The "Birdman of Alcatraz" refers to Robert Stroud, a notorious criminal who was imprisoned at Alcatraz Federal Penitentiary from 1942 to 1963. Stroud became famous for his work with birds, particularly canaries, which he raised and studied while incarcerated. His passion for ornithology led to the publication of a book on the subject, showcasing his knowledge and dedication. Despite his reputation as a violent criminal, Stroud's life in prison was marked by his transformation into a bird expert. The nickname "Birdman" highlights this unusual aspect of his life, contrasting with his past as a convicted murderer. Stroud's story has been popularized in films and books, further cementing his legacy.