Why Is The Hog Deer Endangered?

By Benjamin Elisha Sawe on December 4 2019 in Environment

Hog deer on field, Phukhieo Wildlife Sanctuary, Chaiyaphum province. Thailand.
Hog deer on field, Phukhieo Wildlife Sanctuary, Chaiyaphum province. Thailand.

The hog deer (Axis porcinus) is a relatively small cervid with a stocky, muscular body. The species is endemic to tall moist grasslands of South Asia and Southeast Asia. The species is also found in dense forests depending on the season of the year and food distribution. Hog deer both browse and graze but prefer grazing. Their diet consists of leaves, grass, and fruit. Historically, the species was found in much of lowland Southern and Mainland Southeast Asia. The hog deer was common and widespread in the mid and late twentieth century. However, the species' populations suffered drastic and extensive decline due to hunting and habitat loss as a result of the conversion of floodplain grasslands, their preferred habitat, into agricultural lands. Significant decreases in the population of the hog deer, a species that had not been previously considered threatened, led the IUCN to list the species as endangered in 2008.

Internal Taxonomy

The species’ internal taxonomy is still a highly debated subject. Several taxonomic authorities and published checklists currently classify Axis porcinus as a polytypic species with two subspecies, namely A. p. porcinus, and A. p. annamiticus. Axis porcinus porcinus, commonly known as the Indian subspecies, is found in Pakistan, India, Nepal, Burma, and Bangladesh. On the other hand, Axis porcinus annamiticus, the South-East Asian subspecies, is found in India, Vietnam, China, Thailand, Laos, and Cambodia. In all the listed countries, both A. p. porcinus, and A. p. annamiticus are confined to the flood plains of the various river systems found in their territories. Some experts believe that the boundary between the two subspecies is located in Thailand or Myanmar. It is unclear whether both subspecies have come into contact in recent history.

Axis porcinus porcinus

A.p. porcinus is confined mainly to protected areas in South Asia. In a majority of the protected areas, the hog deer is a lucky resident as they are established for the conservation of the tiger (Panthera tigris) and the Great One-horned Rhinoceros (Rhinoceros unicornis). Axis porcinus occurs in considerable numbers in the Indian dooars and Nepal Terai, alluvial grasslands on the Himalayan foothills. A. porcinus populations are also thought to inhabit Kaziranga National Park. The geographic overlap between well-known megafauna and A. p. porcinus ensures that considerable investment by the government targeting poaching and habitat destruction in protected areas. A. p. porcinus populations in such protected areas are therefore considered relatively secure. A smaller remnant population of A. p. porcinus is also found in Bhutan, Pakistan, and possibly in Bangladesh.

Axis porcinus annamiticus

A. p. annamiticus has almost disappeared throughout its former range. The subspecies is thought to have gone extinct in the wild in several countries including Lao PDR, Thailand, China, and Vietnam. Cambodia is believed to be one of two states that have wild populations of A. p. annamiticus. Thailand has captive bred A. porcinus in several protected areas, but many of them are of unknown origin. Some of the animals in the protected areas are of the Axis porcinus annamiticus subspecies captured from the wild in southern Thailand. Some also believe that a stock of unknown taxonomic identity was introduced into the breeding program from Myanmar. Reintroduced populations are found in Phu Khieo Wildlife Sanctuary. The confirmation of the taxonomic status of hog deer in such protected areas remains a top priority. Hog deer in Phu Khieo Wildlife Sanctuary require specialized care and habitat management (through techniques such as controlled burning to ensure the maintenance of grasslands). Indian scientists also recently discovered the presence of Axis porcinus annamiticus in India. Researchers from the Wildlife Institute of India found the small population of hog deer at the Keibul Lamjao National Park in Manipur. The discovery pushed the western limit of the hog deer to Manipur. The discovery of a genetically distinct population is also thought to be significant in the conservation of the species.

