THE NEARCTIC REGION.
This region consists almost wholly of Temperate North America as defined by physical geographers. In area it is about equal to the Neotropical region. It possesses a vast mountain range traversing its entire length from north to south, comparable with, and in fact a continuation of, the Andes,—and a smaller range near the east coast, equally comparable with the mountains of Brazil and Guiana. These mountains supply its great river-system of the Mississippi, second only to that of the Amazon; and in its vast group of fresh-water lakes or inland seas, it possesses a feature unmatched by any other region, except perhaps by the Ethiopian. It possesses every variety of climate between arctic and tropical; extensive forests and vast prairies; a greatly varied surface and a rich and beautiful flora. But these great advantages are somewhat neutralized by other physical features. It extends far towards the north, and there it reaches its greatest width; while in its southern and warmest portion it suddenly narrows. The northern mass of land causes its isothermal lines to bend southwards; and its winter temperature especially, is far lower than at corresponding latitudes in Europe. This diminishes the available area for supporting animal life; the amount and character of which must be, to a great extent, determined by the nature of the least favourable part of the year. Again, owing to the position of its mountain ranges and the direction of prevalent winds, a large extent of its interior, east of the Rocky Mountains, is bare and arid, and often almost desert; while the most favoured districts,—those east of the Mississippi and west of the Sierra Nevada, bear but a small proportion to its whole area. Again, we know that at a very recent period geologically, it was subjected to a very severe Glacial epoch, which wrapped a full half of it in a mantle of ice, and exterminated a large number of animals which previously inhabited it. Taking all this into account, we need not be surprised to find the Nearctic region somewhat less rich and varied in its forms of life than the Palæarctic or the Australian regions, with which alone it can fairly be compared. The wonder rather is that it should be so little inferior to them in this respect, and that it should possess such a variety of groups, and such a multitude of forms, in every class of animals.
NEARCTIC REGION
Zoological characteristics of the Nearctic Region.—Temperate North America possesses representatives of 26 families of Mammalia, 48 of Birds, 18 of Reptiles, 11 of Amphibia, and 18 of Fresh-water Fish. The first three numbers are considerably less than the corresponding numbers for the Palæarctic region, while the last two are greater—in the case of fishes materially so, a circumstance readily explained by the wonderful group of fresh-water lakes and the noble southward-flowing river system of the Mississippi, to which the Palæarctic region has nothing comparable. But although somewhat deficient in the total number of its families, this region possesses its full proportion of peculiar and characteristic family and generic forms. No less than 13 families or sub-families of Vertebrata are confined to it, or just enter the adjacent Neotropical region. These are,—three of mammalia, Antilocaprinæ, Saccomyidæ and Haploodontidæ; one of birds, Chamæidæ; one of reptiles, Chirotidæ; two of amphibia, Sirenidæ and Amphiumidæ; and the remaining six of fresh-water fishes. The number of peculiar or characteristic genera is perhaps more important for our purpose; and these are very considerable, as the following enumeration will show.
Mammalia.—Of the family of moles (Talpidæ) we have 3 peculiar genera:Condylura,Scapanus, andScalops, as well as the remarkableUrotrichus, found only in California and Japan. In the weasel family (Mustelidæ) we haveLatax, a peculiar kind of otter;Taxidea, allied to the badgers; and one of theremarkable and characteristic skunks is separated by Dr. J. E. Gray as a genus—Spilogale. In the American family Procyonidæ, a peculiar genus (Bassaris) is found in California and Texas, extending south along the mountains of Mexico and Guatemala.Eumetopias, andHalicyon, are seals confined to the west coast of North America. The Bovidæ, or hollow-horned ruminants, contain three peculiar forms;Antilocapra, the remarkable prong-buck of the Rocky Mountains;Aplocerus, a goat-like antelope; andOvibos, the musk-sheep, confined to Arctic America and Greenland. Among the Rodents are many peculiar genera:Neotoma,Sigmodon, andFiber, belong to the Muridæ, or rats;Jaculusto the Dipodidæ, or jerboas. The very distinct familySaccomyidæ, or pouched rats, which have peculiar cheek pouches, or a kind of outer hairy mouth, consists of five genera all confined to this region, with one of doubtful affinities in Trinidad and Central America. In the squirrel family (Sciuridæ),Cynomys, the prairie-dogs, are peculiar; andTamias, the ground squirrel, is very characteristic, though found also in North Asia.Haploodon, or sewellels, consisting of two species, forms a distinct family; andErethizonis a peculiar form of tree porcupine (Cercolabidæ). True mice and rats of the genusMusare not indigenous to North America, their place being supplied by a distinct genus (Hesperomys), confined to the American continent.
Birds.—The genera of birds absolutely peculiar to the Nearctic region are not very numerous, because, there being no boundary but one of climate between it and the Neotropical region, most of its characteristic forms enter a short distance within the limits we are obliged to concede to the latter. Owing also to the severe winter-climate of a large part of the region (which we know is a comparatively recent phenomenon), a large proportion of its birds migrate southwards, to pass the winter in the West-Indian islands or Mexico, some going as far as Guatemala, and a few even to Venezuela.
In our chapter on extinct animals, we have shown, that there is good reason for believing that the existing union of North and South America is a quite recent occurrence; and that theseparation was effected by an arm of the sea across what is now Nicaragua, with perhaps another at Panama. This would leave Mexico and Guatemala joined to North America, and forming part of the Nearctic region, although no doubt containing many Neotropical forms, which they had received during earlier continental periods; and these countries might at other times have been made insular by a strait at the isthmus of Tehuantepec, and have then developed some peculiar species. The latest climatal changes have tended to restrict these Neotropical forms to those parts where the climate is really tropical; and thus Mexico has attained its present strongly marked Neotropical character, although deficient in many of the most important groups of that region.
