Thesis

If Alfred Hitchcock gave us a flock of birds stalking the protagonist, then Alfred Hitchcock is, in fact, the one responsible for the creation of our Mythos; ergo, the Bird Mythos has existed since the 60's.

Proof 1

Alfred Hitchcock made the film The Birds in 1963, in which there are a series of sudden, unexplained bird attacks in Bodega Bay, California.

Digression 1

Though the film is based on the 1952 Daphne Du Maurier story of the same name, from the United Kingdom, Hitchcock's The Birds is considered 'culturally, historically, or aesthetically significant' by the Library of Congress, and, since America are obviously the most important state in the world, we can safely ignore anything from the United Kingdom without any noticeable repercussion.

Proof 2

Hitchcock decided to not make use of a traditional score for his film The Birds, instead making use of sound effects as counterpoints to calculated silence, used as atmosphere. And since the Bird Mythos obviously have no music anywhere in any stories, it is sound to suggest that Hitchcock codified this aspect of the Mythos with his film The Birds.

Digression 2

The Sunsetters do not exist, and Dooling, Jordan and Taylor, Eric have never made any music under that name, and if you think otherwise, you are wrong.

Proof 3

The Birds won the Horror Hall of Fame Award in 1991. Since the Bird Mythos only allow horror stories, it is sound to claim that Hitchcock created the template for all of the Bird Mythos writing, in essence founding the Mythos.

Digression 3

Blogs such as Slender Ran or the Everyblogger Triad do not exist.

Conclusion

Based on the previous points, it is a valid claim to suggest that Alfred Hitchcock created the Bird Mythos, and that giving credit for the creation of the Mythos to alliterator, CuteWithoutThe, DJay32, et. al. is completely false.