Meeting Abstract
We identified and compared yolk carotenoids from the eggs of three species of secondary-cavity-nesting songbirds in west-central Georgia, the Tufted Titmouse (Baeolophus bicolor), Brown-headed Nuthatch (Sitta pusilla), and Carolina Wren (Thryothorus ludovicianus). Carotenoids are biologically-active pigments that act as powerful antioxidants and immunostimulants for both developing embryos and adult birds. Female birds allocate high concentrations of carotenoids to their egg yolks, where the pigments protect developing embryos against damage to lipids, proteins, and DNA. Despite this critical role that yolk carotenoids play in avian reproduction, surprisingly little research has focused on North American songbirds. Therefore, the third-laid egg was collected from 16 nuthatch nests, 7 titmouse nests, and 23 wren nests, for a total of 46 eggs. Yolk carotenoids were extracted and quantified using high performance liquid chromatography. We identified three dietary carotenoids in the eggs of the study species, β-carotene, lutein, and zeaxanthin. Yolk concentrations of β-carotene did not vary across the species, but wrens had the highest concentrations of lutein and total carotenoids, and nuthatches had the lowest concentrations of zeaxanthin. The differences we found in yolk carotenoid concentrations in the three study species are likely linked to differences in diet. Brown-headed Nuthatches consume more seeds than the other two species during egg formation, whereas Tufted Titmice and Carolina Wrens consume more invertebrates. However, further research on dietary sources of carotenoids for these three species is needed to better understand the yolk carotenoid concentration differences we observed.
