Meeting Abstract
In line with finding innovative and less invasive ways to quantify stress in animals, researchers have begun to look at feathers as a repository for corticosterone (CORT), the primary glucocorticoid in birds. It has been shown that CORT is incorporated into birds’ feathers as they grow. However, scientists have found inconsistent relationships between levels of CORT in feathers and plasma CORT levels. We hypothesized that CORT would be incorporated into the feathers preferentially more at night than during the day, since evidence has shown that feathers may be growing more during the nighttime. This could explain why findings have been so inconsistent. In addition, we looked at whether administered CORT is incorporated locally or from the global blood supply. Initially, we plucked seven flight feathers from each wing from 24 European starlings (Sturnus vulgaris) to simulate molt, and reserved the secondary #2 feathers from each wing for analysis. We dissolved CORT in dimethylsulfoxide and applied the solution to the left feather tract. Our experiment had three groups: a control group that received no CORT, an AM CORT group that received a daily dose of CORT in the morning, and a PM CORT group that received a daily dose of CORT in the evening. While significantly more CORT was found in the AM and PM CORT group feathers than in the control group feathers, AM feather CORT levels were also significantly higher than PM feather CORT. There was no significant difference between CORT levels in right versus left feathers for any of the groups, indicating that CORT is incorporated in the feathers from the blood supply, rather than from locally administered or produced CORT. Post-treatment blood sampling showed that repeated CORT administration elevated baseline plasma CORT levels in the experimental groups.
