Social experience and competence in ravens

Studies on children and smart non-human animals like primates indicate a link between complexity in social life and the development of intelligence. Individuals differ substantially in their ability to adjust and optimize the expression of social behaviour, resulting in fitness consequences. Early-life social experience has been identified as a key factor for this variation in individual social competence. However, the role of interaction partners other than the mother on the development of social competence is little understood. Furthermore, the long-term effects of early-life experience have been hardly investigated under dynamic field-like conditions, where individuals can choose whom to join and whom to avoid. Ravens, Corvus corax, are large-brained birds that show sophisticated, primate-like socio-cognitive skills. Raven non-breeders form groups that are structured by different types of social relationships, creating a system of dependent ranks and alliances. Yet, individuals differ substantially in how many conspecifics they interact with and how well they form and maintain relationships. The aim of this project is to investigate how early-life social experience shapes the development of ravens social competence and mediates the expression of their social behaviour in later stages of life. Specifically, we will test the hypothesis that the number of siblings and the patterns of social interactions among siblings and parents will affect individuals opportunities to develop their social competences, resulting in i) different social profiles (diversity of social repertoire, quantity and quality of social relationships), ii) differences in social performance (responsiveness to social cues) and iii) differences in social integration and competitiveness in non-breeder groups. We will experimentally manipulate the brood size of our captive breeding pairs in four subsequent years, varying the number of chicks raised by parents per year; depending on the manipulation, the offspring will have the opportunity to grow up with few or many siblings. Per year, we will follow the young ravens development i) during the entire family period, ii) during the formation of the first non-breeder group with same-aged peers in captivity, and iii) during the integration in wild non-breeder groups after transition into free-flight. This integrative approach promises important new perspectives for studying the causes and consequences of inter-individual variation in social behaviour and cognition.

Studies on children and 'smart' animals like primates indicate a link between complexity in social life and the development of intelligence. Individuals typically differ in their ability to adjust and optimize the expression of social behaviour. Early-life social experience has been identified as a key factor for this variation in individual social competence. However, the role of interaction partners other than the mother on the development of social competence is little understood. Here we focused on ravens, Corvus corax, large-brained birds that show sophisticated, 'primate-like' socio-cognitive skills and substantial individual variation in forming social relationships. Our goal was to investigate how early-life social experience shapes the development of ravens' social competence and mediates the expression of their social behavior in later stages of life. We manipulated the brood size of our captive breeding pairs in six subsequent years, counter-balancing the number of eggs (2 or 4) per pair across years; the pairs' offspring had thus the opportunity to grow up with one or more siblings. We followed the young ravens' development i) during the entire family period, ii) during the formation of the first non-breeder group with same-aged peers in captivity, and iii) during the integration in wild non-breeder groups after transition into free-flight. We show that young ravens growing up in small or large families differ in their behavior at food and during object play; they also differ in their responsiveness to social information in played back calls. Overall, offspring from small families tend to be more selective in social information use, whereas offspring from large families tend to pay attention to several group members. While these findings are partly in line with either of two developmental hypotheses, the longevity of upbringing effects is still unclear. Family size hardly explains how well young ravens integrate into wild non-breeder groups, while familiarity among peers and kin are good predictors for their choices. Likewise, the birds' competitiveness in non-breeder groups may be largely affected by their experiences with peers. Taken together, our studies provide strong support for the importance of early-life social experiences in ravens, with sibling number and familiarity with same-aged peers affecting their behaviors at different times. The project led to the establishment of a substantial data set (>15,000 protocols, 115 birds) that will serve as basis for further studies and the long-term tracking of social behaviors of breeding pairs. It involved >50 national and international students at all educational levels, branched out to other disciplines like AI, social- and neurosciences, and received enormous interest from the lay public as indicated by >20 invitations for talks, contributions to Ars electronica and FÄKT.