THE PHYSICAL GEOGRAPHY OF THE WEST INDIES.
The abundance of birds on the four largest islands of the West Indian archipelago, where indigenous mammals are almost limited to rodents and bats, has often suggested the conjecture that the ancestors of those islanders must have been immigrants from the east coasts of the American mainland; and that theory seems to be confirmed by two facts: the identity, or similarity, of numerous Mexican and West Indian species, and the circumstance that those analogies include so many swift-winged birds.
There are no woodpeckers in the forests of the Antilles, and only two species of large gallinaceous birds, but a prodigious variety of pigeons, swallows, finches, and crows. The _alcedos_ (kingfishers) are scarce, but the blackbirds so numerous that some of the countless species seem to claim a South American and even transatlantic ancestry. The restless _estornino_ of the Cuban highland forests, for instance, might be mistaken for a varnished starling, resembling the _Sturnus vulgaris_ of western Europe in everything but the more brilliant luster of its plumage. The curious _codornilla_, or dove quail, too, has its nearest relatives on the other side of the Atlantic, in Syria, Arabia, and the foothills of the Atlas. It builds its nest on the ground and, judging from its appearance, would seem to form a connecting link between the doves and small _gallinæ_; but its wings are those of a pigeon, and with the assistance of a northeast gale may possibly have carried it across the ocean.
In studying the geographical distribution of animals, we may estimate the prevalence of special genera by the number of their varieties, or by the aggregate sum of individuals, and in the latter sense the migratory pigeons of our forest States once nearly outnumbered all the other birds of North America, though the family is limited to five or six species. But in the West Indies the _Columbidæ_ predominate in both respects. Cuba is a country of wild pigeons as pre-eminently as South Africa is a land of pachyderms and Madagascar of night monkeys. The _Columba leucocephala_ (a congener of our ringdove) inhabits the mountain forests in countless swarms, and at the end of the rainy season visits grainfields in such numbers that hundreds are sometimes captured in nets, by means of corn scattered along the furrows.