SEVEN of the 17 rare black rhinoceros in the world-famous Ngorongoro crater and six lions have died from unidentified causes. Several hundred other animals are believed to have died from lack of water during a prolonged drought in the area in northern Tanzania. An 11-member team is investigating the cause of death of the animals, whose habitat is the floor of the collapsed crater of an extinct volcano. The drought-affected include 323 Cape buffalo, 193 wildebeest, 69 zebra, three antelope and three hippopotamus, the remains of which were found near water points.