The Geographical Distribution of Animals/Chapter 18.3

The Anatidæ, comprehending the Ducks, Geese, and Swans with their allies, are of such universal distribution that there is probably no part of the globe where some of them are not occasionally found. They are, however, most abundant in temperate and cold regions; and, contrary to what occurs in most other families, the most beautifully-coloured species are extra-tropical, and some even arctic. The distribution of the genera is as follows:—

Anseranas (1 sp.), Australia; Plectropterus (2 sp.), Tropical Africa; Sarkidiornis (1 sp.), South America, Africa, and India; Chenalopex (1 sp.), Amazonia; Callochen (1 sp.), South Europe, North, East, and South Africa; Cereopsis (1 sp.), Australia; Anser (13 sp.), Palæarctic and Nearctic regions to Central America and the Antilles; Bernicla (12 sp.), Temperate regions of the Northern and Southern Hemispheres; Chloephaga (5 sp.), South Temperate America and Aleutian Islands; Nettapus (4 sp.), Tropical Africa and Madagascar, India and Ceylon to Malaya and Australia; Cygnus (10 sp.), Temperate regions of the Northern and Southern Hemispheres; Dendrocygna (10 sp.), Tropical and sub-tropical regions; Tadorna (3 sp.), Palæarctic and Australian regions; Casarca (5 sp.), Palæarctic, Oriental, Ethiopian, and Australian regions, to New Zealand; Aix (2 sp.), Temperate North America and Eastern Asia; Mareca (4 sp.), Palæarctic region, North America, Temperate South America, and Australia; Dafila (3 sp.), all America and the Palæarctic region; Anas (16 sp.), cosmopolitan; Querquedula (17 sp.), cosmopolitan; Chaulelasmus (2 sp.), Palæarctic region and North America; Spatula (5 sp.), all Temperate regions; Malacorhynchus (1 sp.), Australia; Cairina (1 sp.), Tropical South America; Branta (1 sp.), Palæarctic region and India; Fuligula (5 sp.), North Temperate regions and New Zealand; Æthya (5 sp.), Palæarctic and Nearctic regions, India, Australia, and South Africa; Metopiana (1 sp.), South Temperate America; Bucephala (4 sp.), Nearctic and Palæarctic regions; Harelda (2 sp.), Northern Palæarctic and Nearctic regions; Hymenolaimus (1 sp.), New Zealand; Camptolaimus (1 sp.), North-east of North America; Micropterus (1 sp.), Temperate South America; Somateria (5 sp.), Arctic and sub-arctic regions; Œdemia (5 sp.), Nearctic and Palæarctic regions; Biziura (1 sp.), Australia; Thalassornis (1 sp.), South Africa; Erismatura (6 sp.), all America, South-east Europe and South Africa; Nesonetta (1 sp.), Auckland Islands; Merganetta (3 sp.), Andes of Columbia to Chili; Mergus (6 sp.), Palæarctic and Nearctic regions, Brazil, and the Auckland Islands.

The Laridæ, or Gulls and Terns, are true cosmopolites, inhabiting the shores and islands of every zone; and most of the genera have also a wide range. They are therefore of little use in the study of geographical distribution. The genera are as follows:—

Stercorarius (6 sp.), cosmopolitan, most abundant in cold and temperate zones; Rhodostethia (1 sp), North America; Larus (60 sp.), cosmopolitan; Xema (1 sp.), North Temperate zone; Creagrus (1 sp.), North Pacific; Pagophila (1 sp.), Arctic seas; Rissa (3 sp.), Arctic and Northern seas; Sterna (36 sp.), cosmopolitan; Hydrochelidon (12 sp.), Tropical and Temperate zones; Gygis (1 sp.), Indian Ocean and Tropical Pacific Islands; Anous (6 sp.), Tropical and Temperate zones; Nænia (1 sp.), South Temperate America; Rhynchops (3 sp.), Tropical America, Africa, and India.

The Procellariidæ, comprising the Shearwaters, Petrels, and Albatrosses, are universally distributed, but some of the genera are local.

Puffinus (20 sp.), Procellaria (18 sp.), and Fulmarus (40 sp.), are cosmopolitan; Prion (5 sp.) and Pelecanoides (3 sp.), belong to the South Temperate and Antarctic regions; Diomedia (10 sp.), comprises the Albatrosses, which are tropical, occasionally wandering into temperate seas.

The Pelecanidæ, comprising the Gannets, Pelicans, Darters, and Frigate-Birds, although universally distributed, are more abundant in tropical and temperate regions.

Sula (8 sp.) and Phalacrocorax (35 sp.), are cosmopolitan; Pelecanus (9 sp.) is tropical and temperate; Fregetta (2 sp.) and Phaeton (3 sp.) are confined to Tropical seas; Plotus (4 sp.) to Tropical and warm Temperate zones.

The Penguins are entirely confined to the Antarctic and South Temperate regions, except two species which are found on the coast of Peru and the Galapagos. They are most plentiful in the southern parts of South America, Australia, New Zealand, and most of the Antarctic islands, and one or two species are found at the Cape of Good Hope. The genera as given in the Hand List are:—

Spheniscus (1 sp.), South Africa and Cape Horn; Eudyptes (15 sp.), with the range of the family; Aptenodytes (2 sp.), Antarctic Islands.

The Northern Divers are confined to the Arctic and North Temperate Seas. The only genus, Colymbus, has one species confined to the West Coast of North America, the others being common to the two northern continents.

