How do birds get their colour?
A question many of us have asked ourselves at some point in time: How do birds get their colour? Bushwise trainer Wayne Lubbe brings his expertise to explain why we see those vibrant colours.
Feathers have made it possible for birds to take to the air efficiently and successfully, enabling species to spread globally. The colour of certain birds has captivated us adding a bit of colour to our daily lives. And it’s not only people who can appreciate these colours. Birds can see in colour too – some birds can even see into the ultraviolet spectrum. This is why colour is incredibly important for birds as it allows them to seek out specific food or to attract a suitable mate.
Feathers are quite unique in terms of their colour, shape, density and structure, and have developed to insulate, camouflage and protect a bird from the many elements of their environments.
For example, not all birds are brightly coloured; many ground nesting birds – such as korhaans, francolins and spurfowls – have evolved cryptically camouflaged feather patterns that help them blend in with their shrub and bushy environment.
There are two main ingredients that are essential in the making of colour. The first is pigment – of which there are three main types – and the second is keratin.
The first pigment is called melanin, and it produces black, deep brown or grey colours. Melanin is also extraordinarily strong and is thus often reserved for the flight feathers. White feathers are caused by a lack of pigmentation and are much weaker than black feathers due to the lack of melanin. This might explain why many predominantly white bird species have entirely black or black-tipped feathers in their wings such as with the southern pied babblers. The wing feathers are exposed to the greatest wear and are required to be stronger than regular feathers.
The second group of pigments are called carotenoids. Carotenoids are the pigments found in vegetables – such as carrots and corn – and produce red, orange and yellow feathers. Carotenoids are produced by plants, so when birds ingest either plant matter or something that has eaten a plant, they also ingest the carotenoids that circulate through the bloodstream and to the feather follicles producing the colours in their feathers. The pink colour of flamingos, for example, is derived from carotenoids found in the crustaceans and algae that the birds feed on in the water.
The third group of pigments is known as unique pigments, as they are found in only a handful of bird species. For example, the red pigment (often called turacin) is found in many turaco species and the green pigment (turacoverdin) is found in many of the same turaco species such as the Knysna or purple-crested turaco.
The other main ingredient in making colours is keratin, which is the tough protein of which feathers are made (like our hair and fingernails) It also covers birds’ bills, feet and legs. Keratin is responsible for the iridescent colouring of many bird species. The brilliant colours tend to change depending on the bird’s orientation to sunlight. The colour of these feathers is not a result of pigments, but rather the reflection and refraction of coloured wavelengths of light. When the bird or the observer moves it appears as though the colour changes, which is due to the angle of the reflection changing.
Keratin produces colour in two main ways: by layering and by scattering. Layering colours are produced when translucent keratin reflects short wavelengths of colours like blues, violets, purples and greens. The other colours are absorbed by an underlying melanin (black) layer. The ways in which the keratin of the feathers is layered will dictate the colour of the iridescence. Examples of layered colouring include the iridescence of glossy starlings, glossy ibis and the wing patches of many duck species.
Scattering is produced when the keratin of feathers is combined with tiny air pockets within the structure of the feathers themselves. These air pockets and the dispersed keratin scatter blue and green light and produce the shimmering colours of birds like kingfishers, rollers and bee-eaters.
Flock to the next Bushwise course to learn even more about birds and other animals. If you have a passion for nature and wildlife, you have a home with Bushwise. Apply today!