Margaret Morse Nice was an American ornithologist, ethologist, and child psychologist who made an extensive study of the life history of the song sparrow and was author of Studies in the Life History of the Song Sparrow (1937). She observed and recorded hierarchies in chicken about three decades ahead of Thorleif Schjelderup-Ebbe who coined the term "pecking order". After her marriage, she made observations on language learning in her children and wrote numerous research papers.

Ernst Walter Mayr was a German-American evolutionary biologist. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.