On an Indian grassland, a herd of blackbucks can look almost as though two different animals have gathered in the same place.

The females move through the grass in shades of pale brown and fawn. Young males look much the same. Then, one male begins to change. The colour around his neck and shoulders deepens. Dark streaks appear along his sides. His back grows darker, until the animal that once blended into the grass develops the unmistakable black-and-white coat that gives the species its name.

He was not born black.

This transformation is one of the most striking examples of sexual dimorphism in India's wildlife — physical differences that develop between males and females of the same species. In the blackbuck (Antilope cervicapra), males gradually develop a dark brown to black upper coat as they mature, while females retain their fawn colouring.

So, what happens beneath that changing coat?

The black comes with growing up

A blackbuck fawn begins life with a light, yellowish-fawn coat. For much of its early life, a young male may look little different from a female.

A 2009 study conducted at Mahendra Chaudhary Zoological Park in Chhatbir observed fawns and documented changes in their coat colour. Researchers found that the transition in males was gradual. Darker hair first appeared around the neck and shoulders before spreading across the back and along the darker streaks on the sides.

The study reported that young males began developing their darker coat at around three years of age.

This timing is significant because it coincides with the animal's transition towards sexual maturity.

The........

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