192 Yellow-billed Pintail neck ring Aberrant plumage in the Yellow-billed Pintail Anas georgica ROBERT E. WILSON1, THOMAS H. VALQUI2 & KEVIN G. MCCRACKEN1 1Institute of Arctic Biology, Department of Biology and Wildlife & University of Alaska Museum, University of Alaska Fairbanks, Fairbanks, AK 99775, USA. Emails: [email protected] & [email protected] 2Louisiana State University Museum of Natural Science, 119 Foster Hall, Louisiana State University, Baton Rouge, LA 99775, USA. Email: [email protected] Abstract Plumage aberrations are common, particularly in waterfowl. There have been numerous proposed causes including the retention of ancestral plumage characters that contain phylogenetic information. A partial white neck ring was observed in Yellow-billed Pintail Anas georgica spinicauda near Cusco, Peru. Non-typical white neck rings have been reported in other waterfowl species. Although the exact cause is unclear, its reoccurrence in other species and the consistent placement suggest that this unusual plumage could be of evolutional signifi cance. Key words: plumage aberration, Yellow-billed Pintail, Anas georgica, Peru. Plumage aberrations that deviate from & Bartholomew 1951; Nero 1954, Harrison typical plumage colour patterns are common, 1955; Gross 1965; Enders & Post 1971). and their prevalence varies among species Waterfowl (Anseriformes: Anatidae) (Hicks 1934; Michener & Michener 1936; have been well documented to show unusual Nero 1954; Gross 1965; Jehl 1985). Multiple plumage patterns. In some cases, these causes of plumage aberrations have been abnormal plumages resemble characters of proposed. These include injury, disease, other closely related species (Harrison 1953, diet, partial leucism, recurrent mutation, 1955). For example, Northern Shoveler infrequent expression of genes that have Anas clypeata males in eclipse plumage have a low expressivities, pigment concealment, or white facial crescent that resembles the facial atavistic retention of ancestral traits (Hubbs pattern of the Blue-winged Teal A. discors ©Wildfowl & Wetlands Trust Wildfowl (2006) 56: 192-196 Yellow-billed Pintail neck ring 193 and the Australasian Shoveler A. rhynchotis. 2002 in the Department of Cusco, Peru But in cases of hybridisation, plumage (UAM-20670, Field catalogue number: REW- patterns also can resemble non-parental 251). This individual had an incomplete species (e.g. Harrison 1954; Harrison & white neck ring, which did not connect on Harrison 1959a,b). the nape. This unusual plumage has not Plumage series and variants have been previously been reported in this species (Fig. thought to be evolutionarily signifi cant 1). Typically, the throat area is pale brown or because different plumage states may refl ect white and fi nely mottled (Blake 1977; Madge phylogeny (Harrison & Harrison 1959b; & Burn 1988). Three other specimens also Olson 1973; Hosner & Lebbin 2006). were collected from this locality and, in Therefore, closely related species such as total, 86 Yellow-billed Pintails were collected Mallard A. platyrhynchos and Northern Pintail elsewhere in Argentina, Bolivia and Peru from A. acuta may be more likely to produce 2001 to 2003. None of the other specimens common features of the other species collected had a white neck ring. However, occasionally (e.g. white neck ring) that are Yellow-billed Pintail has been known to not necessarily due to recent hybridisation. occasionally exhibit a partial white neck One of the most well documented cases ring in captivity at the Wildfowl & Wetlands of aberrant plumages in waterfowl is the Trust (N. Jarrett, pers. comm.). Additionally, presence of a white neck ring. Unusual a photograph of a South Georgia Pintail A. white neck rings have been described in g. georgica shows a male with a faint partial Green-winged Teal A. crecca, Speckled Teal neck ring (Ogilvie & Young 1998). White A. fl avirostris, Blue-winged Teal, Gadwall A. neck rings have been observed in other strepera, and Northern Shoveler (Harrison pintail species. Northern Pintail have been 1946; Harrison & Harrison 1958, 1959a,b,c; observed with a transient white neck ring Trauger 1976). These white neck rings have during eclipse moult (Harrison 1978). been proposed