceroses, giraffes, bison, musk-ox, wild sheep, goats and deer, African antelopes, wild swine, and wild horses, asses and zebras. Of large birds the most conspicuous candidates for training in park life are the ostriches, emus, cassowaries, cranes, pelicans, swans, egrets and herons, geese, ducks, pheasants, macaws and cockatoos, curassows, eagles and vultures. ”

“ The great mass of the vertebrate fossils of the tertiary period consist of mammalia, and this is precisely the class which is of most value in the determination of zoological regions. The animals of the secondary period, though of the highest interest to the zoologist are of little importance to us; both because of their very uncertain affinities for any existing groups, and also because we can form no adequate notion of the distribution of land and sea in those remote epochs. ”

“ It is because all terrestrial and deep-sea animal forms have passed through a littoral phase of existence, and that the littoral animals retain far better than those of any other faunal region the recapitulative larval phases by means of which alone the true histories of their origins can be recovered, that marine zoölogical laboratories on the coast have made so many brilliant discoveries in zoölogy during late years. ”

“ Stations, however, are often so extensive as to include the entire range of many species. Such are the great seas and oceans, the Siberian or the Amazonian forests, the North African deserts, the Andean or the Himalayan highlands.
There is yet another difference in the nature of the change we have been considering. The new animals which we meet with as we travel in any direction from our starting point, are some of them very much like those we have left behind us, and can be at once referred to familiar types; while others are altogether unlike anything we have seen at home. ”

“ As yet there are not so many known to zoologists—that is, not a dozen that have been identified and described as distinct species; but no doubt when the central countries, both of Asia and Africa—with their grand chains of mountains—have been explored by scientific naturalists, at least that number will be found to exist. ”

“ No zoölogist interested in mammals, birds, fishes, or reptiles can fail to find it of value. The geologist finds here the clearest exposition that has been given of the succession of geological events in the mammal-bearing continental formations of the Tertiary and Quaternary of the Western States. The anthropologist finds in the closing chapter on the Pleistocene a key to most of the problems which confront him as to the time of man’s first appearance. The botanist may refer to it for the succession and evolution of flora. ”

“ Although the sub-region we are considering is, for its extent and latitude, richly peopled with animal life, the number of genera altogether peculiar to it is not great. There are, however, several which are very characteristic, and many species, both of the smaller mammalia and of birds, are wholly restricted to it. ”

“ In the other we study fossils in faunal groups, as successive geological faunas, and the geographic diversity in each geological period—i. e., the evolution of geologic faunas and the causes of geographic diversity in each. In a word, we study the laws of distribution of faunas in time geologically and in space geographically, and the causes of these laws in each case. The first is strictly a branch of zoölogy and botany, and we leave it to these specialists. The second alone belongs properly to geology. ”

“ G. Gray, in his "Genera of Birds," enumerates 8000 species. We have still to add the reptiles, and all the invertebrated animals, exclusive of insects. It remains, in a great degree, mere matter of conjecture what proportion the aquatic tribes may bear to the denizens of the land; but the habitable surface beneath the waters can hardly be estimated at less than double that of the continents and islands, even admitting that a very considerable area is destitute of life, in consequence of great depth, cold, darkness, and other circumstances. ”

“ In spite of the rapid progress which the science of zoology has made during the last twenty years, the study of living mammals in captivity remains a comparatively neglected branch of natural history, being almost entirely left to the learned members of zoological societies. The private individuals who have systematically taken up this most interesting work may almost be enumerated on the fingers of one hand—this neglect of so fascinating a pursuit being all the more remarkable considering the activity displayed by naturalists in other departments of the animal world. ”

“ In zoology we must not expect too much. The researches of the expedition will be made in a very high northern latitude, where animal life is scarce. Perhaps the very scarcity of it makes the species which live there more interesting. The extreme northern range of animal or vegetable life is always valuable to know; and accordingly every specimen, more especially of the land fauna, will be an important acquisition to science. ”

“ We studied our type morphologically, when we determined its anatomy and its development, and when comparing it, in these respects, with other animals, we made out its place in a system of classification. If we were to examine every animal in a similar manner, we should establish a complete body of zoological morphology.
Again, we investigated the distribution of our type in space and in time, and, if the like had been done with every animal, the sciences of geographical and geological distribution would have attained their limit. ”

“ No one locality can be regarded as entirely typical of a species' habitat over its range as a whole. According to my philosophy, the ecological niche of a species is subject to geographical variation analogous to the variation to be seen in the morphological characters of the animal itself. Different community associates, including different competitors, prey, and predators, and different physical factors enforce a somewhat different way of life on a species in geographically remote parts of its range. ”

“ For example, in Europe, Asia, and Africa, the large mammals are at present rhinoceroses, hippopotamuses, elephants, lions, tigers, oxen, horses, etc.; and if you examine the newest tertiary deposits, which contain the animals and plants which immediately preceded those which now exist in the same country, you do not find gigantic specimens of ant-eaters and kangaroos, but you find rhinoceroses, elephants, lions, tigers, etc.,—of different species to those now living,—but still their close allies. ”

“ In order to make the book more intelligible to those readers who have no special knowledge of systematic zoology, and to whom most of the names with which its pages are often crowded must necessarily be unmeaning, I give a series of twenty plates, each one illustrating at once the physical aspect and the special zoological character of some well-marked division of a region. Great care has been taken to associate in the pictures, such species only as do actually occur together in nature ”

“ Let us therefore carefully examine the special zoological features of this region, and see how far it resembles, and how far differs from, the Palæarctic.
At first sight the mammalia of North America do not seem to differ much from those of Europe or Northern Asia. There are cats, lynxes, wolves and foxes, weasels, bears, elk and deer, voles, beavers, squirrels, marmots, and hares, all very similar to those of the Eastern Hemisphere, and several hardly distinguishable. ”

“ The aspect of the White River fauna changes in accordance with the direction from which it is approached. If one comes to the study of it from the Eocene, it displays a very modern aspect, given by the almost complete disappearance of the archaic groups of mammals and by the great multiplication of genera and species belonging to the progressive orders. ”

“ We get the reindeer and the mammoth side by side with the hippopotamus and the hyena; we find the chilly cave bear and the Norway lemming, the musk sheep and the Arctic fox in the same deposits with the lion and the lynx, the leopard and the rhinoceros. The fact is, as Mr. Alfred Russel Wallace has pointed out, we live to-day in a zoologically impoverished world, from which all the largest, fiercest, and most remarkable animals have lately been weeded out. And it was in all probability the coming on of the Ice Age that did the weeding. Our Zoo can boast no mammoth and no mastodon. ”

“ Reciprocal influence of aquatic and terrestrial species.—The intimate relation of the inhabitants of the water to those of the land, and the influence exerted by each on the relative number of species, must not be overlooked amongst the complicated causes which determine the existence of animals and plants in certain regions. A large portion of the amphibious quadrupeds and reptiles prey partly on aquatic plants and animals, and in part on terrestrial; and a deficiency of one kind of prey causes them to have immediate recourse to the other. ”

“ Whether, therefore, we consider its richness in peculiar forms of animal life, its enormous variety of species, its numerous deficiencies as compared with other parts of the world, or the prevalence of a low type of organisation among its higher animals, the Neotropical region stands out as undoubtedly the most remarkable of the great zoological divisions of the earth. ”