In view of these recent changes, it seems proper not to draw any decided line between the Nearctic and Neotropical regions, but rather to apply, in the case of each genus, a test which will show whether it was probably derived at a comparatively recent date from one region or the other. The test referred to, is the existence of peculiar species of the genus, in what are undoubtedly portions of ancient North or South America. If, for example, all the species of a genus occur in North America, some, or even all, of them, migrating into the Neotropical region in winter, while there areno peculiar Neotropical species, then we must class that genus as strictly Nearctic; for if it were Neotropical it would certainly have developedsomepeculiar resident forms. Again, even if there should be one or two resident species peculiar to that part of Central America north of the ancient dividing strait, with an equal or greater number of species ranging over a large part of Temperate North America, the genus must still be considered Nearctic. Examples of the former case, areHelminthophagaandMyiodioctes, belonging to the Mniotiltidæ, or wood-warblers, which range overallTemperate North America to Canada, whereallthe species are found, but in each case one of the species is found in South America, probably as a winter migrant. Of the latter, areAmmodramusandJunco(genera of finches), which range over the whole United States, but each have one peculiar species in Guatemala. Thesemay be claimed as exclusively Nearctic genera, on the ground that Guatemala was recently Nearctic; and is now really a transition territory, of which the lowlands have been invaded and taken exclusive possession of by a Neotropical fauna, while the highlands are still (in part at least) occupied by Nearctic forms.
In his article on "Birds," in the new edition of the "Encyclopædia Britannica" (now publishing), Professor Newton points out, that the number ofpeculiar generaof Nearctic birds is much less than in each of the various sub-divisions of the Neotropical region; and that the total number of genera is also less, while the bulk of them are common either to the Neotropical or Palæarctic regions. This is undoubtedly the case if any fixed geographical boundary is taken; and it would thus seem that the "Nearctic" should, in birds, form a sub-region only. But, if we define "Nearctic genera" as above indicated, we find a considerable amount of speciality, as the following list will show. The names not italicised are those which are represented in Mexico or Guatemala by peculiar species:—
List of Typical Nearctic Genera of Land Birds.
The above are all groups which are either wholly Nearctic or typically so, but entering more or less into the debatable ground of the Neotropical region; though none possess any peculiar species in the ancient Neotropical land south of Nicaragua. But we have, besides these, a number of genera which we areaccustomed to consider as typically European, or Palæarctic, having representatives in North America; although in many cases it would be more correct to say that they are Nearctic genera, represented in Europe, since America possesses more species than Europe or North Asia. The following is a list of genera which have as much right to be considered typically Nearctic as Palæarctic:—
The seven genera italicized have a decided preponderance of Nearctic species, and have every right to be considered typically Nearctic; while the remainder are so well represented by peculiar species, that it is quite possible many of them may have originated here, rather than in the Palæarctic region, all alike being quite foreign to the Neotropical.
On the whole, then, we have 47 in the first and 7 in the second table, making 54 genera which we may fairly class as typically Nearctic, out of a total of 168 genera of land-birds, or nearly one-third of the whole. This is an amount of peculiarity which is comparable with that of either of the less isolated regions; and, combined with the more marked and more exclusively peculiar forms in the other orders of vertebrates, fully establishes Temperate North America as a region, distinct alike from the Neotropical and the Palæarctic.
Reptiles.—Although temperate climates are always comparatively poor in reptiles, a considerable number of genera are peculiar to the Nearctic region. Of snakes, there are,Conophis,Chilomeniscus,Pituophis, andIschnognathus, belonging to the Colubridæ;Farancia, andDimodes, Homalopsidæ;Lichanotus, one of the Pythonidæ;Cenchris,Crotalophorus,Uropsophorus, andCrotalus, belonging to the Crotalidæ or rattlesnakes.
Of Lizards,Chirotes, forming a peculiar family;Ophisaurus,the curious glass-snake, belonging to the Zonuridæ; withPhrynosoma(commonly called horned toads),Callisaurus,Uta,Euphryne,Uma, andHolbrookia, genera of Iguanidæ.
Testudinidæ, or Tortoises, show a great development of the genusEmys; withAromochelysandChelydraas peculiar genera.
Amphibia.—In this class the Nearctic region is very rich, possessing representatives of nine of the families, of which two are peculiar to the region, and there are no less than fifteen peculiar genera.Sirenforms the family Sirenidæ;Menobranchusbelongs to the Proteidæ;Amphiumais the only representative of the Amphiumidæ; there are nine peculiar genera of Salamandridæ. Among the tail-less batrachians (frogs and toads) we haveScaphiopus, belonging to the Alytidæ;Pseudacristo the Hylidæ; andAcristo the Polypedatidæ.
