Order X. GRUIFORMES.
The Gruiformes, which lie between the Galliformes and the Charadriiformes, compose a somewhat heterogeneous Order, which includes forms so different as the Rallidae (Rails), Gruidae (Cranes), Aramidae (Limpkins), Psophiidae (Trumpeters), Cariamidae (Seriemá and Chuñia), Otididae (Bustards), Rhinochetidae (Kagu), Eurypygidae (Sun-Bitterns), and Heliornithidae (Finfoots). Of these a large number are Waders, but the Land-Rail, the Wekas, the Kagu, the Bustards, and others, cannot be classed in this category. All agree in having no true crop, a tracheo-bronchial syrinx, and an elevated hallux; while the front toes are never completely webbed, though nearly so in Heliornis; the nares, moreover, are pervious, except in Rhinochetus. In the last-named the condition of the newly-hatched young is unknown, in Heliornis they are said to be naked at first, but in the remainder of the group they are covered with simple down. In structure the nine Families differ widely, a fact which would seem a strong argument against combining them under one head; but the aggregate of such points must be considered, and in any linear system the relationships within every Order cannot possibly be equally close. The present arrangement does not differ greatly from that adopted by Mr. Sclater,[[171]] wherein he accepted the names Alectorides and Fulicariae, used by Nitzsch, but made the former to consist of the Aramidae, Eurypygidae, Gruidae, Psophiidae, Cariamidae, and Otididae, and the latter of the Rallidae and Heliornithidae. Some writers, both modern and ancient, have placed the Otididae in the Limicoline group.
Fam. I. Rallidae.–The Rails constitute a somewhat generalized and very homogeneous Family, found in almost all parts of the world. The body is peculiarly compressed–enabling them to move with ease in dense vegetation–while the keel of the sternum is especially reduced in those flightless forms for which the group is remarkable. The strong bill varies in dimensions, being long in typical Rails, shorter and thicker in Crakes, decidedly curved in Himantornis, and reaching its maximum size among the Gallinules in Porphyrio and Notornis, where it is subconical. A horny shield is present upon the forehead in Megacrex, Habroptila, the Gallinules and the Coots, which is usually rounded or truncated posteriorly, but is reduced to a point in Porphyriops. This excrescence is in most cases red, but is sky-blue, light green, or dusky in Porphyriola, green in Tribonyx, blackish in Megacrex, white, yellow, or brown in Fulica. The lower part of the tibia is bare; the anteriorly scutellated metatarsus is seldom short, though occasionally very stout; the toes are long and slender with the elevated hallux weakest; the claws are fairly long, curved, and sharp. Somewhat shorter digits are found in Tribonyx and Pareudiastes, Fulica has broad lobes of skin along the front toes, while Porphyriops and Gallinula have narrow entire membranous margins to them. The wings are generally short and rounded, with ten or eleven primaries, and from eleven to sixteen secondaries, all the feathers being obtuse; but in many species these members are imperfectly developed, and their coverts actually hide the quills in such cases as Ocydromus and Notornis. This retrograde tendency is clearly evidenced in the "Island Hen" of Tristan da Cunha (Gallinula or Porphyriornis nesiotis) and the Mountain Cock of Gough Island (G. comeri), which flutter along without flying; in the Moho of Hawaii (Pennula ecaudata), Ocydromus and Notornis of New Zealand, and Habroptila wallacii of Halmahera; not to mention Eulabeornis, Porzanula, Nesolimnas, Cabalus, Pareudiastes, and the extinct Aphanapteryx, Aptornis, Diaphorapteryx, and Erythromachus. In several flightless forms, as in the Dodo, the angle between the scapula and the coracoid is obtuse. The tail has from ten to fourteen rectrices, the usual number being twelve; these are short and usually soft, frequently with decomposed webs, and may be concealed by the coverts, as in Megacrex, Amurolimnas, and Pennula. Its form varies from narrow and pointed to comparatively broad and rounded. A large caruncle rises behind the frontal shield in Gallicrex and Fulica cornuta, two knobs being found there in F. cristata: the wing, moreover, is often armed with a sharp spine. The nasal grooves are commonly long and deep; the pervious nostrils being in the hard sheath of the bill in Gallinules, and partially covered by a bony or horny growth in Rallicula, Pareudiastes, and Thyrorhina. The furcula is U-shaped, the tongue lanceolate, the aftershaft very small. Down is plentiful in both adults and young, that of the nestlings being commonly black, while the chicks of our Moor-Hen and Coot have the head adorned with red and blue. Rails, not being born blind, run from the shell, and swim at once.
