Meeting Abstract
We are studying laying-sequence variation in yolk carotenoids and egg metrics of Eastern Bluebirds (Sialia sialis) breeding in Columbus, Georgia, USA. Carotenoids are fat-soluble yellow, orange, and red pigments that are synthesized by plants, algae, and photosynthetic bacteria. These pigments play important roles in immunostimulation, antioxidation, free radical scavenging, sexual signaling, color vision, and embryonic development in birds. We are using high performance liquid chromatography to identify and quantify the carotenoids in Eastern Bluebird egg yolks. Eastern Bluebirds are a particularly interesting study species because no prior research has investigated laying-sequence variation in the yolk carotenoids of the species. We found that the yolks contained β-carotene, β-cryptoxanthin, astaxanthin, lutein, and zeaxanthin, with lutein being the most highly concentrated carotenoid. Contrary to results reported for other Eastern Bluebird populations, we did not detect any significant differences in in the mass, length, or width of the eggs across the laying-sequence. Preliminary results show that total carotenoid concentrations decline across the laying sequence, suggesting that Eastern Bluebirds use a brood reduction strategy in carotenoid allocation.
