Chimpanzees are active mainly during the day. They sleep in nests at night. The nests give the chimps shelter. They help the chimps stay warm. Find out more in Chimpanzee Nests, a title in the Nature's Engineers series. Nature's Engineers is a series of AV2 media enhanced books. Each title in the series features easy-to-read text, stunning visuals, and a challenging educational activity. A unique book code printed on page 2 unlocks multimedia content. These books come alive with video, audio, weblinks, slideshows, activities, hands-on experiments, and much more.