Fresh-water Fishes.—The Nearctic region possesses no less than five peculiar family types, and twenty-four peculiar genera of this class. The families are Aphredoderidæ, consisting of a single species found in the Eastern States; Percopsidæ, founded on a species peculiar to Lake Superior; Heteropygii, containing two genera peculiar to the Eastern States; Hyodontidæ and Amiidæ, each consisting of a single species. The genera are as follows:Paralabrax, found in California;Huro, peculiar to Lake Huron;Pileoma,Boleosoma,BryttusandPomotisin the Eastern States—all belonging to the perch family.HypodelusandNoturus, belonging to the Siluridæ.Thaleichthys, one of the Salmonidæ peculiar to the Columbia river.Moxostoma,Pimephales,Hyborhynchus,Rhinichthys, in the Eastern States;Ericymba,Exoglossum,Leucosomus, andCarpiodes, more widely distributed;Cochlognathus, in Texas;MylaphorodonandOrthodon, in California;Meda, in the river Gila; andAcrochilus, in the Columbia river—all belonging to the Cyprinidæ.Scaphirhynchus, found only in the Mississippi and its tributaries, belongs to the sturgeon family (Accipenseridæ).
Summary of Nearctic Vertebrata.—The Nearctic region possesses 24 peculiar genera of mammalia, 49 of birds, 21 of reptiles, and 29 of fresh-water fishes, making 123 in all. Of these 70 are mammals and land-birds, out of a total of 242genera of these groups, a proportion of about two-sevenths. This is the smallest proportion of peculiar genera we have found in any of the regions; but many of the genera are of such isolated and exceptional forms that they constitute separate families, so that we have no less than 12 families of vertebrata confined to the region. The Palæarctic region has only 3 peculiar families, and even the Oriental region only 12; so that, judged by this test, the Nearctic region is remarkably well characterized. We must also remember that, owing to the migration of many of its peculiar forms during the Glacial period, it has recently lost some of its speciality; and we should therefore give some weight to the many characteristic groups it possesses, which, though not quite peculiar to it, form important features in its fauna, and help to separate it from the other regions with which it has been thought to be closely allied. It is thus well distinguished from the Palæarctic region by its Procyonidæ, or racoons,Hesperomys, or vesper mice, andDidelphys, or opossums, among Mammalia; by its Vireonidæ, or greenlets, Mniotiltidæ, or wood-warblers, Icteridæ, or hang-nests, Tyrannidæ, or tyrant shrikes, and Trochilidæ, or humming-birds, among birds, families which, extending to its extreme northern limits must be held to be as truly characteristic of it as of the Neotropical region; by its Teidæ, Iguanidæ, andCinosternum, among reptiles; and by its Siluridæ, and Lepidosteidæ, among fishes. From the Neotropical region it is still more clearly separated, by its numerous insectivora; by its bears; its Old World forms of ruminants; its beaver; its numerousArvicolæ, or voles; itsSciuropterus, or flying squirrels;Tamias, or ground-squirrels; andLagomys, or marmots, among mammals; its numerous Paridæ, or tits, and Tetraonidæ, or grouse, among birds; its Trionychidæ among reptiles; its Proteidæ, and Salamandridæ, among Amphibia; and its Gasterosteidæ, Atherinidæ, Esocidæ, Umbridæ, Accipenseridæ, and Polydontidæ, among fishes.
These characteristic features, taken in conjunction with the absolutely peculiar groups before enumerated, demonstrate that the Nearctic region cannot with propriety be combined withany other. Though not very rich, and having many disadvantages of climate and of physical condition, it is yet sufficiently well characterized in its zoological features to rank as one of the well-marked primary divisions of the earth's surface.
There is one other consideration bearing on this question which should not be lost sight of. In establishing our regions we have depended wholly upon theirnowpossessing a sufficient number and variety of animal forms, and a fair proportion of peculiar types; but when the validity of our conclusion on these grounds is disputed, we may supplement the evidence by an appeal to the past history of the region in question. In this case we find a remarkable support to our views. During the whole Tertiary period, North America was, zoologically, far more strongly contrasted with South America than it is now; while, during the same long series of ages, it was always clearly separated from the Eastern hemisphere or the Palæarctic region by the exclusive possession of important families and numerous genera of Mammalia, as shown by our summary of its extinct fauna in Chapter VII. Not only may we claim North America as now forming one of the great zoological regions, but as having continued to be one ever since the Eocene period.
Insects.
In describing the Palæarctic and Neotropical regions, many of the peculiarities of the insect-fauna of this region have been incidentally referred to; and as a tolerably full account of the distribution of the several families is given in the Fourth Part of our work (Chapter XXI.), we shall treat the subject very briefly here.
Lepidoptera.—The butterflies of the Nearctic region have lately been studied with much assiduity, and we are now able to form some idea of their nature and extent. Nearly 500 species belonging to about 100 genera have been described; showing that the region, which a few years ago was thought to be very poor in species of butterflies, is really much richer than Europe, and probably about as rich as the more extensive Palæarctic region. There is, however, very little speciality in theforms. A considerable number of Neotropical types enter the southern States; but there are hardly any peculiar genera, except one of the Lycænidæ and perhaps a few among the Hesperidæ, The most conspicuous feature of the region is its fine group of Papilios, belonging to types (P. turnusandP. troilus) which are characteristically Nearctic. It is also as rich as the Palæarctic region in some genera which we are accustomed to consider as pre-eminently European; such asArgynnis,Melitæa,Grapta,Chionabas, and a few others. Still, we must acknowledge, that if we formed our conclusions from the butterflies alone, we could hardly separate the Nearctic from the Palæarctic region. This identity probably dates from the Miocene period; for when our existing arctic regions supported a luxuriant vegetation, butterflies would have been plentiful; and as the cold came on, these would move southwards both in America and Europe, and, owing to the long continuance of the generic types of insects, would remain little modified till now.
