Understanding the intricacy of canid social systems: Structure and temporal stability of red fox (Vulpes vulpes) groups

Abstract

Red foxes have a highly flexible social system. Despite numerous studies worldwide, our understanding of the pattern and stability of fox social relationships remains limited. We applied social network analysis to camera trap data collected at high-quality foraging patches to examine the social structure of a population of urban red foxes. Foxes encountered a conspecific on 13% of patch visits, and had significant preferred and avoided companionships in all seasons. They also associated in communities that matched territorial space use, confirming that territories can be analysed separately to increase power without excluding too many social partners. Foxes maintained stable, long-term relationships with other territory residents, but the average longevity of relationships varied seasonally, suggesting that social connectivity, particularly between foxes from different social groups, is influenced by their annual life cycle. The probability of re-association after a given time lag was highest in spring and summer, during cub birth and rearing, and lowest in the winter mating season, when mean relationship duration was shorter. 33% of fox relationships lasted for four consecutive seasons and were probably between territory residents. 14% lasted for around 20 days and were probably between residents and visitors from adjacent territories. The majority (53%) lasted less than one day, particularly during dispersal and mating, and were probably between foxes from non-adjacent social groups. Social structure varied between groups; in one group the death of the dominant male caused significant social disruption for two seasons. This is the first application of social network analysis to multiple red fox social groups. However, our analyses were based on interactions at high quality food patches; social connections may differ when foxes are resting, travelling and foraging elsewhere in their territory. Our results will inform management practices, particularly for disease spread and population control.

Individual and seasonal variation in contact rate, connectivity and centrality in red fox (Vulpes vulpes) social groups

“…This is probably reflected in group composition, as seasons affected the social behaviour of foxes differently depending on their individual attributes. Consistent within-season lagged association rates 36 suggest that fox network positions were probably repeatable over shorter time periods, but we did not get enough associations/day to make daily or weekly comparisons. Seasonal variation in network centrality may reflect seasonal differences in the roles of individuals 17 , but the lack of consistency also demonstrates a flexibility that may facilitate adaptation to new situations.…”

“…Perhaps the most common notion is that sociality in red foxes is limited to raising cubs 33 . However, solitary foraging does not mean that red foxes do not have a complex social system: they defend common territories 4,6 , share food patches 35 , have a dominance hierarchy that allows the monopolization of resources 35 , and have long-term social relationships indicative of stable group membership throughout the year 7,36 , all of which suggest that their social system is fundamentally the same as other group-living canids.…”

“…Furthermore, individual network strength did not decline when food was unavailable, indicating that spatiotemporal associations were not simply a by-product of parallel feeding. While they were not suitable for analysis, we recorded a diversity of behavioural interactions at food patches and foxes had preferred and avoided companions, both short and long term 36 . Thus sociality was facilitated by patchy resources rather than foxes simply congregating at productive food patches.…”

“…We conducted camera-trap surveys between July 2013 and June 2015 in seven fox territories in the city of Bristol, UK 4,10,25,53 . We selected four to six back gardens (food patches)/territory where householders provisioned foxes ≥2 days/week 35,36 . Cameras were active continuously for 40 days for four consecutive seasons: spring (March-May; birth, early cub rearing), summer (June-August; late cub rearing/early independence), autumn (September-November; onset of dispersal), winter (December-February; peak dispersal/mating).…”

“…Contact rates were calculated for foxes seen ≥5 days/season in any patch: this reduced noise from seldom-observed individuals 37 . Not all patches were included every season 7,36 , so network metrics were calculated for foxes seen ≥5 days in a standardised dataset using the same number of patches/season to ensure comparability within a territory: fox community structure matches territorial space use 36 .…”