Birds have different coloured feathers because of three things working together: pigments (melanins, carotenoids, porphyrins and psittacofulvins) that absorb some wavelengths of light, microscopic structures inside the feather that scatter light, and genes that control which pigments are made and how those structures grow. Over millions of years, natural selection and sexual selection have shaped these colours for camouflage, attracting mates and recognising each other.
This article explains how birds get their colours, why there is no blue pigment in birds, why some feathers shimmer as you move, why birds can see colours we cannot, and why males and females of the same species often look different. There is a short quiz, a wavelength calculator and a garden checklist along the way.
Why do birds have different coloured feathers? The short answer
Every colour on a bird comes from one of two systems. The first is pigment colour: a chemical in the feather absorbs some wavelengths of light and reflects the rest, and the reflected light is the colour you see. The second is structural colour: tiny structures in the feather, about the same size as the wavelengths of visible light, scatter light so that certain colours are strengthened. Many feathers use both at once.
Genes sit behind both systems. They decide which pigments a bird can make or store, and how the nanostructures in a feather are built as it grows. A tyrosinase mutation, for example, stops a bird making melanin and produces an albino. Later in this article you will meet a single enzyme that decides whether a parrot is red or yellow.
The reason these colours exist is a different question, and it has several answers. A nightjar needs to vanish against bark. A peacock needs to impress a peahen. A house finch uses the brightness of its red feathers to show that it is healthy. Each of these is explored below, after we look at how colour is made.
What a feather is made of
A feather is made of a tough protein called beta-keratin. A typical flight feather has a clear structure, from the thick middle to the finest branches:
- Rachis: the central shaft that runs along the feather.
- Barbs: the many branches that grow out from the rachis.
- Barbules: even smaller branches growing from each barb.
- Barbicels: tiny hooks on the barbules that lock neighbouring barbs together to form a smooth vane.
Colour is built into the barbs and barbules, which is why microscopic structure matters so much for the colour of a bird.
A new feather grows from a follicle in the skin. While it is growing it is called a pin feather, or blood feather. Pigments and structures are laid down during this growth, so once the feather is finished the colour is fixed. A feather cannot switch its colour on and off the way a chameleon can change its skin.
How birds get their colours: absorbing, reflecting and scattering light
White light is a mixture of wavelengths. Visible light runs from about 380 nm (violet) to about 750 nm (red), where 1 nm is a billionth of a metre. Roughly, violet is below 450 nm, blue is 450–495 nm, green 495–570 nm, yellow 570–590 nm, orange 590–620 nm and red 620–750 nm. Anything shorter than 380 nm is ultraviolet, which humans cannot see. If you want to see how mixing wavelengths makes colours, the article on why street lights turn purple is a good companion.
A pigment colours a feather by absorbing some wavelengths. The wavelengths it does not absorb are reflected back to your eye, so the feather looks red, yellow, brown or black depending on which pigment is present. A white feather contains no pigment and reflects all visible light.
Structural colour works differently. The barbs of a blue feather contain a spongy network of keratin and air with features around the size of light waves. Features this small interact with light waves, and the waves that bounce back reinforce each other for some colours and cancel for others. In a Eurasian jay, scientists measured a nanostructure of about 150 nm in blue regions of a feather and a coarser structure of about 200 nm in white regions that reflects a broader spread of wavelengths.
| Pigment colour | Structural colour | |
|---|---|---|
| Where it comes from | Chemicals that absorb some wavelengths | Nanostructures of keratin, air and sometimes melanin that scatter light |
| Changes with viewing angle? | No | Not for matt blues; yes for iridescent colours |
| Looks the same in shade? | Yes | Often duller, and may look grey if light passes through |
| Examples | Flamingo pink, crow black, cardinal red | Kingfisher blue, peacock sheen, starling gloss |
Try applying this idea to a famous puzzle before you read on.
A blue jay feather looks grey when you hold it up to a window but blue when light shines on it. Explain why. (2 marks)
The blue is structural colour, so it only appears when light is scattered back from the feather towards your eye. When light passes through the feather you see only the dark melanin in it, which looks grey-brown. There is no blue pigment to colour the transmitted light.
