The place which the Pigeons ought to occupy in the zoological system
has been a very fertile subject of dispute. Linnæus classed them with
the _Passeres;_ Buffon, Pennant, and Latham arrange them as an order
by themselves; while Cuvier and others place them in the category of
Gallinaceous Birds. The settlement of this question is, indeed, a matter
of considerable difficulty, as the habits of the entire race are in many
respects very peculiar. Like the Passerine Birds, they associate in pairs
during the nuptial season, work together in the construction of their
nest, and materially assist in the incubation of their eggs and the
care of their progeny, which latter, blind and helpless when they are
first hatched, are fed in the nest that forms their cradle, and which
they never quit until fully fledged; indeed, for some time afterwards
they are unable to supply their own wants, and depend entirely upon the
assistance of their parents. The features in which they differ from the
Passerine race are, however, equally well marked; these consist in their
manner of drinking and of administering food to their young family, in
the singularity of their caresses, in the nature of their plumage, and
in their vocal capabilities. They neither sing nor utter any cry; their
only voice in the adult state consists of a full, rolling sound, generally
designated by the term "cooing." Other dissimilarities separate them from
the Gallinaceous races, with which they have little in common, either
in their instincts, their manner of life, or their mode of pairing. The
_Gallinæ_ are almost all of them polygamists, and the females, by laying
numerous eggs, produce a covey at a single brood. Moreover, in temperate
climates, this happens but once in the year. The Pigeons, on the contrary,
are all of them strictly monogamous, and the female lays but two eggs for
each sitting, although she has several broods. In the Gallinaceous tribes
the male renders no assistance to the female, either in the construction
of the nest or in the care of their progeny. The chickens are born with
their eyesight perfect, and as soon as they escape from the egg-shell
are able to run about, and procure for themselves their own food. The
principal distinctive character of the _Columbæ_ is furnished by the
structure of the bill. The upper mandible consists of a horny apical
portion, which is often of considerable length and strength, but its
base is formed by a convex cartilaginous plate, in the anterior portion
of which the nostrils are situated. The skin covering the cartilaginous
portion is of a soft texture, very different from the rest of the bill.
It is sometimes smooth, and clothed with a sort of scurf, but in other
cases it is warty, or even developed into a fleshy wattle. This is
especially the case in some domesticated varieties of the Pigeon. The
_Columbæ_ are provided with short tarsi and moderately long toes, all
scutellated. The toes are four in number, three in front and one behind.
The anterior toes are not united by a membrane at the base. The hinder
toe is placed on the same plane with those in front, and the whole sole
of the foot is formed of soft papillated pads, which are usually a good
deal wider than the scutellated upper portion of the toes. The wings,
which are generally long and pointed, contain ten primary quills, and the
tail usually consists of twelve feathers, although in some cases there
are sixteen. Another important character distinguishing these birds, as
compared with the _Gallinæ_, is that their feathers are destitute of the
plumules, or accessory plumes, which are greatly developed in Gallinaceous
Birds. The form of the wing in Pigeons is sufficient to indicate that they
are capable of powerful flight, and many of them are remarkable for the
speed with which they traverse the air, especially when engaged in their
migrations. Most of them are arboreal, and nestle in the holes of trees;
others frequent rocks, but all perch with great facility; nevertheless,
they generally seek their food upon the ground, and walk or run without
difficulty. They are also remarkable for their mode of drinking, in
which they differ from all other birds. The general practice of birds in
drinking is to take up a small portion of water in the bill, and then, by
raising the head, to allow it to run down into the throat. The Pigeons,
on the contrary, dip their bills into the water, and hold them there till
they have quenched their thirst. These birds are inhabitants of the warmer
and temperate regions of the earth, but they are found in most abundance
in hot climates, where, also, their plumage attains a brilliancy of which
that of our native species gives us but an imperfect idea.
* * * * *
The FRUIT PIGEONS (_Trerones_) are recognisable by their compact body,
short, thick beak, powerful, broad-soled, but short feet, moderate-sized
wings, and short tail; the latter is composed of fourteen feathers, and is
either slightly cuneiform or straight at its extremity. The plumage, in
which green predominates, is always brilliant.
The members of this group inhabit the whole of India, the Malayan
Peninsula, Australia, and Africa, and are usually seen in parties of
variable number, perched upon fruit-trees. Their movements much resemble
those of the Parrots, and their voice, unlike that of most of their
congeners, is loud and sweet. Such species of Fruit Pigeons as inhabit
India (and probably Africa) place their very loosely-constructed nest at
the summit of a lofty tree, and lay two white eggs.