Malaysia's last surviving male Sumatran rhino died Monday, wildlife officials said, leaving behind only one female in the country and pushing the critically-endangered species closer to extinction.
Once found as far away as eastern India and throughout Malaysia, the Sumatran rhino has almost been wiped out, with fewer than 80 left, according to the World Wildlife Fund.
Only a handful of the animals remain in the wilds of Indonesia.
Sabah Wildlife Department director Augustine Tuuga said the Malaysian male, Tam, had lived in a nature reserve on Borneo island.
The cause of the animal's death was not immediately clear, but previous media reports have suggested it was suffering from kidney and liver problems.
Tam's death puts pressure on an ongoing effort for conservationists hoping to use in-vitro fertilisation (IVF) techniques to create offsprings from Malaysia's last female Sumatran rhino, Iman, and an Indonesian male.
Tuuga said there were problems with Iman's uterus and that she was incapable of becoming pregnant, but was still able to produce eggs.
"We just have to look after the last remaining rhino. That's all we can do, and try if possible to work with Indonesia," he said.