So how do the pigments themselves work, and which birds use which? That is the subject of the next section.
Bird feather pigments: the four chemical colours
Four groups of pigment are found in bird feathers: melanins (the most common), carotenoids (also common), porphyrins (rare) and psittacofulvins (found only in parrots). Between them they explain blacks, browns, greys, reds, oranges, yellows and, in a few unusual cases, greens. A crucial difference is where each pigment comes from. Birds make some of them in their own bodies, but one group can only be eaten.
Melanins: blacks, browns and greys
Melanins are made by the bird itself and are stored in tiny packages inside the feather called melanosomes. There are two main kinds. Eumelanin produces black, dark brown and grey. Phaeomelanin produces reddish-brown shades such as chestnut and buff. Many owls, nightjars and cuckoos come in both grey and brown forms, depending on which melanin they deposit.
White feathers are different, because they contain no melanin and no carotenoid at all. They look white because they reflect all visible light. That makes pigment loss easy to spot when something goes wrong with it:
- Albinism means no melanin is made. It is caused by a mutation that blocks an enzyme called tyrosinase. Our article on the albino peacock shows what this looks like in a bird that is usually famous for its colour.
- Leucism means pigment is lost from the feathers, but the bird keeps melanin in its eyes and skin.
- Melanism is the opposite: excess melanin gives a bird black feathers.
Albinism removes melanin, not carotenoids, so an albino red-winged blackbird can still show its red and yellow patches. For more on this condition across the animal kingdom, see all about albino animals.
Carotenoids: reds, oranges and yellows from food
Carotenoids give birds their reds, oranges and yellows. Unlike melanins, birds cannot make them. They have to be eaten, usually from plants such as seeds, fruits, flowers and roots, or from animals that have eaten those plants. The bird then deposits the pigment into its feathers while they grow.
A northern cardinal gets its red from carotenoids in its food, including dogwood berries. If a caged cardinal is fed seed that contains no carotenoids, it loses its brilliance over successive moults. The American goldfinch gets its yellow from carotenoids in its plant diet in the same way. What birds eat really does show up in their feathers, which is one reason the article on what birds eat is worth a look.
Eating green plants does not turn a bird green. The chlorophyll that makes leaves green is not passed into feathers. Green feathers have a different explanation, covered later in this article.
Why are flamingos pink? This is the classic carotenoid example. A pigment in their food gives flamingos their flamboyant pink feathers, and the food includes algae and shrimp. Flamingos and roseate spoonbills get their carotenoids from brine shrimp that have themselves eaten algae. Flamingo chicks hatch covered in white down and take several years, and several moults, to become pink. You can read more in our article about flamingo birds.
Carotenoid colour can also be an honest signal of health. In wild male house finches, birds that ate food with more carotenoids grew brighter red plumage. Carotenoid colour is affected by parasites and nutrition, so a bright bird is advertising that it is in good condition. Females in many birds and fishes use this colour when choosing a mate.
Porphyrins: the turaco’s copper pigments
Porphyrins are rare in feathers. The best example is the turaco family, a group of birds called Musophagidae. Their red wing feathers contain turacin, a red pigment that is about 6% copper bound to a molecule called uroporphyrin III. It was discovered by Arthur Herbert Church in 1869. An old belief says that turacin washes out in the rain, but that only happens if the water is very alkaline.
Many turacos are also green, and for a change this green is a real pigment. Turacoverdin, a related copper porphyrin, makes their feathers bright green. That is unusual, because in most other birds green comes from a combination of yellow pigment and structure, which we look at in the next section.
Psittacofulvins: parrots make their own
Parrots use a family of pigments found in no other birds, called psittacofulvins. Parrots make these themselves: they do not rely on what they get from their diet. A parrot’s food does not control its plumage colour.
In 2024 a paper in Science explained how a parrot switches between red and yellow. An enzyme called ALDH3A2 turns the red psittacofulvin into the yellow form. Researchers, including Roberto Arbore and Joe Corbo, studied this in the dusky lory (Pseudeos fuscata) from New Guinea, and confirmed it in the rosy-faced lovebird. One enzyme, in other words, can change a bird from red to yellow.
