Heat-shock proteins (HSPs, also known as stress proteins) are intracellular proteins that prevent cell and protein damage during periods of stress. HSPs have been employed as a measure of stress in a variety of organisms since their discovery in 1962, but their usefulness in field ornithology has only just recently begun to be explored. Human activity impact on wildlife (specifically stress caused by human disturbance) has become an increasingly relevant issue in conservation as human populations expand world-wide. We examined relationships among HSP concentration in blood cells (as a measure of stress), fitness measures (reproduction and physical condition), and human disturbance in American Kestrels. The study was conducted in southwest Idaho during the spring and summer of 2008. We collected blood from adult birds after eggs were layed and from nestlings just about to leave the nest (~23-25 days old). We also recorded measures of size and mass and the number of young produced per pair. Habitat for each nest was given one of three disturbance scores: high, medium, or low (based on human activity near the nest). Blood cells were assayed for total protein content per μl and HSPs per μl were measured by western blot analysis and Kodak Molecular Imaging Software. Results from this study have implications on whether human activities evoke a physiological stress response in breeding adult birds or developing young chicks
