Colorimetric analysis of the dorsal plumage of the red-eyed vireo (Aves: Vireonidae) in Canada
The red-eyed vireo is widely distributed across Canada in the boreal forest. Collections were made at seven localities from central Alberta to central Quebec and potential variation in the olive-green dorsal plumage was analyzed with a recording spectrophotometer equipped with a reflectance attachment. The trichromatic coefficients x (dominant wavelength) and y (purity) and Y (the percentage luminous reflection or brightness) were subjected to an overall analysis of variance, and means were treated with Gabriel's sums of squares simultaneous test procedure. Significant differences were demonstrated among locality samples for Y and x but the STP revealed discordant variation among locality samples, i.e. no east–west clines in character variation were shown. Regressions of Y and x on precipitation were nearly significant and could suggest a weak clinal relationship between color and this climatic variable as predicted by the ecogeographic rule of Gloger.