The ecology of ageing in wild societies: linking age structure and social behaviour in natural populations

Abstract

The age of individuals has consequences not only for their fitness and behaviour, but also for the functioning of the groups they form. Because social behaviour often changes with age, population age structure is expected to shape the social organisation, the social environments individuals experience, and the operation of social processes within populations. Although research has explored changes in individual social behaviour with age, particularly in controlled settings, there is limited understanding of how age structure governs sociality in wild populations. Here, we synthesise previous research into age-related effects on social processes in natural populations, and discuss the links between age structure, sociality and ecology, specifically focusing on how population age structure might influence social structure and functioning. We highlight the potential for using empirical data from natural populations in combination with social network approaches to uncover pathways linking individual social ageing, population age structure and societal functioning. We discuss the broader implications of these insights for understanding the social impacts of anthropogenic effects on animal population demography, and for building a deeper understanding of societal ageing in general.

Age-specificity in territory quality and spatial structure in a wild bird population

“…Age affects many aspects of life, as resources are allocated into processes and traits at different points throughout lifespan to maximise fitness [1] and individuals gain in experience as they age. Further, variation in population age structure may affect population dynamics, via effects on reproductive output and social organisation [2][3][4][5]. There is widespread evidence of temporal variation in age structure in wild populations [4,6,7], but the way in which age structure varies across space seems to be much less well understood.…”