Coleoptera.—Only a few indications can be given of the peculiarities of the Nearctic coleoptera. In Cicindelidæ the region possesses, besides the cosmopoliteCicindela, four other genera, two of which—AmblychileandOmus—are peculiar to the West Coast and the Rocky Mountains. Of Carabidæ it possessesDicælus,Pasimachus,Eurytrichus,Sphæroderus,Pinacodera, and a number of smaller genera, altogether peculiar to it;Helluomorpha,Galerita,Callida, andTetragonoderus, in common with South America; and a large number of characteristic European forms.
The Lucanidæ are all of European types. The region is poor in Cetoniidæ, but has representatives of the South AmericanEuphoria, as well as of four European genera. Of Buprestidæ it has the South AmericanActenodes; a single species of the Ethiopian and EasternBelionota, in California; and about a dozen other genera of European and wide distribution.
Among Longicorns it possesses fifty-nine peculiar genera, representatives of five Neotropical, and thirteen Palæarctic genera; as well as many of wider distribution.Prionusis the chief representative of the Prionidæ;LepturaandCrossidiusof theCerambycidæ;Leptostylus,Liopus,Graphidurus, andTetraopes, of the Lamiidæ, the latter genus being confined to the region.
Terrestrial and Fluviatile Mollusca.
The land-shells of temperate North America almost all belong to the Inoperculate or Pulmoniferous division; the Operculata being represented only by a few species ofHelicinaandTruncatella, chiefly in the Southern States. According to Mr. Binney's recent "Catalogue of the Terrestrial Air-breathing Mollusks of North America," the fauna consists of the following genera:—Glandina(6 sp.);Macrocyclis(5 sp.);Zonites(37 sp.);Vitrina(4 sp.);Limax(5 sp.);Arion(3 sp.);Ariolimax(3 sp.);Prophysaon(1 sp.);Binneia(1 sp.);Hemiphillia(1 sp.);Patula(16 sp.);Helix(80);Holospira(2 sp.);Cylindrella(2 sp.);Macroceramus(2 sp.);Bulimulus(8 sp.);Cionella(2 sp.);Stenogyra(4 sp.);Pupa(19 sp.);Strophia(1 sp.);Vertigo(6 sp.);Liguus(1 sp.);Orthalicus(2 sp.);Punctum(1 sp.);Succinea(26 sp.);Tebennophorus(1 sp.);Pallifera(1 sp.);Veronicella(2 sp.).
All the larger genera range over the whole region, but the following have a more restricted distribution;Macrocyclishas only one species in the East, the rest being Californian or Central;Ariolimax,Prophysaon,Binneia, andHemiphillia, are confined to the Western sub-region. Lower California has affinities with Mexico, 18 species being peculiar to it, of which two are trueBulimi, a genus unknown in other parts of the region. The Central or Rocky Mountain sub-region is chiefly characterised by six peculiar species ofPatula. The Eastern sub-region is by far the richest, nine-tenths of the whole number of species being found in it. The Alleghany Mountains form the richest portion of this sub-region, possessing nearly half the total number of species, and at least 24 species found nowhere else. The southern States have also several peculiar species, but they are not so productive as the Alleghanies. The Canadian sub-region possesses 32 species, of which nearly half are northern forms more or less common to the whole Arctic regions, and several of this character have spread southwards allover the United States. Species ofVitrina,Zonites,Pupa, andSuccinea, are found in Greenland; and Eastern Palæarctic species ofVitrina,Patula, andPupaoccur in Alaska. More than 30 species of shells living in the Eastern States, are found fossil in the Post-Pliocene deposits of the Ohio and Mississippi.
Fresh-water Shells.—North America surpasses every other part of the globe in the number and variety of its fresh-water mollusca, both univalve and bivalve. The numbers up to 1866 were as follows:—Melaniadæ, 380 species; Paludinidæ, 58 species; Cycladidæ, 44 species; and Unionidæ, 552 species. The last family had, however, increased to 832 species in 1874, according to Dr. Isaac Lea, who has made them his special study; but it is probable that many of these are such as would be considered varieties by most conchologists. Many of the species ofUnioare very large, of varied forms, and rich internal colouring, and the group forms a prominent feature of the Nearctic fauna. By far the larger proportion of the fresh-water shells inhabit the Eastern or Alleghany sub-region; and their great development is a powerful argument against any recent extensive submergence beneath the ocean of the lowlands of North America.
The Nearctic Sub-regions.
The sub-divisions of the Nearctic region, although pretty clearly indicated by physical features and peculiarities of climate and vegetation, are by no means so strongly marked out in their zoology as we might expect. The same genera, as a rule, extend over the whole region; while the species of the several sub-regions are in most cases different. Even the vast range of the Rocky Mountains has not been an effectual barrier against this wide dispersal of the same forms of life; and although some important groups are limited by it, these are exceptions to the rule. Even now, we find fertile valleys and plateaus of moderate elevation, penetrating the range on either side; and both to the north and south there are passes which can be freely traversed by most animals during the summer. Previous to the glacial epoch there was probably a warm period, when every part of the range supported an abundant and variedfauna, which, when the cold period arrived, would descend to the lowlands, and people the country to the east, west, and south, with similar forms of life.
The first, and most important sub-division we can make, consists of the Eastern United States, extending across the Mississippi and the more fertile prairies, to about the 100°th. meridian of west longitude, where the arid and almost desert country commences. Southwards, the boundary bends towards the coast, near the line of the Brazos or Colorado rivers. To the north the limits are undefined; but as a considerable number of species and genera occur in the United States but not in Canada, it will be convenient to draw the line somewhere near the boundary of the two countries, except that the district between lakes Huron and Ontario, and probably Nova Scotia, may be included in the present sub-region. As far west as the Mississippi, this was originally a vast forest country; and it is still well wooded, and clothed with a varied and luxuriant vegetation.
