Supplementary material from "No, you go first: phenotype and social context affect house sparrow neophobia"

Novel object trials are commonly used to assess aversion to novelty (neophobia), and previous work has shown neophobia can be influenced by the social environment, but whether the altered behaviour persists afterwards (social learning) is largely unknown in wild animals. We assessed house sparrow (Passer domesticus) novel object responses before, during and after being paired with a conspecific of either similar or different behavioural phenotype. During paired trials, animals housed with a similar or more neophobic partner demonstrated an increased aversion to novel objects. This change did not persist a week after unpairing, but neophobia decreased after unpairing in birds previously housed with a less neophobic partner. We also compared novel object responses to non-object control trials to validate our experimental procedure. Our results provide evidence of social learning in a highly successful invasive species, and an interesting asymmetry in the effects of social environment on neophobia behaviour depending on the animal's initial behavioural phenotype.