The world's rarest antelope is now a little bit less rare. Aerial surveys in Kenya have revealed that 34 hirola antelopes have been born in the past three years. That brings the species' worldwide population up to about 240.

The newborn antelopes owe their existence to a predator-proof fence that was built around the world's only hirola sanctuary in 2012. The sanctuary covers 5,390 acres of the 46,950-acre Ishaqbini Community Conservancy, which was established six years earlier to protect the critically endangered antelope.

Although the conservancy safeguarded the world's last wild population of hirola, its anti-poaching efforts also had an unintended consequence, resulting in an increase in the local populations of predators such as lions, hyenas, and leopards. Those predators started to take a toll on the hirola.

(Photo: Kenneth K Coe, courtesy of The Nature Conservancy)

"If the sanctuary hadn't been there, this slow decline from predators probably would have resulted in the hirola's extinction," said Matthew Brown, Africa deputy director for The Nature Conservancy, which established the conservancy with the Northern Rangelands Trust, the Kenya Wildlife Service, and other partners.

The first 24 hirola were herded into the sanctuary just before the fence was completed. Another 24 were then tranquilized and carried into the predator-proof enclosure by helicopter. Even then the fate of the species was uncertain. "You never really know when you move animals into a captive environment how they're going to adapt," Brown said.

The animals have done well inside the fence. Only a few calves were born in the first year, one of which died, but Brown said breeding started to kick in during the second and third years. "It's great to see this reproduction happening," he said.

(Photo: Kenneth K Coe, courtesy of The Nature Conservancy)

Eventually, some of the hirola from the sanctuary will be released back into the wild to expand the existing herds, which depend on big groups to protect themselves from predators. "Their security is in numbers,” said Brown. “A large herd can move and shake off predators more easily.”

Hirola enjoyed this natural protection until the 1980s, when livestock carried a disease called rinderpest to the region. The disease and a severe drought in 1984 caused the hirola population to crash from an estimated 16,000 animals to as few as 500. Poaching and habitat loss further lowered hirola numbers in the ensuing decades. (Rinderpest was declared eradicated in 2011.)

The hirola had allies, not just in international organizations but in a group of Somali people, called the Pokomo, who live in the antelopes' habitat in Kenya.

"They have an amazing connection to the hirola antelope," Brown said. "They feel the animals are theirs to look after."

He credits the sanctuary's success with the support of the community, many of whom benefit from jobs created by the conservancy. "It hasn't been the case of foreigners protecting a species that the rest of the world cared about at the expense of local people,” Brown noted.

The births are just the first step in the recovery of the animal. Brown said the partners in the sanctuary hope to release their first animals into the wild in another year or two. After that, hopefully populations will continue to expand. "We're probably looking at a 10- to 15-year recovery story," he said.