Billy built a circular summerhouse, which became known as Gran's cage, and in this the old lady sat with her knitting, while Tara prowled free outside

At Tiger Haven, on the border of India and Nepal, they will be celebrating Christmas much as we are. Billy Arjan Singh - big cat specialist extraordinary - is a bachelor, but his tribe has gathered at his white house on the edge of the jungle, and because the family has English connections, proceedings strike a strongly western note.

A blazing log fire in the sitting room will banish the chill of the Indian winter: a tree will be decorated, and Father Christmas, in full regalia, and fortified by a peg or two of whisky, will distribute presents to the children after carols and supper. One notable absentee will be the traditional dish of roast peacock, for the birds are now protected - and perhaps it is just as well that goose will fill the bill, because Billy's tame peacock Tom Dooley, which struts about outside, might take a dim view of any reversion to barbaric customs.

My thoughts were sent winging to Tiger Haven by a television programme about John Aspinall's attempts to reintroduce gorillas to the rain forest of Central Africa. The experiment - as courageous as it was expensive - ended in partial success. Three of the six animals released succumbed to disease brought on by stress, but the others took to the forest eagerly and, when last filmed, were doing well. Yet at the end of the programme came a chilling statistic - that during the time the film was being made, at least 900 other gorillas had been killed.

There is a close parallel between Aspinall's work with apes and that done by Arjan Singh with Tara, a tigress, during the 1970s. At a time when India's stock of tigers had sunk to its lowest ebb, Billy imported a cub from England and brought it up in and around his house, determined to prove that when the animal grew to maturity, its inbred instincts would assert themselves, and it would take to the jungle.

Before that happened, certain problems presented themselves. One was that Billy's mother became scared of this immense cat, which soon weighed 300lbs. To calm her nerves, Billy built her a circular summerhouse thatched with straw, which became known as Gran's Cage, and in this the old lady sat with her knitting, while Tara prowled free outside.

In time Billy's predictions were proved triumphantly right. At the age of three Tara vanished into the forest, never returned, and during a full life bore four litters of cubs to wild males. Yet the experiment made Billy many enemies. Hidebound conservationists accused him of polluting the local strain of Bengal tiger with a "genetic cocktail" - to which he replied that he could imagine nothing better than the infusion of vigorous new genes. He was much excited by the recent appearance of a tiger with distinctly Siberian markings, and it now seems that Tara may have carried echoes of that sub-species in her make-up.

A more sinister accusation was that she had turned man-eater. During the 1970s and 1980s an outbreak of man-eating spread through the district, Kheri. More than 100 humans were killed. Again and again people said, "It's that bloody tiger of yours. Because it was brought up with humans, it has no fear of them."

Being a volunteer wildlife warden, Billy was repeatedly called out to shoot tigers summarily convicted of murder. Always he went with a heavy heart, dreading that the culprit might be Tara. It never was, and she lived on to the age of 14 before - so far as he knew - dying a natural death.

But the moral of the story is exactly that of the gorillas. No matter how much ingenuity, money and love a man may spend in attempts at reintroduction, the real villain is the human raceand its insatiable demand for land.

In India, as in Africa, the ultimate problem for wildlife is not poaching, but shortage of space. The man-eating broke out in Kheri because humans infiltrated the reserves officially set aside for tigers. In Africa the gorillas' habitat is similarly being eaten away.So if Billy Arjan Singh should hear the deep Aa-oum! of a tiger boom out from behind the house on Christmas morning, it will be a present more precious than anything the Magi could have brought him.