20th-century American zoologists

Jean Théodore Delacour (26 September 1890 – 5 November 1985) was a French ornithologist and aviculturist. He later became American. He was renowned for not only discovering but also rearing some of the rarest birds in the world. He established very successful aviaries twice in his life, stocked with birds from around the world, including those that he obtained on expeditions to Southeast Asia, Africa and South America. His first aviary in Villers-Bretonneux was destroyed in World War One. The second one that he established at Clères was destroyed in World War Two. He moved to the United States of America where he worked on avian systematics and was one of the founders of the International Committee for Bird Protection (later BirdLife International). One of the birds he discovered was the imperial pheasant, later identified as a hybrid between the Vietnamese pheasant and the silver pheasant.

Robert Lee Metcalf (November 13, 1916 – November 11, 1998) was an American entomologist, environmental toxicologist, and insect chemical ecologist.

Metcalf was noted for making environmentally safe pest control achievable.Metcalf was a member of the National Academy of Sciences,
a fellow of the American Academy of Arts and Sciences,
a member of National Research Council,
a fellow and president of the Entomological Society of America.
He was a member of Environmental Protection Agency's Pesticide Advisory Panel.
The National Center for Biotechnology Information called Metcalf "one of the leading entomologists of the 20th century".
The National Academies Press called him the twentieth century most influential entomologist.
The University of Florida called him "a brilliant scientist and educator".