Data from: Evidence for personality conformity, not social niche specialization in social jays

Animal personality traits are defined as consistent individual differences in behavior over time and across contexts. Occasionally this inflexibility results in maladaptive behavioral responses to external stimuli. However, in social groups inflexible behavioral phenotypes might be favored as this could lead to more predictable social interactions. Two hypotheses seek to describe the optimal distribution of personality types within groups. The social niche specialization hypothesis states that individuals within groups should partition social roles, like personality types, to avoid conflict. Whereas the conformity hypothesis states that individuals should assort with conspecifics of similar personality. However no research so far has compared these hypotheses using data from wild animal systems. We tested boldness in the wild on two species with different social systems, the Mexican Jay and California Scrub-Jay. We found support for the conformity hypothesis over the social niche specialization hypothesis because individuals within groups of the social species had more similar personalities, and consequently there was a statistically significant group effect. The most likely mechanism for this conformity is social learning of behaviors through development, but more explicit research on this is needed.