There is a need for a non-invasive assessment of stress. This paper describes a simple protocol using thermal imaging to detect a significant response in eye-region temperature in wild blue tits to a mild acute stressor.
Jerem, P., Herborn, K., McCafferty, D., McKeegan, D., Nager, R. Thermal Imaging to Study Stress Non-invasively in Unrestrained Birds. J. Vis. Exp. (105), e53184, doi:10.3791/53184 (2015).