The genus Rhamphastus contains fourteen members, with nearly the same range as that of the Family, including the type and sole Argentine species R. toco, one of the largest forms, two feet in length. This is black, with white rump, throat and fore-neck (the last bordered with red), crimson vent, blue orbits, and orange bill terminally blotched with black, which has been likened to a lobster's claw. Several species have the throat and rump yellow or orange, or the latter scarlet, as in R. ariel. The brilliant bill and orbits vary considerably in colour; the tail is square. Andigena comprises some five forms from the highest forests of Colombia, Ecuador, Peru, and Bolivia, olive-brown or dark green above, and with hair-like bluish-grey plumage below; the crown is black, the nape black or grey, the vent scarlet, the rump yellow, and the tip of the graduated tail chestnut, except in one instance. The bill shews black, yellow, or red, in varied combination, A. laminirostris having a square ivory-white basal plate on each side of the maxilla. A. bailloni, of South-East Brazil, doubtfully placed in this genus, has a scarlet rump, yellow under parts, greenish and reddish bill, and red orbits. Pteroglossus, the most brilliant genus in the Family, exhibits green, scarlet, and yellow hues, with areas or bands of black and scarlet on the lower surface in thirteen out of eighteen species. The tail is graduated, and the feathers below are somewhat hair-like. These Araçarís, as they are called, range from South Mexico to Bolivia and South Brazil. The lovely P. beauharnaisi, of Upper Amazonia, has dark green upper parts, with crimson on the rump and mantle; and light yellow lower parts, tinged with red, which shew a scarlet ventral band and black spots on the throat; the maxilla is black with orange culmen, the mandible white. P. aracari of Guiana and Lower Amazonia has no red on the mantle, the smooth head and throat are black, the maxilla is white with black culmen, the mandible black. Some six species of Selenidera, remarkable for the dissimilar sexes, and generally for the transversely striped or blotched beak, range from South-East Brazil and Upper Amazonia to Nicaragua. The males, except in S. spectabilis, have a distinct nuchal crescent of yellow, less marked in the females; the former have the head and breast black, the latter usually chestnut; but the hen of the above species has the under surface black, that of S. piperivora greyish-green. The general colour is dark green, with brown tip to the tail, yellow or orange ear-coverts, and scarlet vent; the beak is whitish, reddish, or greenish, with black markings. Aulacorhamphus has some dozen fairly uniform green members, relieved by a white, bluish, or black throat. The rump may be crimson or rufous, the rectrices tipped with chestnut, and the bill a mixture of red, black, yellow, or horn-colour, usually with a white line at the base. The range is from Mexico to Guiana and Bolivia.
Fam. XVIII. Picidae.–The Woodpeckers form a very large Family of scansorial birds with zygodactylous feet, which is so natural that Huxley raised it to higher rank as Celeomorphae, while Parker separated it still further as Saurognathae. The two Sub-families are (1) Picinae, or Woodpeckers, and (2) Iynginae, or Wrynecks.
Sub-fam. 1. Picinae.–The chief external peculiarities of this section lie in the form of the large head, the neck, and the tail-feathers. The neck is often much compressed, with exceedingly powerful muscles, which, coupled with the strong, wedge-shaped bill, enable the bird to operate with ease and celerity upon the boles and limbs of trees, whence it procures much of its food, and where it excavates a deep hole for the reception of its eggs. The shafts of the twelve tail-feathers, of which the outer pair are very small, are in the majority of cases stiff and spiny, and therefore well adapted to keep the body close to the bark while climbing; parallel cases being those of the Tree-Creeper (Certhia) and the Dendrocolaptinae. The shape of the tail is rounded or cuneate; the wings are moderate and not very much pointed, with ten primaries and from ten to thirteen secondaries. The metatarsus is short, with a single row of anterior scutes; the claws are large, sharp, and curved.[[260]]
The tongue is excessively long and "worm-like," with horny, barbed tip, and is capable of marvellous protrusion owing to the elongated "horns" of the hyoid apparatus, which in some forms curve round the skull and have their origin near the base of the bill. Facility is thus secured for searching narrow cracks or deep hollows for insects, while the secretion from the large salivary glands secures the adhesion of the objects aimed at. The furcula is U-shaped, the syrinx tracheo-bronchial, the after-shaft rudimentary, while neither adults nor young have down at any stage.
The prevailing colours are green, yellow, black, and white, in various combinations, with spots and bars; brilliant scarlet being commonly present on the crown and frequently also on the back or under parts. From the males the females and young in first plumage may be distinguished by their duller coloration; but in the intermediate stages of growth the latter exhibit a considerable amount of red. Many species have fine crests.
