Table 2.

Definitions of scored behaviour.

behaviour	definition
activity level	total number of movements between perches, floor or sides of the compartment
aggressive interaction	peck, attack (i.e. a fast, direct flight towards the other bird that is perched next to the cage divider) or combat (i.e. both birds repeatedly peck and aggressively vocalize at each other, often when hovering in mid-air) between focal bird and conspecific
winning an interaction	displacement with a winner and a loser (i.e. loser moves away while winner stays put)