Data from: Dietary tryptophan affects group behavior in a social bird

The amino acid tryptophan (Trp) is precursor of the neurotransmitter
serotonin. Trp supplementation or other forms of serotonergic enhancement
generally promote pro-social behavior, decreasing aggression and also
feeding in different animals. However, past research has been conducted in
confined spaces, and there is little work in naturalistic conditions where
animals move and associate more freely. We gave a Trp-enriched diet to a
free-flying flock of common waxbills (Estrilda astrild) in semi-natural
conditions, and monitored group foraging, aggressions during feeding and
the social network. Contrary to expectations, aggressiveness and feeding
increased during Trp supplementation. Consistent with the prediction of
increased social associations, foraging groups became larger and
individuals joined more foraging groups, but these changes appear driven
by increased appetite during Trp treatment. Also, the mean strength of
associations in the social network did not change. Overall, Trp
supplementation affected group behavior in this free-flying flock, but
mostly in directions unanticipated based on research conducted in small
spaces. To harmonize our results with those found in small confined
spaces, we hypothesise that free-flying birds have energetic requirements
not experienced in lab-housed individuals, which may impact social
behaviour and responses to Trp.