The tone of your feathers is a matter of chemistry
The color of the plumage is a differentiating element of the birds, not only between species but also as an element of sexual dimorphism, of the age in certain phases of development, and the health of the individual, the latter can be decisive in the selection of the couple.
Birds have two ways to express the color of their feathers, either through pigments or through the refraction of light. The most common pigments, but not the only ones, are carotenoids, melanins, and porphyrins.
From food to genetic code
Carotenoids are compounds of plant origin, so if a bird has this pigment in its feathers, it means that it has fed on plants that contain it or on animals that had previously ingested it.
Once it has entered your body, it passes into the bloodstream, from where it will reach the dermal follicles.
These pigments are responsible for the yellow, orange, and red colors that some birds have in their feathers. Examples of carotenoids are the pink color of flamingos or the yellow color of the wings of goldfinches.
If they are combined with the melanins, the green color is obtained. Carotenoids also participate in immune processes, are precursors of vitamins, and help control oxidative stress.
Melanins are a large family of pigments, including eumelanin and pheomelanin, generated in melanocytes and genetically encoded.
These types of pigments are responsible for the black, grayish, and tan earth tones that we observe in owls and eagles.
Melanins are also responsible for giving consistency and strength to the feathers. It has been observed that those feathers that are black or brownish in color are stronger than those that lack pigmentation. For this reason, some fishing birds -such as albatrosses or gannets- although they are mostly whitish, have black feather tips, a mechanism to better resist abrasion.
In chickadees, it has been observed how the coloration of its back -more abundant in melanin- wears less than the rest of the feathers. This fact could also explain why the birds that live in the desert, where the sand causes significant abrasion, are of darker shades.
Porphyrins are the pigments responsible for pinks, greens, reds, and browns, and they originate from modified amino acids.
Nanostructures in the animal world
Psittaciformes are typical birds of tropical regions, among which are, example, parrots, cockatoos, and macaws. These birds have a specific pigment known as psittacofulvine, which is responsible for the bright coloration of their feathers and is obtained from specific metabolic pathways in which the structures of carotenoids are modified.
The turacos or musophagids are African birds of striking colors, among which green and purple predominate, and that are due to an exclusive pigment of them known as taurin.
In addition to the pigments, there are some nanostructures that also participate in the coloration of the feathers. Thus, for example, the bald ibis has a singularity in its plumage called iridescence, thanks to which the feathers appear black when observed at a great distance or in low light, while their coloration turns bluish in close proximity or if conditions of light are optimal. In other cases, as in hummingbirds, the barbs of the feathers refract or scatter the light that reaches them and acts as prisms, breaking down the colors.
