Lumped together under the general but well-understood name of “Ducks” are a great variety of forms, not all of which, however, agree quite with the abstract idea of what a “Duck” should be. Broadly speaking, the Ducks are distinguished by having the neck shorter than the body, a broad, more or less flattened, ” Duck-like ” bill, and the front of the tarsus with narrow transverse plates, and shorter than the middle toe. Most of them conform to this plan, but at the outset we meet with a group the so-called Tree-Ducks which afford more or less of a transition between the true Ducks and the Geese, since in these the lower part of the tarsus in front is without the transverse plates, but covered with small, reticulated scales. In their main characters, however, the Tree-Ducks agree with the Ducks and are perhaps best placed with them, although in voice and vegetarian habits of feeding they certainly suggest the Geese.
The Tree-Ducks (Dendrocygna) number about ten species and enjoy a very wide, though mainly tropical, distribution. They have rather long necks and legs, short and rounded wings and short tail, and the plumage is either spotted and speckled or uniform with the different colors arranged in definite areas. In length they range from about sixteen to some twenty-four inches, and the sexes are very nearly alike. In habits they are mainly arboreal, perching readily on the limbs of trees, shrubs, or even stalks of corn. One of the most remarkable, at least as regards its distribution, is the Fulvous Tree-Duck (D. Fulva), or Whistling Teal, as it, or its near ally, is called in India. It is found from the southern border of the United States through Mexico, then skipping Central America and Amazonia, it ranges from Venezuela and Peru to Argentina. Thence, according to Salvadori and others, it is found from tropical Africa and Madagascar through the Indian peninsula to Burma; but it seems more than probable that the Old World form is distinct, in which case it should be known as the Dendrocygna major of Jerdon. It is also possible that the South American bird, which is brighter colored and larger, is subspecifically separable from the northern bird, but in any case the three forms are close, if not indeed identical, and it is as difficult to explain the geographical distribution of the three as of one. It has been suggested that the bird was originally a native of the Old World and was brought by slaves from Africa to America, but this is unsupported by any evidence.
The distribution of the true Tree-Duck (D. Viduata) is also very strange, as at present accepted, being tropical South America and the West Indies, and tropical Africa and Madagascar, but here again is the possibility of two species being confounded. The remaining species of the genus are more limited in their distribution.
The Fulvous Tree-Duck is a handsome bird, about twenty inches long, with the back and scapulars black, the under parts cinnamon or fulvous, the flanks marked with paler stripes; the head and neck are like the lower parts, and the upper tail-coverts are white. The late Colonel. Grayson, writing of this bird as he observed it in western Mexico, says that although inhabiting the coast region it is never found in the sea, being strictly a fresh-water Duck. It arrives at the close of the rainy season in great numbers, frequenting fresh-water ponds and lakes, where it feeds upon grain and seeds, often visiting the corn-fields at night for grain. He did not procure the nest himself, although he was informed by the natives that they nested on the ground among grasses, and not in trees. This view is strengthened by the observations of Hudson, who met with it very abundantly in eastern Argentina, where it makes its appearance in the spring, in very large numbers, to breed in the marshes and on the pampas. Of the nests he says: “So extremely social are these Ducks that when breeding they keep together in large flocks. The nest is made of stems and leaves, on the water among the weeds and aquatic plants; and sometimes large numbers of nests are found close together, as in a gullery. The eggs are pure white, and each bird lays,I believe, ten or twelve, but I am not sure about the exact number; and I have so frequently found from twenty to thirty eggs in a nest that I am pretty sure that it is a common thing for two or three females to occupy one nest.” In India, Hunt mentions the finding of but a single nest, and this was placed in a large hollow tree overhanging the water. It contained seven eggs.