Becca Safran , Matt Wilkins, Joey Hubbard and Julie Marling have published a paper in PLOS One , describing the dynamic nature of carotenoid concentrations in barn swallows, and relationships with fitness. Here is a link to the paper: www.plosone.org/article/metrics/info%3Adoi%2F10.1371%2Fjournal.pone.0009420 Congratulations to the Safran Lab !