Birds are a daily occurrence where ever we live, but have you ever wondered how they have different coloured feathers? And how in the breeding season, some drab brown birds morph into these brightly coloured creatures? I was thinking this the other day and thought I would share my findings with you.
The colours are derived in two general ways, pigments or iridescence. Pigments are chemicals found in the feathers or skin, and can be divided into roughly two groups, cartenoids (the reds, oranges, yellows and subsequent mixes) and the melanin’s (the darker shades of brown through to black), these can then combine to produce any shade you can dream of.
Iridescence means the showing of rainbow like colours, and is a structural mechanism producing the colour changes in certain light and at different angles. The feathers have a substance called keratin that surrounds the feather barbs and which is clear and is made up of crystalline cell structure producing different cell structure and angles. Light of certain wavelengths, usually of the blue shades, is then reflected off these cells producing the subtle variations of colour seen. Variations of colour iridescence can be produced by a combination of both pigment and iridescence producing even more shades and colours.
Turacos are unique all around the world in that they have pigments that are only found in their species. The brilliant red that you see on the Purple Crested Turacos’ wings in flight is found only in turacos, and is called turacin, the green seen in the Livingstones Turacos found in the Eastern Highlands is an uncombined pigment, and the only pure green found in bird feathers. The green seen in other birds is either a result of iridescence or a combination of yellow pigment with melanin.
The change in the plumage for the breeding season is the result of a metabolic pigment production from the normally camouflaged pigment production cells. So once they receive the message that the breeding season is coming round again, the birds body changes the colour message that is sent to the newly growing feathers.
So the next time you are enjoying the flash of bird colour as it flits past your window, remember the complicated process behind it.