An elderly northern white rhino lives under armed guard in Kenya as his species quickly heads toward

In Ol Pejeta Conservancy, Kenya

It’s not that Sudan didn’t want a baby. Researchers had watched the 42-year-old northern white rhinoceros try to mount a female. Rangers had seen him stare across the enclosure at the ladies “admiringly,” sharpening his horn like he was preparing to win them over.

But age had caught up with him. His hind legs were weak. The quality of his sperm was poor. And as the odds dimmed that he would mate successfully, conservationists had to reckon with their own failure.

How had the fate of an entire subspecies of rhinoceros been left to one elderly male?

In just a few decades, a large population of northern white males has been reduced to a single 3,500-pound bull living in a 10-acre enclosure with round-the-clock guards. There are also four females left: two in Kenya, and one each in the United States and the Czech Republic. But none of them are fertile, meaning the population is on the verge of extinction.

FULL story at link. Photo gallery: http://www.washingtonpost.com/world/africa/the-last-stand-for-the-northern-white-rhino/2015/06/16/22cfbdb2-1213-11e5-9726-49d6fa26a8c6_gallery.html