ORNITOLOGIA NEOTROPICAL ______Volume 20 2009 No. 1 ______

ORNITOLOGIA NEOTROPICAL 20: 1–18, 2009 © The Neotropical Ornithological Society

THE CURRENT STATE OF KNOWLEDGE ON MOLT AND PLUMAGE SEQUENCES IN SELECTED NEOTROPICAL FAMILIES: A REVIEW

Thomas B. Ryder1,3 & Jared D. Wolfe2

1Department of Biology, University of Missouri-St. Louis and Whitney R. Harris Center for World Ecology, 1 University Blvd., St. Louis, Missouri, 63121, USA. E-mail: [email protected] 2Humboldt State University, Wildlife Department, 1 Harpst St., Arcata, California, 95521, USA.

Resumen. – El estado de conocimiento actual en mudas y secuencia de plumajes en siertas familias tropicales: una revisión. – Las mudas anuales y sus subsecuentes plumajes se encuentran ampliamente representados en la historia de vida de las aves. La investigacion relacionada a la utilidad de mudas y plumaje ha producido un marco conceptual confiable para la caracterizacion de edad en la mayoria de la avifauna de la zona temperada. En comparacion a la zona temperada; sin embargo, cono- cemos muy poco sobre las mudas y plumajes de las aves tropicales residentes. Los datos publicados con respecto a mudas y secuencias de plumaje son limitados en rango, cubren pocas especies, y, hasta nuestro entendimiento, no estan actualmente resumidos. Aqui combinamos nueva informacion recolec- tada en trabajo de campo y en museos con una sintesis de un trabajo previo para revisar muda y plu- maje para 15 familias de paserinos y cuasi-paserinos del Nuevo Mundo. Especificamente, resumimos secuencias y extension de mudas debido a que se encuentran relazionadas con la categorizacion de edad; ademas, asignamos estrategias de muda generales basadas en patrones encontrados entre ge- neros dentro de cada familia. Dada la diversidad de la mayoria de familias de paserinos tropicales, este resumen no incluye a todas ellas; sin embargo, lo presentamos como un marco conceptual amplio con el fin de incrementar nuestro entendimiento de la muda y secuencia de plumaje en la avifauna tropical.

Abstract. – Annual molts and the subsequent plumages they produce are a ubiquitous element of avian life history. Research pertaining to the utility of molt and plumage has produced a robust framework of age-categorization for the vast majority of temperate avifauna. In comparison to temperate bird , however, we know very little about resident topical bird molt and plumage. Published data pertaining to molt and plumage sequences are limited in scope, covering few species, and, to our knowledge, are not currently synthesized. Here we combine new information gathered from field and museum specimens ______3Current address: Smithsonian Migratory Bird Center, National Zoological Park, PO Box 37012-MRC 5503, Washington, DC, 20013, USA.

1 RYDER & WOLFE with a synthesis of previous work to review molt and plumage for 15 families of New-World tropical and near-passerines. More specifically, we outline plumage sequences and molt extent as it relates to age-categorization; we also assign generalized molt strategies based on common patterns found among genera within each family. Given the diversity of most tropical families, this syn- thesis is not all-inclusive; however, it is presented in a broad framework with the goal of advancing our knowledge of tropical avian molt and plumage sequences. Accepted 19 November 2008.

Key words: Molt, plumage, plumage-sequence, tropical, New World.

INTRODUCTION be warranted in species where a phylogenetic analysis of molt shows well-conserved pat­ The utilitarian value of molt and plumage across closely related species (Hall & sequences, as it pertains to aging , is well Tullberg 2004). Some related species that established in both Europe (Jenni & Winkler occur in different habitat types appear to have 1994) and North America (Mulvihill 1993). different molt strategies, which may be corre­ However, the applicability of these practices lated with different environmental attributes is wholly reliant on available information for (e.g., amount of solar radiation in open vs. families, genera and species of interest. In shady habitats). temperate North America, molt and plumage Previous studies suggest that most tropi­ information on passerines and near-passe­ cal residents have a single annual prebasic and rines have been summarized by Pyle (1997), partial preformative molt (Dickey & Van Ros­ which facilitates the placement of captured sem 1938, Piratelli et al. 2000, DuVal 2005, individuals into accurate and repeatable age Mallet-Rodrigues 2005, Ryder & Durães 2005, classes. Despite recent advances in our under­ Doucet et al. 2007). The existence of a partial standing of molt and plumage development preformative molt in many tropical taxa for temperate species, relatively little is known makes molt-based aging criteria (i.e., retained about resident terrestrial bird taxa in the Neo­ juvenile plumage, delayed plumage matura­ tropics (Pyle et al. 2004). Moreover, there is a tion and molt-limits) possible for tropical res­ need for a new progressive system of age clas­ idents. Here, we present data compiled from sification for tropical resident birds given the contemporary literature, personal field obser­ potential difficulties of applying the calendar- vations, and review of museum specimens to based age-classification system to tropical summarize what is known about tropical bird taxa (Wolfe et al. unpubl data). molt. We use our findings to develop conser­ The majority of work on molt in tropical vative estimates of molt strategy, extent, and resident birds has focused on the timing of associated plumage sequences (when avail­ molt in relation to other activities in the able) for 15 Neotropical avian families. We annual cycle (Snow & Snow 1964, Foster also include information on other relevant 1975, Poulin et al. 1992, Piratelli et al. 2000, characters that vary by age (i.e., and bill Marini & Duraes 2001, Mallet-Rodrigues color). 2005) rather than duration and extent of molts, and progression of plumages (Pyle et al. METHODS 2004, Ryder & Durães 2005, Doucet et al. 2007). In families for which these data are Field observations were made at two study available, information is limited to few species sites in Central America and northern South with the assumption that related species show America. The Central American site is located similar characteristics. This assumption may in Tourtuguero, Costa Rica (10°33’51”N,

