 Around a quarter of the common impala populations occur in protected areas , such as the Okavango Delta ( Botswana ) ; Masai Mara and <unk> ( Kenya ) ; Kruger National Park ( South Africa ) ; the Ruaha and Serengeti National Parks and Selous Game Reserve ( Tanzania ) ; Luangwa Valley ( Zambia ) ; Hwange , <unk> and Zambezi Valley ( Zimbabwe ) . The rare black @-@ faced impala has been introduced into private farms in Namibia and the Etosha National Park . Population densities vary largely from place to place ; from less than one individual per square kilometre in <unk> National Park ( Tanzania ) to as high as 135 individuals per square kilometre near Lake Kariba ( Zimbabwe ) . 
