Data from: Within-flock heterogeneity in exploration affects flock behaviour in a highly gregarious bird

How individual differences translate into group outcomes is a
controversial issue and depends on the phenotypic composition of the
group. Research on the effect of within-group homogeneity/heterogeneity in
phenotypic composition provided contrasting results, with some studies
supporting benefits of homogeneity and others the opposite. We
characterized a personality trait in a gregarious bird, the European
starling (Sturnus vulgaris), and investigated how different degrees of
within-flock variation in exploration affect flock behavioural responses.
Based on consistent individual differences in exploration, we formed
flocks of 4 birds differing in mean and variation of exploration scores.
These flocks underwent an exploration test and a perturbation test to
assess escape response. We found that, compared to less exploratory
individuals, more exploratory individuals enter the test room earlier and
start and stop flying sooner upon frightening (escape response). Flocks
with a more homogeneous distribution of the individual exploration scores
are significantly faster to enter the exploration room, but there is no
clear effect on the escape response. The mean exploration score of the
flock or the maximum exploration score of purported ‘key’ individuals
within groups do not explain differences in group performance. The results
indicate that it may not be the individual that drives the flock
behaviour, but rather the phenotypic variation within the group, and
suggest that a homogenous distribution of personality types could speed up
collective decision-making in gregarious species.