The next, or Central sub-region, consists of the dry, elevated, and often arid district of the Rocky Mountains, with its great plateaus, and the barren plains of its eastern slope; extending northwards to near the commencement of the great forests north of the Saskatchewan, and southward to the Rio Grande del Norte, the Gulf of California, and to Cape St. Lucas, as shown on our maps. This sub-region is of an essentially desert character, although the higher valleys of the Rocky Mountains are often well wooded, and in these are found some northern and some western types.
The third, or Californian sub-region, is small, but very luxuriant, occupying the comparatively narrow strip of country between the Sierra Nevada and the Pacific. To the north it may include Vancouver's Island and the southern part of British Columbia, while to the south it extends to the head of the Gulf of California.
The fourth division, comprises the remainder of North America; and is a country of pine forests, and of barren wastes towards the Arctic Ocean. It has fewer peculiar species to characterise it than any other, but it possesses several characteristic arcticforms, while many of those peculiar to the south are absent; so that it is a very convenient, if it should not be considered an altogether natural, sub-region.
We will now give an outline of the most important zoological features of each of these divisions, taking them in the order in which they are arranged in the Fourth Part of this work. California comes first, as it has some tropical forms not found elsewhere, and thus forms a transition from the Neotropical region.
I. The Western or Californian Sub-region.
This small district possesses a fruitful soil and a highly favourable climate, and is, in proportion to its extent, perhaps the richest portion of the continent, both zoologically and botanically. Its winters are far milder than those of the Eastern States in corresponding latitudes; and this, perhaps, has enabled it to support several tropical forms which give a special character to its fauna. It is here only, in the whole region, that bats of the families Phyllostomidæ and Noctilionidæ, and a serpent of the tropical family, Pythonidæ, are found, as well as several Neotropical forms of birds and reptiles.
Mammalia.—The following genera are not found in any other part of the Nearctic region.Macrotus(Phyllostomidæ), one species in California;Antrozous(Vespertilionidæ), one species on the West Coast;Urotrichus(Talpidæ) one species in British Columbia; sub-genusNesorex(Soricidæ), one species in Oregon;Bassaris(Procyonidæ), California;Enhydra(Mustelidæ), Pacific Coast;Morunga(Phocidæ), California;Haploodon(Haploodontidæ) a rat-like animal, allied to the beavers and marmots, and constituting a peculiar family found only in California and British Columbia. The following characteristic Nearctic forms also extend into this sub-region:—Taxidea,Procyon,Didelphys,Sciuropterus,Tamias,Spermophilus,Dipodomys,Perognathus,Jaculus.
Birds.—Few genera of birds are quite peculiar to this sub-region, since most of the Western forms extend into the central district, yet it has a few.Glaucidium, a genus of Owls, is confined(in the Nearctic region) to California;Chamæa, a singular form allied to the wrens, and forming a distinct family, is quite peculiar;Geococcyx, a Neotropical form of cuckoo, extends to California and Southern Texas. The following genera are very characteristic of the sub-region, and some of them almost confined to it:Myiadestes(Sylviidæ);Psaltriparus(Paridæ);Cyanocitta,Picicorvus(Corvidæ);Hesperiphona,Peucæa,Chondestes(Fringillidæ);Selasphorus,Atthis(Trochilidæ);Columba,Melopelia(Columbidæ);Oreortyx(Tetraonidæ).
Reptiles.—The following genera are not found in any other part of the Nearctic region:Charina(Tortricidæ);Lichanotus(Pythonidæ);Gerrhonotus(Zonuridæ);Phyllodactylus(Geckotidæ);AnoliusandTropidolepis(Iguanidæ).Sceloporus(Iguanidæ) is only found elsewhere in Florida. All the larger North American groups of lizards and snakes are also represented here; but in tortoises it is deficient, owing to the absence of lakes and large rivers.
Amphibia.—California possesses two genera of Salamandridæ,AneidesandHeredia, which do not extend to the other sub-regions.
Fresh-water Fish.—There are two or three peculiar genera of Cyprinidæ, but the sub-region is comparatively poor in this group.
Plate XVIII. Illustrative of the Zoology of California and the Rocky Mountains.—We have chosen for the subject of this illustration, the peculiar Birds of the Western mountains. The two birds in the foreground are a species of grouse (Pediocætes Columbianus), entirely confined to this sub-region; while the only other species of the genus is found in the prairies north and west of Wisconsin, so that the group is peculiar to northern and western America. The crested birds in the middle of the picture (Oreortyx picta), are partridges, belonging to the American sub-family Odontophorinæ. This is the only species of the genus which is confined to California and Oregon. The bird at the top is the blue crow (Gymnokitta cyanocephala), confined to the Rocky Mountains and Sierra Nevada from New Mexico and Arizona northwards, and more properly belonging to the Central sub-region. It is allied to the European nutcracker; but according to the American ornithologist, Dr. Coues, has also resemblances to the jays, and certainly forms a distinct genus. The grizzly bear (Ursus ferox) in the background, is one of the characteristic animals of the Californian highlands.
Plate XVIII.
SCENE IN CALIFORNIA, WITH SOME CHARACTERISTIC BIRDS.
SCENE IN CALIFORNIA, WITH SOME CHARACTERISTIC BIRDS.
