Molts and Plumages of Orange-Breasted Buntings (Passerina leclancherii): Implications for Theories of Delayed Plumage Maturation

We document the sequence of molts and plumages in Orange-breasted Buntings (Passerina leclancherii), a nonmigratory passerine that is endemic to southwestern Mexico, and discuss implications of our results for theories of male and female delayed plumage maturation. This species has the same sequence of molts and plumages as all five other species of Passerina. However, in subadult (predefinitively plumaged) males and females, the intensity and extent of molts, as well as the plumage color (definitive malelike versus definitive femalelike) resulting from these molts, differ in many respects from other Passerina. The most significant difference is that female Orange-breasted Buntings exhibit delayed plumage maturation. For males and females, our results strongly support winter- and summer-status-signaling hypotheses for the evolution of delayed plumage maturation, and are inconsistent with winter- and summer-cryptic hypotheses, the female-mimicry hypothesis and the juvenile-mimicry hypothesis.