Bird pigments compared
| Pigment | Colours | Made by the bird or eaten? | Example birds |
|---|---|---|---|
| Melanins | Black, dark brown, grey, reddish-brown | Made by the bird | Crows, nightjars |
| Carotenoids | Red, orange, yellow | Eaten | Flamingos, cardinals, goldfinches |
| Porphyrins | Red (turacin), green (turacoverdin) | Made by the bird | Turacos |
| Psittacofulvins | Red, yellow | Made by the bird | Parrots |
Test what you have learned. Which pigment explains each of these birds? Tap a card to flip it.
Pigments cannot explain everything, though. Look at a kingfisher and you will find that its blue is not a pigment at all.
Structural colour: why blue birds have no blue pigment
Here is one of the best surprises in biology: no pigment makes bird feathers blue. Birds can make or eat reds, yellows, browns and blacks, but there is no blue pigment in feathers. Every blue jay, kingfisher and macaw is blue because of how its feathers are built.
Inside the barbs of a blue feather is a spongy, irregular network of beta-keratin and air. This nanostructure scatters light in a coherent way, which means the waves bouncing back from different parts of the network reinforce one another for blue wavelengths while other colours are weakened. The same kind of structure, with different dimensions, also produces white. In the Eurasian jay, blue regions have a nanostructure of about 150 nm, while white regions have a coarser one of about 200 nm that reflects a broader spread of wavelengths.
These structures are not carved by the bird. Studies of the blue feathers of the blue-and-yellow macaw show that they assemble themselves inside the cells as the keratin separates from the cell fluid, by a process called phase separation, a little like oil separating from water. That makes structural colour another gift of chemistry and physics, controlled by genes.
The common kingfisher is the standard British example. The RSPB notes that a kingfisher’s feathers contain no blue pigment: they are really a dull brown, and the blue comes from tiny structures that scatter light. Remember the blue jay question from earlier. Hold up a blue feather against the light and the scattered blue disappears, leaving only the grey-brown pigment behind.
How green feathers are made
If blue is structural, what about green? In most birds green is a mixture: yellow pigment laid over a blue structural colour. The budgerigar is a tidy example, because it has only black and yellow pigments. White means no pigment, yellow means yellow pigment, blue means structure (with melanin underneath) and green means yellow pigment over blue structure.
The exception is the turaco, which, as described earlier, makes a real green pigment called turacoverdin. Everywhere else, green is a colour made by two systems working together.
Iridescent feathers: colours that change as you move
Pigment colours stay the same whichever way you look at them. Iridescent colours do not. Turn a peacock feather, a grackle or a hummingbird’s throat and the colour shifts. This comes from ordered, layered arrays in the barbules, often made of melanin granules and air. Light waves reflected from the different layers interfere with one another, so each viewing angle reinforces a different wavelength. Iridescent birds look their shiniest in bright sunlight.
The peacock’s coloured barbules contain a two-dimensional photonic crystal: rods of melanin separated by channels of air in the keratin. Changing the spacing of this lattice produces the different colours, and fewer layers give mixed colours. Starlings use layers too. In starlings such as the superb starling, iridescent blue feathers contain hollow, flattened eumelanin melanosomes, while non-iridescent red feathers contain solid ones. Even a black pigment, arranged in precisely the right way, can create a rainbow.
Can birds see ultraviolet? How bird vision changes the picture
Humans have three types of colour-sensitive cone cell in the eye. Birds have four, and the extra one is tuned to ultraviolet or violet light, depending on the species. For a bird, a feather can therefore have a colour pattern that we cannot see at all.
The most striking evidence comes from wild broad-tailed hummingbirds in Colorado. Researchers ran 19 experiments over three summers, with more than 6,000 visits to feeders, and found that the birds could tell apart nonspectral colours, such as ultraviolet plus green versus pure green, and ultraviolet plus red mixes. Purple is our own example of a nonspectral colour: no single wavelength of light looks purple, so our brains build it from red and blue light. The team also analysed 3,315 feather and plant colours and concluded that birds probably see many colours as nonspectral that humans do not. The experiments used feeders, and our guide to hummingbird feeders explains more about them.
