What does the author want to suggest about the in the end of her short novel The Birds?

Feeding into much of the fearful atmosphere of the world
stage after World War II, the story's conclusion brings to light the belief that the
birds will overcome civilization.  The bird attacks have swept the nation, and have
rendered human beings as almost defenseless to stop them.  In this light, the context in
which du Maurier is writing is extremely meaningful.  In a setting where the fear of
nuclear holocaust was real, along with the fear of "the other," in the form of
Communism, the end of the world feel of the story is brought to light.  While human
advancement has reached its zenith, at its heart, the ending of the story is one of
survival, where human beings can only fend for themselves against adversarial forces
that overwhelm the individual.  The ending of the story where Nat and his family hear
the "tearing sound of splintering wood" indicates that the birds have won in
overwhelming the humans.  All the family can do is sit and listen to what will bring
about their own end, just as other families like the Triggs.