SOCIAL CONTEXT MODULATES DIGESTIBILITY IN GREYLAG GEESE (ANSER ANSER)

SOCIAL CONTEXT MODULATES DIGESTIBILITY IN GREYLAG GEESE (ANSER ANSER) Lara Iaiza1, Carla Fabro1, Federico Mason1, Chiara Sarnataro1, Stefano Filacorda1, Didone Frigerio2 1Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Università degli Studi di Udine 2Core facility KLF for Behaviour and Cognition, University of Vienna In group living animals, social context is known to modulate physiology, behaviour, fertility and immune system of individuals. Furthermore, individuals’ nutritional strategies may profoundly affect their performance, also impacting their social interactions. In the present study we discuss the results of a pilot study conducted on N = 38 individuals of the semi-tame, long-term monitored and individually marked flock of Greylag geese (Anser anser) at the Konrad Lorenz Research Station in Upper Austria. Focal animals belonged to different social categories within the flock, i.e. paired with and without offspring, single and juveniles (5 males and 3 to 5 females per category). The animals are well habituated to the close presence of humans and are used to get fed twice a day on the meadow in front of the Research Station. During 9 consecutive days in winter 2017, when the snow pack was closed, we standardized the food given to the birds and collected a total number of 184 individual droppings from the focal individuals (mean=4,8; SD=0,4) after the morning and afternoon feedings. Samples were analysed at the lab facilities of the Department for Agro-Food, Environmental and Animal Science, University of Udine (Italy) by determining the apparent digestibility of total organic matter. Preliminary results show similarities between males and females but hint at differences depending on the social category with parental individuals showing higher digestive capability than unpaired individuals or paired without offspring. We discuss our findings with respect to the complex relationships between social status, physiology and the capacity of digesting food, extracting nutrients and improving fitness.