Apes consist of species of gibbons, siamangs, chimpanzees, gorillas, orangutans and humans. They are found in humans, bonobos, chimpanzees, gorillas, orangutans, some cetaceans, and elephants. They studied chimpanzees, gorillas and orangutans respectively. Parallel bottlenecks were proposed to exist among chimpanzees, gorillas, rhesus macaques, orangutans and tigers. The exhibit was designed to house western lowland gorillas, Bornean orangutans, and chimpanzees. Potential predators of orangutans include tigers, clouded leopards and wild dogs. Some propose that males were substantially larger than females similar to gorillas and orangutans. The Sumatran orangutan ("Pongo abelii") is one of the three species of orangutans. These forests are home to wildlife including gibbons, orangutans, and crocodiles. Cross species infection to orangutans and gibbons occurred within the last 6,100 years. They awake on an island in the Pacific populated by friendly orangutans and gibbons. Male Sumatran orangutans grow to about tall and . This land is taken from the forest in which Sumatran orangutans live. Sumatran orangutans have been observed making and using tools. Tapanuli orangutans resemble Sumatran orangutans more than Bornean orangutans in body build and fur color.