Bill covering and nape feather ruffling as indicators of calm states in the Sulphur-crested cockatoo (Cacatua galerita).

Parrots are highly social birds that are recognized for their primate-like cognitive abilities but their way to express emotions remain overlooked. Herein we explored potential facial indicators of emotions in cockatoos. We predicted that facial feather ruffling is an indicator of a cockatoo's emotional state and hypothesized that specific facial feather positions would be present more during positive valence and low arousal situations.

Facial display and blushing: Means of visual communication in blue-and-yellow macaws (Ara Ararauna)?

Mainly recognized for their cognitive performance, the visual communication system and, particularly, the potential function of facial displays in parrots remain thus far unexplored. Here, we provide the first descriptive study of facial display use in captive blue-and-yellow macaws. We observed the feather position (sleeked or ruffled) on the crown, nape and cheek at the group level during the macaws' daily routine and individually while interacting with a familiar animal caretaker.