Africa's game parks have lost well over half of their big mammals, such as the lions and buffalos that draw millions of tourists each year, to rampant hunting and farming since 1970, a study has found. The continent-wide study by specialists, including from the London Zoological Society and UN environment programme (UNEP), found big mammal populations inside national parks declined 59% between 1970 and 2005. "These results illustrate that African PAs (protected areas) have generally failed to mitigate human-induced threats to African large mammal populations," the report in Biological Conservation journal said. Elephants and rhinos were not included in the study because of special trade restrictions relating to them. "It's perhaps not (surprising)," UNEP spokesman Nick Nuttal said. "Africa has undergone a large population increase since that period of time. There's incredible pressure from hunting for food." Another pressure was conversion to agricultural land. Nuttal said a comparative study would be needed on wildlife loss outside national parks to determine if they'd at least managed to slow the decline of mammal populations.