2 MOLT AND PLUMAGE IN THE NEOTROPICS

83°31’7”W), in lowland Caribbean rain forest. ‘prejuvenile molt’ as the ‘first prebasic molt,’ Klamath Bird Observatory and Redwood Sci­ and the traditional ‘first prebasic molt’ as the ences Laboratory (USFS) have operated a ‘preformative molt.’ Molt and their corre­ monitoring station at five sites around Tour­ sponding cycles are named for the plumage tuguero since 1994 (Ralph et al. 2005). Both they produce (e.g., the preformative molt pro­ authors served as primary banders at these duces the formative plumage). We use the stations for a total of three years, during term ‘juvenile’ in place of ‘first basic’ because which time information on molt and plumage the former is more widely recognized. Also of sequence was compiled. The South American note is the use of ‘definitive’ instead of the site is located in eastern Ecuador at the Tipu­ more commonly used ‘adult’ to describe tini Biodiversity Station (0º38’S, 76º08’W), plumage and molt cycles associated with later also in lowland rain forest. TBR conducted phases of a bird’s life cycle. The term ‘defini­ his dissertation research at this site over the tive plumage’ describes attainment of plum­ past five years, during two of which JDW was age maturation (e.g., a Pipra filicauda male after present; both authors documented plumage the third prebasic molt has attained definitive and molt information. plumage). The term ‘adult’ often implies sex­ In addition to field observations, we vis­ ual maturity, which typically has no relevance ited museum to document when considering plumage maturation or plumage sequences and the extent of molt in molt (e.g., a formative plumaged Setophaga previously unstudied tropical families. We vis­ ruticulla male is in a predifinitive plumage, yet, ited the Field Museum of Natural History in it is capable of breeding and can be consid­ Chicago (n = 3522 specimens), California ered sexually an ‘adult’ or ‘mature’). Following Academy of Sciences, Department of Orni­ Howell et al. (2003), we have assigned families thology and Mammalogy, San Francisco (n = to molt strategies: either Complex Basic Strat­ 477) and the Smithsonian National Museum egy (CBS), Complex Alternate Strategy of Natural History, Washington, D.C. (n = (CAS), or both. 589). Here we chose to examine 14 families, 1 RESULTS subfamily, and 106 genera based on their diverse taxonomic relationships and the avail­ Molt and plumages of tropical families ability of previously published molt and plum­ age data. Given the astounding diversity of Trogonidae (CBS and CAS). The juvenile plum­ tropical taxa not all representative families age in Trogonidae is variable, with some spe­ could be included. All taxonomic assignment cies in the having spotted included in this paper follow the recommen­ plumage (Dickey & van Rossem 1938), buffy­ dations of the AOU South American Classifi­ tipped flight- coverts, brownish over­ cation Committee. The subfamily Dendrocol­ all plumage, barred and/or spotted under aptinae was included because of its diversity parts (Stiles & Skutch 1989). and distinct molt and plumage patterns. Apparently all Trogon species retain all or To limit confusion, promote molt homol­ some of their rectrices during the preforma­ ogies across taxa, and encourage non-ambigu­ tive molt. Formative plumage in Trogonidae ous nomenclature, we have used modified generally resembles either female definitive Humphrey-Parkes terminology (Howell et al. plumage, or respective definitive plumage 2003). The most relevant terminological (Dickey & van Rossem 1938). Evidence from changes are the renaming of the traditional museum suggests that all formative

3 RYDER & WOLFE

FIG. 1. Formative plumage (top) and definitive plumaged (bottom) Motmotus mexicanus can be distin­ guished by the wear and coloration pattern of retained flight and coverts (photo: P. Pyle). plumaged Trogonidae typically have distinctly ondaries and one or more rectrices (Pyle retained tails, and/or a differential amount of 1997). Definitive prebasic molts in most spe­ iridescence in body and head plumage in rela­ cies appear to be complete. Rectrix replace­ tion to definitive plumage. Some species ment in Trogon sallaei and T. elegans may be within the genus Trogon (e.g., T. elegans) have unique where some individuals molt the cen­ age-specific tail patterns (see Pyle 1997). The tral tail feathers first, and others the lateral preformative molt in Euptilotis neoxenus and ones. In some instances these species may some Trogon species can be incomplete, replace one entire side before the other including the tertials and one or more second­ (Dickey & van Rossem 1938). The prealter­ aries. Interestingly, in E. neoxenus, definitive nate molt can be limited to the head, upper- prebasic molts can retain one or more sec­ parts or back in T. melanocephala, T. sallaei, and