The Grebes are universally distributed. The genera are Podiceps (26 sp.), cosmopolitan; and Podilymbus (2 sp.), confined to North and South America. Some ornithologists group these birds with the Colymbidæ.

The Alcidæ, comprising the Auks, Guillemots, and Puffins, are confined to the North Temperate and Arctic regions, where they represent the Penguins of the Antarctic lands. One of the most remarkable of these birds, the Great Auk, formerly abundant in the North Atlantic, is now extinct. The genera are as follows:—

Alca (2 sp.), North Atlantic and Arctic seas; Fratercula (4 sp.), Arctic and North Temperate zones; Ceratorhina (2 sp.), North Pacific; Simorhynchus (8 sp.), North Pacific; Brachyrhamphus (3 sp.), North Pacific to Japan and Lower California; Uria (8 sp.), Arctic and North Temperate zones; Mergulus (1 sp.), North Atlantic and Arctic Seas. The last three genera constitute the family Uriidæ, of some ornithologists.

The Anseres, or Swimmers, being truly aquatic birds, possess, as might be expected, a large number of cosmopolitan families and genera. No less than 5 out of the 8 families have a world-wide distribution, and the others are characteristic either of the North or the South Temperate zones. Hence arises a peculiarity of distribution to be found in no other order of birds; the Temperate being richer than the Tropical regions. The Nearctic and Palæarctic regions each have seven families of Anseres, two of which, the Colymbidæ and Alcidæ, are peculiar to them. The Ethiopian, Australian, and Neotropical regions, which all extend into the South Temperate zone, have six families, with one peculiar to them; while the Oriental region, which is wholly tropical, possesses the five cosmopolitan families only.

There are about 78 genera and 552 species of Anseres, giving 69 species to a family, a high number compared with the Waders, and due to there being only one very small family, the Colymbidæ. The distribution of the Anseres, being more determined by temperature than by barriers, the great regions which are so well indicated by the genera and families of most other orders of birds, hardly limit these, except in the case of the genera of Anatidæ.

The Ostriches consist of two genera, sometimes formed into distinct families. Struthio (2 sp.) inhabits the desert regions of North, East, and South Africa, as well as Arabia and Syria. It therefore just enters the Palæarctic region. Rhea (3 sp.) inhabits Temperate South America, from Patagonia to the confines of Brazil.

The Cassowaries and Emeus are confined to the Australian region. The Emeus, Dromæus (2 sp.), are found only on the main-land of Australia (Plate XII. Vol. I. p. 441). Casuarius (9 sp.) inhabits the islands from Ceram to New Britain, with one species in North Australia; it is most abundant in the Papuan Islands.

The species of Apteryx are entirely confined to the two larger islands of New Zealand. They are supposed to have some remote affinity with Ocydromus, a genus of Rails peculiar to Australia and New Zealand; but they undoubtedly form one of the most remarkable groups of living birds (Plate XIII. Vol. I. p. 445).

A number of sub-fossil remains of birds, mostly large and some of gigantic size, having affinities to the Apteryx and, less closely, to the Cassowaries, have been discovered in New Zealand. These are all classed by Professor Owen in the genus Dinornis and family Dinornithidæ; but Dr. Haast, from the study of the rich collections in the Canterbury (New Zealand) Museum, is convinced that they belong to two distinct families and several genera. His arrangement is as follows. (See Ibis, 1874, p. 209).

Dinornis (5 sp.); Meiornis (2 sp.).

These had no hind toe, and include the largest species. Professor Newton thinks that they were absolutely wingless, being the only birds in which the fore limbs are entirely wanting.

Palapteryx (2 sp.); Euryapteryx (2 sp.).

These had a well-developed hind toe, and rudimentary wings.

A gigantic Struthious bird (Æpyornis), belonging to a distinct family, inhabited Madagascar.

It was first made known by its enormous eggs, eight times the bulk of those of the ostrich, which were found in a sub-fossil condition. Considerable portions of skeletons have since been discovered, showing that these huge birds formed an altogether peculiar family of the order.

With the exception of the Ostrich, which has spread northward into the Palæarctic region, the Struthious birds, living and extinct, are confined to the Southern hemisphere, each continent having its peculiar forms. It is a remarkable fact that the two most nearly allied genera, Struthio and Rhea, should be found in Africa and South Temperate America respectively. Equally remarkable is the development of these large forms of wingless birds in Australia and the adjacent islands, and especially in New Zealand, where we have evidence which renders it probable that about 20 species recently coexisted. This points to the conclusion that New Zealand must, not long since, have formed a much more extensive land, and that the diminution of its area by subsidence has been one of the causes—and perhaps the main one—in bringing about the extinction of many of the larger species of these wingless birds.

The wide distribution of the Struthiones may, as we have already suggested (Vol. I., p. 287.), be best explained, by supposing them to represent a very ancient type of bird, developed at a time when the more specialized carnivorous mammalia had not come into existence, and preserved only in those areas which were long free from the incursions of such dangerous enemies. The discovery of Struthious remains in Europe in the Lower Eocene only, supports this view; for at this time carnivora were few and of generalized type, and had probably not acquired sufficient speed and activity to enable them to exterminate powerful and quick-running terrestrial birds. It is, however, at a much more remote epoch that we may expect to find the remains of the earlier forms of this group; while these Eocene birds may perhaps represent that ancestral wide-spread type which, when isolated in remoter continents and islands, became modified into the American and African ostriches, the Emeus and Cassowaries of Australia, the Dinornis and Æpyornis of New Zealand.