Late in the 20th century, conservation workers established a DNA identification system to trace the origin of poached ivory. Due to poaching to meet high demand for ivory, the African forest elephant population approached critical levels in the 1990s and early 2000s. Over several decades, numbers are estimated to have fallen from approximately 700,000 to less than 100,000, with about half of the remaining population in Gabon. In May 2013, Sudanese poachers killed 26 elephants in the Central African Republic's Dzanga Bai World Heritage Site. Communications equipment, video cameras, and additional training of park guards were provided following the massacre to improve protection of the site. From mid-April to mid-June 2014, poachers killed 68 elephants in Garamba National Park, including young ones without tusks.