4 MOLT AND PLUMAGE IN THE NEOTROPICS

T. elegans. Additionally, Pyle (1997) found that variation in bill coloration. Subadult individu­ northern populations of T. elegans lack a pre­ als are marked by an incomplete color pattern, alternate molt. Prealternate molts in other with dull orange to yellow mandibles, which trogonids are undocumented. are distinguishable from the adults more uni­ form bill coloration. Momotidae (CBS). Evidence from museum Evidence for several genera suggests that skins suggests that juvenile plumage in Elec- the preformative molt in Bucconidae is either tron, Eumomota, Baryphthengus, Hylomanes, and complete (e.g., Notharcus, Bucco, and Malacop- Momotus are typically duller, sometimes lacking tila) or sometimes uniquely incomplete (e.g., tail-rackets (when appropriate) and central Notharchus hyperrhynchusas; Dickey & van Ros­ breast spots (Dickey & van Rossem 1938, sem 1938). The preformative molt in Nothar- Stiles & Skutch 1989, Howell & Webb 1995). chus hyperrhynchusas is characterized by Rectrices and possibly flight feathers scattered replacement of secondaries and/or appear to be universally retained during the primaries. In addition, this species has unique preformative molt across the family. Dickey & feather replacement patterns during defini­ Van Rossem (1938) describe Momotus and tive prebasic molts as well as an incomplete Eumomota as having a preformative molt, prealternate molt which includes all body which lasts no more than two months. Flight plumage, irregular replacement of tertials, feathers and rectrices are retained until the inner primaries, and rectrices (Dickey & van second (definitive) prebasic molt (Fig. 1). Rossem 1938). Investigation of museum skins Retained first prebasic rectrices are easily dis­ for three species of Monasa (e.g., M. atra, nigri- tinguishable by their brown slate color and frons, and morpheus) revealed retained greater, terminally tapered shape, where definitive median, and lesser coverts in a mixed pattern. central rectrices are more truncate. Retained The retained coverts show extensive wear and juvenile flight feathers are washed brownish. discoloration and are easily differentiated Other than retained flight feathers and rec- from fresh coverts. Despite the apparent trices, definitive plumaged and formative retention of primary and secondary coverts, plumaged birds appear similar. Protracted no retained flight feathers or rectrices have definitive prebasic molts in Momotus and been documented. Lesser, median, and Eumomota conclude with the flight feathers, greater coverts are either retained during an and finish at the same time as the rectrices incomplete preformative molt or during an (Dickey & van Rossem 1938). There appears incomplete prealternate molt. The lack of to be no prealternate molt in this family. retained flight feathers and rectrices point to a partial or incomplete prealternate molt, which Bucconidae (CBS or CAS). Juvenile plumages could create a mixed-wear pattern in the are reportedly often indistinguishable from coverts. Specimen evidence for other bucco­ definitive plumages, although juvenile plum­ nids, however, suggests a single annual molt. ages in Bucco, Malacoptila, and Hypenelus The unique feather replacement patterns as museum skins are typically duller with promi­ described by Dickey & van Rossem (1938) nent plumage markings greatly reduced. In may account for mixed age and wear in the comparison, juvenile individuals of Monasa are greater coverts of bucconids. more readily distinguishable, with a body plumage being heavily veiled grayish-brown as Thamnophilidae (CBS). Juvenile plumage compared to the glossy black definitive plum­ resembles female plumage (Zimmer & Isler age. In addition, Monasa species show age 2003), although subtle differences in colora­

5 RYDER & WOLFE

FIG. 2. A) Formative-plumaged male Dysithamnus mentalis showing replaced lesser coverts and retained flight feathers and greater, primary, median coverts; B) formative plumaged Myrmotherula hauxwelli showing replaced greater coverts with a broad white edging. Note that retained juvenile tertials and outer greater coverts in many Myrmotherula species have a buffy orange coloration. tion, as in Pipridae, may be detected with ­ Drymophila, Terenura, Cercromacra, Myrmoborus, ther study. See Howell & Webb (1995) for Hypocnemis, Percnostola, Schistocichla, and Hylo- genera specific details on Taraba, Thamnophi- phylax) and males may not attain definitive lus, Dysithamnus, Microphias, and Cercromacra. plumage until their second or possibly third The duration of these juvenile plumages prebasic molt. Some genera have eccentric or remain undocumented but are likely to last no incomplete preformative molts (e.g., Cymbilia- more than one to two months. mus, Pygptila, Microphias, and some species of Subsequent preformative molts are partial Myrmoborus, Formicivora, and Cercromacra) while for many genera (e.g., Taraba, Thamnophilus, other genera appear to have complete prefor­ Neoctantes, Dysithamnus, Thamnomanes, Myrmo- mative molts (e.g., Gymnopithys, Rhegmatorhina, therula, Dichrozona, Herpsilochmus, Formicivora, Sclateria, Pyriglena, and Phlegopsis). Formative

6 MOLT AND PLUMAGE IN THE NEOTROPICS plumages in thamnophilids are more easily indeed suggest an overlap of annual activities recognized in males, which show a mixture of or high asynchrony in annual activities (see male and juvenile (female type) plumage (e.g., Mallet-Rodrigues & de Noronha 2001). Hylophylax, Myrmeciza, Myrmoborus, Myrmothe- rula, Thamnophilus, Thamnomanes, etc.) indicat­ Rhinocryptidae (probably CBS). Little is known ing delayed plumage maturation (Zimmer & about the plumage and molt patterns in tapac­ Isler 2003). However, the extent of male ulos, which is in part due to the complexity of plumage gained during the preformative molt species identification of juveniles. The juve­ varies individually and by genera. The extent nile plumage in this family remains largely of the partial preformative molt in this family unknown. Barred juvenile plumages have is variable, but is most broadly characterized been observed in the field (e.g., Scytalopus) and by replacement of body feathers, lesser and are also known from museum skins (e.g., median coverts, and a variable number of Myornis, and Eugralla). Juvenile plumages in inner greater coverts while outer greater Rhinocrypta specimens are similar to definitive coverts, primary coverts, , rectrices, and plumages, except that the breast, throat, and flight feathers are retained (Fig. 2A). In some crown stripes are washed buff, and small genera, alula’s may be replaced (e.g., Hylophy- patches of buff are scattered on the back and lax), but this pattern needs further documen­ uppertail coverts. Juveniles of Scelorchilus are tation. Taxa with incomplete (or possibly similar to those of Rhinocrypta, except more eccentric) preformative molts typically replace heavily scalloped in buff on the flanks and one to three tertials, a variable number of uppertail coverts and scalloped white on the outer secondaries, and a variable number of crown. Juveniles of Myornis are washed inner primaries. In all cases, the correspond­ brownish with light barring on the tertials and ing primary coverts are also replaced. The uppertail coverts, while the juvenile plumage retention of juvenile feathers in formative- in Pteroptochos tarnii is generally darker rufous plumaged thamnophilids is distinct, thereby on the underparts. Additionally, specimens of facilitating easy recognition of molt limits. the latter have white lower mandibles, which Replaced coverts have distinct broad edging become completely black prior to the initia­ in many taxa, which contrast markedly with tion of the preformative molt. retained juvenile coverts that differ in color Several genera in this family exhibit com­ and extent of edging. For example, in Myr- plex and irregular plumage and molt patterns. motherula species with wing bars and tertial tip­ Evidence from museum skins suggests that ping (e.g., M. hauxwelli, and axillaris, etc.) Scytalopus, Myornis, and Eugralla may have suc­ retained juvenile tertials and coverts have a cessive molts after the preformative molt, buffy orange coloration compared with white resulting in one or two predifinitive plumages, tips and edging of adult feathers (Fig. 2B). No but occasionally an individual may change prealternate molt has been documented in directly into a nearly definitive plumage this family. (Krabbe & Schulenberg 2003b). Possibly, indi­ The timing of molt and breeding appear viduals may undergo a two- to three-year tran­ to overlap greatly in this family (Snow & sition into a predictable definitive plumage Snow 1964, Foster 1975). However, overlap (e.g., Scytalopus, Myornis, and Eugralla), facilitat­ data may be inconclusive because individuals ing accurate age categorization. Review of captured in breeding condition while under­ museum skins suggest that in other genera going a corresponding molt were not used to (e.g., Melanopareia, Rhinocrypta, and possibly estimate overlap frequency. The data may Scelorchilus, and Pteroptochos) a transition to a

