Bird-Language

"Trying to understand the words
Uttered on all sides by birds,
I recognise in what I hear
Noises that betoken fear.

Though some of them,
I'm certain, must
Stand for rage, bravado, lust,
All other notes that birds employ
Sound like synonyms for joy."
W.H. Auden, Collected Poems (1976)

But sometimes behaviour is the best clue to emotion.