ura_. 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).

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.

Interbreeding

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