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Extramural Research

Grantee Research Project Results

Grantee Research Project Results

The Effect of Dietary Carotenoid Access on Sexual Dichromatism and Plumage Pigment Composition in the American Goldfinch

EPA Grant Number: U915842
Title: The Effect of Dietary Carotenoid Access on Sexual Dichromatism and Plumage Pigment Composition in the American Goldfinch
Investigators: McGraw, Kevin
Institution: Cornell University
EPA Project Officer: Manty, Dale
Project Period:    
Project Amount: $102,000
RFA: STAR Graduate Fellowships (2000)
Research Category: Academic Fellowships , Ecological Indicators/Assessment/Restoration , Fellowship - Ecology and Ecosystems



The objective of this research project was to investigate potential dietary and biochemical bases for carotenoid-based sexual dichromatism in American goldfinches (Carduelis tristis).


Captive male and female finches were given access to the same type and amount of carotenoid pigments in the diet during their nuptial molt to assess differences in the degree to which the two sexes incorporated ingested pigments into their plumage. When birds were fed a uniform, plain-seed diet, or one that was supplemented with the red carotenoid canthaxanthin, we found that males grew more colorful plumage than females. High performance liquid chromatography analyses of feather pigments revealed that male finches incorporated a higher concentration of carotenoids into their pigmented feathers than females. Compared to females, males also deposited significantly more canary xanthophyll B into feathers when fed a plain-seed diet and a greater concentration and proportion of canthaxanthin when fed a carotenoid-supplemented diet. These results indicate that sex-specific expression of carotenoid pigmentation in American goldfinches may be affected by the means by which males and females physiologically utilize (e.g., absorb, transport, metabolize, deposit) carotenoid pigments available to them in the diet.

Supplemental Keywords:

fellowship, American goldfinch, Carduelis tristis, dietary carotenoid access, sexual dichromatism, plumage pigment, canthaxanthin.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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