The Chicken Hilton and other comments on carotenoids

One of the Cathedral kids -- chest seems to be fading a bit -6/23/06
Photo by Bruce Yolton http://www.urbanhawks.blogs.com

Website correspondent Judy Glattstein sends in her [oblique] contribution to the orange-chest mystery. Chris Lyons adds another thought:

Marie,

When I kept a small flock of backyard chickens (The Chicken Hilton, room rates one egg a day, occupancy: 6) It was easy to tell which hens were laying well. They lose yellow pigment first from their legs, which become progressively paler and paler as pigment is taken from there and deposited in the yolks. Then skin (which can be seen by picking up a bird and gently blowing feathers aside (does that tickle, I wonder?) Free-range chickens who get to eat grass and bugs and stuff have deeper colored yolks than factory birds. And it is my understanding that Mr. Purdue's chickens are fed marigold petals to give a richer color to the packaged chicken pieces skin.

Captive flamingos must be fed shrimp, shells and all, for deep pink feather color. Until zoos discovered this, all their flamingos looked bleached.

regards,
Judy

From Chris Lyons:

While diet is obviously an important factor in
carotenoid accumulation, I've noted from some sources
that some animals with very low carotenoid content in
their diet nonetheless have high carotenoid content in
their tissues--indicating that they are particularly
well-adapted to extract carotenoids from what they
eat.  

Carotenoids are probably more important to some
animals than others, and some animals with
high-carotenoid diets have low carotenoid
accumulation.  So maybe Red-Tails are just very good
at using whatever carotenoids come their way to make
those red tails and those orangey chests.  

I'm not honestly sure if science has even devoted much
attention to this question--to carotenoids in general,
yes--but maybe not to Red-Tails and carotenoids, or
even raptors and carotenoids.  It would take more than
a google search to find out, probably.  Maybe I'll hit
some of the biology databases I can access via the
library, and see if I can find a paper.