The Birds could be called a hybrid of Shadow of a Doubt and Psycho. It combines the former's character-exploration with the latter's shock-effects, and emerges as one of Alfred Hitchcock's most striking and formidable achievements. On any level, a masterpiece….
The Birds is a modern fable about the complacency of Man and the uncertainty of his position in the universe. Life is going carelessly by, but out of nowhere comes a dreadful enemy—one that no amount of reasoning can put down. Without explanation, seemingly without reason, the enemy strikes and persists until it has won. Man is powerless under its force; his struggles, however valiant (and Hitchcock feels that people show great bravery during times of crisis) are futile. The Birds is a fearful parable of the twentieth century….
Hitchcock calls the movie a fantasy, but it is not approached that way; reality is the keynote…. This is part of the film's brilliance: it is happening and so you believe it. Such is the strength of Hitchcock's genius.
There are sequences in The Birds that will literally leave you limp. (p. 69)
Reviewers say it all the time: it's indescribable. But this movie is. The savage impact, the staggering effects, the uncompromising intensity, the depth, the artistry. Let's stop calling Hitchcock a wry trickster, a great craftsman, an enterprising entertainer, the master of suspense. He's all that too. But, mainly, he is a consummate artist. (p. 70)
Peter Bogdanovich, "'The Birds'," in Film Culture (copyright 1963 by Film Culture), No. 28, Spring, 1963, pp. 69-70.