7 RYDER & WOLFE nearly definitive plumage occurs immediately have been observed in Central American after the preformative molt. The preforma­ Grallaria (see Howell & Webb 1995). The pre­ tive molt in Melanopareia, Rhinocrypta, Scelorchi- formative molt in Grallaria guatimalensis lus, and Pteroptocho appears not to include appears to be partial, including several inner flight feathers, primary coverts, and rectrices. greater coverts and several median coverts No prealternate molt has been documented (Dickey & van Rossem 1938). Examination of in the family. specimens of five other Grallaria species (e.g., G. squamigera, quitensis, bangsi, and rufficapilla) (probably CBS). Juvenile plum­ indicate that the preformative molt is partial, ages have been documented in a number of with formative-plumaged individuals having different genera (e.g., Formicarius, Chamaeza, retained outer greater coverts, primary Grallaria, Myrmothera, , Pittasoma, coverts and a variable number of median and and Grallariculla) and have been described as lesser coverts. In most cases, these juvenile being loosely textured (Krabbe & Schulen­ coverts have buffy or rufous edging and dis­ berg 2003a). Juvenile Formicarius in Mexico tinctly contrast with the replaced coverts that and Peru have sooty brownish throats and lack edging. Likewise, the preformative molt olive washed chests (Howell & Webb 1995, D. in Myrmothera and Pittasoma is partial and does Lebbin pers. com.). Field observations of the not include primary coverts, flight feathers, genus Grallaria indicate a fluffy juvenile plum­ and, in some cases, several outer greater age that is replaced by a barred formative coverts (e.g., Pittasoma michleri). The extent and plumage (N. Krabbe pers. com., Krabbe & duration of juvenile and formative plumages Schulenberg 2003a). However, the barred across other taxa remains undocumented but plumage may actually represent the juvenile could prove useful in age- differentiation. stage, some of which is retained after the pre­ No prealternate molt has been documented formative molt. Juveniles may rather have in this family. very dark breasts, throat, crown, and nape, with white to buffy shaft streaks throughout Furnariidae (probably CBS and CAS). Many the plumage as documented in Grallaria guati- species appear to have distinct juvenile plum­ malensis museum specimens. In Conopophaga ages, although documentation is lacking and species, juvenile plumages are characterized plumage categorization may be difficult by barred or scalloped underparts, and at least (Remsen 2003). Some genera may lack age- one species (e.g., C. lineata) shows distinct related differences (e.g., Sclerurus) (Howell & rufous edging on the median and greater Webb 1995). Juvenile plumage in some Fur­ coverts. Juvenile-plumaged Myrmothera and nariidae is characterized by the reduction or Grallaricula have extensive buffy-tipped wing absence of contrasting plumage patches coverts, otherwise, juvenile plumage resem­ found in definitive plumage, duskier feather bles definitive plumage. Lastly, juvenile - margins in the throat and breast, and an soma michleri specimens exhibit a distinct ochraceous wash on the underparts (Remsen ochraceous wash across the throat, with lim­ 2003). The duration of the juvenile plumage ited amounts of black in the throat, under­ likely lasts from a few weeks to a few months parts washed buff, and limited to no white (Howell & Webb 1995, Remsen 2003). spotting on the wing coverts. The extent of the preformative molt in The extent of the preformative molt in furnariids is highly variable, with several gen­ Formicariidae is reportedly either partial or in era (e.g., Hyloctistes, Syndactyla, Philydor, and some genera limited. Formative plumages Automolus) showing evidence of a complete

