The body of a male one-horned rhinoceros was found with its horn gouged out on Saturday in Nepal’s Chitwan Park.

Chitwan Park was gearing up to celebrate three consecutive years without any rhino poaching.

Nepal has one of the world’s most effective anti-poaching programs, and the country’s rhino population is on the rise.

Investigations are underway to locate the poachers responsible for killing a rare one-horned rhinoceros (Rhinoceros unicornis) in Nepal’s Chitwan National Park.

The male rhino was found Saturday shot dead and with its horn gouged out. Its death comes just weeks after conservationists celebrated 1,000 days without a rhino being poached in Chitwan, and as they were looking forward to reaching the three-year no-poaching mark in early May.

This has ended that excitement, said Chiran Pokharel, a veterinarian at the National Trust for Nature Conservation’s office in Sauraha, Nepal. “It is sad news for us,” he told Mongabay. “Obviously we are not feeling good with this, since the government is putting a lot of effort to control poaching.”

Since May 2014 — the last time a rhino was poached in Chitwan — only one of these rare animals has been killed in all of Nepal. In August 2016, a rhino was shot outside the park. Its horn was intact, leaving doubt about whether it was the victim of a failed poaching attempt or of human-wildlife conflict.

The investigation into this new poaching case is only beginning, Pokharel said, and officials do not yet have information about the culprits, such as whether the poachers were local or foreign.

Despite these recent setbacks, the tiny Himalayan country has been lauded for its commitment to protecting rhinos. Nepal’s rhino population grew from just 375 in 2005 to 645 in 2015 — even as demand for rhino horn in nearby China and Vietnam drove a global poaching epidemic.

In explaining the country’s success in protecting wildlife, experts generally point to a strong collaboration between officials, local and international conservation organizations, the military and local residents. In addition to forest guards, Nepal’s military and community-based anti-poaching units patrol critical wildlife areas.

However, the killing last weekend highlights the animals’ vulnerability and the ongoing need for better anti-poaching enforcement in Chitwan and the adjacent community forests, Pokharel said. “There are many institutions [working to protect rhinos]; there’s the local people, the government, the army. But if poachers are able to get there before them, that’s a very big challenge.”

Mongabay correspondent Alex Dudley contributed reporting from Nepal.

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