They reached a peak of about 3000 in the late 1970s, before the poachers hit in force. By the end of the carnage in the mid-1980s, the remnant elephants were acting crazily, bunched up in tight herds, ranging far out into the Serengeti Plains, and running rapidly in the opposite direction whenever they saw a vehicle. Many people think that poachers are a ragtag bunch scrabbling to make a living. They are not. Poaching for rhinos and elephants is big business, just like cocaine.
Money comes from outside to finance it, and most of the profit flows there also.
The most famous of Serengeti's predators is the lion. Predators have been more thoroughly studied than anything else in the Serengeti, and lions have been studied more intently than any other predator, with research dating since the 1960's. This research has been entirely behavioral, and little is known of other aspects of carnivore ecology. In fact, there are not even good estimates of population sizes of the large carnivores. We do know that the lion population on the Serengeti Plains dropped by about a third during the 1990's due to disease that is believed to have spread into the park from surrounding domesticated animals.