8 MOLT AND PLUMAGE IN THE NEOTROPICS

FIG. 3. The retention of central rectrices may be useful for age class differentiation in some species of Dendrocolaptids. Dendrocolaptes certhia is pictured here showing retained center retrices. preformative molt, whereas other genera (e.g., with breeding remain poorly documented for Synallaxis, and Cranioleuca) show substantial the family (Remsen 2003), although a male evidence of a partial preformative molt. Synallaxis erythrothora tending a nest in El Dickey & Van Rossem (1938) documented Salvador was collected in extensive body retention of rectrices and flight feathers in molt, suggesting breeding-molt overlap in at Synallaxis during the preformative molt. Our least one species (Dickey & Van Rossem studies of specimens of eight other Synallaxis 1938). species (e.g., S. ruficapilla, azarae, frontalis, obscura, cabanisi, spixi, hypospodia, and albescens) Subfamily Dendrocolaptinae (CBS). The existence and seven Cranioleuca species (e.g., C. pyrrho- of a distinct juvenile plumage in most dendro­ phia, erythrops, curtata, subcrista, vulpina, marca- colaptids is undocumented. Many taxa may patae, and albiceps) revealed a partial preforma­ have a juvenile plumage that resembles a tive molt with retained rectrices, flight loosely textured definitive plumage, or have feathers, and alula feathers, which contrast distinctly barred underparts, yet further docu­ with the replaced lesser and median coverts. mentation is required. Juvenile plumage in The retention of greater coverts varies by gen­ Lepidocolaptes closely resembles definitive era, with Synallaxis species showing complete plumage, although it may have darker and replacement and Cranioleuca species replacing richer color overall and more prominent black zero to all greater coverts. These two genera edging to the streaking. The bill is dark col­ both probably retain all primary coverts. ored, attaining its full degree of lighter color Dickey & Van Rossem (1938) also docu­ when several months old (Dickey & van Ros­ mented an extensive definitive prealternate sem 1938). molt in Synallaxis erythrothora which includes The extent of molt in this family is cur­ some body feathers and (usually) complete rently poorly known. Some species of wood- retrix replacement. Further field and museum creepers undergo a single definitive prebasic information is needed for genera that appear molt which lasts four to six months (Marantz to have complete preformative molts (see et al. 2003), while other species complete the above). Molt timing, sequence, and overlap definitive prebasic molt in two months (e.g.,

9 RYDER & WOLFE

Lepidocolaptes souleyetii) (Dickey & van Rossem Tyrannidae (CBS & CAS). Juvenile plumages 1938). For some species, age class differentia­ are distinguishable from definitive plumages tion may be complicated by a complete pre­ in many genera (e.g., Colonia, Tyrannus, Platyrin- formative molt (e.g., Dendrocincla, Sittasomus, chus, Tolmomyias, Lophotriccus, Capsiempis, Elae- Glyphorynchus, Nasica, Dendrocolaptes; Howell & nia (brown above), and Leptopogon (typically Webb 1995), although Dendrocolaptes certhia in paler below). Juvenile plumages in Myiarchus Central America can apparently retain two to are charcterized by the presence of buffy or three central retrices (Fig. 3). Recent photo­ rufous-edged wing coverts that are distin­ graphic evidence of Xiphorhynchus flavigaster guishable from the yellowish white coverts from El Salvador suggests a partial preforma­ of definitive plumages. In several other genera tive molt, including retained greater coverts the color and width of the edging of (Pyle, per. com.). Field evidence suggests that rufous on wing coverts can help distinguish formative-plumaged Xiphocolaptes tend to have juveniles from adults (e.g., Legatus, Megarhyn- more buffy coloration. This criterion, com­ chus, Myiodynastes, Myiozetetes, Pitangus, and bined with retained flight feathers (tapered, Terenotriccus). shorter, with more extensive rufous on the The preformative molt is partial in many inner webs) (Dickey & van Rossem 1938) and genera (e.g., Contopus, Empidonax, Sayornis, retained greater coverts (Pyle, pers. com.), Megarynchus, Myiozetetes, Myiodynastes, Mionectes, may facilitate accurate age categorization. Myiarchus, Lophotriccus, Oncostoma, Rhynchocy- However, the above characters, except for the clus, Legatus, and Tyrannus) to complete in oth­ tapered nature of retained flight feathers, ers (e.g., Todirostrum, Tolmomyias, Tyrannus, and were not found in museum specimens of two Camptostoma) and highly variable across the other Xiphocolaptes species (e.g., X. promeropi- family (Dickey & van Rossem 1938, Howell & rhynchus, and major). Tapered flight feathers Webb 1995, Pyle 1997, Pyle et al. 2004, Wolfe may be the best way to age woodcreeper spe­ & Pyle unpubl.). The preformative molt cies that retain flight feathers during the pre­ replaces some, none or all of the primaries, formative molt. Unlike Xiphocolaptes flavigaster, secondaries and rectrices, but most or all of which replaces rectrices during the preforma­ the primary coverts are usually retained (Pyle tive molt, the preformative molt in Lepidoco- et al. 2004). The presence, extent, and/or col­ laptes souleyetii does not include the center pair oration of wing bars on the coverts are useful of rectrices, although flight feathers are criteria for differentiating formative from replaced (Dickey & Van Rossem 1938). This later plumages in many genera (e.g., Contopus, very unique replacement pattern is similar to Empidonax, Sayornis, Megarynchus, Myiozetetes, Dendrocolaptes certhia (see above) and may Myiodynastes, Legatus, and Tyrannus) (Howell & reflect true retention of juvenile rectrices or a Webb 1995)(see above). ‘suspension limit’ derived from the retention Prealternate molts occur in many genera of retrices from a previous definitive prebasic (e.g., Pitangus, Empidonax, Pachyramphus, Platyp- molt. saris, and Myiarchus) yet are variable in nature, Apparently no prealternate molt occurs in being partial in first-year birds of some spe­ this family. Typically, woodcreepers molt after cies, to nearly complete in others (Dickey & the breeding season, although the timing of van Rossem 1938, Lanyon 1975, Pyle 1997, molt and breeding season may overlap in Den- Wolfe & Pyle unpubl.). The extent of these drocolaptes, Lepidocolaptes, and Xiphorhynchus molts remains undocumented for many tropi­ (Dickey & Van Rossem 1938, Foster 1975, cal species. Generally, many genera also show Marantz et al. 2003). distinct and recognizable eye color variation

10 MOLT AND PLUMAGE IN THE NEOTROPICS

FIG. 4. Formative plumage in Chiroxiphia pareola (A) (photo: J. Blake) and formative plumage in C. linearis (B) with distinct molt-limits in the inner greater coverts designated with a white arrow. Note that retained juvenile coverts are shorter and more loosely textured than replaced feathers.

