I've worked with so many parrots sick parrots, fat , liver disease , eating only sun flowers, parrots . Lots of first person experience , looking at feathers in person. So from my years of experience with thosee kinds of parrots, I stand very firm.
With parrots like you mentioned , you can have dull feathers, yellowing of feathers, change in color of feathers, bronzing, worn feathers that loose some of the color at the festher tips. But they won't be black feather tips, prolonged molt, or delayed molt, retaining feather sheaths. Stress bars.
Nutrition and feather health definitely important, I agree with you on that.
I'm just sharing to get the right info out there about black feather tips. From my first hand experience, medical fosters with every kind of issues. Maybe there are others who have linked it to health, but its possible those parrots had mixed issues, both Nutrition and behavior.
Example, thinking Amazon on only sunflower seeds, fatty liver, vitamins A deficiency. I haven't seen one with black tipped. This species is less likely to over preen and pluck. ( edit: I'm sure there are some, I've just seen several with above issues that did not)
Some more examples, parakeets and cockatiels are often victims of an all seed diet. Suffer low vitamin A, fatty liver, nutritional issues. But also are a species that rarely over preens or plucks . Think of all that you have seen, no black feather edges.
With this parrot being a macaw, already has behavior issues of screaming , is eating veggies and fruits. All indicators point to over preening starting feather destruction behavior.
Pictures would definitely clarify.
I'm passionate, because I really want to help parrots.
And recognizing over preening, and or barbering feathers, and taking action can prevent more feathers destruction. Help now can prevent feather plucking from starting. Its a big clue that changes need to be tried and our parrots are feeling stressed.
