You Can't Judge a Pigment by its Color: Carotenoid and Melanin Content of Yellow and Brown Feathers in Swallows, Bluebirds, Penguins, and Domestic Chickens

McGraw, Kevin J.; Wakamatsu, Kazumasa; Itô, Shôsuke; Nolan, Paul M.; Jouventin, Pierre; Dobson, F. Stephen; Austic, R. E.; Safran, Rebecca J.; Siefferman, Lynn; Hill, Geoffrey E.

doi:10.1093/condor/106.2.390

Cited by 73 publications

(85 citation statements)

References 27 publications

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“…This shows that the yellow-orange skin colour of common lizards stem from carotenoids and not from melanins or pteridins, neither of which are soluble in acetone [61]. In total, the skin contained 54.09 µg±4.67 SE carotenoids per gram tissue (5.144 µg±0.467 SE carotenoids per gram fresh weight), including lutein, zeaxanthin, astaxanthin, and canthaxanthin.…”

Section: Resultsmentioning

confidence: 89%

Carotenoid-Based Colours Reflect the Stress Response in the Common Lizard

et al. 2009

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Under chronic stress, carotenoid-based colouration has often been shown to fade. However, the ecological and physiological mechanisms that govern colouration still remain largely unknown. Colour changes may be directly induced by the stressor (for example through reduced carotenoid intake) or due to the activation of the physiological stress response (PSR, e.g. due to increased blood corticosterone concentrations). Here, we tested whether blood corticosterone concentration affected carotenoid-based colouration, and whether a trade-off between colouration and PSR existed. Using the common lizard (Lacerta vivipara), we correlatively and experimentally showed that elevated blood corticosterone levels are associated with increased redness of the lizard's belly. In this study, the effects of corticosterone did not depend on carotenoid ingestion, indicating the absence of a trade-off between colouration and PSR for carotenoids. While carotenoid ingestion increased blood carotenoid concentration, colouration was not modified. This suggests that carotenoid-based colouration of common lizards is not severely limited by dietary carotenoid intake. Together with earlier studies, these findings suggest that the common lizard's carotenoid-based colouration may be a composite trait, consisting of fixed (e.g. genetic) and environmentally elements, the latter reflecting the lizard's PSR.

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Section: Resultsmentioning

confidence: 89%

Carotenoid-Based Colours Reflect the Stress Response in the Common Lizard

et al. 2009

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“…the throat ‘bib’ of the house sparrow Passer domesticus ), and that we are just now beginning to understand the control agents and signaling function of phaeomelanin‐containing traits (e.g. in barn swallows and eastern bluebirds Sialia sialis ; McGraw et al 2004, Siefferman and Hill 2004).…”

Section: Discussionmentioning

confidence: 99%

“…Parrots, for example, use a unique class of polyenal lipochromes to generate their spectrum of plumage colors (Stradi et al 2001). McGraw et al (2004) showed that the yellow downy plumage of domestic chicks Gallus domesticus and the yellow feathers of adult king Aptenodytes patagonica and macaroni Eudyptes chrysolophus penguins lack carotenoids and instead harbor as‐of‐yet uncharacterized fluorescent compounds. Still others have shown that melanin pigments are responsible for the buff‐yellow feather colors in certain breeds of chicken (Frank 1939), turkey Meleagris gallopavo (Somes and Smyth 1965) and quail Coturnix japonica (Shiojiri et al 1999).…”

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confidence: 99%

Red‐winged blackbirds Agelaius phoeniceus use carotenoid and melanin pigments to color their epaulets