II. The Central, or Rocky Mountain Sub-region.
This extensive district is, for the greater part of its extent, from 2,000 to 5,000 feet above the sea, and is excessively arid; and, except in the immediate vicinity of streams and on some of the higher slopes of the mountains, is almost wholly treeless. Its zoology is therefore peculiar. Many of the most characteristic genera and families of the Eastern States are absent; while a number of curious desert and alpine forms give it a character of its own, and render it very interesting to the naturalist.
Mammalia.—The remarkable prong-horned antelope (Antilocapra), the mountain goat (Aplocerus), the mountain sheep or bighorn (Ovis montana), and the prairie-dog (Cynomys), one of the Rodentia, are peculiar to this sub-region; while the family of the Saccomyidæ, or pouched rats, is represented by many forms and is very characteristic. Here is also the chief home of the bison. The glutton (Gulo) and marmot (Lagomys) enter it from the north; while it has the racoon (Procyon), flying squirrel (Sciuropterus), ground squirrel (Tamias), pouched marmot (Spermophilus) and jumping mouse (Jaculus) in common with the countries east or west of it.
Plate XIX. Illustrative of the Zoology of the Central Plains or Prairies.—We here introduce four of the most characteristic mammalia of the great American plains or prairies, three of them being types confined to North America. The graceful animals on the left are the prong-horned antelopes (Antilocapra americana), whose small horns, though hollow like those of the antelopes, are shed annually like those of the deer. To the right we have the prairie-dogs of the trappers (Cynomys ludovicianus) which, as will be easily seen, are rodents, and allied to the marmots of the European Alps. Their burrows are numerous on the prairies, and the manner in which they perchthemselves on little mounds and gaze on intruders, is noticed by all travellers. On the left, in the foreground, is one of the extraordinary pouched rats of America (Geomys bursarius). These are burrowing animals, feeding on roots; and the mouth is, as it were, double, the outer portion very wide and hairy, behind which is the small inner mouth. Its use may be to keep out the earth from the mouth while the animal is gnawing roots. A mouth so constructed is found in no other animals but in these North American rats. In the distance is a herd of bisons (Bison americanus), the typical beast of the prairies.
Birds.—This sub-region has many peculiar forms of birds, both residents, and migrants from the south or north. Among the peculiar resident species we may probably reckon a dipper, (Cinclus);Salpinctes, one of the wrens;Poospiza,Calamospiza, genera of finches;Picicorvus,Gymnokitta, genera of the crow family;CentrocercusandPediocætes, genera of grouse. As winter migrants from the north it hasLeucosticteandPlectrophanes, genera of finches;Perisoreus, a genus of the crow family;Picoides, the Arctic woodpecker; andLagopus, ptarmigan. Its summer migrants, many of which may be resident in the warmer districts, are more numerous. Such are,Oreoscoptes, a genus of thrushes;CampylorhynchusandCatherpes, wrens;Paroides, one of the tits;Phænopepla, allied to the waxwing;EmbernagraandSpermophila, genera of finches;Pyrocephalus, one of the tyrant shrikes;CallipeplaandCyrtonyx, American partridges. Besides these, the more widely spread genera,Harporhynchus,Lophophanes,Carpodacus,Spizella, andCyanocitta, are characteristic of the central district, and two genera of humming-birds—AtthisandSelasphorus—only occur here and in California. Prof. Baird notes 40 genera of birds which are represented by distinct allied species in the western, central, and eastern divisions of the United States, corresponding to our sub-regions.
Plate XIX.
THE AMERICAN PRAIRIES, WITH CHARACTERISTIC MAMMALIA.
THE AMERICAN PRAIRIES, WITH CHARACTERISTIC MAMMALIA.
It is a curious fact that the birds of this sub-region should extend across the Gulf of California, and that Cape St. Lucas, at the southern extremity of the peninsula, should be decidedly more "Central" than "Californian" in its ornithology. Prof. Baird says, that its fauna is almost identical with that of the Gila River, and has hardly any relation to that of Upper California. It possesses a considerable number (about twenty) of peculiar species of birds, but all belong to genera characteristic of the present sub-region; and there is no resemblance to the birds of Mazatlan, just across the gulf in the Neotropical region.
Reptiles, Amphibia, and Fishes.—A large number of snakes and lizards inhabit this sub-region, but they have not yet been classified with sufficient precision to enable us to make much use of them. Among lizards, Iguanidæ, Geckotidæ, Scincidæ, and Zonuridæ, appear to be numerous; and many new genera of doubtful value have been described. Among snakes, Calamariidæ, Colubridæ, and Crotalidæ are represented. Among Amphibia,Siredon, one of the Proteidæ, is peculiar. The rivers and lakes of the Great Central Basin, and the Colorado River, contain many peculiar forms of Cyprinidæ.
III. The Eastern or Alleghany Sub-region.
This sub-region contains examples of all that is most characteristic of Nearctic zoology. It is for the most part an undulating or mountainous forest-clad country, with a warm or temperate climate, but somewhat extreme in character, and everywhere abounding in animal and vegetable life. To the west, across the Mississippi, the country becomes more open, gradually rises, becomes much drier, and at length merges into the arid plains of the central sub-region. To the south, in Georgia, Florida, and Louisiana, a sub-tropical climate prevails, and winter is almost unknown. To the north, in Michigan and New England, the winters are very severe, and streams and lakes are frozen for months together. These different climates, however, produce little effect on the forms of animal life; the species to some extent change as we go from north to south, but the same types everywhere prevail. This portion of the United States, having been longest inhabited by Europeans, has been more thoroughly explored than other parts of North America; and to this more complete knowledge its superior zoological richnessmay be to some extent due; but there can be little doubt that it is also positively, and not merely relatively, more productive in varied forms of animal life than either of the other sub-regions.
