Ronald M. Nowak is the author of the fifth and sixth editions of Walker's Mammals of the World. His other works on mammalogy include North American Quaternary Canis and several sections in the National Geographic Society's Wild Animals of North America, for which he also was editorial consultant. He received a Ph.D. in biology from the University of Kansas in 1973 and was staff mammalogist at the former Office of Endangered Species, U.S. Fish and Wildlife Service, from 1974 to 1987.