A Sumatran rhino at an Indonesian sanctuary has given birth in a rare success for efforts to save the critically endangered species.

The International Rhino Foundation said the female calf was born on Thursday, weighs about 20 kilograms and looks healthy and active.

"We haven't stopped smiling since the moment we were sure she was alive and healthy," said IRF's executive director Susie Ellis in a statement. "While one birth does not save the species, it's one more Sumatran rhino on Earth."

Only an estimated 100 Sumatran rhinos remain, mostly on the island of Sumatra, and several are in captivity. They are threatened by destruction of their tropical forest habitat and poachers who kill the animals for their horns.

The species was rediscovered in the Indonesian part of Borneo through trails and footprints in 2013.

But one member of the small population on Borneo died in April after a wound from a poacher's trap became infected.

The calf is the second to its mother Ratu, who gave birth to a male named Andatu in 2012, which was the first rhino birth in captivity in Indonesia in 124 years. The father, Andalas, was born at the Cincinnati Zoo in 2001.

IRF established the rhino sanctuary in the Way Kambas National Park on Sumatra in 1997. It praised the sanctuary's staff as "topnotch experts" and said the second birth shows that the expertise exists in Indonesia to increase the rhino population.

The foundation said Ratu was given a hormone supplement daily during her pregnancy to help ensure it went to full-term.

(China Daily 05/14/2016 page8)