It's early morning at the headquarters of Virunga National Park, and the hounds are restless. They bark and howl as the rangers talk amongst themselves in Kiswahili.

As Africa's oldest national park, Virunga is famous for high biodiversity and rare animals that only exist there. But it's also home to some pretty hardworking domestic animals with a very special job: hounds.

"They track the rebels who kill the elephants," says David Twiringire-Niezehose, a ranger with Virunga's special canine unit.

Among the friendliest of hounds, beagles were bred as pack hunters and are enthusiastic trackers

Set up in 2011, the special unit has spent years learning from international hound tracking experts. It's already seen some success, Niezehose adds.

Sabrina - three years old and born in the United States - is Niezehose's favorite dog. An American dog, he says with a laugh.

"She found an elephant killed in the Rwindi sector, this dog," Niezehose says, pointing to Sabrina. "You will see what she is able to do!"

The hounds often work with bullet casings, since discarded cartridges hold the scent of a poacher. Today, Niezehose takes Sabrina out for her daily training, with fellow ranger Fidele acting as the poacher. All Sabrina has to work with is a bullet casing Fidele handled.

Niezehose puts the shell casing into a Ziploc bag and briefly places it under Sabrina's nose.

"OK, charge," Niezehose says.

Sabrina darts off into the forest, her nose to the ground. The rangers jog behind her in single file.

Niezehose is one of 380 park rangers who patrol the 790,000 hectares of jungle, savannah and rainforest. The park even holds alpine forest and glaciers. Even though nearly 400 rangers may seem like a lot, the park's scale makes patrolling it a massive undertaking.

Lucrative business

The root causes of poaching lie in the history and economy of the region. Decades of instability have forced millions from their homes, and seen the rise of powerful rebel groups. The opening of the region to mining - coupled with weak governance and widespread poverty - have allowed for the rise of illegal poaching rackets.

Elephants are most commonly targeted for their valuable ivory tusks. Primates, including the mountain gorilla, are hunted for bush meat, and for the exotic animal trade. Other animals are simply collateral damage, caught in a poacher's snare.

The mountain gorilla is critically endangered due to habitat loss, poaching, disease and war

Chairul Saleh, species coordinator for the World Wildlife Fund (WWF) in Indonesia, said endangered animals all over the world are facing similar problems as populations grow, habitats shrink and resources become more limited. A joint effort is needed to combat the problem, he thinks.

"On the site level, we must strengthen the patrols, with the collaboration with local communities and the government," Saleh said.

Economic alternatives

Critics, however, have said that arming rangers has militarized the situation, escalating conflict with poachers. The poachers, for their part, see themselves as tapping natural resources that have been cut off from public use.

The rangers undergo a seven-month, military-style training under the tutelage of former Belgian commandos.

The job presents serious risks: Since 1994, Virunga has lost more than 140 rangers while protecting the park.

And according to Saleh, simply patrolling isn't enough. The roughly 4 million people who live in and around the park - most of them surviving off less than a dollar a day - need to find a way to make a better living. Many of the poachers come from these communities.

"We try to find other alternatives for their income, for increasing their livelihood," Saleh said.

The staff at Virunga also knows that to combat poaching, more economic opportunities have to be available.

Betting on hydropower

That's why Virunga management is pinning its hopes on hydroelectricity. Emmanuel De Merode, director of Virunga National Park, plans to develop a number of medium-sized hydroelectric plants.

De Merode is convinced that developing hydropower will help the park - and the people

The power the plants generate can first of all be sold to sustainably fund park operations. "And downstream, you can use that electricity to empower small-scale agro-industry and many new businesses," said Merode.

Virunga already has one hydroelectric plant - at Mutuanga, in the far north of the park - which is expected to generate up to 500 jobs. And the park plans to build another six hydro plants over the next seven years.

Merode paints a bright picture, saying these plants could offer from 80,000 to 100,000 jobs in the region. "And that is giving real opportunities for a more dignified and more affluent future," he added.

WWF is supporting the development of medium-sized hydroelectric plants in the park as an example of sustainable development. But it will take years for this to affect the poaching problem.

On the front line

Back in the park, spirits are high. Rangers talk and laugh amongst themselves. And Sabrina receives much deserved praise: She has successfully located the ranger Fidele, who had concealed himself in a nearby village.

The exercise today was just that - an exercise. But that won't always be the case.

"You know if anything happens, you are all ready to fight," Niezehose says.