This is one of Alfred Hitchcock's last movies, and probably the greatest.
The Birds is certainly different, because the antagonist is not an evil person or persons, but simply one aspect of nature -- birds.
There's certainly a psychological element, but it's not as clearcut -- though perverted -- as Norman Bates in Psycho.
To what extent are the bird attacks some kind of reaction to the arrival of Tippi Hedron in the small town. She does upset its emotional balance.
The school teacher Annie Hayworth who remains though she knows that her love for Rod Taylor is hopeless? Taylor's mother Jessica Tandy and Taylor have a complex relationship. In the scene where the teacher and Tippi discus it, Hayworth insists that it's not incestuous, but it's also clearly deeper than the usual mother/son relationship. Jessica Tandy insists she's weak and needs someone to look after her since her husband died four years ago - but she's strong enough to keep Taylor away from women -- until now.
Maybe the key lies with eleven year old Cathy. Maybe she unconsciously brought the birds to free her brother -- who is quite a bit older than herself -- from her mother. After all, when they leave the farm house, she's the one who points out that the love birds brought by Tippi as a device to engratiate herself into Taylor's affections, so they represent the love between those two, haven't hurt anybody.
Of course, it's also true that these love birds have been kept in a cage. Yet I think that if Hitchcock wanted us to believe the love birds were also hostile, he'd have showed that to us.
The first bird attack was of a sea gull dive bombing Tippi Hedron after she snuck the love birds into Taylor's house.
And perhaps Cathy didn't like school or her friends. The next big attack was on her friends at her birthday party. And then of course the famous scene where the crows mass in the school yard while Tippi sits smoking a cigarette and the students are in the classroom singing a folk song.
Then the crows attack. And Annie is killed after pushing Cathy inside.
Hmmm, perhaps there's some kind of illicit emotional relationship between Tippi and Cathy? Maybe Cathy is jealous of her brother - after all, Tippi gave the love birds to her, not to him. Maybe she wants the beautiful newspaper heiress's love for herself. Maybe that explains the final scene, where Tippi is the one traumatized.
And after all, Cathy is at least ten, and probably more like fifteen, years younger than her brother. She must have been a very late baby, so she's used to being the baby of the family with all the attention on her. Her older brother the lawyer would seem more like a father figure than a brother.
So she wants Tippi for herself.
Or perhaps she has the traditional Electra complex for her brother instead of her deceased father. So the birds are her weapon against the beautiful woman who's come to take her Taylor away from her.
Now the movie makes sense.