Fig. 1: Social groups and aggressive social interactions within groups on day 3.

a The social group triad is observed as well as the feeder in top left corner and automatic nipple in bottom left corner of the apparatus. b–f Schematic representation of the direction of the aggressive social interactions (dark red arrow) present between individuals in the triad of two females (gray background) and one male (white background) 48 h after being placed in the novel social environment. Red indicates dominant birds (aggressive score ≥ 4.9), blue, subordinate birds (aggressive score ≤ −4.9) that receive pecks from dominant birds, and black those birds that are neither dominant nor subordinate (4.9 > aggressive score > −4.9). f represents neutral groups (i.e. the group did not include any dominant member).