Milestone of India - The mystery of the Colour-changing hen . (Keraka - India.)

Thiruvananthapuram: What's the colour of your hen? A question as simple as that will leave Selvaraj fumbling for an answer.

The small-time farmer is yet to figure out the real colour of the hen strutting about on the premises of his house at Mukkola near Vizhinjam here.

The six-year-old bird is now a celebrity of sorts for its capacity to change colour periodically from black to white and back. Scientists are studying the hen that has already changed colour four times.

It was after the first egg-laying period that Mr. Selvaraj and family noticed the black hen gradually changing to white without completely shedding its feathers. In about a year, the bird became completely white.

The new white hen continued to lay eggs, and in a year it started turning black. It was then that Mr. Selvaraj decided to inform the Zoology Department of the University of Kerala about the puzzling event.

A team of researchers led by CSIR emeritus scientist, Zoology Department and Centre for Bioinformatics, Dr. Oommen V. Oommen, examined the hen in 2008. The team included R. Dileep Kumar, K. Ramachandran and L. Divya. They tagged the bird and collected blood samples for investigation, and continued to observe the hen that was superficially black with patches of white underneath.

The bird turned black and white in 2009 and almost white in 2010. The blood samples collected in 2008, 2009 and 2010 were analysed for several hormones, including estrogen (female sex hormone). The team also consulted Chandana Haldar from the Benares Hindu University and other scientists.

The colour change in the bird was found to coincide with an abnormal increase in the level of estrogen, peaking at almost six times more than normal for a hen. An experiment conducted by Professor Thapliyal (Dr. Oommen's mentor) of the BHU in the 1960s had established that estrogen can inhibit pigmentation in females.

Though it is natural of high concentration estrogen to inhibit the colour pigmentation process to turn the bird's black plumage to white, the reversal process remains a mystery to scientists. “It will require detailed genetic studies to unravel the science of this recurrent colour change,” Dr. Oommen said.