Differences in exploration behaviour in common ravens and carrion crows during development and across social context

Abstract

Exploration is particularly important for young animals, as it enables them to learn to exploit their surroundings. It is likely to be affected by species ecology and social context, though there are few comparative, longitudinal studies that control for effects of early experience. Here, we investigated group level exploration behaviour in two closely related and identically reared, generalist corvid species: common ravens (Corvus corax) and carrion crows (C. corone, C. cornix), during development and across social context. Subjects were repeatedly presented with a range of novel items, whilst alone and in a dyad/ subgroup, at the fledging (1–2 months old), juvenile (3–8 months old) and sub-adult (14–18 months old) stages. Whilst alone, they were also presented with a novel and familiar person, at the fledging and juvenile stages. We expected developmental differences and a facilitating influence of social context on exploration. Developmental differences were present, with both species interacting most frequently with novel items as juveniles, which may relate to major developmental steps, such as dispersal and a neophobia increase as sub-adults. When a conspecific(s) was present, subjects generally interacted more frequently, though took longer to interact, with novel items. Additionally, we found unexpected species differences, with the most striking difference being the crows’ significantly lower rate of interaction with the novel person, though not the familiar person; a species difference that was present from fledging. We discuss these findings by relating to potential differences in the two species ecology and behaviour, such as habitat use and caching proficiency.