Behavioral changes associated with a population density decline in the facultatively social red fox

Abstract

Understanding the causal mechanisms promoting group formation in carnivores has been widely investigated, particularly how fitness components affect group formation. Population density may affect the relative benefits of natal philopatry versus dispersal. Density effects on individual behavioral strategies have previously been studied through comparisons of different populations, where differences could be confounded by between-site effects. We used a single population of red foxes (Vulpes vulpes) in the city of Bristol, UK, that underwent a natural perturbation in density to compare key changes in 1) group structure, 2) within-group relatedness, 3) mating system, 4) dispersal, and 5) dominance attainment. At high densities (19.6-27.6 adults km 22), group sex ratios were equal and included related and unrelated individuals. At low densities (4.0-5.5 adults km 22), groups became female biased and were structured around philopatric females. However, levels of within-group relatedness were unchanged. The genetic mating patterns changed with no instances of multiple-paternity litters and a decline in the frequency of extrapair litters of cubs from 77% to 38%. However, the number of genetically monogynous groups did not differ between periods. Dispersal was male biased at both high and low densities. At high density, most dominant males in the study groups appeared to have gained dominance after dispersing, but natal philopatry was an equally successful strategy at low density; conversely, most dominant females were philopatric individuals at both high and low densities. These results illustrate how density may alter behavioral strategies such as mating patterns and how this, in turn, alters group structure in a single population.

Two's company? Solitary vixens’ motivations for seeking social contact

“…competition for social dominance, causing injuries and stress to the animals . However, red fox vixens in the wild often live in social groups consisting of both related and unrelated females (Iossa et al, 2009), and here females' social interactions include amicable allo-grooming and play (Macdonald et al, 2004), although aggressive displays can still escalate into fights (White and Harris, 1994). The social dynamics within free-living groups of foxes depend on factors like food predictability and resource competition (e.g.…”

Male alliance behaviour and mating access varies with habitat in a dolphin social network

“…refs 13, 14, 15, 16), as has the relationship between social systems, ecology and demography (e.g. refs 17 and 18).…”

Seasonal and Sex-Specific Differences in Feeding Site Attendance by Red Foxes Vulpes vulpes

“…One key difference may result from motivation, with the intruding males seeking reproductive opportunities and not food, which does not translate into visits to feeding sites. In addition, females in neighbouring groups are typically closely related through more limited dispersal distances (Iossa et al 2009). Therefore intruding females may be more related to residents and so more tolerated.…”