David is a San Francisco photographer specializing in maco-photography of endangered species. He was assistant to photographic luminaries Richard Avedon and Mary Ellen Mark, and worked with film maker Martin Bell.

In 1986, Liittschwager began a collaboration with Susan Middleton that has produced three magnificent books, Here Today, Portraits of Our Vanishing Species; Witness, Endangered Species of North America; and Remains of a Rainbow: Rare Plants and Animals of Hawaii. They have produced exhibitions that travel to major museums, including the American Museum of Natural History and the National Academy of Science in New York, and the California Academy of Sciences in San Francisco. His work is featured in articles in such magazines as National Geographic, and Life.