CINCINNATI – With the survival of a species on the line, Cincinnati Zoo scientists are hoping to mate their lone female Sumatran rhino with her little brother.

The desperation breeding effort follows a recent crisis summit in Singapore where conservationists concluded as few as 100 of the two-horned, hairy rhinos might remain in their native Southeast Asia. The species numbers have fallen by up to 90 percent since the mid-1980s as development takes away habitat space and poachers hunt them for their prized horns.

Rhinos overall are dwindling globally, and the Sumatran species descended from Ice Age woolly rhinos is one of the most critically endangered.

The Cincinnati Zoo has been a pioneer in captive breeding of the rhino species, producing the first three born in captivity in modern times. Its conservationists this month brought back the youngest, 6-year-old Harapan, from the Los Angeles Zoo and soon will try to have him mate with the zoo’s female — his biological sister — 8-year-old Suci.

“We absolutely need more calves for the population as a whole; we have to produce as many as we can as quickly as we can,” said Terri Roth, who heads the zoo’s Center for Research of Endangered Wildlife. “The population is in sharp decline and there’s a lot of urgency around getting her pregnant.”

Critics of captive breeding programs say they often do more harm than good and can create animals less likely to survive in the wild. Inbreeding increases the possibility of bad genetic combinations for offspring.

“We don’t like to do it, and long term, we really don’t like to do it,” Roth said, adding that the siblings’ parents were genetically diverse, which is a positive for the plan. “When your species is almost gone, you just need animals and that matters more than genes right now — these are two of the youngest, healthiest animals in the population.”