Hans Julius Duncker (26 May 1881 in Ballenstedt, Anhalt, now Saxony-Anhalt – 22 December 1961 in Saarbrücken) was a German ornithologist, geneticist and eugenicist.
[1] In the early 1920s, he began conducting several breeding experiments on birds to study the heritability of plumage colors and structures, such as the hood.
[2] From 1925 Duncker collaborated with the wealthy businessman and aviculturist Carl Hubert Cremer and extended his experiments to include budgerigars.
[1][3][4] In 1927 he established a journal Vogel ferner Länder (which later became AZ-Vogelinfo) and in 1928 he published a book on canary genetics Genetik der Kanarienvögel.
In 1934, he published a book Neue Ziele und Wege des Biologieunterrichts on teaching biology along with Friedrich Lange.