Phoebe has had about 5 red neck feathers and a splattering of them on her legs--they were there when I got her at 11 years and her first mom said they started coming in when she was maybe 7-8 years old. I've recently seen that she had one bright red one on her back, hidden by the wing but she was flapping and I noticed it. I've been looking at her today, trying to find her red neck feathers, and they are all gone!
I'll be curious to see if they come back in, or if they have been gradually disappearing. I've recently seen only one, not several around her neck like she had before. I've read several theories, but have never seen anything definitive on why some greys have these.
Was so funny--while I was looking at her and trying to find her red feather, I was asking her where it went and looking all over the floor and cage bottom. She was leaning way over, looking with me, and she seemed so serious about the whole thing.