Across their habitat in southern, eastern and central Africa, poaching drove the black rhinos to near extinction. Their numbers fell by 98 percent between 1960 and 1998, but have doubled since then to about 5,400 due to conservation efforts.
In a statement over the weekend, African Parks, a non-profit organisation that runs Zakouma, said the carcasses of one male and one female rhino were discovered in separate locations in the park on October 15.
It said the rhinos were not poached but that the exact cause of death was not yet known. Gilles Desesquelles, an African Parks representative, said a virus could be to blame.