On August 18, 1961, residents in the town of Capitola, California, awoke to find shearwaters slamming into their rooftops, and their streets covered with dead birds. News reports suggested domoic acid poisoning (amnesic shellfish poisoning) as the cause.
According to the local Santa Cruz Sentinel, Hitchcock requested news copy in 1961 to use as “research material for his latest thriller.” He then hired Evan Hunter to adapt Daphne du Maurier‘s novella, “The Birds,” first published in her 1952 collection The Apple Tree.
Hunter had previously written “Vicious Circle” for Alfred Hitchcock’s Mystery Magazine, which he adapted for the TV anthology series Alfred Hitchcock Presents. He also adapted Robert Turner’s story “Appointment at Eleven” for the same television series. Hunter suspected that he was hired because of his demonstrated skills with suspense (the 87th Precinct novels, as Ed McBain) and his novel The Blackboard Jungle, which had received critical acclaim and was made into a controversial yet commercial movie in 1955, starring Glenn Ford and Sidney Poitier.
The relationship between Hunter and Hitchcock during The Birds was documented by the writer in his 1997 autobiography Me and Hitch, which contains correspondence between the writer, director and Hitchcock’s assistant, Peggy Robertson.
Hunter began working on the screenplay in September 1961. He and Hitchcock developed some new elements of the basic story, such as the townspeople having a guilty secret to hide, and the birds’ attack as a form of punishment. He suggested that the film begin with some elements borrowed from screwball comedy, and then have evolve them into “stark terror”.
This appealed to Hitchcock because it conformed to his love of suspense: the title and the publicity would have already informed the audience that birds attack, but they do not know when. The initial humor followed by horror would turn the suspense into shock.
Hitchcock also solicited comments from several people regarding the draft of Hunter’s screenplay. Consolidating their criticisms, Hitchcock wrote to Hunter, suggesting that the script (particularly the first part) was too long, contained insufficient characterization in the two leads, and that some scenes lacked drama and audience interest.
Hitchcock at later stages consulted with his friends Hume Cronyn, who played in the 1944 film Lifeboat and whose wife, the great Jessica Tandy played Lydia in The Birds. He also showed it to V.S. Pritchett. Both men offered detailed comments on the script.