"white" American robin
grrlscientist | September 12, 2007tags: birds, "white" American Robin, Turdus migratorius, Image of the Day
"White" American Robin, Turdus migratorius, on a sidewalk in Casper, Wyoming.
Image: Norma Brown. [wallpaper size].
I am going to speculate here, but I think that, because this bird is pale colored everywhere it would normally be brown, grey or black, this bird's melanin-producing gene(s) have been deactivated. However, because the bird's breast is red, as is typical for this species, carotenoids (red pigments obtained from the bird's diet) are still being added to the bird's feathers when they are growing, as normal…