Social attention across development in common ravens and carrion crows

Abstract

Underlying social learning and other important aspects of successful adaptation to social life is social awareness, where individuals are required to pay attention and respond flexibly to others in their environment. We tested the influence of social context (alone, affiliate, non-affiliate, heterospecific) on behavioural interactions (manipulation, caching, head & body out of sight i.e. barrier use) with food and objects during development at fledging (1-2 months), juvenile (3-8 months) and sub-adult (14-18 months old) in 10 carrion crows (Corvus corone; C. cornix) and nine common ravens (C. corax). These species are closely related, generalist corvids and subjects were all hand-reared and housed in highly comparable conditions. Both species will routinely cache, i.e. hide food and other items for later recovery, and engage in cache-pilfering (stealing) strategies. They will interact and play with objects, potentially as part of developing social bonding and/or physical skills. We found that corvid behaviour was influenced by social context, with birds showing higher frequency of head & body out of sight behaviour while others were observing than when alone, suggesting they have an awareness of others presence and respond by using barriers when interacting with items. There were no differences based on observer identity, supporting an interpretation of item interaction and play potentially driving development of physical skills in this setting. There were developmental effects, including increased manipulation and use of barriers as juveniles as well as increased caching with age. Ravens generally cached more than crows. Objects were manipulated more frequently than food, while barriers were used more with food, indicating that food was more likely to be actively hidden while objects may promote open play. We discuss our findings in relation to other social and developmental influences on behaviour and the wider ramifications for identifying the drivers of play in animals.