The Western Lowland Gorilla lives in montane, primary and secondary forests and lowland swamps in central Africa where they eat around 19 kg of roots, shoots, fruit, wild celery, tree bark and pulp which is provided for in the thick forests. Their black skin along with coarse black hair that covers their entire body except for the face, ears, hands, and feet. At the largest, they can stand at 1.5-1.8 m tall and weigh 140-270 kg. They travel within a home range averaging 8-45 sq Km and usually go as far as 5-3 km per day in family groupings of 4 to 8 members in each. The leader organizes group activities, like eating, nesting, and traveling in their home range. Females do not reach sexual maturity until the age of 8 or 9 when they can give birth to one infant after a pregnancy of nearly nine months. The infants ride on their mothers' backs from the age of four months through the first two or three years of their lives and can be dependent on their mother for up to five years. Their intelligence can be seen through their ability to fashion tools by selecting branches, remove projections such as leaves and bark, and adapting their length to the depth of the holes. Koko, a trapped gorilla mastered more than 1,000 signs in order to communicate with her human captors. A number of factors threaten their extinction. They are hunted illegally for their skins and meat in Africa and captured to be sold to zoos, and they are affected by deforestation, farming, grazing, and the expanding human settlements that cause forest loss.