This is not urgent, but I have been curious. I notice that sometimes my chickens combs will turn bluish purple on only parts. Sometimes just the back, sometimes just the tips of the points. Sometimes cold days, sometimes warm. Sometimes an older bird, sometimes young (who've never been through a winter--I was thinking frostbite). They're fine, though. I notice sometimes in pictures of showbirds or even pictures in a magazine they'll have this. Anyone know what causes it? Just curious. Laureen