(e.g., Oncostoma, Todirostrum, Tolmomyias, and no rectrices, resulting in distinguishable molt Attila; see Howell & Webb 1995 for detailed limits (Ryder & Durães 2005, Doucet et al. descriptions). 2007). Retained juvenile outer greater coverts in most genera are shorter and more Pipridae (CBS). Molt in the family Pipridae is loosely textured than the replaced inner fairly well documented. The juvenile plumage greater coverts (Fig. 4A & B) (also see figures is similar to female plumage in Pipra, in Ryder & Durães 2005). Consecutive molts Machaeropterus, Chiroxiphia, and Manacus, are complete, and males within sexually although it is likely duller in color and more dimorphic genera often reach definitive plum­ loosely textured (Ryder, pers. obs.). Docu­ age during their second (Manacus species and mentation of the juvenile plumage is still Pipra mentalis), third (other Pipra species), needed for Neopelma, Xenopipo, Corapipo, and fourth, and/or fifth (Chiroxiphia species) pre­ Masius species. basic molts (Foster 1987, McDonald 1993, The preformative molt is partial, where DuVal 2005, Ryder & Durães 2005, Doucet et birds replace all body tracts and a variable al. 2007). Many species in the genus Pipra also number of greater coverts (Snow 2004) but show variation in eye color with age (Ryder

11 RYDER & WOLFE pers. obs., Howell & Webb 1995). The single tropical genus, Cistothorus, undergoes a partial annual molt of occurs at the end of prealternate molt before breeding, but this the breeding seasons, although non-breeding appears rare in the family (Kroodsma & males initiate molt before breeding females Brewer 2005). and adult males (Ryder unpubl.). No prealter­ nate molt has been documented for this fam­ Turdidae (CBS & rarely CAS). Juvenile plum­ ily. ages of tropical Turdus, Myadestes, and Catharus are characterized by either buffy margins or Troglodytidae (CBS & rarely CAS). Some taxa spotting on the breast feathers and buffy show distinct juvenile plumages (e.g., Thryotho- shaft-streaking on back and covert feathers rus, Henicorhina, Microcerculus, and Campylorhyn- (Dickey & van Rossem 1938, Howell & Webb chus) (Howell & Webb 1995, Kroodsma & 1995). Brewer 2005). The juvenile plumages in many Juvenile plumage is replaced by the pre­ other genera resemble the definitive plumage formative molt one to two months after except for some subtle differences in colora­ fledging and is typically partial (Pyle et al. tion. 2004). However, some tropical species may Little is known about the molt patterns of have incomplete (Pyle et al. 2004) or complete Central and South American wren species preformative molts (Howell & Webb 1995, (Kroodsma & Brewer 2005). The preforma­ Collar 2005). Age categorization is facilitated tive molt is typically partial (Howell & Webb by retention of inner greater coverts, primary 1995) and rarely incomplete. The preforma­ coverts, and rectrices. The second prebasic tive molt occurs within two or three months molt is typically complete (Pyle 1997). Much after fledging, where body feathers, and in like temperate thrushes, most tropical species some species, only a few flight feathers are likely undergo one annual molt per year, but it replaced (Kroodsma & Brewer 2005). Based is more protracted and may overlap with the on both field observations and museum skins, reproductive cycle (Collar 2005). Prealternate the preformative molt in Thryothorus nigricapil- molts are reported to occur in Turdus infusca- lus includes all wing coverts, usually the ter­ tus; this prealternate molt includes body feath­ tials and (occasionally) the central rectrices. ers and sometimes one or two rectrices Variability in the Thryothorus genera is evi­ (Dickey & van Rossem 1938). In addition, denced by other species that only replace sev­ some species show variation in bill color with eral inner greater coverts and sometimes one age (Howell & Webb 1995). or more tertials, but no flight feathers or rec- trices (Fig. 5). The replacement of flight Thraupidae (CBS & CAS). Molt in tropical feathers in some species during the preforma­ thraupid varies and is insufficiently known. tive molt is often incomplete and eccentric, Most species likely have juvenile plumages with southern populations of at least one spe­ that are similar to definitive plumages but cies (e.g., Thryomanes bewickii) replacing more drabber in color and with more loosely tex­ feathers than northern populations tured feathers. Juvenile plumages have been (Kroodsma & Brewer 2005). Therefore, observed in Ramphocelus and Tangara (D. Leb­ other species with a broad latitudinal range bin pers. com.), but the extent and duration of (e.g., Troglodytes aedon) should be tested in these plumages remains poorly documented to reveal if this trend is more common (but see Mallet-Rodrigues et al. 1995). Many among members of this family. Definitive tropical tanagers attain a definitive plumage prebasic molts are complete. At least one after the preformative molt. Data taken from

12 MOLT AND PLUMAGE IN THE NEOTROPICS

FIG. 5. Formative plumaged Thryothorus rufalbus with a molt-limit in the greater coverts and replaced ter­ tials contrasting with retained secondary and primary flight feathers (photo: P. Pyle). Note the more exten­ sive barring on the replaced greater coverts and tertials. museums skins, however, suggest that some categorization is still possible, due to distinct species of Euphonia have delayed plumage preformative plumages (Dickey & van Ros­ maturation, with males attaining a mottled sem 1938). Some species of Ramphocelus (e.g., appearance in second basic plumage. In addi­ R. nigrogularis, and passerini) and Euphonia (e.g., tion, bill coloration maybe useful for aging E. affinis) have incomplete preformative molts species in at least two genera (e.g., Habia, and where tertials and some primaries and sec­ Ramphocelus). ondaries are replaced. Nevertheless, these Both field studies and evidence from incomplete preformative molts are highly museum specimens suggest that the prefor­ variable. Alternatively, Ramphocelus bresilius has mative molt in many tropical tanagers is par­ been documented as having a complete pre­ tial in nature (Tangara, Dacnis, Tachyphonus, formative molt (Mallet-Rodrigues et al. 1995). Chlorophonia, Piranga, Euphonia, and Thraupis). Euphonia spp. show large amounts of variabil­ A few genera appear to have complete prefor­ ity both within and between species. In the mative molts (Buthraupis, Anisognathus, and genus Piranga, incomplete prealternate molts Cyanerpes), and some species within several occur, which include some or all greater genera possibly exhibit an incomplete prefor­ coverts and often the tertials and central rec- mative molts (Rhamphocelus, and Euphonia). trices (Dickey & van Rossem 1938, Pyle Extent of the preformative molt in most gen­ 1997). Other genera with documented partial era of tropical tanagers follows temperate pat­ prealternate molts are Thraupis, Habia, and terns in which body plumage, lesser, median Cyanerpes (Dickey & van Rossem 1938), but and a variable number of greater coverts are the existence of prealternate molts in most replaced, with rectrices, flight feathers and genera remains unknown. In all genera, the primary coverts retained. According to annual prebasic molt likely takes place after Dickey & van Rossem (1938) and Howell & the breeding season. Webb (1995), Cyanerpes has a complete prefor­ mative molt. Despite the complete nature of Emberizidae (CAS & CBS). Streaky juvenile the preformative in Cyanerpes, accurate age plumage is recognizable in many genera (for

