Private nature reserves and adjoining large national parks such as the 2.2 million ha Kruger National Park (KNP) in South Africa, not only need to function as integrated ecological units but also need to be financially viable to support efficient management practices. The Association of Private Nature Reserves (APNR), on the western boundary of the KNP encompass an area of 180 000 ha and forms one of the largest private nature reserves in the world. These reserves host from time to time some of the few remaining large tusked bulls, which periodically emerge from the KNP. As hunting is permitted within the APNR, trophy bulls are of economic importance to the reserves. Green hunting of elephant bulls was pioneered by Save the Elephants within the Timbavati Private Nature Reserve in 1998.