A novel method for quantifying the glossiness of animals

Matthew B. Toomey, Michael W. Butler, Melissa G. Meadows, Lisa A. Taylor, H. Bobby Fokidis, Kevin McGraw

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


The glossy sheen of healthy hair is an ideal of human beauty; however, glossiness has never been quantified in the context of non-human animal signaling. Glossiness, the specular reflectance characteristic of polished surfaces, has the potential to act as a signal of quality because it depends upon material integrity and cleanliness. Here, we undertook two studies of glossiness in avian plumage to determine (a) the repeatability of a recently developed measure of glossiness, (b) the relationship between glossiness and conventional measures of coloration, and (c) how glossiness is associated with quality signaling. Using museum specimens of three North American bird species with glossy plumage (red-winged blackbird, Agelaius phoeniceus; great-tailed grackle, Quiscalus mexicanus; Chihuahuan raven, Corvus cryptoleucus), we found that the glossiness measure was highly repeatable for all species and was significantly correlated with plumage coloration (e.g., chroma, brightness) in male great-tailed grackles. We then used wild-caught grackles to examine sexual dimorphism in plumage glossiness and its correlation to a potentially sexually selected trait in this species, male tail length. We found that males were significantly glossier than females and that male, but not female, glossiness correlated positively with tail length. This study provides a repeatable method to measure glossiness and highlights its potential as a signal of individual quality in animals.

Original languageEnglish (US)
Pages (from-to)1047-1055
Number of pages9
JournalBehavioral Ecology and Sociobiology
Issue number6
StatePublished - May 2010


  • Bird plumage
  • Image statistics
  • Iridescence
  • Sexual selection

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology


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