Table 2.

List of social behaviors used to calculate the hierarchy and affiliations (affiliative behaviors that occurred <2 times in total were not included into the analysis)

Behavior	Description (Recorded Information)
Unidirectional affiliative behavior
Allopreening	One bird touches the feathers of another bird with its beak for longer than 2 s (who touches whom). It often incorporates up and down or sideward movements of the beak through the plumage.
Unidirectional agonistic behavior
Mildly forced retreat	One bird approaches another without physical contact, forcing it to retreat while producing defensive vocalization (who is the attacker, whom the recipient).
Forced retreat	One bird approaches another by engaging in physical contact, forcing it to retreat while producing defensive vocalization (who is the attacker, whom the recipient).
Approach–retreat	One bird approaches another, forcing it to silently retreat within 2 s (who is the attacker, whom the recipient).
Threatened approach–retreat	One bird approaches another, forcing it to silently retreat after being visually threateneda within 2 s (who is the attacker, whom the recipient).

^aA visual threat is generally indicated by extension of the crest and bill gaping (sometimes additionally with fluffing of the plumage and fanning of the tail). Physical contact is not achieved.