Annie, Mitch's ex-girlfriend, is down to earth.
The first time we see Annie, she's covered in dirt from gardening. And, when we first see her and Melanie in a scene together, the contrast couldn't be more striking:
- Melanie is blonde; Annie is brunette.
- Melanie is a rich socialite from the big city; Annie is a schoolteacher in a small town.
- Melanie is witty and flirtatious and energetic; Annie is direct and no-nonsense.
Annie tries to size up Melanie:
ANNIE: Did you drive up from San Francisco by the coast road?
ANNIE: Nice drive.
MELANIE: It's very beautiful.
ANNIE: Is that where you met Mitch?
ANNIE: I guess that's where everyone meets Mitch.
Annie still has a thing for Mitch even though they broke up years ago. Considering that Melanie is obviously Mitch's new love interest, Annie is pretty nice to her. She even confides in her about her feelings for Mitch and why she moved to Bodega Bay from the city—very different from Melanie, who's not revealing much of anything and has been lying since the minute she got to Bodega Bay.
ANNIE: I wanted to be near Mitch. It was over and done with, and I knew it, but I wanted to be near him, anyway. You see, I still like him a hell of a lot. I don't want to lose that friendship ... ever.
Annie's openness finally lets Melanie admit that the reason she's in Bodega Bay is to see Mitch, too. Annie finds a way to be okay with that. She even clues Melanie in to the big potential problem with Mitch: his mother. Evidently, Lydia didn't warm up to Annie until she and Mitch broke up:
MELANIE: Well, what had you done?
ANNIE: Nothing. I simply existed. So, what's the answer? A jealous woman, right? A clinging, possessive mother? Wrong. With all due respect to Oedipus, I don't think that was the case.
MELANIE: Then, what was it?
When Melanie arrives at the school, she and Annie work together to save the children, leading them out of the building and telling them to run, run, run. Annie brings Cathy to her house for safety.
Later, when Melanie and Mitch go looking for Annie and Cathy, they find Annie dead on the front lawn and Cathy inside the house, terrified. Cathy describes it:
CATHY: All at once the … the birds were everywhere. All at once. She … she pushed me inside and … they covered her. Annie. She pushed me inside.
Annie dies heroically, at least. She's been a hugely sympathetic character all along and didn't seem to deserve a gruesome death.
But, that's Hitchcock. He doesn't work in clichés or do what you expect. These bird attacks are totally arbitrary.