In 2002, Equatorial Guinea's most significant environmental problems were deforestation, water pollution, desertification, and the preservation of wildlife. The forests are threatened by agricultural expansion, fires, and grazing. The nation has 30 cubic kilometers of renewable water resource with 6% used for farming purposes. As of 2002, the nation's wildlife is threatened by the expansion of population centers and none of the nation's natural areas are protected. Of 184 mammal species, 12 are endangered. Four species of birds in a total of 273, two types of reptiles, and one amphibian are also endangered. Six species of plants are threatened with extinction. Endangered species include the drill ( Papio leucophaeus ), Preuss's monkey, and the green sea, hawksbill, and olive ridley turtles.