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Black-headed Antbird (Percnostola rufifrons) are found in shrubby borders, edges, gaps, and second growth in the northern Amazon basin and Guiana Shield. Sexes are indistinguishable and female-like early in life, washed brown-gray throughout with buffy-tipped coverts, until the preformative molt (FPF). These are the only known Amazonian species that exhibit a limited presupplemental (FPS) also known as the auxiliary preformative molt (FPX). Thus, this species' molt pattern is strikingly similar to Northern Cardinal (Cardinalis cardinalis) where the FPS is limited, while the subsequent FPF and definitive prebasic molts (DPB) are complete. FPS includes body feathers, and variable numbers of less coverts and med coverts. After supplemental plumage (FAS) males are black with white-edging to the wing coverts. The profile photo is of an FAS female followed by a series of synchronous age photos of male wings. 

Percnostola rufifrons

FCJ - First Cycle Juvenile

First cycle juvenile (FCJ ) individuals characterized by a single generation of loosely textured and gray-brown plumage. Coverts edged buff. Tail feathers noticeably more tapered than FAS individuals.

FCS - First Cycle Supplemental

First cycle supplemental (FCS) individuals have replaced and female-like body plumage with noticeable molt limits between juvenal greater coverts and replaced less and med coverts. Sometimes these molt limits extend to the greater coverts. Sexes are often indistinguishable at this age, however, occasionally, males will replace one to several coverts that are black and edged white. FCS plumage is quickly replaced during the preformative molt (FPF).

FPF - First PreFormative

First preformative (FPF) molts are complete whereby juvenal remiges and retrices are symmetrically and sequentially replaced by maturated plumage. FPF is most obvious in males whereby gray-brown juvenal plumage is replaced by black feathers. It is often more difficult to separate definitive prebasic (DPB) from FPF females because juvenal and female plumage is similar in color. In such cases, females can be aged as after supplemental plumage (FAS) or as an unknown molting individual (UPU). 

FAS - After First Cycle Supplemental

After first cycle supplemental (FAS) individuals are characterized by a single generation of plumage. Because the preformative molt is complete, it is often impossible to differentiate formative and definitive basic plumages. The WRP system accounts for this conundrum with the central "A" code, indicating that this bird is at least after the supplemental plumage (FAS). 

DPB - Definitive PreBasic

Definitive prebasic molt (DPB) is characterized by non-juvenal plumage (either formative or definitive basic plumage) being replaced by definitive basic plumage. Because the preformative molt is complete, and results in a formative plumage indistinguishable from the definitive basic plumage, it is often impossible to seperate SPB from DPB birds. Thus, individuals replacing maturated plumage with definitive basic feathers can be classified as DPB.

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