Mammalia.—There seems to be only one genus absolutely peculiar to this sub-region—the very remarkableCondylura, or star-nosed mole, only found from Pennsylvania to Nova Scotia, and as far as about 94° west longitude. It also has opossums (Didelphys) in common with California, and three out of four species ofScalops, a genus of moles; as well as the skunk (Mephitis), American badger (Taxidea), racoon (Procyon), pouched rat (Geomys), beaver rat (Fiber), jumping mouse (Jaculus), tree porcupine (Erethizon), and other characteristic Nearctic forms.
Birds.—The birds of this sub-region have been carefully studied by American naturalists, and many interesting facts ascertained as to their distribution and migrations. About 120 species of birds are peculiar to the east coast of the United States, but only about 30 of these are residents all the year round in any part of it; the bird population being essentially a migratory one, coming from the north in winter and the south in summer. The largest number of species seems to be congregated in the district of the Alleghany mountains. A considerable proportion of the passerine birds winter in Central America and the West Indian Islands, and go to the Middle States or Canada to breed; so that even the luxuriant Southern States do not possess many birds which may be called permanent residents. Thus, in East Pennsylvania there are only 52, and in the district of Columbia 54 species, found all the year round, out of about 130 which breed in these localities; very much below the number which permanently reside in Great Britain.
This sub-region is well characterised by its almost exclusive possession ofEctopistes, the celebrated passenger pigeon, whose enormous flocks and breeding places have been so often described; andCupidonia, a remarkable genus of grouse. The only Nearctic parrot,Conurus carolinensis, is found in the Southern States; as well asCrotophaga, a South American genus usually associated with the cuckoos.HelmintherusandOporornis, genera of wood-warblers, may be considered to be peculiar to this sub-region, since in each case only one of the two species migrates as far as Central America; while two other genera of the same family,SiurusandSetophaga, as well as the finch genus,Euspiza, do not extend to either of the western sub-regions.Parus, a genus of tits, comes into the district from the north;Otocorys, an alpine lark, andCoturniculus, an American finch, from the west; and such characteristic Nearctic genera asAntrostomus(the whip-poor-will goatsuckers);Helminthophaga,Dendræca, andMyiodioctes(wood-warblers);Vireo(greenlets);Dolichonyx(rice-bird);Quiscalus(troupial);Meleagris(turkey); andOrtyx(American partridge), are wide-spread and abundant. In Mr. J. A. Allen's elaborate and interesting paper on the birds of eastern North America, he enumerates 32 species which breed only in the more temperate portions of this province, and may therefore be considered to be especially characteristic of it. These belong to the following genera:—Turdus,Galeoscoptes,Harporhynchus,Sialia,Dendræca,Wilsonia,Pyranga,Vireo,Lanivireo,Lophophanes,Coturniculus,Ammodromus,Spizella,Euspiza,Hedymeles,Cyanospiza,Pipilo,Cardinalis,Icterus,Corvus,Centurus,Melanerpes,Antrostomus,Coccyzus,Ortyx, andCupidonia.
Reptiles.—In this class the Eastern States are rich, possessing many peculiar forms not found in other parts of the region. Among snakes it has the generaFaranciaandDimodesbelonging to the fresh-water snakes (Homalopsidæ); the South American genusElaps; and 3 genera of rattlesnakes,Cenchris,Crotalophorus, andCrotalus. The following genera of snakes are said to occur in the State of New York:—Coluber,Tropidonotus,Leptophis,Calamaria,Heterodon,Trigonocephalus,Crotalus,Psammophis,Helicops,Rhinostoma,Pituophis, andElaps.
Among lizards,Chirotes, forming a peculiar family of Amphisbenians, inhabits Missouri and Mexico; while the remarkable glass-snake,Ophisaurus, belonging to the family Zonuridæ, is peculiar to the Southern States; and the South AmericanSphærodactylus, one of the gecko family, reaches Florida. Other genera which extend as far north as the State of NewYork are,Scincus,Tropidolepis,Plestiodon,Lygosoma,Ameiva, andPhrynosoma.
Tortoises, especially the fresh-water kind, are very abundant; and the generaAromochelys,Chelydra,Terrapene, andTrionyx, are nearly, if not quite, confined to this division of the region.
Amphibia.—Almost all the remarkable forms of Urodela, or tailed batrachians, peculiar to the region are found here only; such asSirenandPseudobranchus, constituting the family Sirenidæ;Menobranchus, allied to theProteusof Europe;Amphiuma, an eel-like creature with four rudimentary feet, constituting the family Amphiumidæ;Notopthalmus,Desmognathus, andMenopoma, belonging to the Salamandridæ; together with several other genera of wider range. Of Anura, or tail-less batrachians, there are no peculiar genera, but the Neotropical genus of toads,Engystoma, extends as far as South Carolina.
Fishes.—Owing to its possession of the Mississippi and the great lakes, almost all the peculiar forms of North American fishes are confined to this sub-region. Such arePerca,Pileoma,Huro,Bryttus, andPomotis(Percidæ); the families Aphredoderidæ and Percopsidæ; several genera of Cyprinodontidæ and Cyprinidæ; and the family Polydontidæ.
Islands of the Alleghany Sub-region.
