Feather corticosterone: does it reflect fear or stress in greenfinches? — ASN Events

Feather corticosterone: does it reflect fear or stress in greenfinches? (#493)

Tuul Sepp 1 , Peeter Hõrak 1 , Richard Meitern 1
  1. University of Tartu, Tartu, TARTU MAAKOND, Estonia

Stress hormone corticosterone extracted from feathers provides a long-term perspective on stress physiology for birds. This method is being increasingly used as an alternative for quantifying glucocorticoids from blood in both physiological and ecological research. In our study system, wild caught captive greenfinches, we tested for the associations between wild grown and lab grown feathers’ corticosterone content and correlation of feather CORT levels with behavioral responses to different fear eliciting situations. We also tested for the existence covariation of individual responses to different fear-eliciting situations (“fearfulness syndrome.”). We assessed the propensity to give distress calls at handling, latency to feed at the presence of a predator image, and changes in locomotor activity in response to distress calls of conspecifics. Additionally, we measured the frequency of flapping flight movements against cage bars and tendency to damage tail feathers in captivity as indicators of the ability of birds to cope with captive conditions. We found a strong correlation between wild grown and lab grown feathers’ CORT content, as well as individual repeatability in time for all of the behavioral traits. CORT levels were 20% lower for lab grown feathers. However, no correlations was found between individual fear responses and corticosterone levels. The findings of this experiment challenge the concept of a single internal variable responsible for fearfulness and support the proposed multidimensional nature of fear responses.