Here are some facts about orangutans: Size Orangutans are the biggest tree-dwelling mammals in the world. Lifespan Orangutans can live up to 50 years old. In the wild, they can live about 35 to 40 years. Diet Orangutans eat more than 400 different plant varieties, and nearly 90% of their diet is fruit. They especially favor durians, which are covered in sharp spines and have a strong smell. Habitat Orangutans are only found in the rainforests of the Southeast Asian islands of Borneo and Sumatra. They spend most of their lives in trees, swinging and building nests for sleep. Intelligence Orangutans are known for their high intelligence. They have an IQ of around 75, which is lower than the average human IQ of 100. They can use tools for foraging, nest building, and acoustic communication. Endangered status All three species of orangutans are critically endangered by the International Union for the Conservation of Nature (IUCN). The main threat to orangutans is habitat loss from logging and clearing forests for palm oil plantations and other industries.