Being present on a few parrot forums, I often see people project human emotions on parrots, sometimes where's it's not entirely justified. I, myself, try to keep things neutral most of the time and not delve into that slippery slope.
However, over the past weeks I've noticed something that does resemble jealousy.
I've often mentioned in the past that Zuri and Shade seemed to be good bird "friends" - often preening one and other. Generally, this is where Shade draws the line, although if she can get Zuri to feed her (she's a glutton) then all the better. Poor Zuri, who from time to time seems to be thinking things might go further will immediately get shot down at that time.
Since Zuri's collar has come off, Pixel has started to want to get close to him; why Zuri, I don't know. She's never hidden the fact that she hasn't really ever liked Shade (yet is fine with all other birds most of the time). She has tried to get him to preen her when Shade wasn't around him.
What has happened then though is that Shade will fly to them to interrupt whatever is going on. Just now, she was perched quite happily on my shoulder and Zuri had actually started feeding Pixel - she immediately flew over and I got up fast to intervene as things would generally degenerate into a possible fight. I ended up having to remove Pixel as Zuri has moved onto being aggressive. Right after I separated them, Shade went to preen Zuri's head for a few seconds, asked to be preened in return and has since started to ignore him once again.
But there was no way she was going to let anything happen between Zuri and Pixel.