to be analogous to the white Most cases of plumage aberrancy have neck ring of the male Mallard, a typical been reported as partial leucism. Individuals plumage character that also is common in with abnormal plumages typically do not several other species of waterfowl (Harrison resemble plumage characters of other & Harrison 1959b). However, Trauger (1976) species. The amount and location of white suggested that the white neck ring of Blue- spotting can be quite variable, as seen in winged Teal was due to leucism – complete the Eared Grebe (Podiceps nigricollis; Jehl loss of pigmentation in birds ranging from 1985). It is evident in these cases that the just one feather to the entire body (Buckley cause is leucism. However, the recurrence 1982) – because it was found in both males and consistent placement of non-typical and females along with unusual white white neck rings in several waterfowl species feathering on other parts of the body. is noteworthy, and researchers should A Yellow-billed Pintail male A. georgica not dismiss the possible phylogenetic spinicauda was collected in a fl ock of signifi cance of this character. It could be approximately 15 individuals on 15 October that the expression of a set of genes for this ©Wildfowl & Wetlands Trust Wildfowl (2006) 56: 192-196 194 Yellow-billed Pintail neck ring Figure 1. Male Yellow-billed Pintail Anas georgica with aberrant white neck ring (University of Alaska Museum catalogue number: UAM-20670, Field catalogue number: REW-251). common colour pattern has been activated plumages (red on the metacarpal) of the but its expression is low outside the few Red-winged Blackbird Agelaius phoeniceus are a species that retain this character. The regular occurrence but are normally masked retention of ancestral plumage traits has by a darker pigment. When expressed, this been proposed in the Red-legged Seriema plumage variant showed similarities to Cariama cristata. For example, an aberrant closely related South American blackbirds, individual had dark, streaky plumage that was where the colouration is normal. thought to be ancestral to the typical light- The mechanism producing the aberrant tone plumage that is seen as an adaptation to white neck ring in waterfowl is still not clear. arid grasslands (Olson 1973). Harrison (1946, 1953) suggested that it Another mechanism that might indicate was due to an autophoric reverse mutation, that there is a phylogenetic component the recombination of gene(s) resulting responsible for aberrant plumages is that in a mutation that causes characters (e.g. expression of darker pigments could mask plumage features) to resemble a different expression of lighter pigments. For example, species in the absence of hybridisation. Nero (1954) argued that the aberrant Whether it is due to the low expression of a ©Wildfowl & Wetlands Trust Wildfowl (2006) 56: 192-196 Yellow-billed Pintail neck ring 195 set of genes, mutation or pigment masking, and laboratory costs were funded by the these aberrant plumages cannot be solely Institute of Arctic Biology at the University seen as abnormalities and warrant further of Alaska Fairbanks, Alaska EPSCoR investigation. (NSF EPS-0092040). Grants were received from the Delta Waterfowl Foundation, the Acknowledgments Frank M. Chapman Fund at the American Museum of Natural History and NSF (DEB-0444748). Nigel Jarrett and Glyn We thank Rosario Acero, Yanina Arzamendia, Young provided helpful comments and Daniel Blanco, Guillermo Cao, Raúl Cardón, suggestions. Sonia Chavarra, Claudio Chehébar, Raúl Clarke, Mike Christie, Adrian Contreras, Victor Hugo Eztellan, Martin Funes, Sergio References Goldfeder, Alejandro Gonzalez, Mauricio Herrera, Gordon Jarrell, Kevin Johnson, Blake, E.R. 1977. Manual of Neotropical Birds. University of Chicago Press, Chi- Cecilia Kopuchian, Antony Lancaster, Dario cago, Illinois. Lijtmaer, Pamela McCracken, Rodolfo Miatello, Manuel Nores, John O’Neill, Buckley, P.A. 1982. Avian genetics. In M. Carmen Quiroga, Daniel Ramadori, Karina Petrak (ed.), Diseases of cage and aviary birds, 2nd edition, pp. 21-110. Lea & Ramirez, Abraham Rojas, Pablo Rubaro, Febiger, Philadelphia, Pennsylvania. 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