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The "churkey" owes its distinctive look to a complex genetic mutation, according to scientists.

Experts at Edinburgh University set out to discover how the Transylvanian naked neck chicken came by its appearance.

The bird, which has also been dubbed the turken, has the neck of a turkey and the body of a chicken.

The scientists said the effects of the genetic mutation were enhanced by a vitamin A-derived substance produced around the bird's neck.

This causes a protein, BMP12, to be produced, suppressing feather growth and causing the bird to have its bald neck, according to researchers at the Roslin Institute at Edinburgh University.

The team said the findings could help poultry production in hot countries because chickens with naked necks were better equipped to withstand the heat.

They also have implications for understanding how birds, including vultures, evolved to have featherless necks.

Transylvanian naked neck chickens, which are thought to have originated from the north of Romania, were introduced to Britain in the 1920s.

Researchers analysed DNA samples from naked neck chickens in Mexico, France and Hungary to find the genetic mutation.

Skin samples from embryonic chickens were also analysed using complex mathematical modelling.

Dr Denis Headon, who led the research, said: "Not only does this 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."

The research, published in the journal PLoS, was funded by the Biotechnology and Biological Sciences Research Council.