By Subir Bhaumik
BBC News, Calcutta
Pygmy hogs were thought to have died out in the 1960s (Photos: Dr Goutam Narayan)
The world's smallest and rarest species of wild pig was once believed to be extinct - but it may now be saved thanks to conservation efforts.
The pygmy hog (Porcula salvania) stands barely 25-30 cm (10-12 inches) high and weighs up to 9kg (20lb).
Just a few hundred at most are thought to remain, all of them in India's north-eastern state of Assam.
Over the past decade the pigs have been bred in captivity and the process of releasing them into the wild has begun.
After 12 years of patient conservation effort, which began with six wild pygmy hogs, Assam Forest officials and experts from the Pygmy Hog Conservation Programme (PHCP) have now released 16 hogs into the Sonai Rupai wildlife sanctuary, about 175km (110 miles) north of the state capital, Guwahati.
"This is a great day in the history of animal conservation throughout the world and we are proud of the achievement," Assam's chief wildlife warden MC Malakar said.
Dr Goutam Narayan of Durrell Wildlife and EcoSystems-India is the man credited with the success of the programme.
"The hogs are going through a soft release process. We have kept them in an enclosure in the Sonai Rupai grasslands," he told the BBC.
"After a while, we will open the gates of the enclosures and let them out in the wilds, but will closely monitor them."
Dr Narayan and his team of wildlife experts have achieved their success with support from the Durrell Wildlife Conservation Trust (DWCT), a Jersey-based conservation organisation started by naturalist Gerald Durrell.
"By 1964, the pygmy hog was thought to be extinct with no sightings reported for several years. Then in 1971, four pygmy hogs were recovered from a market in Paneri in north Assam and that gave everyone cause for hope," Dr Narayan said.
He said there could be fewer than 400 pygmy hogs in the world and all of them are in Assam's Manas national park in the foothills of Bhutan.
It was at Manas that six pygmy hogs were captured in 1996 and the conservation programme was started.
Much of the pygmy hogs habitat has been lost to man
"The present 16 animals are the result of the only captive population of the species in the world," Dr Narayan said.
Once out in the wilds, the pygmy hogs will be threatened by pythons and tigers - but their biggest threat is the destruction of their grassland habitats by man.
Experts say the pygmy hogs' preferred grassland habitat across the southern foothills of the Himalayas has been largely gobbled up by human encroachment.
"It's a great loss of habitat," said William Oliver, chairman of the Pigs, Peccaries and Hippos Specialist Group of the International Union for Conservation of Nature.
"Ceaseless population expansion have diminished those habitats to a few isolated fragments and those isolated fragments are susceptible to other forms of disturbance like annual dry season burning and livestock grazing."