13 RYDER & WOLFE

Zonotrichia description see Miller 1961). The genera (e.g., Spizella, Aimophila). Complex juvenile plumage in genera, such as Atlapetes, plumage sequences occur in the family; for and Aimophila, can be characterized by having example, Dickey & van Rossem (1938) stated buffy-tipped greater coverts, a duskier and that Sporophila minuta takes three years to streakier breast and throat. Sporophila juvenile reach definitive plumage. Aimophila ruficauda plumage is typically brownish overall with has been documented to have breeding-molt buffy-tipped greater coverts. Oryzoborus juve­ overlap (Dickey & van Rossem 1938). nile plumage is more loosely textured, yet resembles female and formative-plumaged Parulidae (CBS and CAS). Review of the litera­ individuals. Arremon typically has darker and ture and study of museums skins indicate that browner flanks, and sooty breast and throat many genera (e.g., Parula, Geothlypis, Myioborus, (Stiles & Skutch 1989). Basileuterus, Euthlypis, and Granatellus) have dis­ After leaving the nest in juvenile plumage tinct juvenile plumages (Curson et al. 1994). In and prior to the preformative molt, at least many genera, juvenile plumages are character­ one genus, Passerina, has a presupplemental ized by buff, brown or rufous edging on the molt comprised of only body plumage median and greater coverts forming two (Thompson & Leu 1995). Additionally, these indistinct wing bars (e.g., Parula, Myioborus, presupplemental molts may also occur in Euthlypis, and Basileuterus) (for species specific Aimophila spp. (Pyle pers. com.). Preformative details see Curson et al. 1994). Duller body molts are variable, but generally partial to and head plumage in relation to definitively- incomplete in extent, and in just a few genera, plumaged individuals may be apparent as well. complete (e.g., Arremonops and Volatinia; Preformative molts appear to be partial in Dickey & Van Rossem 1938, Miller 1961, most genera (e.g., Geothlypis, Myioborus, Parula, Howell & Webb 1995, Wolfe & Pyle unpubl.). Euthlypis, and Basileuterus) and are partial or Although male Volatinia may have complete incomplete/complete in other genera (e.g, preformative molts, distinct delayed plumage Granatellus). Typically, flight feathers, rectrices, maturation within the species is conducive to primary coverts and a variable number of accurate age categorization (formative plum­ outer greater coverts are retained. These pat­ aged males are similar to females except for terns result in molt-limits typically occurring dark flight feathers and rectrices edged brown in the outer greater coverts or between or gray; Dickey & van Rossem 1938, Howell greater and primary coverts, with the retained & Webb 1995). Saltator species apparently juvenile feathers often showing distinct buffy retain rectrices and flight feathers during the or rufous tipping (Curson et al. 1994, Pyle preformative molt (Dickey & van Rossem pers. com.). Curson et al. (1994) document 1938). Some Oryzoborus species have partial unclear patterns for Granatellus, in which G. preformative molts which include body and pelzelni and venustus both show a partial prefor­ some or all of the wing coverts, whereas the mative with retained flight feathers and rec- second prebasic molt in other members of trices while, G. sallaei, replaces tertials and this genus is incomplete or eccentric (e.g., outer secondaries. They assume the replace­ Oryzoborus funereus). ment of flight feathers suggests a complete Prealternate molts in the Emberizidae are molt but could also represent an incomplete sometimes absent (e.g., Buarremon, Arremonops, preformative. A commonly used aging crite­ Oryzoborus, Saltator), partial (e.g., Melozone, rion for north temperate parulids that can be Aimophila, Volatinia, Guiraca, Sporophila, Zono- readily applied to their resident Neotropical trichia, Junco, Saltator), or incomplete in other counterparts is rectrix shape (see Pyle 1997).

