Molts and Plumages of Ducks (Anatinae) Author(s): Peter Pyle Source: Waterbirds, 28(2):208-219. 2005. Published By: The Waterbird Society DOI: http://dx.doi.org/10.1675/1524-4695(2005)028[0208:MAPODA]2.0.CO;2 URL: http://www.bioone.org/doi/ full/10.1675/1524-4695%282005%29028%5B0208%3AMAPODA%5D2.0.CO %3B2 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/ page/terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non- commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Molts and Plumages of Ducks (Anatinae) PETER PYLE The Institute for Bird Populations, P.O. Box 1436, Point Reyes Station, CA 94956, USA Internet: [email protected] Abstract.—Ducks are unusual in that males of many species acquire brightly pigmented plumages in autumn rather than in spring. This has led to confusion in defining molts and plumages, using both traditional European terminology and that proposed by Humphrey and Parkes (1959). To investigate molt patterns in waterfowl relative to molt and plumage nomenclature, 2,227 specimens of ducks and geese were examined. Both the “first prebasic” (“post-juvenile” using traditional European terminology) and the “definitive prebasic” (“adult post-breeding”) body molts in most ducks, the latter producing the cryptic spring (female) and summer (male) plumages preceding the wing molt, are considerably more variable and less extensive than reported. By contrast, the “definitive prealter- nate” (“adult pre-breeding”) body molt of most ducks, which follows the wing molt and produces the brightly col- ored plumages of males, is complete or virtually so. Based upon presumed homologies with the molts of geese, the wing molt and ensuing complete body molt of ducks are better considered the prebasic rather than the prealternate molt and, thus, the bright feathering of male ducks should be considered the basic plumage. The incomplete and ephemeral cryptic plumages, attained by some ducks in spring and summer, may have evolved more recently in spe- cies that benefit from camouflage at this time, and should be considered alternate plumages. The molts and plum- ages of the adult Ruddy Duck (Oxyura jamaicensis) appear to be homologous with those of other Anatine ducks, with a slight temporal shift in the hormonal cycles that control pigment deposition (as opposed to differences in molt patterns) explaining the differences in plumage-coloration patterns in males. Because feather pigment-deposition patterns are controlled by various factors related to seasonal and reproductive phenomena, which differ consider- ably both among and within taxa, plumage color should not be a critical factor in attempts to define homologous molts and plumages. Received 25 July 2004, accepted 12 January 2005. Key words.—Anas, Anser, duck, molt terminology, Melanitta, Oxyura jamaicensis, plumage, Ruddy Duck, scoter. Waterbirds 28(2): 208-219, 2005 Among birds, many ducks (Subfamily “summer plumage,” which occurs primarily Anatinae) are unusual in that brightly pig- in winter. Variations of this interpretation mented plumages of males are acquired in have persisted in the literature (Schiøler autumn rather than spring. In boreal spe- 1921; Witherby et al. 1939; Dement’ev and cies, feathers of the wing tracts (including Gladkov 1952; Oberholser 1974; Cramp and the primaries, secondaries, and wing co- Simmons 1977; Marchant and Higgins 1990; verts) are replaced synchronously in the late but see Sutton 1932; Stresemann 1948). summer or early autumn, in between two Consequently, the bright plumages acquired separate molts of body-feather tracts (Cramp in autumn have been referred to as “nuptial” and Simmons 1977; Hohman et al. 1992; or “breeding,” and the cryptic summer Bellrose and Holm 1994). In Anas, Aythya, plumages acquired in spring and summer as and Somateria, the body molt prior to the “eclipsed” or “non-breeding,” despite confu- wing molt occurs in the early spring in fe- sion resulting from the fact that females of males and in the summer in males, often these genera nest in “non-breeding” plum- producing a cryptic plumage that provides age (cf. Cramp and Simmons 1977). camouflage for females during nesting and Humphrey and Parkes (1959) cited such for both sexes during the flightless period confusion in support of their revised molt and accompanying wing molt (Hohman et al. plumage nomenclature, which excluded 1992). Jackson (1915) first suggested that terms correlated with “seasonal, reproductive, this summer body molt in males be aligned developmental, or other phenomena” within with the wing molt to form the complete an- the annual cycle. The “Humphrey-Parkes” (H- nual molt. Because the body feathering pro- P) system attempts to recognize