Young conures do play on their bsck a lot,, thsts normal. Scalloped neck feathers is normal.
How often does he take a bath? Does he have his own areas in the house, or just hangs out on furniture? Having his own perches in the home can really lower stress. Increase easily destroy type toys, like shredders, yucca chips, bird bagels, and foraging toys.
His over preening and messing with feet is a sign of stress. So I strongly recommend trying to figure out cause, and trying things to lower his stress. Each parrot is different, and some are more sensitive to things thst wouldn't bother a different parrot
Here is Ta-dah, I know she us a different color mutation but look at the ends of feathers. This is normal feathers, and also all my parrot feathers look smooth because of lots if veggies and leafy greens, occasionally a little yogurt, or boiled egg, and time outside in light shade.
Also before molting i bump protein, with walnut, egg, boiled chicken ( thumbnail size piece) takes a lot of protein to grow feathers. You won't see feathers different until they molt out.
Tadah was eating black berries do thats why beak looks weird! I get a picture of Orbit who has mild over preening for yiu to see too.
Ok Orbit has some dark edges from over preening. And some normal feathers in this picture. I got him 2 months ago from pet store and he was stress over preening, he has molted a few feathers and seems to leaving them alone, but I won't know till spring molt..
