Common Green Magpie

Green magpies are a beautiful mid-sized songbird in the family Corvidae. The striking emerald green coloration of most of its body plumage is the result of yellow carotenoid pigments from dietary sources combined with the blue that is due to structural arrangement of the keratin in its feathers. Over time, in life and in museum drawers, the yellow pigment fades or wears away. Thus older feathers look turquoise blue. These birds have a bright orange-red bill, somewhat heavier than other corvids, and a strong black facial mask. Flight feathers are chestnut with faint barring. Bold white tips on black feathers decorate the tertiaries and underside of the tail. Green magpies are native to southeast Asia.

A cross section of the rami from head feathers in this species (Hudon 2005) shows a basal layer of dark melanin around the medulla, surrounded by a wider layer (described as a "homogenous cloudy cell"). Interference of light through this cloudy layer, when backed by the dark pigment, results in the blue that we can see. When feathers are green, they have a thin layer of yellow pigment in the cortex outside of the cloudy cell layer. Blue feathers lack pigment in the cortex layer. Authors have suggested that the yellow pigment wears away, so that the bird turns blue over time. Why are other green birds not prone to this color change? Perhaps the layer of pigment is particularly thin in Cissa species or perhaps there is some other reason why the pigment is more easily lost.