( Cincinnati Zoo & Botanical Gardens ) - Scientists at the Cincinnati Zoo are working to keep the Sumatran rhino species going. It's estimated that there are less than 100 left in the world, and only two are in North America.

Those two, 6-year-old male Harapan (pictured) and 9-year-old Suci are brother and sister, and scientists say they're going to try to breed them.

"It does get to a point if a species drops to such low levels that the most important priority is to produce as many animals as possible, and so genetics kind of take a second seat," says Dr Terri Roth, Vice President of Conservation and Science.

Dr Roth says they first have to see if Harapan is sexually mature, and then it's a matter of tracking hormone levels and finding the right day to put the pair in a room together. She says it's a very difficult process and there's no guarantee of anything.