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The Sub-Order Columbae must certainly be divided into the Families Dididae for the Dodo and Solitaire, and Columbidae for the Pigeons, while a third, Didunculidae, may be added to contain the Tooth-billed Pigeon of Samoa, to which Otidiphaps of Papuasia is possibly allied. For convenience sake we may accept four Sub-families of the Columbidae, namely (1) Gourinae, (2) Peristerinae, (3) Columbinae, and (4) Treroninae, though the arrangement is somewhat arbitrary. Dr. Gadow[[207]] segregates Caloenatinae, but not Peristerinae, while he and Count Salvadori[[208]] agree in considering Didunculus merely on a level with these subdivisions.
Throughout the group the body is compact, while the bill varies from stout to slender, being swollen and hardened at the decurved tip, which forms a hook in the Dididae and Didunculidae. The base of this feature is covered with a soft skin or cere, containing the nostrils; Globicera, Vinago calva, and Ptilopus insolitus have a fleshy or bony knob at the posterior part of the culmen, said to be most prominent in the breeding season; and Didunculus has the mandible toothed and truncated. The metatarsi, reticulated in the Gourinae, but scutellated elsewhere, are usually partly feathered, especially in Fruit-Pigeons; some species of Columbigallina, however, have them naked; Drepanoptila has them entirely covered; and in many domestic breeds the plumage extends over the toes, which are all on the same level, and possess moderate claws. The skin is more or less expanded on each side of the digits. The rounded wings are commonly long, but are short in Ground-Pigeons, and aborted in the flightless Dididae, the primaries numbering eleven and the secondaries from ten to seventeen; the former are bifurcated at the tip in Drepanoptila, attenuated in some members of Ptilopus, Oxypelia, Peristera, and Leptoptila, while one or more of the three outer feathers is not uncommonly scalloped. The tail varies considerably in form and dimensions, being wedge-shaped in Sphenocercus, rounded in Zenaida, Phabotreron, and Megaloprepia, acuminate in Ectopistes, long and graduated in Oena, Macropygia, and Reinwardtoenas, and so forth. The rectrices range from twelve to twenty, sixteen being the normal number in the Gourinae, twelve in the Columbinae, and fourteen in the Treroninae. The neck-feathers may be bifurcated, as in Alectoroenas, Columba guinea, and occasionally in Turtur, or those of the breast, as in some species of Macropygia, Ptilopus, and Phaenorrhina; the neck, moreover, is hackled in Caloenas and Lopholaemus, and the body-plumage is generally narrow with widely-separated barbs in Chrysoenas. Five members of Phlogoenas have a patch of stiff feathers over the crop; while the splendid decomposed crest of Goura is exceptionally striking, and more ordinary tufts grace the head in Lopholaemus, Coryphoenas, Lophophaps, Ocyphaps, and elsewhere. The forehead is sometimes nearly bare, as are the lores and eyelids in Gymnophaps; naked red or yellow orbits are found in Gymnopelia, Reinwardtoenas, Macropygia, Turacoena, Didunculus, and Columba gymnophthalma, not to mention other instances; while the tendency reaches its height in the huge circumocular wattles of several fanciers' races. In Serresius a feathered "saddle" extends over half the culmen.
The furcula is U-shaped, being much reduced in the Dididae; the syrinx is remarkable for the asymmetrical union of the sterno-tracheal muscles; the tongue is lanceolate; the impervious nostrils are linear in the Columbidae and Didunculidae, oblique in the Dididae. The crop is more highly developed than in other Families. The gizzard of Caloenas is remarkable for an indurated horn-like patch on each side of the epithelial lining, that of Carpophaga latrans has the interior beset with similar conical prominences, correlated with a diet of hard fruit. Phaenorrhina has these cones still more developed, and Ptilopus agrees with Drepanoptila in possessing four pads in the above organ instead of two, the regular number in Birds. The after-shaft is rudimentary or absent, the adults have no down, the young are hatched blind and naked, and remain for a long time in the nest. The plumage is commonly dull blue or brown, with an iridescent sheen; but remarkably brilliant purple, red, yellow, and green hues manifest themselves in forms such as Ptilopus, Chrysoenas, and Caloenas from the islands of the Eastern Seas, the headquarters of the Family. Though smaller, the female usually resembles the male; but Turturoena, Oena, and Peristera are examples of diversity, while immature examples are duller than adults. Goura approaches the size of a goose, whereas Columbigallina is little larger than a sparrow. Of domestic Pigeons the Rock-Dove is undoubtedly the origin, but the breeds are now infinite in their variety.[[209]]
