Heart rate modulation in bystanding geese watching social and non-social events

摘要

Simply observing other individuals interacting has been shown to affect subsequent behaviour and alsonhormones in ‘bystander’ individuals. However, immediate physiological responses of an observer havenbeen hardly investigated. Here we present results on individuals’ heart rate (HR) responses during variousnsituations, which occur regularly in a flock of greylag geese (Anser anser, e.g. agonistic encounters, vehiclesnpassing by).We recorded simultaneously HR and behaviour of 21 semi-tame free-roaming geese, equippednwith fully implanted transmitters. We considered 304 social and 81 non-social events during which thenfocal individuals did not respond behaviourally. Independent of the spatial distance to the event, thesenHR responses were significantly greater in social contexts (e.g. departing or landing geese, agonisticninteractions) than in non-social situations (e.g. vehicles passing by, thunder). Focal individuals showed ansignificantly higher maximum HR as well as a greater HR increase in response to agonistic interactions, innwhich the pair partner or a family member was involved, as compared with a non-affiliated goose. Also, HRnwas significantly higher when the bystander watched non-affiliated geese interacting, which were highernranking than the focal. We conclude that these differences are due to different relevance of the recordednevents for the focal individual, depending on the individuals involved in the observed interaction