At the base of Ngulia Hills, this 90-sq-km area is surrounded by a 1m-high electric fence and provides a measure of security for around 80 of the park's highly endangered black rhinos. There are driving tracks and waterholes within the enclosed area, but the rhinos are mainly nocturnal and the chances of seeing one are slim – black rhinos, apart from being understandably shy and more active at night, are browsers, not grazers, and prefer to pass their time in thick undergrowth.
These archaic creatures are breeding successfully and around 15 have been released elsewhere in Tsavo West National Park. For all the security, one rhino was poached from inside the sanctuary in April 2014, with two more taken on 31 December 2016 amid reports of budget cuts and diminishing resources to fight poaching. Even so, there are plans to expand the boundaries of the sanctuary to the south.