Ralline birds are under ordinary circumstances non-gregarious, and inhabit tangled marshes or damp localities near rivers and lakes; but many, and especially the flightless forms, have a predilection for dry plains, as for instance Pennula of Hawaii, Ocydromus of New Zealand, Cabalus of the Chatham Islands, Habroptila of Halmahera, Tricholimnas of New Caledonia, and Pareudiastes of Samoa. Crex pratensis of the Palaearctic Region also haunts dry lands. Fulica gigantea occurs only on the lakes in the Andes of Chili, Bolivia, and Peru. Some species are partly crepuscular, and in Britain the Spotted Crake is certainly little heard except towards evening. Rails walk easily with bobbing head and jerking tail, while they prefer running to flying, as the flight is laboured and requires continuous action of the wings. As may be readily seen in the case of Coots and Moor-Hens, some difficulty is experienced in rising from water, the feet trailing along the surface for several yards; but, when once fairly launched in the air, the legs, which at first hang down, are drawn up below the tail, and a steady pace is maintained for considerable distances. Most species swim and dive with facility, and will even remain with only the bill above water; perching and climbing, too, are common habits. Generally speaking, the members of this Family are silent birds, though they may be constantly heard calling towards dusk; the more or less melancholy notes are less varied than in many other groups, but may be harsh and sonorous, or loud and clear. The groaning noise uttered by the breeding Water-Rail, the somewhat frog-like sound made by the Moor-Hen, the continuous craking of the Corn-Crake, the "cackling" of the Clapper-Rail, the shrill whistle of the Wekas, the rasping cry of Ocydromus sylvestris, the deep trumpeting of the Purple Gallinule, and the clearer call of the Coot are some of the most notable exceptions. The food consists of worms, molluscs, insects and their larvae, green herbage, tubers, roots of aquatic plants and seeds; Porphyrio and Tribonyx cause serious damage to potato-, rice-, and corn-crops: while the former bird is said to have a curious habit of holding the larger edibles in its claws and nibbling them like a Parrot. Some of the stronger species occasionally prey on mice, lizards, young birds, and eggs. The nest may be a large mass of aquatic plants or dry flags, as in the Coots, or a similar but smaller structure, as in the Gallinules; the former being commonly founded under water, though raised above it, whereas the latter is generally near the bank or–exceptionally–at the height of a few feet in a tree or bush. Rails and Crakes make a more or less substantial fabric in sedges, grass, clover, and so forth, Creciscus and Porzanula a spherical mass with an entrance at the side; but Pareudiastes, Cabalus, and Ocydromus are stated to breed in most cases in burrows. Gallicrex occasionally fashions its nest on floating leaves, and the writer has seen a Moor-Hen's nest in a similar situation. The eggs, from two to ten or more in number, are generally white or cream-coloured with red-brown, olive, or blackish markings, and often with faint lilac spots; those of the Coot are stone-drab with small black specks; those of Cabalus modestus are white with a few indistinct rufous and grey flecks; those of Zapornia parva and Porzana bailloni are instances of a thick olive-brown mottling. The adults are stated sometimes to carry their young in their claws.
Exceptionally the plumage of the Rallidae is nearly black, as in Limnocorax, Fulica, and Habroptila; slightly browner, as in Gallinula; blue or greenish-blue as in Porphyrio: but the coloration is normally sober, with a tendency to olive, brown, or chestnut. This may be relieved by stripes of white, especially on the flanks; the under parts may be nearly red as in Creciscus levraudi; and both surfaces may be spotted with white as in the male of Corethrura pulchra, or flecked and barred with it, as in Rallus maculatus. The sexes are usually alike, but Rallicula, Zapornia, Gallicrex, and Corethrura are instances of the contrary.
Space, however, is wanting to give in detail a description of every form, which is the less necessary in view of their general similarity; but the following examples will enable a fair idea to be gained of the group.
Rallus aquaticus, the Water Rail of Europe and Central Asia, which winters in North-West India and North Africa, is olive-brown above with darker streaks, and lead-coloured below, the flanks being barred with black and white. The genus is found in most parts of the world, with the apparent exception of North-West Africa and the Australian Region. Rallus elegans, the King-Rail, R. longirostris (crepitans), the Clapper-Rail, and R. virginianus are well-known North American species, while R. madagascariensis is confined to Madagascar.
In Hypotaenidia, which ranges from India and South China to the Pacific Islands generally, the whole lower parts are barred with black and white, except in H. striata and H. mülleri, where these markings are restricted to the sides and abdominal region, and in H. brachypus, where the belly is plain.
Cabalus modestus and Nesolimnas dieffenbachi of the Chatham Islands are curious little brown forms with no visible tail, closely allied to the next genus, which they resemble in being flightless, and apparently in general habits. Ocydromus contains the Wood-Hens, or Weka Rails, of New Zealand, of which O. greyi of the North Island is tawny above with dark shaft-stripes or bars, and grey below with fulvous fore-neck and sides. O. carli of the South Island is more cinnamon in hue; O. australis, also of the South Island, is less grey below, and usually has barred flanks; O. fuscus of the south-west of the South Island is blacker than the first-named; O. hectori is a paler race of O. australis. These Rails are semi-nocturnal, and sometimes excavate burrows, in which, or in the scrub, they pass much of the day; the localities preferred are dry woods, ravines, and sandy shores, O. fuscus obtaining the name of Kelp-Hen from the stretches of sea-weed that it frequents. This species feeds on sea-molluscs, but its congeners will eat young birds, lizards, caterpillars, worms, insects, and berries. The cry is a sharp whistle, often preceded by a growl, the birds being very tame when unmolested. They are pugnacious, inquisitive, and thievish, stealing articles from tents or houses, attacking fowls, or sucking their eggs. Their own eggs are from five to seven, both these and the nest, which is generally in a burrow, much resembling those of other Rails. Ocydromus sylvestris, of Lord Howe Island, is nearly uniform rufous above and brownish below, with barred wings and tail; it lays similar eggs upon the ground.
The dusky Tricholimnas lafresnayi of New Caledonia is remarkable for its soft hair-like plumage, and the purplish-brown and black Gymnocrex rosenbergi of Celebes for its bare yellowish orbits.