HUGGINS, KA; NAVARA, KJ; HILL, GE; MENDON�A, MT; Auburn University, Auburn, AL: Are Carotenoids Toxic In Songbirds With Extensive Carotenoid-Based Plumage Coloration?

Although there is extensive literature addressing the beneficial effects of carotenoids as anti-oxidants, there are also studies that indicate that high doses of carotenoids may actually have a toxic effect. In songbirds with extensive carotenoid-based ornamentation, several hypotheses have arisen concerning a trade-off between use of carotenoids for signaling vs. the use of carotenoids to bolster immune function. However, none have addressed the possibility that the elevated levels of carotenoids required to produce carotenoid-based plumage coloration may instead have a physiologically detrimental effect. To test this latter hypothesis, we maintained American goldfinch males on either a high (n = 40) or a low (n = 40) dose of lutein/zeaxanthan treatment for 90 days during the time of molt. We took blood samples from animals before, during, and after the treatment, and analyzed the samples for several measures of physiological and oxidative stress, i.e. baseline and post-ACTH challenge corticosterone levels, liver enzymes, and glutathione oxidation. Preliminary results indicate that high doses of this treatment resulted in significant increases in baseline corticosterone levels. Further results will be discussed.