Daily ranging and den usage patterns structure fission-fusion dynamics and social associations in spotted hyenas

Environment structure often shapes social interactions. Spatial attractors
that draw multiple individuals may play a particularly important role in
dispersed groups, where individuals must first encounter one another to
interact. We use GPS data recorded simultaneously from five spotted hyenas
(Crocuta crocuta) within a single clan to investigate how communal dens
and daily ranging patterns shape fission-fusion dynamics (subgroup splits
and merges). We introduce a species-general framework for identifying and
characterizing dyadic fission-fusion events and describe a taxonomy of ten
possible configurations of these events. Applying this framework to the
hyena data illuminates the spatiotemporal structure of social interactions
within hyenas' daily routines. The most common types of
fission-fusion events involve close approaches between individuals, do not
involve co-travel together, and occur at the communal den. Comparison to
permutation-based reference models suggests that den usage structures
broad-scale patterns of social encounters, but that other factors
influence how those encounters unfold. We discuss the dual role of
communal dens in hyenas as physical and social resources, and suggest that
dens are an example of a general "social piggybacking" process
whereby environmental attractors take on social importance as reliable
places to encounter conspecifics, causing social and spatial processes to
become fundamentally intertwined.