Older chickens getting white feathers - why?

[RAREROO]

I'm pretty sure its quiet common for black breeds especially to start turninig white when they get older, I 've heard of it before and I have a Black Swedish duck hen that in her first year, she was black with just the white bib under her throat, and now, most of her neck, black and underside is white, she just keeps getting whiter each time she molts.

 

[americana-chick]

One of my RIR hens was completely dark red and then all of the sudden when she lost a feather she would grow a white one back. It did look pretty cool.. but thankfully when she molted next time her original color came back, and this time it was even better

 

[swedishfish]

I understand your theory though SteveH! Sometimes when a horse gets a cut, the scar will grow in with lighter hair. My horse has a few white hairs just from old age, so I guess that would make sense that that's what would happen to chickens too.
I must admit it looks pretty awesome.