Time allocation to balance group living trade-offs in Ethiopian wolves

Abstract

Living in groups requires individuals to make trade-offs to maintain group cohesion and enhance individual and inclusive fitness. One way animals can do this is by adjusting the way they allocate time to different behaviours. Ethiopian wolves (Canis simensis) are highly social, cooperative breeders (only the dominant pair breeds and all members help to raise the litter), but solitary foragers. To investigate how Ethiopian wolves allocate their time to balance the costs and benefits of group living, we analysed the time budgets of 47 wolves across six behaviours. We hypothesized that group size and territory density would affect wolves’ time allocation between solitary (foraging) and communal activities (patrolling and socialising) differently in relation to their age, dominance status or sex, and whether the pack was breeding or not. Our results showed that the time spent foraging alone increased at higher territorial densities, as expected from interference competition, particularly among subadults, subordinates and individuals in breeding packs. On the other hand, as pack size increased, adult wolves spent a lower proportion of time patrolling, while the time spent socialising did not change. Living in groups reduces the costs of communal activities, but crowded territories come at the cost of interference competition for solitary foragers, particularly the animals further down the hierarchy ranks, subadults, and individuals investing in breeding. Such trade-offs could impose an upper limit to group size and population growth within a limited space. Furthermore, anthropogenic disturbance could alter the balance of social and solitary activities of Ethiopian wolves.