Sixteen of the world’s smallest and rarest pigs will take their first tentative steps in the wild today after the species was rescued from the brink of extinction.

The pygmy hog (Porcula salvanius), once common in India, Nepal and Bhutan, was thought extinct in the 1960s after years passed without a sighting of the mammal, which stands up to 30cm high and weighs a maximum of nine kilogrammes (20lb).

In 1971 four were rescued from a market in the state of Assam, in the north of India, a discovery that alerted the world to a further handful surviving in the region's tea gardens. After a 13-year captive breeding programme led by Durrell Wildlife, the Jersey-based conservation centre founded by the author Gerald Durrell, the descendents of those surviving hogs are being reintroduced to their natural habit at the foot of the Himalayas.

For the past couple of days conservationists have been making final preparations for the release of three pig families in the Gelgeli grasslands of Sonai Rupai Wildlife Sanctuary in Assam, a move that will boost a wild population that may have sunk as low as 100.

When released the animals will be at the mercy of their natural predators - chiefly pythons and Asiatic wild dogs - for the first time in their lives. By far the greatest danger, however, will come from man. The tall grasses favoured by the pygmy pigs thrive in alluvial rich soils that attract farmers. Human encroachment, livestock grazing and grass burning were the key causes of the species' dramatic decline, conservationists say.

“By far the main threat will be conflicts with the local community,” Andrew Terry, conservation manager for the Durrell Wildlife Conservation Trust, said. “We have been educating the local population on how to live with the hogs - how to manage grass burning where it's necessary and also on how such methods mean short-term gains in return for a long-term problem.”

Early signs bode well for the pigs' prospects. The 16 hogs due to return to the wild - taken from a captive population of only 79 - have been kept in large pre-release enclosures that replicate their natural habitat for the past five months and have become progressively shyer, their keepers say. “Up to release date, the hogs have shown naturalistic behaviour and an aversion to human contact, which is a positive sign that they will fair well when released,” the project said in its latest update.

Those behind the pygmy hogs' rehabilitation say that what is good for the world's smallest pig has implications for much larger animals, including Assam's rhino population. “The pygmy hog is an important indicator for the state of the tallgrass habitat, which is crucial for the survival of a number of other endangered species such as the swamp deer, wild buffalo, hispid hare and Bengal florican,” Mr Terry said.

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