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How does a chicken get its feathers?

Researchers have discovered how bird feather patterns form, which has led to some interesting insights.

Have you ever wondered how a chicken gets its feathers? Scientists at The Roslin Institute have set out to answer this question, and compared feather development between birds that fly and those that cannot.

Feathers of birds that can fly are arranged in a highly regular pattern, like tightly packed hexagonal tiles laid out perfectly across a floor. This allows them to have a high density of feathers while being aerodynamic and symmetrical on each side. Flightless birds on the other hand, have feathers that are much less organised in their positions.

Ostrich Feather development patterns on embryo skin
Feather development as viewed down a microscope

How do feathers grow?

Feathers are arranged in clusters called tracts. Feather development begins when embryonic skin cells (which have the potential to become either feather or skin) pack together. The very first feathers to form begin along the middle of the chicken embryo’s back and spread out in a wave in response to chemical signals.

How do chicken feathers form a pattern?

Two theories existed about how chicken feathers form. One theory thought that the cells in the embryo do not move, and chemical signals coordinate the way in which they develop. The other theory states that the cells themselves can move about, and coordinate their own growth by forming clusters.

The truth lies somewhere between the two, where chemical diffusion and cell movement occur together.

Repeated waves of chemical signals and moving cells create a uniform hexagonal pattern of feathers that move out from the back to cover the entire bird.

Do feathers grow the same way in all birds?

The pattern of feather development is different in non-flighted birds like emus and ostriches. In these birds, the evolutionary pressure to grow organised feathers has been lost. Research has shown that both birds lost their ability to fly independently, and they have slightly different feather growth mechanisms. Ostriches lack the chemical wave pattern, which means that their feathers grow in a less organised manner. Meanwhile, emus have a different type of skin cell that cannot organise in the same way. The comparisons done show that both types of bird evolved from a common bird ancestor that could fly, and lost their capability to do so separately. This helps us to understand the complex history and development of birds.

Chicken breed with no feathers on their necks

Something that emus and ostriches have in common, is their adaptation to hot climates and long necks with fewer feathers. Some breeds of chicken also lack feathers on their neck or other areas of the body, which may help them to stay cool.

How can this improve chicken welfare?

Poultry are farmed around the world in a variety of farming systems and weather conditions. In hot climates, chickens can suffer from overheating due to their dense feathering. This can lead to a decrease in productivity in addition to being a welfare concern. Understanding how genes control feather growth could help scientists and chicken breeders produce birds with less dense feathers, that are better adapted to hot conditions.

In the face of global population increase and climate change, combining food production efficiency and animal welfare is becoming increasingly important. Chickens that can better regulate their temperature in hot climates will increase their productivity and welfare.

Not only does this work help our understanding of developmental biology and give insight into how different breeds have evolved, but it could have practical implications for helping poultry production in hot countries, including those in the developing world

Dr Denis HeadonThe Roslin Institute, University of Edinburgh

Further reading

How bird feathers form in wave-like motion

Original publication