The Bermudas.—These islands, situated in the Atlantic, about 700 miles from the coast of Carolina, are chiefly interesting for the proof they afford of the power of a great variety of birds to cross so wide an extent of ocean. There are only 6 or 8 species of birds which are permanent residents on the islands, all common North American species; while no less than 140 species have been recorded as visiting them. Most of these are stragglers, many only noticed once; others appear frequently and in great numbers, but very few, perhaps not a dozen, come every year, and can be considered regular migrants. The permanent residents are, a greenlet (Vireo noveboracensis), the catbird (Galeoscoptes carolinensis), the blue bird (Sialia sialis), the cardinal (Cardinalis virginianus), the American crow (Corvusamericanus), and the ground dove (Chamæpelia passerina). The most regular visitants are a kingfisher (Ceryle alcyon), the wood-wagtail (Siurus noveboracensis), the rice-bird (Dolichonyx oryzivorus), and a moorhen (Gallinula galeata). Besides the American species, four European birds have been taken at the Bermudas:Saxicola œnanthe,Alauda arvensis(perhaps introduced),Crex pratensis, andScolopax gallinago.
A common American lizard,Plestiodon longirostris, is the only land reptile found on the islands.
IV. The Sub-Arctic or Canadian Sub-region.
This sub-region serves to connect together the other three, since they all merge gradually into it; while to the north it passes into the circumpolar zone which is common to the Palæarctic and Nearctic regions. The greater portion of it is an extensive forest-district, mostly of coniferæ; and where these cease towards the north, barren wastes extend to the polar ocean. It possesses several northern or arctic forms of Mammalia, such as the glutton, lemming, reindeer, and elk, which barely enter the more southern sub-regions; as well as the polar bear and arctic fox; but it also has some peculiar forms, and many of the most characteristic Nearctic types. The remarkable musk-sheep (Ovibos) is confined to this sub-region, ranging over a considerable extent of country north of the forests, as well as Greenland. It has been extinct in Europe and Asia since the Post-pliocene epoch. Such purely Nearctic genera asProcyon,Latax,Erethizon,Jaculus,Fiber,Thomomys, andHesperomys, abound, many of them ranging to the shores of Hudson's Bay and the barren wastes of northern Labrador. Others, such asBlarina,Condylura, andMephitis, are found only in Nova Scotia and various parts of Canada. About 20 species of Mammalia seem to be peculiar to this sub-region.
Plate XX. Illustrating the Zoology of Canada.—We have here a group of Mammalia characteristic of Canada and the colder parts of the United States. Conspicuous in the foreground is the skunk (Mephitis mephitica), belonging to a genus of the weasel family found only in America. This animal iscelebrated for its power of ejecting a terribly offensive liquid, the odour of which is almost intolerable. The skunks are nocturnal animals, and are generally marked, as in the species represented, with conspicuous bands and patches of white. This enables them to be easily seen at night, and thus serves to warn larger animals not to attack them. To the left is the curious little jumping mouse (Jaculus hudsonius), the American representative of the Palæarctic jerboa. Climbing up a tree on the left is the tree porcupine (Erethizon dorsatus), belonging to the family Cercolabidæ, which represents, on the American continent, the porcupines of the Old World. In the background is the elk or moose (Alces americanus), perhaps identical with the European elk, and the most striking inhabitant of the northern forests of America, as the bison is of the prairies.
Birds.—Although the Canadian sub-region possesses very few resident birds, the numbers which breed in it are perhaps greater than in the other sub-regions, because a large number of circumpolar species are found here exclusively. From a comparison of Mr. Allen's tables it appears, that more than 200 species are regular migrants to Canada in the breeding season, and nearly half of these are land-birds. Among them are to be found a considerable number of genera of the American families Tyrannidæ and Mniotiltidæ, as well as the American generaSialia,Progne,Vireo,Cistothorus,Junco,Pipilo,Zonotrichia,Spizella,Melospiza,Molothrus,Agelæus,Cyanura,Sphyrapicus, and many others; so that the ornithology of these northern regions is still mainly Nearctic in character. Besides these, it has such specially northern forms asSurnia(Strigidæ);Picoides(Picidæ);Pinicola(Fringillidæ); as well asLeucosticte,Plectrophanes,Perisoreus, andLagopus, which extend further south, especially in the middle sub-region. No less than 212 species of birds have been collected in the new United States territory of Alaska (formerly Russian America), where a humming-bird (Selasphorus rufus) breeds. The great majority of these are typically American, including such forms asColaptes,Helminthophaga,Siurus,Dendræca,Myiodioctes,Passerculus,Zonotrichia,Junco,Spizella,Melospizpa,Passerella,Scoleophagas,Pediocetes, andBonasa; together with many northern birds common to both continents. Yet a few Palæarctic forms, not known in other parts of the sub-region, appear here. These areBudytes flava,Phylloscopus kennicottii, andPyrrhula coccinea, all belonging to genera not occurring elsewhere in North America. Considering the proximity of the district to North-east Asia, and the high probability that there was an actual land connection at, and south of, Behring's Straits, in late Tertiary times, it is somewhat remarkable that the admixture of Palæarctic and Nearctic groups is not greater than it is. The Palæarctic element, however, forms so small apportion of the whole fauna, that it may be satisfactorily accounted for by the establishment of immigrants since the Glacial period. The great interest felt by ornithologists in the discovery of the three genera above-named, with a wren allied to a European species, is an indication that the faunas even of the northern parts of the Nearctic and Palæarctic regions are, as regards birds, radically distinct. It may be mentioned that the birds of the Aleutian Isles are also, so far as known, almost wholly Nearctic. The number of land-birds known from Alaska is 77; and from the Aleutian Isles 16 species, all of which, except one, are North American.
Plate XX.