communicating with gorillas via sign language. One gorilla, Koko, was born in San Francisco Zoo on July 4, 1971. Francine Patterson officially started working with Koko on July 12, 1972, with the goal of teaching her sign language. In the beginning, Patterson focused on teaching Koko only three basic signs: "food", "drink", and "more". Koko would learn signs through observation and from Patterson or one of her colleagues molding Koko's hands into the correct sign. On August 7, Patterson began a more formal routine of teaching Koko the signs, "food", "drink", and "more". In the couple weeks before that, Koko had been using gestures that seemed like attempts at the signs taught, but were deemed as coincidental and random and not intended for the actual purpose. Only two days after they started the more formal routine, Koko started responding consistently with the sign "food" when prompted to. Within the first three months, Koko made 16 different combinations of signs and was also starting to form simple questions by using eye contact and different positioning of signs by the body. Koko mastered more than 1,000 signs and was said to be able to connect up to eight words together to form a statement expressing wants, needs, thoughts, or simple responses. There has been a study examining the ability of western lowland gorillas to give to and exchange with humans. This involved humans holding objects such as fruit, leaves or peanuts in one hand. Once the gorillas had given twigs to the humans, they would receive one of these objects. If the gorillas did not give them a twig, they would not get their desired object. The gorillas were shown to quickly learn about receiving rewards as mistakes made by the gorillas in the beginning of the experiments gradually decreased. Ecology Habitat Western lowland gorillas primarily live in rainforest, swamp forest, brush, secondary vegetation, clearing and forest edges, abandoned farming fields and riverine forest. They live in primary and secondary lowland tropical forest at elevations that extend from sea level up to . The average amount of rainfall in the areas where western lowland gorillas typically reside is about a year with the greatest rainfall between the months of August and November. Western lowland gorillas are not typically observed in areas that are close to human settlements and villages. They have been known to avoid areas with roads and farms that show