An update on the honesty of melanin-based color signals in birds

• Published in: Pigment cell and melanoma research Vol. 21; no. 2; pp. 133 - 138
• Main Author: McGraw, Kevin J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.04.2008
• Subjects: amino acids; Amino Acids - pharmacology; Animal Communication; Animals; barn owl; barn swallow; Birds; Hormones - pharmacology; house sparrow; Melanins - physiology; metals; Metals, Alkaline Earth - pharmacology; minerals; Pigmentation - drug effects; plumage; testosterone; Visual Perception - physiology; zebra finch
• ISSN: 1755-1471; 1755-148X
• DOI: 10.1111/j.1755-148X.2008.00454.x

Summary The control mechanisms and information content of melanin‐based color signals in birds have generated much recent interest and controversy among evolutionary biologists. Initial experimental studies on this topic manipulated coarse metrics of an individual’s condition (i.e. food intake, disease state) and failed to detect significant condition‐dependence of melanin ornament expression. However, three new lines of research appear profitable and target specific factors associated with the production of melanin pigments. These include the role of (i) metals, (ii) amino acids, and (iii) testosterone and social interactions in shaping the extent and intensity of melanin‐colored plumage patches. Here, I review recent studies of and evidence for these honesty‐reinforcing mechanisms.