Molting Undeveloped Feathers

[Michael]

Does anyone know what causes new growing blood feathers to fall out before they even reach full size? A few times I spot under developed feathers that were recently growing in entirely shed at the bottom of the cage. It's just the occasional feather but it's surprising to see it molt before it has even grown in entirely. Is this any kind of sign of health issues or just some anomaly that happens from time to time?

[escouve]

It's happened with my red-rumped parrot after a nightmare: he wakes me up and he's significantly less fluffy, with the loss of blood feathers too.

I know that guinea fowls (try to) escape predators by spontaneously shedding, making them 'slippery' - and I've been wondering for ages whether parrots have a similar strategy. Have you noticed any kind of environmental trigger?

If not, it might be a skin problem??? Any signs of irritation or parasites?