Meeting Abstract
The study of individual differences in behaviour that persist over time and across contexts, or personality, has become a new paradigm for behavioural research and has been applied to a wide range of animal species. Yet the physiological underpinnings of personality remain poorly understood. As most personality tests measure reactions to novel stimuli and other potential stressors, personality differences may be linked to individual differences in the physiological stress response. Until now, there is only weak evidence for a link between personality and the hormone-mediated stress response (i.e. increased corticosterone in the blood), which may be because behaviour is usually measured in short tests lasting 1-2 minutes, and before corticosterone increases in the blood. An additional stress response occurs in the autonomic nervous system (ANS) immediately during stress, and before hormones increase in circulation. ANS activity during stress may therefore show a stronger correlation with behaviour from short-term tests. Heart rate (HR) and HR variability (HRV) provide a non-invasive measure of the balance between the activity of the two branches of the ANS: the parasympathetic nervous system (PNS), which promotes self-maintenance and restoration, and the sympathetic nervous system (SNS), which prepares an animal to survive danger. We attached ECG loggers to streaked shearwaters (Calonectris leucomelas) and from HR and HRV, quantified their PNS and SNS activity during and after handling stress. We also measured behaviour in various standardised tests. We repeatedly tested both ANS activity and behaviour in the same individuals over the course of two breeding seasons. We evaluate the evidence for individual differences in stress sensitivity of the ANS and discuss the implications for the study of personality.
