Table 2. Ethogram defining the aggressive interactions recorded: Aggressive pecks, chases, leaps, threats and fights.

Ethogram for aggressive interactions (Adapted from Estevez et al. 2002 [13])
Aggressive peck (event)	The bird raises its head and vigorously stabs its beak towards another bird (usually directed to the head and neck region).
Chase (event)	The bird runs after another bird for at least three steps in an aggressive manner.
Leap (event)	The bird jumps and kicks its feet forward towards another bird.
Threat (event)	The bird stands with head clearly raised (sometimes accompanied with raising of the neck feathers) in front of another bird who held its head at a lower level.
Fight (event)	Two birds stand in front of each other threating and delivering pecks to each other in rapid succession, sometimes accompanied by jumps. Peaks, leaps and threats occurring during a fight sequence were not recorded independently.