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_.
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).
The point to be made here is simply this: If the species in question are to be considered congeneric then it might reasonably be expected that they would display some similarity in nidification and egg-laying. If their habits varied considerably it would not necessarily mean that their relationship was more distant, but similarities can usually be considered indicative of affinities because they are the phenotypic expression of the partially unaltered genotype of the common ancestor.
Intergeneric crosses of columbids in captivity are common, but in nature there is little evidence that even interspecific crosses occur. Only one apparent hybrid between members of the genus _Zenaida_ and genus _Zenaidura_ has ever been discovered. The individual was taken on the Yucatan peninsula of Mexico, and was described and named as a new species (_Zenaidura yucatanensis_).
Salvadori (1893:373), Ridgway (1916:353) and Peters (1934:213-215) agree that _Zenaidura yucatanensis_ Lawrence is a hybrid between _Zenaidura macroura marginella_ and _Zenaida aurita yucatanensis_. Ridgway (1916:355), however, notes that "... If _Zenaidura yucatanensis_ Lawrence should prove to be really a distinct species, and not a hybrid ... unquestionably _Zenaida_ and _Zenaidura_ can not be separated generically, since the former is in every way exactly intermediate between the two groups." In the event that the unique type is a hybrid, the very fact of its existence supports the hypothesis that the genera are more closely related than is currently recognized.