We may never know the answer to this question. But this movie is unquestionably a classic.
Like it or not (it is impossible to not like it), this is a standard by which other movies are judged. The script, actors (some of whom are Rod Taylor and Suzanne Pleshette), and execution are always being compared to earlier and later movies.
The story adapted from Daphne du Maurier, does seem to be a little mysterious as to why the birds suddenly appear and as to the ending if that is what it is; however the build up and execution of the conflict with birds, and between women is defiantly worth watching.
A small town is devastated when a bunch of birds terrorize the inhabitants in what seems to be an all out war. The graphics leave a little to be desired but you will be so absorbed that you do not care.
If you have the DVD watch the movie before the goodies (extras.)
Feel the tension build up and be sure to duck at the appropriate time. After all this is an Alfred Hitchcock movie. Also, see if you spot his cameo appearance.The Trouble with Harry