CU's Safran and her team, which included dozens of CU students and volunteers, trapped scores of barn swallows with mist nets in rural sites around Boulder County, Colo., measuring and weighing them and taking blood and feather samples before releasing them back into the wild. Each bird was sampled between two and four times over the breeding season. Blood analysis work was done in McGraw's lab at ASU.

Three carotenoids were measured by McGraw - lutein, zeaxanthin, and beta-cryptoxanthin - all of which are sold in health food stores around the world. The swallows acquire carotenoids from the bodies of insects they eat, which get the antioxidants from feeding on plants, McGraw said.

"The biggest contribution of this study is the fresh perspective on assessing each animal's dynamic changes in antioxidant status over time, as opposed to just before or after a given task in life," McGraw explained. "So many variables like diet, genetics and exercise contribute to how good or healthy an individual is at any snapshot in time, and we believe we took a more holistic view of a swallow's condition by longitudinally tracking their own performance over the season."

Interestingly, McGraw equated this to how humans are coming to view personal wellness programs.

"Humans also are incredibly variable in their diet, genetics and health, so rather than focus on a universal goal and set-point to achieve for all people, a more reasonable assessment might be to focus on the fluxes and improvements of individuals," McGraw explained.

He added that these findings dovetail nicely with previous work on barn swallows. Safran and McGraw have shown that barn swallows with more intensely colored feathers circulate more carotenoids through their bodies and reproduce the most in a year.