McGraw¹,

Wakamatsu

Clark

et al. 2004

Journal of Avian Biology

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Over the past three decades, the red-winged blackbird Agelaius phoeniceus has served as a model species for studies of sexual selection and the evolution of ornamental traits. Particular attention has been paid to the role of the colorful red-and-yellow epaulets that are striking in males but reduced in females and juveniles. It has been assumed that carotenoid pigments bestow the brilliant red and yellow colors on epaulet feathers, but this has never been tested biochemically. Here, we use high-performance liquid chromatography (HPLC) to describe the pigments present in these colorful feathers. Two red ketocarotenoids (astaxanthin and canthaxanthin) are responsible for the bright red hue of epaulets. Two yellow dietary precursors pigments (lutein and zeaxanthin) are also present in moderately high concentrations in red feathers. After extracting carotenoids, however, red feathers remained deep brown in color. HPLC tests show that melanin pigments (primarily eumelanin) are also found in the redpigmented barbules of epaulet feathers, at an 'approximately equal concentration to carotenoids. This appears to be an uncommon feature of carotenoid-based ornamental plumage in birds, as was shown by comparable analyses of melanin in the yellow feathers of male American goldfinches Carduelis tristis and the red feathers of northern cardinals Cardinalis cardinalis, in which we detected virtually no melanins. Furthermore, the yellow bordering feathers of male epaulets are devoid of carotenoids (except when tinged with a carotenoid-derived pink coloration on occasion) and instead are comprised of a high concentration of primarily phaeomelanin pigments. The dual pigment composition of red epaulet feathers and the melanin-only basis for yellow coloration may have important implications for the honesty-reinforcing mechanisms underlying ornamental epaulets in red-winged blackbirds, and shed light on the difficulties researchers have had to date in characterizing the signaling function of this trait. As in several other birds, the melanic nature of feathers may explain why epaulets are used largely to settle aggressive contests rather than to attract mates.

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“…Because hue (calculated as maximum slope) of the chestnut breast feathers expressed very little variation among males, we do not report hue for breast coloration. Unlike the analyses in Siefferman and Hill (2003), we analyzed the plumage color of the rump, tail, and breast feathers separately because 1) yearling and older birds molt tail feathers at different times, and 2) the UV‐blue coloration of the rump and tail is produced by the feather nanostructure (Shawkey et al 2003) while the chestnut coloration of the breast is caused by the deposition of melanin pigments (McGraw et al 2004).…”

Section: Methodsmentioning

confidence: 99%

Ornamental plumage coloration and condition are dependent on age in eastern bluebirds Sialia sialis

Siefferman

Hill²,

Dobson³

2005

Journal of Avian Biology

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2005. Ornamental plumage coloration and condition are dependent on age in eastern bluebirds Sialia sialis. Á/ J. Avian Biol. 36: 428 Á/435.Male eastern bluebirds Sialia sialis have striking ultraviolet (UV)-blue coloration on their heads, backs, rumps, wings, and tails and bold chestnut coloration on their breasts. These colored areas are ornaments that correlate with pairing date and reproductive effort, and thus probably influence the choice of mates by females. Such ornaments are expected to increase in color with age and body condition. We investigated the effects of age on body condition and the UV-blue and chestnut coloration of males over four years using both cross-sectional (comparing age classes) and longitudinal analyses (following individuals as they age). We found that both the body condition index and brightness of UV-blue rump coloration increased with age, while UV-blue tail plumage coloration increased between yearling and older males, and the chestnut breast coloration decreased in the oldest age class. The proximate mechanisms whereby individuals reliably signal age via rump brightness and tail coloration are probably different. Contour feathers, including rump feathers, are molted at approximately the same time in all age classes and are likely subject to the same production costs in all age classes. In contrast, the molt schedule of the tail and wing feathers differs between individuals of yearling and older age classes, with yearlings retaining wing and tail feathers for several months longer than adults. The relationship between tail color and age was probably, in part, a consequence of yearlings expressing tails that have increased feather wear and accumulation of dirt. In general, UV-blue coloration increased with age while chestnut plumage decreased with age, indicating that older individuals may tradeoff investing energy in structural and melanin ornaments. By assessing overall plumage coloration, female eastern bluebirds could estimate age class when choosing mates.

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You Can't Judge a Pigment by its Color: Carotenoid and Melanin Content of Yellow and Brown Feathers in Swallows, Bluebirds, Penguins, and Domestic Chickens

Cited by 73 publications

References 27 publications

Carotenoid-Based Colours Reflect the Stress Response in the Common Lizard

Carotenoid-Based Colours Reflect the Stress Response in the Common Lizard

Red‐winged blackbirds Agelaius phoeniceus use carotenoid and melanin pigments to color their epaulets

Ornamental plumage coloration and condition are dependent on age in eastern bluebirds Sialia sialis

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