The films strength lies in its ability to turn the ordinary into the extraordinary, and then by not explaining the extraordinary. Why are the birds attacking? There is no answer. And why do the attacks only begin when Daniel's arrives in town? Is she connected, as some suggest? Again, there is no answer, the audience is left to form their own views.
Shooting of the film was not without problems. The Birds was Hedren's film debut, and Hitchcock was hoping to groom her into his next Grace Kelly. Unfortunately his behaviour became more and more obsessive and during the filming of the final sequence he had the bird handlers throw real birds at her instead of the mechanical ones she had been expecting. Hedren was terrified and was ordered by her doctor to have several days of bed rest to recover.