Omitting the abnormal Didine Birds, the habits of the members of this group are fairly uniform, the majority of them inhabiting wooded country; while even those like Phaps, Lophophaps, and Geophaps, which occupy the arid plains of Australia, are to be found at times where vegetation is plentiful; and in all cases the proximity of water seems indispensable. Fruit-Pigeons frequent trees, and the most typical Columbine forms are found in woods or among rocks, though the smaller Doves naturally prefer the lower bushes. Wood-Pigeons towards winter, and Passenger-Pigeons when nesting–not to mention other instances–gather in large flocks; in some cases, however, the parties only number about half a dozen, and more solitary habits are by no means uncommon. The flight is strong, rapid, and direct, though the Ground-Pigeons remain a comparatively short time upon the wing, and some species prefer to run unless forced to rise, Oena being an especially good walker. The well-known "homing" powers of trained birds, the curious backward somersaults of the Tumbler, and the sudden rise and clap of the wings so noticeable in the Wood-Pigeon when courting, merit a passing mention. Every member of the Family perches, and many delight to bask in the sun. The note is always of the nature of a coo, but is especially loud and deep in Myristicivora, Megaloprepia, and some members of Carpophaga, guttural in Haplopelia, mournful in Peristera and Zenaidura, harsh and trumpet-like in Goura; the voice of the Turtle-Dove suggests a purr, while Tympanistria and Starnoenas possess powers of ventriloquism. The food of the Wood-Pigeon is grain, beech-mast, acorns, turnips, and tender shoots of plants; that of Fruit-Pigeons consists of figs, palm-nuts, grapes, and so forth, plucked from the tree, and in the case of Myristicivora bicolor and Globicera myristicivora, largely of the mace which encases the nutmeg; Ground-Doves and other small forms subsist mainly on seeds of grasses; and it may be safely inferred that in most cases the diet varies considerably. Turturoena is stated to eat Cicada larvae; Leucosarcia those of Diptera; Goura and Otidiphaps worms, snails, and insects. Pigeons, unlike birds generally, take continuous draughts of water, immersing the bill to the base. The nest is usually a slight platform of sticks, placed aloft on a branch or in a bush; but our Rock-Dove and Columba phaeonota of South Africa breed in caves or holes in rocks; the Stock-Dove prefers hollow trees, rabbit-burrows, and the like; Geophaps the bare soil; and so forth. Phaps, Peristera, and Zenaida nest either on the ground or in bushes, but the latter appear to be almost invariably chosen by Ground-Doves like Columbigallina and Geopelia. The white eggs are two, or exceptionally three, in number; the Dodo, however, laid only one, and so do Caloenas, Ectopistes, Didunculus, and some species of Carpophaga and Columba, as well as Goura, where it is larger than that of a tame Duck. Societies, such as those of Ectopistes and Caloenas, are most unusual. Some Pigeons breed three times a year, the male commonly assisting in incubation, which lasts from fourteen to twenty-eight days. The members of this Family are shy, but readily tamed; yet the Collared Turtle-Dove is perhaps the only really good cage-bird. Most of them are excellent for the table, Leucosarcia, Geophaps, Goura, and the Treroninae being accounted particularly delicate, while the Wood-Pigeon and the domestic breeds speak for themselves. The great damage, however, done to crops, such as turnips, peas, or barley, by the flocks counterbalances their economic value to a considerable extent, the most typical forms being undoubtedly the worst offenders.
Fam. X. Dididae.–This consists of three extinct species–Didus ineptus, the Dodo of Mauritius, D. borbonicus of Réunion (Bourbon), and Pezophaps solitarius, the Solitaire of Rodriguez.
The Dodo, familiar to all by name, if not by pictures, was an immense Pigeon-like bird bigger than a Turkey, with an aborted keel to the sternum and the wings also aborted. The coracoid and scapula met at an obtuse angle, as in many other flightless species. The huge blackish bill terminated in a large horny hook, the cheeks were partly bare, the short yellow legs were stout, scaly, and feathered on the upper portion; the plumage was dark ash-coloured, with whitish breast and tail, yellowish-white wings, and black tips to their coverts. The short rectrices formed a curled tuft, and the first four primaries were directed backwards.
Fig. 66.–Dodo. Didus ineptus. (After Savery's Vienna picture.)
This uncouth and unwieldy species, of which a full account will be found in the works mentioned below,[[210]] which have been largely utilized here, was noticed as early as 1598 by the Dutch, who called it Walghvogel, or Nauseous Bird, from their dislike of its flesh, and the island, where it was then found abundantly, Mauritius. The earliest representation was given in 1601 by De Bry, who stated that an example was brought alive to Holland. Other Dutch fleets subsequently visited the island, and several sketches of the Dodo were made, while one of the captains records that it was indifferently called Dodaars or Dronte. Roelandt Savery of Courtrai (1576-1639) painted the Dodo–probably from life–more than once, pictures by him still existing in Berlin (1626), Vienna (1628), the Hague, Pommersfelden, Stuttgart, and London, the last-named belonging to the Zoological Society. The British Museum also possesses an undated picture, another is at Haarlem, a third at Oxford; while one by Goiemare at Sion House (dated 1627), and one said to be by Hoefnagel in the library of the late Emperor of Austria (circa 1620) were possibly taken from living birds. In 1628 Englishmen appeared on the scene, Emanuel Altham having sent a specimen home alive to his brother, while Herbert, accompanying the same fleet, mentioned the Dodo and figured it. About 1634 an example was given to the Anatomy School at Oxford by a Mr. Gosling, and some four years later Sir Hamon Lestrange saw a captive bird in London. Finally, we may note that individuals existed in Mauritius until 1681, as proved by the journal of Benjamin Harry.