According to Hargitt[[261]] the number of genera is fifty, including three hundred and eighty-five fairly defined species; though both genera and species depend chiefly on colour. He mentions Colaptes as an instance of the possible formation of races by hybridization or climatic influences, and Gecinus as an example of diversely coloured forms, perhaps originating from a common ancestor. The well-known colour-phases of Dendrocopus major and of the genus Iyngipicus may be mentioned in this connexion; the species becoming larger and whiter as they range eastwards through Central Asia to Japan, and the former also shewing a tendency to a crimson tint on the breast as it nears Africa southwards.
Woodpeckers are, with a few exceptions, solitary woodland birds of a particularly shy and retiring nature, and therefore somewhat difficult of observation. When seeking food they usually ascend a tree in spiral fashion assisted by their tail and claws, and carefully examine every chink or cranny in the bark; on reaching the higher limbs they betake themselves at once to fresh hunting-grounds, often alighting at the very base of a trunk, but equally often flying straight to some promising half-decayed branch. In some cases, however, high flights are essayed. The species of Colaptes and Geocolaptes feed upon the ground; many forms, such as Picus martius, Gecinus viridis, and Melanerpes formicivorus, prey largely upon ants and take great pains to make a thorough clearance of the nest; the last-named stores up acorns; while Sphyrapicus varius and its congeners suck the sap of trees and also hawk for flies: others again devour a large quantity of fruits, seeds, and perhaps even Indian corn. Omitting, however, the sap-sucking propensities of the American species, the harm done is outweighed by the good.
In spring the laughing, ringing, or other cries may be heard in most wooded districts; the sounds being somewhat harsh, and consisting of more or less continuous notes according to the species, while the duration is commonly about thirty seconds. The curious "drumming" noise produced in particular by the Spotted and Black Woodpeckers is also chiefly heard early in the year, though it ceases not with the courting, but when the young are hatched. This sound, which can be heard for a mile, is caused by the bill hammering on the bark–usually of some rotten branch, while the bird's head moves backwards and forwards with extraordinary rapidity; a stationary position, however, is not invariably preserved, nor the quest of food interrupted. The hen sometimes hisses loudly if disturbed upon her eggs; both parents are said to "purr" in certain American species when the hole is interfered with, and they certainly utter continuous, sharp alarm-notes in Britain. It is probable, but perhaps hardly certain, that the female drums as well as the male. The sense of hearing is extremely acute in the Family. The flight is strong and undulating with constant "dips," and when once witnessed can be recognised at considerable distances. Both sexes help to excavate the hole for their eggs, which is a neat circular aperture, worked from the centre outwards, and carried inwards to the core of the wood, to descend thence for at least a foot; as soon as it turns downwards it gradually enlarges, until the whole presents the form of a long-necked bottle. Abortive borings are often made, of considerable depth; while the chips may be found lying at the foot of the tree in a heap, if not removed by the birds, as occasionally happens. Firs, oaks, poplars, beeches, ashes, and willows, both high and low, furnish many breeding places, but wooden walls or towers are also utilized, and two species, mentioned below, bore like Kingfishers in banks. The same hole is occasionally tenanted in successive years, but natural cavities are rarely used. It is commonly stated that Woodpeckers always choose for their excavations decayed or decaying limbs; but the soundest branches, or even the thickest parts of the trunks of huge oaks, are not unfrequently selected. The oval, glossy, white eggs are deposited on a few chips, and usually number from three or five to ten; nevertheless as many as seventy-three are recorded as the produce of one Woodpecker, and forty-two in the case of the Wryneck, when robbed on successive days.[[262]] Both sexes are known to incubate in certain cases: they sit very closely towards the end of the period, which lasts fourteen days or more, yet often leave their hole quite readily at first. Many species have been tamed, but they are wild and destructive in captivity.
The Family ranges over the greater portion of the globe, except the Australian Region, Madagascar, and Egypt. Its members are most abundant in the Indian and Neotropical Regions, several forms occurring in the Antilles.
Geocolaptes olivaceus, an olive-coloured bird with whitish marks on the wings and tail, crimson rump, and crimson-washed abdomen, is common in the Cape Colony and Natal, and is remarkable for nesting in holes in banks or mud-huts: it feeds upon the ground, and family-parties are stated by Mr. Layard to keep together until the following breeding-season. Similar habits have been observed in Colaptes agricola of the Argentine Republic and Patagonia, in timberless districts; but, as the trees grow, it recurs to its natural habits. C. auratus, the golden-winged Flicker of North America, has a phase (C. mexicanus) found west of the Rocky Mountains and in Mexico, with red coloration of the wings in place of yellow, intermediate races occurring in the intervening regions; considerable controversy has consequently arisen as to whether hybridization has taken place, or whether this is a case of specialized forms of a generalized ancestor, due to climatic or other causes. The colour above is dove-brown with black streaks; the head being lead-coloured with a crimson band on the nape, the rump white, the lower throat black, the under parts pinkish-brown with round black spots, and the wings strongly washed with yellow on both surfaces. The bill is more arched and less wedge-shaped than usual. The food consists of fruit, wood-lice, ants, and so forth, much of which is procured upon the earth.