The Decline Of Axis porcinus

The drop in population of Axis porcinus is attributed mainly to habitat loss and hunting. In countries such as Cambodia, the reduction of A. p. annamiticus occurred at a faster rate compared to other similar-sized mammals. The phenomenon is attributed to the specific habitat requirements of the species that make it difficult for the species to survive when the former habitat is destroyed. Its habitat, which typically consists of grasslands, is targeted for housing development and agricultural conversion. Mismanagement of its habitat, which falls outside the traditional protected areas such as forests, is also a matter of concern. Intense human activity in grasslands also means that A. p. annamiticus is more exposed to hunting compared to other ungulates. During and after the Khmer Rouge regime, wildlife was heavily hunted, leading to rapid declines in the population of several species, including A. p. annamiticus. The subspecies in Cambodia went unrecorded from the 1970s to the 1990s due to civil unrest. By 2013, just two small A. porcinus populations remained. Scientists have identified five locations within Cambodia, where hunting persists.

Challenges In Eradicating Hog Deer Hunting In Cambodia

In Cambodia, hunting is generally not regarded as a legal or conservation issue as small deer such as Muntiacus muntjak are considered “common species” by government agencies and some NGOs. Conservationists are, therefore, concerned that locals may not be able to differentiate between the various species while hunting. It is also thought that dogs opportunistically take fawns even when humans are not actively hunting the species. The population is particularly vulnerable to hunting by dogs during the wet season when the hog deer move to higher ground. Floods in several areas are also driving the remaining populations to the brink of extinction as they have limited spaces with suitable habitats to move to due to increased agricultural practices.

Effect Of Habitat Fragmentation On Population Viability

Scientists are worried that since the populations of A. p. annamiticus subspecies lack connectivity and reduced population viability due to inbreeding, it could negatively affect the species. Several studies indicate that fragmented herds of species, such as the hog deer, may be susceptible to increased population differentiation due to genetic shift, heterozygosity, and inbreeding depression. The effect of isolation on hog deer populations cannot be overstated. Genetic diversity allows species to adapt to changing environments. Higher levels of genetic variation mean that some individuals in a herd always possess variations of alleles that will enable adaptation to a changing environment. The ability to adapt consequently enables populations to persist for more generations. Without adequate genetic variation, populations are unable to persevere for long periods in an ever-changing world. The effect of habitat fragmentation and isolation is observed at the KLNP, where a 50% loss in genetic diversity was found in the resident population. Experts believe that such reductions in genetic variation could, in the long run, prove detrimental to isolated hog deer populations in Asia.

Conservation Of Axis porcinus annamiticus

A small A. p. annamiticus population was rediscovered in 2006 by WWF along the Mekong River, about 4.97 miles north of Kratie town in Cambodia. After preliminary surveys, scientists estimated that about 50 to 80 individuals inhabited an area of 1,200 hectares of flooded grasslands. WWF later initiated a conservation program for the subspecies at the site. Under the plan, community-based patrols were launched with the support of military police and Forestry Administration. Community engagement was also carried out in fifteen villages to build support for the Axis porcinus annamiticus conservation. The organization also developed a proposal to establish a protected area at the site to safeguard the rare subspecies. The plan, however, failed, and the organization consequently ceased all conservation efforts at the site as of 2008. Global Wildlife Conservation rediscovered the other population in 2008 in a coastal lowland situated to the southwest of Cambodia. The herd was located through camera-trapping surveys south of the Chi Phat stream near Botum Sakor National Park. The region consists of highland and marshy grasslands, scrubland, remnant Melaleuca woodland, and agricultural land. The population of A. porcinus in the area is thought to be less than that found around Kraite. The Cambodian government is critiqued for half-heartedly enforcing laws meant to protect the species in the country. Enforcement efforts are reportedly, severely under-resourced, particularly outside protected areas. The government also faces criticism for the slow adoption of conservation proposals.

Suggested Conservation Measures

Several researchers and organizations have suggested captive breeding programs as a means of saving remnant hog deer populations in Cambodia. Such a plan would provide safety and mitigate risks associated with the potential failure of in-situ conservation efforts. A captive breeding program could also restock wild populations when needed. For instance, international organizations are reluctant to invest resources in such a program until the captive breed population in Thailand is identified. Several organizations believe that if the herd in Thailand is identified as A. p. annamiticus, the taxon can then be regarded as relatively safe. Money meant for captive breeding programs can then be channeled to other priority areas. Some experts, however, believe that populations in Cambodia are of vital importance, and their conservation should not face impediment by pending identification of Thai herds.

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