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How feather colour reflects its melanin content

  1. K. J. McGRAW1,*,
  2. R. J. SAFRAN2,
  3. K. WAKAMATSU3

Article first published online: 27 SEP 2005

DOI: 10.1111/j.1365-2435.2005.01032.x

Issue

Functional Ecology

Functional Ecology

Volume 19, Issue 5, pages 816–821, October 2005

Additional Information

How to Cite

McGRAW, K. J., SAFRAN, R. J. and WAKAMATSU, K. (2005), How feather colour reflects its melanin content. Functional Ecology, 19: 816–821. doi: 10.1111/j.1365-2435.2005.01032.x

Author Information

  1. 1

    School of Life Sciences, Arizona State University, Tempe, AZ 85287–4501, USA,

  2. 2

    Laboratory of Ornithology and Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA, and

  3. 3

    Fujita Health University, School of Health Sciences, Toyoake, Aichi 470–1192, Japan

* †Author to whom correspondence should be addressed. E-mail: Kevin.McGraw@asu.edu

Publication History

  1. Issue published online: 10 OCT 2005
  2. Article first published online: 27 SEP 2005
  3. Received 25 March 2005; revised 10 May 2005; accepted 18 May 2005

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Keywords:

  • Barn Swallow;
  • eumelanin;
  • Hirundo rustica;
  • phaeomelanin;
  • plumage coloration;
  • sexual selection

Summary

  • 1
    Melanin coloration is the most common type of colour in animals. Many species use melanin-based black, brown, grey or earth-toned colours as intraspecific signals of quality.
  • 2
    Melanin comes in two main forms in vertebrates – eumelanin and phaeomelanin – and these are said to create different colours, with eumelanin giving a darker black, brown or grey appearance and phaeomelanin a lighter reddish or buff hue.
  • 3
    However, the few studies that have examined the melanin content of animal colours, namely from bird feathers, have shown that both phaeomelanin and eumelanin are present in nearly all melanized patches. These pigment types also have different synthetic origins and may be differentially costly to display.
  • 4
    Thus, to fully understand the costs and benefits of melanic colours, we must first quantitatively determine the relationship between pigment composition and colour characteristics.
  • 5
    We studied melanin content and colour variation in the ventral chestnut-coloured plumage of male and female Barn Swallows (Hirundo rustica erythrogaster) from North America.
  • 6
    Total melanin concentration explained significant variation in the hue, saturation and brightness of male breast plumage and female breast plumage. Eumelanin is the predominant type in these feathers, constituting over 75% of total melanins. Eumelanin and phaeomelanin concentration were significantly positively correlated in the feathers of females but not males.
  • 7
    In both sexes, levels of both eumelanin and phaeomelanin concentrations were significantly and positively correlated with hue, saturation and brightness. In males but not females, however, the ratio of eumelanin-to-phaeomelanin was also an important predictor of colour, with smaller ratios conferring browner hues. Males also deposit more phaeomelanins, but not eumelanins or total melanins, in breast feathers than do females. These results suggest that phaeomelanin plays a unique role in the colouring strategy of male Barn Swallows.
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