Foraging behaviour alters with social environment in a juvenile songbird

Early independence from parents is a critical period where social information acquired vertically may become outdated, or conflict with new information. However, across natural populations it is unclear if newly-independent young persist in using information from parents, or if group-level effects of conformity override previous behaviours. Here we test if wild juvenile hihi (Notiomystis cincta, a New Zealand passerine) retain a foraging behaviour from parents, or if they change in response to the behaviour of peers. We provided feeding stations to parents during chick-rearing to seed alternative access routes, and then tracked their offspring’s behaviour. Once independent, juveniles formed mixed-treatment social groups, where they did not retain preferences that we detected when with parents. Instead, juvenile groups converged over time to use one access route per group, and juveniles that moved between groups switched to copy the locally-favoured option. Juvenile hihi did not copy specific individuals, even if they were more familiar with the preceding bird. Our study shows that early social experiences with parents affect initial foraging decisions, but social environments encountered later on can update transmission of arbitrary behaviours. This suggests that conformity may be widespread in animal groups, with potential cultural, ecological, and evolutionary consequences.
Methods
Data on visits to feeders were collected using Radio Frequency Identification (RFID) Passive Integrated Transponder (PIT) tags fitted to each individual bird in our study population. Individual-level data (i.e. metal ring number, age) on the birds associated with each transponder ID were collected as part of the ongoing yearly monitoring of the study population during the breeding season. Social network metrics (i.e. degree) were obtained prior to main experiment data collection. Full information can be found in the Methods sections of the article.