The setting of Daphne du Maurier's short story, "The Birds," is the Cornish coast of England in autumn during the threat of Cold War in the 1950's and 1960's.
This time of year is appropriate to the theme of du Maurier's story because autumn is a season that presages change from the beauty and calm of the fullness of the year to a time of death with winter. At this time of the year, the birds are restless as the sea gulls run on the beaches and sandpipers scurry back and forth. Both seem to feel an "impulse to flight."
The restless urge of autumn, unsatisfying, sad, had put a spell upon them and they must flock, and wheel, and cry; they must spill themselves of motion before winter came.
For some reason, however, the birds are more restless than ever. Perhaps, then, there is a certain pathetic fallacy with the stirrings of the Cold War. That is, as the fear of communism spreads and increases suspicion among people, perhaps nature senses this trepidation and paranoia, sending currents of anxiety that affect the birds. Not only are they present and restless, but the farmer Nat Hocken notices that there are more birds than is customary for this town on the coast.
It is the resilient nature of Nat Hocken that keeps him in the fight; however, even he eventually succumbs to the power of Nature that is disturbed by unnatural occurrences in this horrifying tale.