Pygmy hog
The pygmy hog (Porcula salvania) is a very small and endangered species of pig and the only species in the genus Porcula. Endemic to India, the pygmy hog is a suid native of the alluvial grasslands in the foothills of the Himalayas, at elevations of up to 300 m (980 ft). Populations of pygmy hogs were once widespread in the tall, dense, wet grasslands in a narrow belt of the southern Himalayan foothills from north-western Uttar Pradesh to Assam, through southern Nepal and North Bengal, and possibly extending into contiguous habitats in southern Bhutan.[3] Due to human encroachment and destruction of the pygmy hogs’ natural habitat, the species was thought to have gone extinct in the early 1960s. However, in 1971, a small pygmy hog population was rediscovered as they were fleeing a fire near the Barnadi Wildlife Sanctuary in Assam. Today, the only known population of pygmy hogs resides in Manas National Park in Assam, India.[3] The population is threatened by livestock grazing, fires and poaching. With an estimated population of less than 250 mature individuals, the pygmy hog is listed as an Endangered species on the IUCN Red List, and conservation efforts such as captive breeding and re-release programs are currently being employed.[2]
Distribution and habitat[edit]
The pygmy hog is endemic to northeast India and was once widespread in the tall, wet grasslands of the Terai from Uttar Pradesh through Nepal to Bangladesh, northern West Bengal and Assam.[8][9][2] The species was dependent on early successional riverine communities which were tall, dense grasslands, commonly referred to as ‘thatchland’. In its most pristine state, this ‘thatchland’ was intermixed with a wide variety of herbaceous plants and early colonizing shrubs and young trees.[3] Although many species of tall grasses dominated these various areas, the most important to the pygmy hog communities were areas which dominated by Saccharum munja, S. spontaneum, S. bengalenis, Themeda villosa, Narenga porphyrocoma, and Imperata cylindrical. Growing up to 1 to 4 m in height, these grass species were maintained by periodic burning, which posed a great threat to the pygmy hog communities. Since these grass species were also commercially important thatching grasses, they were harvested annually, thereby also causing great disruption to the pygmy hog habitat.[3]
The pygmy hog is currently on the verge of extinction. By 2002, the only viable population, consisting of only a few hundred individuals, currently exists in small grassland pockets of Manas National Park in Assam, India, and an adjacent reserve forest in the Manas Tiger Reserve, and nowhere else in the world.[13][14] Today, it is estimated that only about 250 pygmy hogs still remain in existence.[15]
Behavior and ecology[edit]
Pygmy hogs are social animals that live in small family groups consisting of one or two females and their offspring. They are non-territorial, and sometimes family groups can consist of as many as 20 individuals. Adult males are generally solitary and live separately rather than with the family group. However, they do maintain loose contact with the basic family group throughout the year.[12]
Pygmy hogs also have a unique nesting behavior which the tall grasses of their habitat enable them to perform. In the wild, they make firm nests in which to sleep by digging small trenches, using dry grasses and vegetation to line them.[16] They sleep in these nests at night, but also retreat to these nests during the heat of the day, and use them to warm up in the winter. The nests are also used for birthing and to hide and protect newborn piglets.
Piglets are born greyish-pink in color, and develop a brown coat with faint yellow stripes along their body length before they attain their final adult coloring. Their average lifespan is between 8 and 14 years in the wild, and they become sexually mature at one or two years old. Breeding occurs seasonally before the monsoons, and after a gestation period of 100 days, females give birth to litters ranging between two and six offspring, with the average litter size being three to four piglets.[3]
Pygmy hogs are diurnal and forage for food during the daylight hours. Foraging usually takes place for about 6 to 10 hours a day, with the pygmy hog generally taking a break midday in order to escape the high heat of the afternoon. Pygmy hogs are also omnivorous and feed primarily on roots, tubers, and other vegetative food, as well as on insects, rodents, eggs, young birds, and small reptiles.[12][17]
Pygmy hogs also fulfill important ecological roles within their ecosystems, since by using their snouts to dig for food, they not only spread seeds from plants, but they also enhance the quality of the soil. They sometimes fall prey to pythons, raptors and other carnivores.[17]
Threats[edit]
The pygmy hog is considered to be one of the most threatened mammalian species today, and has been listed as “critically endangered” by the International Union of Conservation (IUCN) since 2008. Unfortunately, humans have posed one of the greatest threats to pygmy hogs, as they have severely and negatively impacted the pygmy hogs’ natural habitat. Since pygmy hogs live among some of the most important ‘thatching grasses’, their native environments are being destroyed by humans for commercial purposes. Most of these grasses are harvested annually (even those in areas which are supposedly protected), and most of them are subjected to wide-scale annual or twice-annual burning as a means of maintenance. Although ecologists have suggested burning at the beginning of the dry season in December or early January, and only once every 2–3 years, most of the grasslands continue to be burnt annually during the dry season, thereby drastically affecting the flora and faunal diversity of the area.[3]
As the survival of the pygmy hog is dependent on these tall grasses, the pygmy hog has been driven further into the corner as many of the tall grasses are continuously being harvested and burned, and others are being replaced by short grass species. In Assam, much of the pygmy hog's habitat has also been lost to settlements and agriculture due to rapid human population growth. Loss and degradation of habitat has also occurred due to livestock grazing, commercial forestry and the planting of trees in the grasslands, and due to flood control schemes. In addition, although hunting the pygmy hog for meat by the native tribes of Assam had previously not been a problem, it is now posing a very real threat to the small population of pygmy hogs that still exist in the wild.[3]