A familiar garden bird shows this well. The blue tit’s crown reflects most strongly at about 352 nm, in the ultraviolet. Males and females differ in several areas of plumage, including the crown, in ways people cannot see. In laboratory choice trials, females preferred males with the brightest crests.
Try the calculator at 352 nm, the blue tit’s crown peak. The calculator calls this “ultraviolet (invisible)”, but invisible here means invisible to humans: a blue tit’s fourth cone can detect it. Then try 450 nm, which is blue and which both of us can see, and compare the photon energies. The shorter ultraviolet wavelength carries more energy per photon.
Male and female blue tits look the same to us, but not to each other. Suggest why. (2 marks)
Their crowns reflect ultraviolet light at about 352 nm, which a bird’s fourth cone cell can detect but human eyes cannot. Males and females differ in how much ultraviolet they reflect, so they look different to another blue tit.
All this raises an obvious question. If birds can see, and sometimes choose by, colours we miss, why did such a range of plumage evolve in the first place? That question is next.
How feather colours help birds survive
Feather colours do four main jobs: they hide a bird, attract a mate, help birds recognise and signal to each other, and advertise a bird’s condition. We have already seen the last one, in house finches whose red carotenoid feathers reflect their diet and health.
Camouflage
The European nightjar is a master of disguise. The RSPB describes its grey and brown mottled, streaked and barred feathers as creating the perfect illusion of bark. It relies on camouflage and staying still by day, and feeds at dusk and dawn. In the UK it is a summer visitor, arriving from late April to May on heathland, moorland and in clearings, and it winters in Africa.
The ptarmigan shows seasonal camouflage. In winter it becomes totally white, except for its tail and eye-patch, which remain black. In the UK it breeds on the highest mountains of the Scottish Highlands. Remember the myth earlier in this article: the ptarmigan does not recolour its old feathers. It grows new white ones in a moult.
To explore this idea in more depth, read what camouflage is in biology and adaptations seen in plants and animals. Camouflage also featured in a famous Victorian argument. Alfred Russel Wallace argued that the dull plumage of females evolved as camouflage while they sat on a nest.
Sexual selection: Darwin’s peacock problem
Charles Darwin struggled to explain the peacock’s elaborate train by natural selection alone. In The Descent of Man, and Selection in Relation to Sex (1871), he proposed that sexual selection has two parts: competition between males, often using weapons, and female choice “according to their standard of beauty”. In a letter to Asa Gray on 3 April 1860, he wrote that “the sight of a feather in a peacock’s tail, whenever I gaze on it, makes me sick!” Darwin accepted that protective coloration matters too, but he kept stressing sexual selection.
The peacock’s famous “tail” is really a train of elongated upper tail coverts, not the true tail. Its blue and green come from microstructure, not coloured pigment. The cocks shed train feathers from late July and regrow them by about February or March. The peahen is mainly brown.
What exactly do peahens choose? A 2011 study of feral peacocks found that adult males had a consistent maximum of about 165–170 eyespots, and that natural variation in eyespot number did not explain mating success. Removing 20 or more of the outer eyespots did lower success, but that is an unnatural reduction. Eye-tracking has shown that peahens mostly look at the lower train during close courtship, and largely ignore the head, crest and upper train. Train-rattling and wing-shaking held their attention. The picture is more complicated than “more eyespots wins”. For birds that stay together for years, see birds that mate for life.
Why birds of the same species look different
Birds of the same species can look very different because of sex, season and age.
The mallard is the textbook case of sexual dimorphism, where males and females differ. The drake has a dark green head, a yellow bill and a grey body. The duck is mottled brown with an orange bill. Both have a purple-blue wing flash.
