Media playback is unsupported on your device Media caption Anbarasan Ethirajan goes on patrol with an anti-poaching team in Nepal protecting the one-horned rhino

Once Chitwan National Park in Nepal was the favourite hunting ground of poachers, but now it is they who are on the run and being hunted.

It is a rare successful conservation story in South Asia, where park officials and the Nepalese army have managed to turn the tide against poaching in the last few years.

Wild animals such as tigers, rhinos, elephants and leopards have been regularly killed by poachers for their body parts and skin, which fetch thousands of dollars on the black market.

The national park in the foothills of the Himalayas has succeeded particularly in protecting its most famous resident - the one-horned rhinoceros, also known as the Great Indian rhinoceros - from poachers.

Anti-insurgency operations

Some conservationists believe it is one of the most endangered animals in the world - it features prominently on the red list of the International Union for Conservation of Nature (IUCN).

Around 20 or 25 elephants will take part in the exercise and we will scour an entire area with bushes or tall grass looking for poachers' dens or hide outs Rupak Mahajan, Chitwan national park co-ordinator of anti-poaching operations

The World Wildlife Fund (WWF) says that one-horned rhinos are hunted because its horn is used in traditional East Asian medicines - though there is no scientific proof of its medicinal value.

About 10 years ago, when the country was deeply mired in a civil war between government forces and Maoist rebels, there was hardly any focus on wildlife protection in one of Nepal's most famous parks.

The number of army monitoring posts in and around the park was reduced from 30 to seven as soldiers were shifted to anti-insurgency operations.

In 2002, about 37 rhinos were killed by poachers, triggering grave concern over the future of one-horned rhinos.

Their numbers dropped from an estimated 612 in 2000 to less than 375 in 2005.

"According to our last rhino census in 2011 the number of rhinos in the park has risen to more than 500," said Kamal Jung Kunwar, a senior official at the Department of National Parks and Wildlife Conservation.

As the chief of the anti-poaching operation from 2003 to 2007, Mr Kunwar played a key role in the conservation of rhinos in Chitwan National Park.

Spread over an area of more than 930 sq km, the park consists mostly of Sal trees and grasslands. Its flat lowlands are home to a variety of endangered animals like Royal Bengal tigers, rhinos, leopards and Gharial crocodiles.

Crucial re-deployment

The successful conservation effort is attributed to a variety of initiatives, including tough action against poachers, enhanced intelligence and involving villagers living around the park in conservation efforts.

Image caption One-horned rhinos have been described as some of the most endangered animals in the world

It has crucially involved the re-deployment of soldiers inside the park.

Park officials gave me rare access to the park's anti-poaching teams whose trained elephant teams have performed so well in reducing rhino poaching over the last seven years.

In 2012, only one rhino was shot dead by poachers, while in 2011 no rhino was killed.

As part of their strategy, anti-poaching teams regularly use elephants to go deep inside the forest in search of poachers. The animals provide greater mobility in areas where there are few tracks or roads.

"Sometimes we bring elephants from other parks to hold a sweeping exercise. Around 20 or 25 elephants will take part in the exercise and we will scour an entire area with bushes or tall grass looking for poachers' dens or hide outs," Rupak Mahajan, co-ordinator of anti-poaching operations in the park told me.

Tip-offs

The important role of the army in anti-poaching efforts can be seen by the various soldiers manning posts in different parts of the forest. They regularly do joint patrols with park officials.

Image caption Officials say that there is no room for complacency over the success of the anti-poaching initiaitive

There are more than 1,000 soldiers in the park operating from more than 40 positions, some deep inside the forest.

As we moved to another side of the forest, we shifted to a four-wheel drive vehicle. Mr Mahajan explained that they help his team to track poachers speedily if they get any tip-offs about their presence.

Sometimes it is necessary for the team to patrol on foot and sometimes they use speed boats on the rivers and canals which criss-cross the park.

The involvement of villagers living around the park in the conservation effort has been mutually beneficial.

Kamal Jung Kunwar explained that they have received between 30-40% of tourism revenue from the park for development projects in their villages.

"That gives them a sense of ownership," said Mr Kunwar, whose book Four Years for the Rhino details the meticulous planning that has gone into the conservation project.

The WWF has also developed pilotless special drone aircraft to detect poachers, locate forest fires and detect illegal felling of trees.

WWF-Nepal Wildlife Trade Control Co-ordinator Diwakar Chapagain says that it is not a battle that will be won quickly.

"There is a huge demand for horns and it is increasing," he says.

"The poachers and traffickers have lots of money and are using poor people, including villagers living near the park area. If we cannot control market demand, threats to wildlife will always exist."

But at the same time law enforcement has had an impact on saving the rhinos.

Around 150 poachers and their collaborators have been convicted and jailed in the last few years. Sentences ranged from five to 15 years. The chief warden of the parks even has quasi-judicial powers.

"The tough punishments have acted as a deterrent," Mr Kunwar said.

While the poaching of rhinos may have been reduced considerably, it has gone up dramatically at India's Kaziranga National Park, home to the world's largest concentration of one-horned rhinos. At least 17 have been killed by poachers there since the beginning of 2013.

Conservationists say that the likelihood is that poachers are turning to Kaziranga because of tighter controls in Nepal.