The first critically endangered Sumatran rhino to be found in an area of Borneo for 40 years has died, wildlife experts said.
The species had been thought to be extinct in Kalimantan, Indonesian Borneo, until a few years ago when surveying found evidence through camera traps and footprints of 15 Sumatran rhinos in the area.
Last month conservationists hailed the first physical contact with a Sumatran rhino for decades when a four- or five-year-old female was safely captured in Kutai Barat, with plans to move her to a protected forest around 90 miles away.
But now wildlife charity WWF has said it is saddened by news the animal had died.
While the cause of death was still being determined, the conservation group said there were indications that the rhino was suffering from a severe infection caused by snares from an earlier poaching attempt.
Sumatran rhinos are one of two rhino species found in Indonesia, along with the critically endangered Javan rhino which survives in just one place in Java, and are threatened by poaching for their horn and habitat loss.
Carlos Drews, director of the WWF International Global Species Programme, said: "WWF is saddened by the news of the death of the Sumatran rhino found in Kalimantan.
"The hope we felt a few days ago was in celebration of the first live sighting of a rhino that was thought to be extinct in the Indonesian part of Borneo until recent surveys revealed footprints of this unique species.
"Today we feel despair over the loss of that same rhino. We now know that there are more Sumatran rhinos in this region and we will work to protect the remaining individuals.
"This was the first physical contact with the species in the area for over 40 years, we will make great efforts to make sure that it is not the last."
Arnold Sitompul, WWF Indonesia conservation director, added that the indication the rhino was suffering infection as a result of poaching snares demonstrated the threats faced by the species.
It underscored the need to work with strong government and expert support to save the remaining population in the area, he said.