inga: despite extreme environment, poaching, andnd mas mortrtality, kazakakhstan's anct animal has survived for millennia, but conservationists are worried ththat another m mas die-off could be the last. narrator: rhinos have been under threat of extinction for many years. both the black and white species are found in the southern african countries of zimbabwe, kenya, namibia, and south africa, which now has a population of araround 21,000 rhinos. but that number used to be far higher.. the horns of the aninimals are very valuable, which m makes thm an attractive target for poachers. since the turn of the millennium, there's been a dramatic rise in rhino poaching. rhino horn is worth billions on the black market, fetching an average of $60,000 u.s. per kilo. the battle to end poaching is a tough one, but the outlook isn't entirely hopeless. reporter: kruger national park in south africa -- nowhere else in the world are there so many rhinoceros, and nowhere else are so many killed by poachers. the investigative unit is on its way to the scene of a crime. the helicopter spotted a rhino cadave