The Smithsonian East Africa Expedition amassed a collection of 23,151 natural history specimens, totaling 160 species of carnivores, ungulates, rodents, insectivores, and bats. The mammals alone numbered 5,013 specimens, including nine lions, thirteen rhinoceros, twenty zebras, eight warthogs, and four hyenas. In addition to collecting specimens of African flora and fauna the expedition also collected ethnographic objects for the Museum. Each specimen was carefully documented by the Smithsonian naturalists to ensure its research value. It took eight years to catalogue all of the material. Ned Hollister, a zoologist and the superintendent of the National Zoo, completed the catalogue, East African Mammals in the United States National Museum, in three volumes (1918 to 1924).