The last members of the family to be considered are the Wood Ibises, or Wood Storks. Although it seems now to be pretty definitely settled that their affinities are with the Storks, they form, nevertheless, a sort of connecting link between them and the Ibises. By many students the characters of the Wood Ibises are regarded of sufficient importance to entitle them to be ranked as a family or subfamily of equal value as that including the Storks, but it perhaps is best in the present instance to consider them as a well-marked group of the Ciconiidae.
The Wood Ibises are large Stork-like birds, with long legs and a long neck and beak, the latter being thickened at the base, but much attenuated toward the tip, where it is turned downward, much as in the true Ibises. The legs are covered with small hexagonal scales, while the toes are long, very slender, and connected basally by a well-developed web. The plumage is compact above but rather loose below; the wings are long and broad, the second, third, and fourth quills being nearly equal in length, while the tail is short, or moderately long, and composed of twelve broad, strong feathers.
Only four species of Wood Ibises are known, these being separable into two genera, Tantalus, which includes the single American species, and Pseudotantalus, which embraces the three Old World forms. In the first, the adult has the whole head and upper half of the neck naked, the skin being hard and scurfy, while in the Old World species only the fore part of the head is naked, the hinder half, as well as the entire neck, being densely feathered. In Tan-talus, however, the young birds have the head and neck feathered. In all the species the general color is white, in some tinged with pink or rosy, while the quills and tail are black or brownish. In young birds the mantle is usually darker.
The American Wood Ibis (T. Loculator) is a curious bird in many respects. It is widely distributed over tropical and warm-temperate America, extending north regularly to the Gulf States, lower Mississippi Valley, lower Colorado Valley, etc., and casually or in some instances regularly to New York, Illinois, Utah, and California. It is from thirty-five to forty-five inches in length and white in color, with the quills,secondaries, and tail glossy greenish black with purple and bronze reflections. In the breeding season the under wing-coverts are rosy pink. The bare portions of the head and neck are livid bluish; the bill yellowish; the legs blue, becoming blackish on the toes.
Its habits have been variously described, some regarding it as a solitary bird, while others have found it usually in small parties. Hudson, who saw it in Argentina, says : “On the pampas it is not uncommon in summer and autumn, and goes in flocks of a dozen or twenty. The birds are usually seen standing motionless in groups or scattered about in spiritless attitudes, apparently dozing away the time.” It frequents both fresh and salt waters, feeding largely upon fishes, which, according to Audubon, it catches by dancing around in the water to render it muddy, then killing all that come to the surface. It also feeds on frogs, crabs, snakes, turtles, young alligators, young birds, etc. The nest, a rude platform of sticks, is placed in trees often of great height. In the shallow depression two or three white eggs are laid, which are about two and one half by two inches. The nesting site is used for many years, the birds refusing to leave even under great persecution.
The Ibises are medium or large sized wading birds most closely related to the Storks, but distinguished from them at once by the bill, which is rather slender, more or less cylindrical throughout, and evenly bent downward after the manner of the Curlews. The bill is also rather soft, except at the tip, and the nostrils are slit-like, and placed in a deep, narrow groove which extends quite to the end of the bill. The legs are thick and strong, of moderate length, and the toes long, the front ones being connected by a short web, while the claws are long and slender. The wings are rather long and pointed, and the tail, of twelve feathers, is short and square-cut at the end. As Ridgway has said, “A great diversity of form and plumage is to be seen among the various species, some being trim and graceful in their build, and others uncouth, with Vulture-like head and neck, some plain in colors, while others are among the most brilliant of birds.”
The Ibises enjoy a wide geographical distribution, although most abundant in the intertropical regions. They are also a very old group, as some three or four fossil forms have been described from the middle Tertiary of England, France, Patagonia, etc. About thirty living species are known, these being distributed among some twenty or more genera. The New World is the richest in forms, possessing more than a third of the known species, while of the Old World species Africa possesses six or seven, Asia about eight, and Madagascar and Australia two each.