Cincinnati - A zoo that has the last Sumatran rhino in the United States on Tuesday announced plans to send him to Southeast Asia on a mission to mate and help preserve his critically endangered species.Conservation experts at the Cincinnati Zoo say 8-year-old Harapan could be on his way within several weeks to Indonesia, where nearly all of the estimated 100 remaining Sumatran rhino live. Numbers of the two-horned descendants of Ice Age wooly rhino have fallen by around 90% since the mid-1980s as development of their Southeast Asia forest habitat and poachers seeking their prized horns took their toll.Cincinnati's zoo has been a pioneer in breeding the species, also called "hairy rhino", producing the first three born in captivity in modern times. Harapan will join the eldest, Andalas, who has been in Indonesia since 2007 and has produced one male offspring. Andalas which will turn 14 next month.Roth said final details and permits are still being worked out so the transfer timetable is uncertain. It's expected Harapan will be flown to Jakarta, then taken by ferry to his ancestral island home of Sumatra.Rhino preservation officials in Indonesia weren't immediately available for comment on Tuesday because of the time difference.Veteran zoo rhino keeper Paul Reinhart will accompany Harapan. He and others will work with Harapan, who already has travelled across the US, to condition him to being in a crate for the long flight.Harapan and Andalas' sister, Suci, died from illness last year at the zoo, after the Cincinnati conservationists had discussed trying to mate the siblings in a desperation move. Harapan was brought back to Cincinnati two years ago after being on loan to the Los Angeles Zoo. He also spent time in Florida's White Oak conservation centre.He will join Andalas at the Sumatran Rhino Sanctuary, where he lives with three females and his one male offspring, born in 2012, on the Indonesia island. With three Sumatran rhino in a sanctuary in Malaysia and Harapan, there are only nine in captivity globally. Some scientists recently concluded that there are no more Sumatran rhino living in the wild in Malaysia.Conservationists and government officials met in Singapore in 2013 for a Sumatran Rhino Crisis Summit to discuss increasing action to protect the species.Environment ministry officials in South Africa, home to most of the world's remaining rhino overall, reported a total of 393 rhino poached through April, an increase of more than 20% over the same period in 2014. Rhino advocates said recently they believe the losses are even higher.South Africa has struggled to counter poaching syndicates cashing in on high demand for rhino horns in parts of Asia where some people claim they have medicinal properties for treating everything from hangovers to cancer.