Join Date: Jun 2013
Location: NYC, USA
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It depends what feathers are being fluffed. I remember reading in one of my parrot behavior books that different patterns of fluffed feathers mean different things. I can't remember exactly, but I do remember the fluffed up feathers by the beak means the bird is friendly (it's like they are trying to make their beaks less intimidating), but fluffed up feathers by the nape and fanned out tail is aggressive (think strutting amazon).
The feather fluffing is kind of like a dog's wagging tail--can mean happy or aggressive, you have to know how to read it.