I agree. With all that has happened, when she heard the noise upstairs didn't she think "it's probably birds in there"

I recently re-watched the film on Blu-ray (local video store - remember them? - had just gotten it for their collection, so I hired it out) and a thought occurred to me during that scene; something in the way she moaned "Oh, Mitch" which sounded less like exhaustion, and more like a sexual moan (!): what if all the bird attacks are a screen memory for Melanie's rape by Mitch?
I know at first blush it might sound preposterous (the sort of fanboy pretentiousness you find popping up like weeds on these internet forums), but I found myself wondering if the whole film is actually a reconstructed narrative in which the various bird attacks are screen memories inserted to hide the truth of Mitch's abusive proclivities (which his Mother and former girlfriend, the schoolteacher, and possibly the whole community - through small town gossip - are aware of yet keep secret). Imagine an alternative narrative in which there are no bird attacks and Melanie Daniels ends up spending a night at Mitch's house, during which he rapes her in the upstairs bedroom (while his mother and sister are asleep downstairs), tearing her clothes and leaving her catatonic, then blaming her state on some random bird that flew in through the window and attacked her. His mother, who probably suspects the truth but doesn't want to believe it, goes along with this and the traumatised Melanie is led to believe them.
So now imagine the film, as it is, as her recollection of the days leading up to, and including, her rape in which all the clues to Mitch's true nature are screened out with bird attacks; conjured up to account for her unexplained fears and ominous associations. Because of the trauma she cannot remember the rape, but her recollections are littered with moments of dread, signifying "warnings" about Mitch, which are accounted for by imagining that "the bird(s)" are attacking her (and others, who might also know the truth about Mitch but stay silent).
It's a stretch, I know, but considering the role such traumatic screen memory plays in 'Marnie', I wonder if Hitchcock didn't perhaps have this in mind as a narrative conceit for 'The Birds' as well. Has anyone else come across this theory before, or thought the same?

This movie was made in 1963 and I guess at that time the dumb Blonde stereotype was at full force and Alfred Hitchcock decided to exploit that at an all time high.
The way Melanie Daniels decided to check the attic was extremely dumb. If she really wanted to check out that room knowing that the house was previously attacked by the birds, then the proper course of action would be to:

1. Slowly and carefully open the door.
2. Open the door with a two inch gap, which is big enough to look in while small enough for the birds to escape.
3. All the while keeping a hand on the door knob and remaining in the hallway. Under no circumstances do you enter the room without checking it extensively first. This way, in the case there's any danger there's a quick escape plan by quickly closing the door should the birds attack again.
   But what she did was really stupid. She decided to open the door wide open, step inside the room with the door partially closed behind her. This essentially eliminates the window of escape when the birds attacked again.

Yeah, seemed like typical "Don't go in there, girl" horror. And when she sees the hole, to go in and pull the door, instead of trying to leave.
Also bugs me that the entire time Mitch is dragging her out, not one bird gets into the house in the giant opening above her. Can't tell me that the old lady waving her hands was enough to keep all the birds in. Unless they just didn't want to go out of the room.
Science doesn't care what you believe.

The nature of humans, always doing what's against our best interests.

I just watched the movie for the first time and I kept shouting IDIOT when she went in there.

Its the same as opening Pandora's Box. She knew she was going to be in trouble, but she opened it anyway. I loved the scene! Someone had to get attacked and it might as well be her.

^My thoughts as well. Guilt is a common motivator in Hitchcock's films, after all. Melanie pursues Mitch into Bodega Bay because she feels marked by her history as a spoiled prankster and wants to prove to herself that she isn't that girl. I also thought that the mother's rantings in the restaurant must have had an effect on Melanie, like a darker version of Mitch tormenting Melanie when they first meet in the birdshop. Melanie goes into the bedroom aware that something could be there, but feeling that if she can take care of it on her own she has paid for her sins, both as a prankster and the cause of the harm she feels she's brought on the Brenners.
Half-Blood 15
After all, tomorrow is another day ~ Gone with the Wind

It was a form of self-sacrifice.
"
Evan Hunter, the film's screenwriter, has expressed his understanding that when Melanie enters the attic, it is an act of self-sacrifice
".
https://goo.gl/bhV5WO
I guess she started to believe the mother, in the restaurant, who was yelling that it was all Melanie's fault.