Season matters too. Moult usually happens once a year in birds, though some species moult twice, which can change colour for mate choice (sexual selection) or camouflage (natural selection). The American goldfinch is the only cardueline finch that moults twice a year. After its spring moult the male is brilliant lemon yellow with a jet-black cap. After the autumn moult it is dull olive-brown and buff, and the sexes look nearly alike. Many male ducks moult into a dull “eclipse” plumage after breeding in mid-summer, shedding all their flight feathers at once and becoming briefly flightless.
Age matters as well. Male and female European robins look identical, but juveniles have no red breast and are speckled brown.
Genes underlie all these patterns, from the pigments a bird can make to the layers in its barbules. If you want the basics, read our guide to genetics, DNA, RNA, mitosis and meiosis. Even extinct animals show the same chemistry. Melanosomes are preserved in the fossil feathers of early birds and in the filaments of non-avian dinosaurs, and the dark tail stripes of the dinosaur Sinosauropteryx were probably chestnut to reddish-brown. Our article on what birds and dinosaurs have in common explores the link.
Garden colour detective
Next time you are outdoors, see how many of these you can spot. Ticks are remembered in your browser.
- A blue tit’s blue cap: structural blue that also reflects ultraviolet
- A starling’s glossy sheen that shifts as it turns: iridescence
- A mallard drake and duck side by side: sexual dimorphism
- A speckled brown young robin with no red breast yet
- A kingfisher by a river or lake: blue with no blue pigment
Frequently asked questions about bird feather colours
Why do birds have different coloured feathers?
Birds have different coloured feathers because of pigments such as melanins and carotenoids, nanostructures that scatter light, and genes that control both. These colours evolved for camouflage, attracting mates and recognising other birds. Many feathers combine pigment and structure to make their final colour.
How do birds get their colours?
Birds get colours in two ways. Pigments absorb some wavelengths of light and reflect the rest, while microscopic structures in the barbs and barbules scatter light to make blues and iridescence. The colour is laid down as the feather grows, so it is fixed until the next moult.
Why are there no blue pigments in birds?
No pigment makes feathers blue. Blue comes from a spongy nanostructure of keratin and air inside the barbs, which scatters blue wavelengths strongly. A kingfisher’s feathers are really dull brown, and a blue jay feather looks grey when light shines through it instead of reflecting off it.
Why are flamingos pink?
Flamingos are pink because of carotenoid pigments in their food, which includes algae and brine shrimp. Birds cannot make carotenoids themselves. Chicks hatch with white down and take several years and moults to become pink, and captive flamingos fade without carotenoid supplements.
Why are male birds often more colourful than females?
In many species females choose their mates, and Darwin proposed that this sexual selection favoured showy males. Females, meanwhile, are often drab, which Wallace argued is camouflage while nesting. It is not universal: male and female robins look identical, for example.
Can birds see colours that humans cannot?
Yes. Humans have three types of colour cone, but birds have four, and the extra one detects ultraviolet or violet light depending on the species. Blue tit crowns, for instance, reflect most strongly at about 352 nm, in the ultraviolet, which people cannot see.
Why do peacock feathers change colour when they move?
Peacock feathers are iridescent. Their barbules contain a two-dimensional photonic crystal of melanin rods and air channels in keratin, and light reflecting from it reinforces different wavelengths at different angles. Because the colour comes from structure, not pigment, it shifts as you or the feather move.
How do parrots get such bright red and yellow feathers?
Parrots make their own pigments called psittacofulvins, found only in parrots, so their diet does not control their colour. An enzyme called ALDH3A2 turns the red form into the yellow form, as shown in a 2024 study of the dusky lory.
Do birds change colour in winter?
Some do, but not by changing the colour of existing feathers. They moult into new ones. A rock ptarmigan grows white feathers for winter, while the American goldfinch moults from lemon yellow to dull olive-brown in autumn. Many male ducks also moult into a dull eclipse plumage after breeding.
What is the difference between an albino and a leucistic bird?
An albino bird makes no melanin because a mutation blocks the enzyme tyrosinase. A leucistic bird loses pigment from its feathers but keeps melanin in its eyes and skin. Albinism removes melanin only, so an albino can still show carotenoid colours.
