Mourning Doves (Zenaida macrura) might seem dull at a casual glance, but a closer look reveals subtle graduations of color in addition to the prominent black spots on the wings and below the eye.
Like all birds, doves have different sets of feathers (plumages) at different stages during their life. Nestling birds have very different plumage than adult birds. This set of feathers (called natal down) is lost and replaced (molted) to a juvenal plumage, which is molted in turn to a “basic” plumage. Some birds follow the “basic” plumage by an “alternate” or breeding plumage (for example the Goldfinch). Our example here, the Mourning Dove does not have a specialized “alternate” plumage.
There is some difference in basic plumage between Mourning Dove sexes. Males have a blue iridescence on the top of their head and shoulders and a pinkish breast.
The scaly-looking bird shown in the third photograph is in the process of molting from the juvenal to the basic plumage. When all its feathers are replaced, it will have a similar appearance to the first bird pictured.