An attempt will be made here to summarize all the available evidence, direct or indirect, which bears on the problem of relationship of these genera. The original dissections which are discussed in this report are only valuable as one more bit of evidence concerning one characteristic that aids in clarification of generic relationship, and it is only in conjunction with other evidence that any satisfactory conclusion may be forthcoming.
Morphology
My dissections demonstrated that, in relation to the size of the doves, the jaw musculature of all the specimens investigated was so nearly alike that only one major difference was detected. M. pseudotemporalis profundus appeared to be enlarged in the White-winged Dove. This might have been predicted, since the white-wing was also shown to possess an elongated beak, presumably an adaptation for nectar-feeding, which would necessitate additional muscle development in order to compensate for the added length. Measurements recorded from several skulls indicated that the heads of the birds (excluding the beak) are nearly proportional.
Perhaps plumage patterns are the most widely used characters for determining generic relationships of birds. Ridgway (1916:339-385) followed the columbid classification of Salvadori (1893) using plumage patterns and body proportions to distinguish between the genera. In the genus Zenaidura he included the unique specimen Zenaidura yucatanensis, and he placed auriculata in Zenaida. The White-winged Dove was referred to a separate genus, Melopelia. He described the genus Zenaidura in the following manner:
"Plumage of head, neck and under parts soft and blended; bare orbital space moderate, broadest beneath eyes. Coloration plain, the proximal secondaries (sometimes adjacent wing-coverts and scapulars also) spotted with black; rectrices (except middle pair) with a black band across postmedian portion, the apical portion paler gray than basal portion, sometimes white; a small black subauricular spot; adult males with head, neck and anterior under parts more or less vinaceous and sides of neck glossed with metallic purple."
He noted that the plumage of Zenaida was almost precisely as described for Zenaidura. Also, although all members of Zenaida reputedly possessed twelve rectrices, a characteristic of the genus, it was later found that auriculata possessed fourteen rectrices. The species was promptly placed in the genus Zenaidura by Peters (1934:213-215). In plumage and coloration, Melopia was described as similar to Zenaida and Zenaidura but without black spots on the wings.
The White-winged Dove also has twelve rectrices, but Bond (1940:53) and Goodwin (1958:330-334) considered the number and shape of rectrices to be of minor importance when compared to the homologous markings of the plumage. Goodwin stated that his conclusion was emphasized by the fact that the tail of auriculata is intermediate in length and shape between those of macroura and aurita. In summary Goodwin "lumped" the genera Zenaida and Zenaidura under the genus Zenaida.
Nidification
It has been adequately documented that members of these genera closely resemble one another in their nesting and egg-laying habits. Bent (1932:407, 417), Davie (1889:157), Goss (1891:242) and Nice (1922:466) have described the two, white eggs of the clutch of the Mourning Dove. They have also noted that their nests are composed mainly of twigs and may be constructed in trees, shrubs or on the ground. The Eared Dove has nearly identical habits (Bond, 1961:104), and a similar situation exists with the Zenaida Dove (Audubon, 1834:356; Bent, 1932:418-419).
Like the other species, White-winged Doves lay two white or buffy eggs per clutch and build frail nests of sticks (Bent, 1932:431; Wetmore, 1920:141; Baird, Brewer and Ridgway, 1905:377).