Group-level repeatability of seasonal home ranges in a non-territorial bird

Mina Ogino and Danai Papageorgiou, Department of Biology, University of Konstanz, Konstanz, Germany, Mina Ogino, Danai Papageorgiou and Damien Farine, Department of Collective Behavior, Max Planck Institute of Animal Behavior, Konstanz, Germany, Mina Ogino, Danai Papageorgiou and Damien Farine, Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland, Mina Ogino, Danai Papageorgiou, Lucy Aplin and Damien Farine, Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany, Mina Ogino, Brendah Nyaguthii, Danai Papageorgiou and Wismer Cherono, Mpala Research Centre, Nanuyki, Kenya, Brendah Nyaguthii and Damien Farine, Ornithology section, National Museums of Kenya, Nairobi, Kenya, Lucy Aplin, Cognitive and Cultural Ecology Research Group, Max Planck Institute of Animal Behavior, Radolfzell, Germany

Background/Question/Methods
Group living can bring many benefits. To reap these benefits, groups must maintain cohesion and, therefore, effectively decide where to go. For many species, the space available for groups to move in, and their subsequent home range, is determined by territorial boundaries. But how do non-territorial species deal with this challenge of deciding where to go when their range is not limited by social boundaries? One solution is to establish routine ranging patterns, and partition the pattern of space use with other groups. Here we study the spatial and social partitioning of space among groups of vulturine guineafowls (Acryllium vulturinum). These are an excellent species to investigate this as groups frequently roost communally and have overlapping home ranges. We fitted GPS tags to members in all of the groups in a study population in Kenya, allowing us to quantify how repeatable ranging behaviour is over different timescales spanning multiple years and seasonal conditions – within season, across seasons, and across years. We estimated home ranges (i.e. 95% auto-correlated kernel density estimation) of each group in each month, and then estimated the fidelity of groups’ home ranges and the overlap among groups across different timescales.
Results/Conclusions
Our results show that groups of vulturine guineafowls have distinct and highly consistent home ranges. Within-group home range fidelity between consecutive months is high, and remains high in the same season for at least two years. While groups ranged in different areas between drier and wetter seasons, group home ranges in the same seasons remained consistent across years. Such within-group fidelity contrast with the substantially lower within-month average overlap between different groups. Overall, our results suggest that non-territorial vulturine guineafowl groups establish consistent ranging patterns that are maintained across long periods of times, even with demographic changes in group compositions. How these routines are established and maintained can provide important insights into the emergence of socio-spatial group-level behaviours, such as how territoriality play a role in other species, as well as potential fitness consequences of variation in the consistency in ranging patterns.