Early-life social environment predicts social network position in wild zebra finches

Abstract

Early-life experience can fundamentally shape individual life-history trajectories. Previous research has suggested that exposure to stress during development causes differences in social behaviour later in life. In captivity, juvenile zebra finches exposed to elevated corticosterone levels were less socially choosy and more central in their social networks when compared to untreated siblings. These differences extended to other aspects of social life, with 'stress-exposed' juveniles switching social learning strategies and juvenile males less faithfully learning their father's song. However, while this body of research suggests that the impacts of early-life stress could be profound, it remains unknown whether such effects are strong enough to be expressed under natural conditions. Here, we collected data on social associations of zebra finches in the Australian desert after experimentally manipulating brood sizes. Juveniles from enlarged broods experienced heightened sibling competition, and we predicted that they would express similar patterns of social associations to stress-treated birds in the captive study by having more, but less differentiated, relationships. We show striking support for the suggested consequences of developmental stress on social network positions, with our data from the wild replicating the same results in 9 out of 10 predictions previously tested in captivity. Chicks raised in enlarged broods foraged with greater numbers of conspecifics but were less 'choosy' and more central in the social network. Our results confirm that the natural range of variation in early-life experience can be sufficient to predict individuals' social trajectories and support theory highlighting the potential importance of developmental conditions on behaviour.

Effect of rearing style on the development of social behaviour in young ravens (Corvus corax)

“…Ultimately, this may have increased hand‐raised ravens’ propensity to interact with others and to form bonds with multiple partners. Moreover, being reared collectively, hand‐raised individuals might have also faced with higher degree of competition earlier in life (e.g., for food, space, social status in the group), which was found in zebra finches ( Taeniopgygia guttata ) to increase individuals’ connectivity later in life (Brandl, Farine, Funghi, Schuett, & Griffith, ). Further studies should therefore examine in more details the effect of the presence versus.…”

The importance of individual-to-society feedbacks in animal ecology and evolution

“…Early-life conditions can modulate later-life social behaviour, shaping the population-level social patterns along the way. For instance, zebra finch nestlings exposed to stress develop more gregarious social phenotypes, maintaining a greater number of social partners but choosing partners more randomly (Boogert, Farine & Spencer 2014;Brandl et al 2019a). The proximate mechanisms that underpin inter-individual differences in the development of social behaviour are also becoming clearer.…”

Wild songbirds exhibit consistent individual differences in inter-specific social behaviour

“…How differences in individual association pattern can shape the local structure of populations is demonstrated by carry-over effects of social behaviour. For example, associations among wild zebra finches, Taeniopygia guttata during the nesting period predict pattern of interactions in subsequent years (Brandl et al 2019), while winter social networks among great tits translate to breeding neighbourhoods during spring (Firth & Sheldon 2016). The patterns of local structure arising from interactions among individuals can then translate into local communities, and, in turn, these communities can generate repeatable hierarchical social structures (Farine & Sheldon 2019).…”