Free-living birds are subjected to both external and internal stresses which can affect their health, activity, and reproductive success. To study stress in free living birds, they must be captured in nets and handled by the researcher to take blood samples for commonly used measures of stress, an activity which itself can induce stress and confound results. This study compares the effects of handling time on three different measures of stress: levels of the stress hormone corticosterone (CORT), levels of Heat Shock Protein 60 (HSP 60) and the ratio of heterophils to lymphocytes (H/L ratio) in tufted titmouse (Baeolophus bicolor) captured at feeders between December and January (2011-2013) in Fredericksburg, VA. Blood samples collected between two and 15 minutes from 12 birds were assayed for levels of CORT and HSP and from 24 birds for H/L ratios. Relationships were examined between these stress indicators and handling time, body mass and body condition. CORT was significantly correlated with handling time (p<0.01), which reinforces existing evidence of CORT’s sensitivity to the way subjects are handled immediately prior to blood collection. HSP or H/L ratios were not affected by handling time, suggesting that they may be preferable indicators of stress in free living birds under some circumstances.
O'Dell, D. A., M. A. Carlo, A. Kimmitt, E. Bikowski, K. R. Morris and A. Dolby. 2014. A Comparison of Techniques Measuring Stress in Birds. Virginia Journal of Science 65 (3): 133-149.