homologous duced by this molt was cryptic, Jackson molts across taxa by defining a “molt cycle” considered it the “winter plumage,” followed (usually a year in boreal species) during which by a partial molt into the brightly pigmented a single complete or near-complete molt oc- 208 MOLTS AND PLUMAGES OF DUCKS 209 curs and is termed the “prebasic molt.” Addi- Despite an extensive literature, gaps re- tional, less-complete inserted molts, defined main in our understanding of the precise tim- by the shedding of feathers more than once ing and extent of molts in ducks (Hohman et within the molt cycle, are termed “prealter- al. 1992). Palmer (1976) described the first nate molts,” and if more than one inserted prebasic (post-juvenile) molt as involving molt occurs, the second inserted molt (de- most or all body feathers; however, the few fined by the replacement of feathers three studies that have critically examined this molt times within the molt cycle) is termed the either have involved captive ducks subjected “presupplemental molt.” Regarding molts in to non-natural feeding and lighting regimes adult ducks, Humphrey and Parkes con- that likely affected molts (Weller 1957, 1970), curred with previous opinion that the spring/ or have found it at most to include only a few summer body molt should be aligned with the feathers of the head or underparts (Mendall wing molt, terming this the complete prebasic 1958; Oring 1968; Bellrose and Holm 1994). (“post-breeding” of traditional European ter- Furthermore, studies such as that of Hoch- minology) molt resulting in “basic plumage,” baum (1944) have suggested that the sum- followed by the partial prealternate (“pre- mer body molt in certain adult ducks, breeding”) molt in autumn resulting in “alter- defined as part of the prebasic or post-breed- nate plumage.” Humphrey and Parkes rea- ing molt, might be limited to a small propor- soned that the bright plumage stage in males tion of feathers or be lacking altogether, such has evolved more recently, and should be con- that males molted directly from one bright sidered the alternate plumage to conform to plumage to the next, without a more cryptic nomenclature in other birds that have bright summer plumage. Humphrey and Parkes seasonal plumages. (1959) and Palmer (1976) acknowledged Palmer (1972) further elaborated upon Hochbaum’s (and other similar) findings, H-P molt and plumage terminology in ducks but did not discuss the discrepancy in H-P ter- and subsequently (Palmer 1976) applied it to minology that results from the replacement the molts and plumages of all North Ameri- of alternate with alternate feathering without can species. Palmer defined duck molts in an intervening basic plumage. the first cycle as consisting of a partial “first To investigate molt phenology in ducks prebasic” (“post-juvenile”) molt of all or relative to molt and plumage terminology, most body feathers in late summer, followed 2,227 specimens of North American ducks rapidly by another partial “first prealternate” and geese (Anserinae), the latter widely con- (“first pre-breeding”) molt of all body feath- sidered ancestral to ducks (Delacour and ers in autumn and winter, resulting in bright Mayr 1945; Palmer 1976), were examined. first-winter plumages in males. The Ruddy The objectives were: (1) to confirm the tim- Duck (Oxyura jamaicensis) differs from other ing and determine the extent of each molt in North American species in that adult males ducks; and (2) to attempt tracing the evolu- acquire bright plumage during a prealter- tion of homologous molts from Anserinae nate molt in spring rather than in autumn, (which lack additional inserted molts) to and the complete prebasic molt consists of Anatinae in order to properly apply molt ter- the wings followed by the body molt in early minology to ducks. autumn (Palmer 1976). The H-P molt and plumage terminology for ducks described by METHODS Palmer (1972, 1976) has been widely accept- Specimens of geese and ducks were examined at the ed in North America (Hohman et al. 1992; California Academy of Sciences (CAS), San Francisco; Poole and Gill 1992-2003), and this sequence the Museum of Vertebrate Zoology (MVZ), University and extent of molts and plumages (albeit of California at Berkeley; the Museum of Wildlife and Fisheries Biology (MWFB), University of California at with different terminologies) has been ac- Davis; the Provincial Museum of Alberta (PMA), Ed- cepted throughout the world (Dement’ev monton; and the National Museum of Natural History and Gladkov 1952; Cramp and Simmons (USNM), Washington, D.C. Specimens examined were collected throughout the year (sample range 119-230 per 1977; Marchant and Higgins 1990).