"Our findings in this study contradict the prevailing scientific views regarding the immense physiological costs of reproduction in birds," Safran said. "While evolutionary theory says individuals that pay the greatest cost in parental care do so at the expense of self-preservation, we found some individuals are good at doing it all -- maintaining their own nutritional status while bearing the costs of reproduction."
The researchers also found that barn swallows carrying more carotenoids had deeper red breasts a sign of healthy, robust individuals and that those individuals darker in color had greater circulating levels of carotenoids at the start of the breeding season. Previous studies by Safran and her colleagues suggest females are more attracted to males with deep red breasts and that they "cheat" less on their male partners than other females. The breast coloring appears to be an indication of status, performance, testosterone and nutrition, she said.
The study was funded in part by the National Science Foundation, the Howard Hughes Medical Institute and CU-Boulder's Undergraduate Research Opportunities Program and the Biosciences Undergraduate Research Skills and Training. Both CU-Boulder programs offer undergraduates hourly wages or stipends to work with faculty members on innovative research projects.
"One of the most exciting things that I do in my job is train students both in the field and in the lab," said Safran. "Because this work requires many hands, it would be impossible to do these kinds of studies without them."
A 2008 study by Safran and her colleagues showed the testosterone of male North American barn swallows skyrocketed early in the breeding season when their breast colors were artificially enhanced to the deep red most attractive to females. The birds likely
|Contact: Rebecca Safran|
University of Colorado at Boulder