Birds of a feather: indicators in urban versus rural Eastern bluebirds (Sialia sialis)

Urban and rural populations of songbirds face different challenges in their habitats, including differences in predator types, food types and abundance, anthropogenic disturbances, and environmental cues such as temperature. These differences could affect individuals’ body condition, including the investment they put into and speed at which they produce feathers. Feathers are an integral characteristic of bird anatomy and aid in functions such as flight, insulation, and display; they have been shown to vary in quality among populations. Using Eastern bluebird feathers collected from two urban and two rural sites, I measured the microstructure (barbule density), growth rate (growth bars), and weight/length of tail feathers to determine their quality. I also compared individuals’ body weights and wing, tail, and tarsus lengths for urban versus rural populations and correlations with feather quality. I found positive correlations between the feather and body measurements, suggesting they both represent condition. There was a significant difference in the barbule density, tarsus length, and body weight across the four locations; however, the two urban sites had the best and worst conditions for these measurements. This suggests that urbanization could result in variable habitat qualities