If it hadn’t been cecil that said it, i’d never have believed the shrimp/pink flamingo connection. Because I learned in biology that bird’s feathers were much like hair or fur and even colored with the same pigment - melanin (I think). IIRC, melanin creates different colors in feathers by being arranged in such a way that it refracts light like a prism, giving the appearance of - say red or yellow - when light is bounced off of it.
(Experimentation on my own parrot bears that out. If you look at one of her bright green feathers by lighting it from behind so that the light shines through it (rather than being reflected off it) you find that the feather is “really” brown. Like my hair.)
So somehow in flamingos (and I guess canaries) a pigment other than melanin can get into the feather and change it’s color. Which finally leads me to my question - will this work with my own hair? If I eat the same shrimp can I turn my hair pink? Will too many carrots turn my hair orange? Is that how we get redheads?