Pygmy Hog in Bhutan

The pygmy hog (Porcula salvania) is the smallest member of the family Suidae, with adults reaching only about 25 cm at the shoulder and 8–9 kg in weight. The species is restricted to tall, dense, wet alluvial grasslands of the southern Himalayan foothills and is listed as Critically Endangered on the IUCN Red List. The entire global wild population numbers roughly 250 individuals across reintroduction sites and the source population in Manas National Park in Assam, India.^[1][2]

The species was first scientifically described from the Sikkim terai by the British naturalist Brian Houghton Hodgson in 1847. Its historical range extended along the alluvial belt south of the Himalaya from north-western Uttar Pradesh to central Assam, including the duars of southern Bhutan adjoining what is now Royal Manas National Park. The species is now considered probably extirpated from Bhutan and Nepal, although confirmed survey data from the Bhutanese side of the border are thin.^[1][3]

A 2018 study supported by the Rufford Foundation assessed the potential for pygmy hog occurrence in Royal Manas National Park and Khaling Wildlife Sanctuary, but produced no confirmed sightings. There are no recent confirmed records of the species in Bhutan, and its presence today is best described as historical.^[3]

Historical Bhutanese range

The pygmy hog requires undisturbed tall grassland of the type historically found along the Manas, Aie, Sankosh and Pagladiya river systems where they emerge from the Himalayan foothills onto the Brahmaputra plain. The Bhutanese duars — the strip of low-lying country at the base of the foothills — formed part of this contiguous habitat. References in nineteenth and early twentieth century literature mention pygmy hogs in southern Bhutan, but no specimen or photographic record from Bhutanese territory is held in any public museum collection.^[1][2]

The most plausible Bhutanese habitat lay in the duars adjoining the Indian Manas Tiger Reserve, in what is now Royal Manas National Park, and in the grassland areas of Phipsoo Wildlife Sanctuary on the Sarpang–Dagana border. The 2018 Rufford-funded survey targeted both areas without success, although the difficulty of detecting such a small and secretive animal in tall grass means absence cannot be conclusively proven.^[3]

Causes of decline

The principal cause of the pygmy hog's collapse across its former range is the conversion and degradation of tall alluvial grassland, primarily through clearance for agriculture and tea estates and through dry-season burning of grasslands for grazing or fire-breaks. The species is highly sensitive to grassland height, requiring grass tall enough to conceal individuals from predators and to provide year-round cover. Where grasslands have been replaced by shorter pastures or by arable land the species cannot persist.^[1][2]

Fire in particular is destructive. The pygmy hog builds small thatched nests on the ground for shelter and farrowing, and dry-season burns kill animals directly and destroy the structure of the grassland for several seasons. The Indian source population at Manas survived through the second half of the twentieth century only because of the size and relative inaccessibility of the Manas grasslands.

Conservation programme and Bhutan prospects

The Pygmy Hog Conservation Programme is a partnership between Durrell Wildlife Conservation Trust, Aaranyak, EcoSystems-India, the Wild Pig Specialist Group of the IUCN, and the Assam Forest Department. The programme runs a captive breeding facility at Basistha near Guwahati and has undertaken phased releases into Sonai Rupai Wildlife Sanctuary, Orang National Park, Bornadi Wildlife Sanctuary and Manas National Park since 2008.^[2][4]

Royal Manas National Park is contiguous with Manas National Park across the international border and forms part of a transboundary protected area complex. The two parks have cooperative management arrangements that include joint patrolling and shared species monitoring. Pygmy hog reintroduction into Bhutan would require both restored tall-grassland habitat in the Manas duars and a controlled-burn regime, neither of which is currently in place. Bhutan-specific reintroduction has not been formally proposed, and the species' return to the country is contingent on the source population at Manas first reaching a level of stability that would justify dispersal-driven natural recolonisation across the border.^[2][3]

References

1. Porcula salvania — IUCN Red List of Threatened Species
2. Pygmy Hog Detailed Profile — IUCN Wild Pig Specialist Group
3. Assessing Population Status of Pygmy Hog in Royal Manas National Park and Khaling Wildlife Sanctuary — Rufford Foundation
4. Nine more pygmy hogs return to their historical home in Manas National Park — Durrell Wildlife Conservation Trust
5. Pygmy Hog: Back from the Brink — FAO India case study