Beebe undertook an expedition to Brazil in 1915, to capture more birds for the zoo. This expedition was an important turning point for Beebe in several ways. Beebe had far more field experience than either of the two others accompanying him on the expedition, G. Inness Hartley and Herbert Atkins, making this his introduction to the role of a mentor. During this expedition, Beebe was also amazed to discover the number and variety of organisms living under a single tree and pioneered the method of studying a small area of wilderness for an extended amount of time. This expedition marked the beginning of a shift for Beebe from ornithology to the study of tropical ecosystems.