Two different studies aimed to understand why birds have red colored feathers in their body. This is a mystery that has revolved bird watchers and scientists for several years. Both of the investigations, held separately, discovered the gene that allows red coloration.

The red color is commonly associated with energy, passion and action thanks to the warm it transmits. In color psychology, red is associated with human physical needs and with the will to survive. It’s energizing and excites emotions.

Birds' red color
Two recent studies, held separately, found the gene that allows red coloration in birds. Credit:

In the animal world, the color is associated with attraction to possible mates and rivals. Yet, researchers have wondered what causes the pigmentation on the bird world.

Two different investigations have discovered birds change yellow pigments from their diet into red pigments. The color could also be a sign of good health and diet in birds, meaning that when a bird is redder is a better mate.

One study was looking for loss-of-function in the mutation of the birds, meaning the red pigment to the yellow pigment. While the other investigation was looking for gain-of-function-mutation, which would be the red pigmentation gene.

Both of the investigations can be found published in the Current Biology Journal website.

Red pigment in different species of birds

The first investigation was held by Miguel Carneiro from the Universidade do Porto in Portugal along with a team of researchers who discovered that the red pigment is produced by birds when eating yellow dietary pigments, called carotenoids, to transform them into red pigments in their feathers.

Carneiro’s research explains that the red pigment is also found in their paws and eyes. Birds transform these pigments in order to better their color vision with the pigment on the photoreceptor of the retina.

The origins of the investigation started when the team studied data from the 1920s, when bird fanciers crossed common yellow canaries with a red South American bird that had “ketocarotenoid” pigmented feathers.

The crossing resulted in a red pigmented common canary or a hybrid bird, creating multiple generations and mutations of the genes. Investigators wanted to understand which gene in the birds’ DNA was responsible for the pigmentation.

The team performed genome sequences of the birds’ DNA generating 1.5 billion sequence reads to understand the canary genome and identify the pigmented gene. Researchers discovered a cytochrome p450 enzyme, which is the responsible for the red pigmentation on birds feathers and bodies.

“Birds cannot synthesize these red pigments endogenously, they have to obtain them from their diet. It was known for a long time that an enzymatic conversion is needed to produce the red pigments, so many groups of geneticists and physiologists have tried to identify the enzyme for decades,” said Dr. Miguel Carneiro from the Universidade do Porto in Portugal to BBC News.

The finding of the “cytochrome p450” enzyme on Dr. Carneiro’s investigation came at the same time a team from the University of Cambridge in the UK discovered the exact same gene.

Red pigment and detoxification

Nick Mundy from the University of Cambridge in the United Kingdom along with a team of researchers wanted to understand the cause of red pigmentation, just like Dr. Carneiro’s investigation.

Mundy’s research team focused on the variety of pigmentations across the avian species and the importance of the red pigmentation in bird mating and health.

The team held a series of investigations comparing DNA from zebra finches, a type of birds with yellow dots on their feathers with red breaks across their body. Discovering that the species had cytochrome p450 genes in their DNA.

While studying the p450 gene the team discovered it also plays a relevant role when it comes to detoxification in the bird’s systems.

“Our results link a detoxification gene to carotenoid metabolism, this may shed new light on the debated honesty of carotenoid-based signals,” said Staffan Andersson co-author of the study.

The discovered gene p450 belongs to a wider family that helps with detoxification in the bird’s body, meaning that the redder the bird is the higher its health is, as well as the mate’s qualities.

The team also found that the family of cytochrome p450s work as the same way as the human system metabolizes drugs.

Common findings

Even though investigations were held separately in different places and in different manners it has greater implications in the science world.

“The fact that we identified the same gene in two deeply divergent species suggests that this is likely to be very general in the bird world and many species will use the same mechanism to produce red pigments,” said Dr. Carneiro to the BBC.

Both of the investigations findings complement each other and give a wider answer to the red pigmentation question in the scientific world.

Source: Current Biology