I have not taken the time to do any research into this odor, but I do catch a whiff of it now and then with Mimi, our amazon. I have been a hunter all of my life as well as having spent most of my life working with various animals in different capacities and all animals have their own odors. Much of the time the odor is caused or altered by the animals diet, and of course there is the fact that different species of animals share a specific scent that identifies them to other animals that are able to pick up on the scent. Some odors are only emitted at certain times such as those used to attract a mate or those used in self defense. As far as I am aware of there has never been a reason suggested for the smell of the amazon parrot, but since nature does not tend to waste energy without having a survival purpose could this odor be related to camaflage in some way and therefore be used to mask the regular scent of this bird from certain predators?
Just a thought, something to consider.