14 MOLT AND PLUMAGE IN THE NEOTROPICS

The retained first-basic rectrices in many taxa rule out the possibility that documented pre­ are considerably more tapered than adult rec- alternate molts might actually represent pro­ trices, which facilitates aging given experience tracted preformative or prebasic molts. with the species. Additionally, the amount of Overall, our results largely reflect patterns of white in the outer rectrices of Myioborus and plumage progression and molt extent in tem­ that of color in the crown of some species of perate zones. Basileuterus, and Myioborus can help facilitate Molt and plumage criteria facilitate accu­ their age and sex categorization (Wolfe & Pyle rate age classification in the vast majority of unpubl. data). The existence of prealternate temperate landbird species (Jenni & Winkler molts is not well documented in resident trop­ 1994, Pyle 1997). Yet, research pertaining to ical parulids, but limited prealternate molts molt of New World tropical residents has just for certain species in Geothlypis and Basileuterus begun receiving interest. In contrast, other have been reported (Dickey & van Rossem attributes of avian life history are more often 1938). studied and, as a result, better represented in the contemporary ornithological literature. DISCUSSION We believe this allocation to be disproportion­ ate given the critical nature of molt in relation Here, we have compiled general information to the avian annual cycle (i.e., certain species on molt strategy, plumage sequences, and may forgo migration and breeding events but extent of molt for 14 families and 1 subfamily no species has been documented forgoing the of New World tropical landbirds. Our data on annual molt cycle). Recent work has shown molt and plumage sequences collected for that molt sequences in temperate passerines selected Neotropical avian families detail the can provide a framework for understanding existence of previously undocumented juve­ variation in patterns of feather replacement nile plumages and the extent of partial and among tropical residents (Ryder & Durães incomplete preformative molts in a substan­ 2005). Following the model presented here, tial number of genera. Of the 15 families further molt and plumage sequence docu­ treated, 11 showed distinct juvenile vs. adult mentation will inevitably facilitate the accurate plumages while four proved to be indistin­ age classification of tropical resident land- guishable by plumage alone. We examined the birds. extent of the preformative molt in 106 genera Our presentation is a review and a call for and found that 67 genera (63%) had partial tropical ornithologists to begin collecting the preformative molt and 25 genera (24%) had molt data necessary to promote more detailed incomplete preformative molts, providing dis­ research into avian natural history and demo­ tinguishable criteria useful for age categoriza­ graphics. We have illustrated the potential for tion. The remaining 14 genera (13%) had ornithologists to accurately age the majority complete preformative molts making age cat­ of tropical residents via molt and plumage- egorization difficult. Our review shows that based criteria. Complete preformative molts the existence of prealternate molts is variable. sometimes confound aging attempts in tem­ Of the 15 families treated, ten lack a prealter­ perate latitudes in species, such as Chamaea fas- nate molt, three have a limited or partial pre­ ciata and Psaltriparus minimus, and undoubtedly alternate molt, and two have an incomplete tropical ornithologists will face similar prob­ prealternate molt. The existence of prealter­ lems (e.g., subfamily, Dendrocolaptidae). nate molts in tropical taxa, however, requires However, given our current state of knowl­ further documentation. As such, we do not edge, complete preformative molts appear

15 RYDER & WOLFE rare in New World tropical taxa. The docu­ tion. This research was conducted in accor­ mented presence of delayed plumage matura­ dance with permit number 13-IC-FAUDFN, tion in several families (Pipridae, Rhino­ Ministerio de Ambiente, Distrito Forestal cryptidae, Thamophilidae) should facilitate Napo, Tena, Ecuador. We thank them for accurate age classification for many species allowing us to conduct our research at the well into the second, third, and in some cases Tiputini Biodiversity Station. Funding was fourth molt cycle. provided by the International Center for We do not claim that our data or presenta­ Tropical Ecology, AFO’s Alexander Berg­ tion are exhaustive, but they rather provide a strom Award, National Geographic Society framework for further studies in the field as (7113-01) and National Science Foundation well as in museum collections. We believe this (IBN 0235141, IOB 0508189, OISE will facilitate and draw further interest to molt 0513341). This has been a contribution of the research at tropical latitudes. These data will Tortuguero Integrated Bird Monitoring ultimately enable us to place individuals into Project. age classes, thereby enhancing our ability to model population demographics. Moreover, REFERENCES these models are essential for proactive popu­ lation-level management. As tropical orni­ Collar, N. J. 2005. Family Turdidae (thrushes). Pp. thology advances so must research on tropical 514–811 in del Hoyo, J., A. Elliot, & D. A. molt patterns to begin building a robust age Christie (eds.). Handbook of the birds of the categorization framework for tropical taxa. world. Vol. 10: -shrikes to Thrushes. Lynx Edicions, Barcelona, Spain. ACKNOWLEDGMENTS Curson, J., D. Quinn, & D. Beadle. 1994. Warblers of the Americas: An identification guide. We are grateful to the many people who pro­ Houghton Mifflin, Boston, Massachusetts. vided personal observations or data to Dickey, D. R., & A. J. Van Rossem. 1938. The birds improve the manuscript: N. Krabbe, D. Leb­ of El Salvador. Field Mus. Nat. Hist. Zool. 23: bin, T. Schulenberg, S. Woltmann, C. J. Ralph, 1–609. Doucet, S. M., D. B. McDonald, M. S. Foster, & R. F. Mallet-Rodrigues, and A. Brown. Construc­ P. Clay. 2007. Plumage development and molt tive comments on earlier drafts of this manu­ in Long-tailed Manakins (Chiroxiphia linearis) script were provided by J. Blake, P. Pyle, J. C. variation according to sex and age. Auk 124: Eitniear and one anonymous reviewer. J. 29–43. Hidalgo kindly provided assistance with DuVal, E. H. 2005. Age-based plumage changes in abstract translation. Special thanks to the the Lance-tailed Manakin: a two-year delay in many volunteer banders at the Caribbean plumage maturation. Condor 107: 915–920. Conservation Corporation in Tortugero, Foster, M. S. 1975. The overlap of molt and breed­ Costa Rica. Thanks to Klamath Bird Obser­ ing in some tropical birds. Condor 77: 304– vatory, Point Reyes Bird Observatory, Red­ 314. wood Sciences Laboratory and Humboldt Foster, M. S. 1987. Delayed plumage maturation, neoteny, and social system differences in two Bay Bird Observatory. Special thanks to manakins of the genus Chiroxiphia. David and Consuelo Romo, Kelly Swing, 41: 547–558. Jaime Guerra and all the Tiputini Biodiversity Hall, K. S. S., & B. S. Tullberg. 2004. Phylogenetic Station staff for their tireless logistical and analyses of the diversity of moult strategies in field support. IACUC protocol number 5-12­ Sylviidae in relation to migration. Evol. Ecol. 20 for fieldwork at Tiputini Biodiversity Sta­ 18: 85–105.

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