Meeting Abstract
Current techniques for measuring glucocorticoid levels in avian species are invasive, require displacing birds from their natural habitat, and are known to themselves elevate glucocorticoid levels, thus complicating measurement of biologically relevant stressors. Observations from poultry suggest that stress in birds may be accompanied by an increase in temperature of exposed extremities. Thus, we hypothesized that increases in glucocorticoid levels might be associated with measurable increases in heat output at unfeathered body parts in birds, e.g., the feet, eyes, and beak. If true, thermal imaging technology might make it possible to create an alternative field method for measuring stress in free-living wild birds without handling them. We investigated the correlation between corticosterone (secreted during times of stress) and thermal output by simultaneously sampling blood plasma and heat signatures from house sparrows (Passer domesticus) during a 60 min acute stress series protocol. Heat signatures were measured from sparrow beaks, eyes, and lores with an infrared camera. Our results suggest that development of a thermal measurement of stress will require further experimentation. House sparrow beak temperatures varied in complex ways with corticosterone levels over time; detectable heat output is probably complicated by multiple factors. We found no significant relationship between the temperature of the eye, or the lores, and corticosterone levels.
