Birdman of Alcatraz (1962)

Sentenced to life in solitary confinement after killing a prison guard, despondent inmate Robert Stroud (Burt Lancaster) combats loneliness and tedium by nursing an ailing bird back to health. Stroud develops an interest in caring for birds and becomes a talented ornithologist. After publishing a book on bird diseases from jail, he meets and marries Stella (Betty Field), a fellow bird enthusiast. When Stroud is suddenly moved to Alcatraz, though, his marriage and work are both threatened.