The First Basic Problem: A Review of Molt and Plumage Homologies

Abstract

All birds have fundamentally similar patterns of plumage succession. Thus Humphrey and Parkes (1959) proposed a system of nomenclature (the H-P system), based on homologies, that has become standard for molt studies in North America. However, presumably analogous similarities in pattern between first basic and definitive basic plumages have obscured homologies. Many plumages conventionally known as “first basic” are better considered as novel first-cycle plumages that lack homologous counterparts in subsequent cycles. Consequently, current nomenclature does not consistently reflect between-species homologies. Howell and Corben (2000b) proposed that traditional juvenal plumage can be considered an unambiguous starting point for a terminology that better reflects presumed homologies in basic plumages; alternate and other nonbasic plumages may not necessarily be homologous between species. Four underlying strategies of increasing complexity incorporate all known patterns of plumage succession: the Simple Basic Strategy, the Complex Basic Strategy, the Simple Alternate Strategy, and the Complex Alternate Strategy. We review inconsistency in the H-P system; explain the four underlying strategies; and discuss how one can identify homologies (if any) between plumages in first and subsequent cycles and among taxa. Many species have novel plumages added into their first plumage cycle; we argue that existing terminology for these plumages is unsuitable and we term them formative plumages attained by preformative molts. Finally, we provide examples of how this modified H-P system can be applied to diverse taxa of birds while reflecting the homology underlying all basic plumage cycles. Our revision validates the flexibility and utility of the H-P system.El Problema del Primer Plumaje Básico: Una Revisión de las Homologías de la Muda y del PlumajeResumen. Todas las aves tienen patrones de sucesión del plumaje fundamentalmente similares. De este modo, Humphrey y Parkes (1959) propusieron un sistema de nomenclatura (el sistema H-P), basado en homologías, el cual ha sido de uso común en estudios de muda de plumaje en Norte América. Sin embargo, supuestas similitudes análogas entre el primer plumaje básico y el plumaje definitivo básico han confundido las homologías. Muchos plumajes convencionalmente conocidos como “primer básico” son considerados mejor como plumajes originales del primer ciclo que carecen de contrapartes homólogas en los ciclos siguientes. Consecuentemente, la nomenclatura actual no refleja las homologías entre especies. Howell y Corben (2000b) propusieron que el tradicional plumaje juvenil puede ser considerado como un punto de partida inequívoco para una terminología que refleje mejor las homologías presuntas en los plumajes básicos; los plumajes alternos y otros plumajes no básicos pudieran no ser homólogos entre especies. Cuatro estrategias de creciente complejidad incorporan todos los patrones conocidos de sucesión de plumajes: La Estrategia Básica Simple, La Estrategia Básica Compleja, La Estrategia Alterna Simple, y La Estrategia Alterna Compleja. Examinamos ciertas inconsistencias en el sistema H-P; explicamos las cuatro estrategias subyacentes, y discutimos cómo se pueden identificar homologías (cuando existen) entre los plumajes del primer ciclo y de los ciclos siguientes, y entre taxa diferentes. Muchas especies tienen plumajes originales adicionales en su primer ciclo de plumaje; sostenemos que la terminología actual para estos plumajes es inadecuada y los denominamos como plumajes formativos, logrados por mudas preformativas. Finalmente, damos ejemplos de como este sistema H-P modificado puede ser aplicado a diversos tipos de aves y al mismo tiempo reflejar la homología subyacente a todos los ciclos de plumajes básicos. Nuestra revisión valida la flexibilidad y utilidad del sistema H-P.

Factors influencing the evolution of moult in the non-breeding season: insights from the family Motacillidae

“…Until now, most studies have emphasized the evolution of the preformative and definitive prebasic moults (equated to the postjuvenile and postnuptial moults, respectively; terminology follows Howell et al, 2003), while other moults have received less attention. The presence of a single moult within the annual cycle, the prebasic moult, is the ancestral state in passerines, and the addition of the prealternate moult (equivalent to the prenuptial moult) is considered an autapomorphy with multiple independent evolutionary origins (Figuerola & Jovani, 2001;Howell et al, 2003).…”

“…The presence of a single moult within the annual cycle, the prebasic moult, is the ancestral state in passerines, and the addition of the prealternate moult (equivalent to the prenuptial moult) is considered an autapomorphy with multiple independent evolutionary origins (Figuerola & Jovani, 2001;Howell et al, 2003). In particular, the replacement of feathers upon arrival at the winter groundsusually in early autumnis rarely acknowledged as an independent episode (Howell et al, 2003;Newton, 2008: 305-306). However, the existence of other moult episodes is controversial.…”

Moult in the Loggerhead Shrike Lanius ludovicianus is influenced by sex, latitude and migration

“…The species exhibits a ‘complex alternate strategy’ of moult (Howell & Corben , Howell et al . ) involving a preformative moult followed by a prealternate moult (Howell et al . , Burnside ).…”

Variations in moult, morphology, movement and survival rates of the Sombre Greenbul Andropadus importunus within southern Africa

“…Adults and juveniles were compared with z-tests, and differences between regions were tested with ANOVA. The classification and nomenclature of Howell et al (2003) is followed: after fledging the juveniles undergo pre-formative moult followed by their second pre-basic moult in their second year. During the first pre-basic, i.e.…”