Her behavior is completely in character. In the first twenty minutes she is shown to be a risk taker and assertive; she went along with Mitch thinking she was a shop girl, she gets her father's employee to track down Mitch's identity, she buys the love birds and decides to drive to Bodega Bay to deliver them, she gets the postman and the schoolteacher to reveal details about the Brenner's, she can handle an out board motor with lan, she doesn't hesitate entering the Brenner's home, and she drives a remarkable Aston Martin. Just the type to investigate a strange sound.

It bothered me but what bothered me more was that she never once screamed! Hello?!?! You're getting attacked by a roomful of birds and the only peep you make is a little moaning? I would think anyone in that situation would scream involuntarily; I know I wouldn't be able to NOT scream! I guess it didn't fit the plot (i.e. if Mitch had heard her and rescued her sooner they wouldn't have needed to leave in order to get her to a hospital).

This from an idiot who wastes his time wondering if Neil Patrick Harris is a top or bottom. Time to get off the govt. dime and educate yourself.

In the frozen land of Nador they were forced to eat Robins minstrels. And there was much rejoicing.

'Even though she clearly heard wings flapping, and thus the reason she went up there in the first place??'

You are assuming she 'clearly' heard wings flapping. To her, from the distance she was, it sounded like noise, not necessarily wings flapping. When she entered the room she didn't know there would be 200 birds there, or she would be not have entered. It was not terrible directing/ writing.

did anyone question the invisibility cape in harry potter? omg everyone. Get over the details and enjoy the film!

The world doesnt owe you a damn thing.

It's a typical horror movie trope a character going somewhere he/she shouldn't, while the audience is thinking or saying, "NO, DON'T GO IN THERE!"
Of course it doesn't make sense. Going in the bedroom in "The Birds," going in the attic/basement/shed/whatever in other horror movies.

Even though she clearly heard wings flapping, and thus the reason she went up there in the first place??
Terrible script writing/directing. Yet another reason to dislike the movie, and quite honestly, the overrated director.

The hole in the roof was a breach in the security of the house. She went in to get a better look, unaware that several birds were already in the room.

She goes back because she's is now ready to face and overcome the female superego of Brenner's mother.

Maybe she went to check if the birds are running aloose at the first floor and maybe she could alarm Mitch if she saw a broken parts that needs to be fixed? She didn't know if that is so, so that's why she didn't wake up Mitch.
This is the only explanation that is rational to me, why she went inside.

Before filming the final attack scene when Melanie goes upstairs, Tippi Hedren asked Alfred Hitchcock , "Hitch, why would I do this?" Hitchcock's response was, "Because I tell you to."
Well, at least he didn't say "It's just a movie!"

There is a lot of illogical behavior in this, but going into the bedroom is the most ridiculous. I suppose if the characters had all gone into a bathroom, windowless cellar, etc, it would have been a boring movie.
I couldn't see a teacher sending all the kids out to be attacked. Again, the drama/horror would be lost if she had corralled them all into a safe room, or escorted them one by one to Melanie's car for a ride home, or called their parents and asked what they would prefer. Sending them out with the only instruction of "run down the hill!" ?!

From the trivia section:
Before filming the final attack scene when Melanie goes upstairs, Tippi Hedren asked Alfred Hitchcock , "Hitch, why would I do this?" Hitchcock's response was, "Because I tell you to."

It didn't ruin the movie for me, but I agree with you about the whole scene in the bedroom. It's kind of like in spooky movies when there is a monstrous killer on the loose breaking into houses and someone is alone at home and hears a noise in the basement and goes to see what it is.