AN EASY, INEXPENSIVE MEANS TO QUANTIFY PLUMAGE COLORATION

The Colortron (Light Source, San Rafael, California) is an inexpensive , compact, Macintosh-compatible reflectance spectrophotometer that can be used to quantify the coloration of the plumage and soft parts of b irds. The Colortron provides a reflectance spectrum (390-700 nm) of th e object being measured as well as tristimulus color scores that can b e compared to scores from the Methuen or Munsell color references. Bec ause the Colortron fails to measure ultraviolet light (wavelength <390 nm), which is visible to some species of birds, Colortron output must be interpreted cautiously when it is used to describe plumage that ma y reflect UV, especially if the focus of the study is understanding th e function of coloration. The Colortron is especially useful for quant ifying carotenoid-based plumage coloration, which reflects primarily i n the visible spectrum. I compared visual scores of carotenoid-based o rnamental plumage of House Finches (Carpodacus mexicanus) made by comp arison to The Methuen Handbook of Colour to tristimulus color scores g enerated by the Colortron. Hue and saturation scores from visual asses sment were significantly positively correlated with hue and saturation scores from the Colortron. I recommend the use of the Colortron as a means to quantify plumage and soft-part coloration.