In Daphne du Maurier's short story The Birds, Nat Hocken has been slightly bewildered by the strange behavior of the region's bird. Nat observes the birds' seeming restlessness and their apparent lack of interest in their usual feeding patterns. He initially ascribes the birds' strange behavior to the approach of winter, a time when many of these winged creatures will certainly perish from the cold. The farmer for whom he labors several days a week concurs in this assessment, stating, "It will be a hard winter. That’s why the birds are restless.”
The first attack in du Maurier's story involves Nat, and he is quick to reaffirm the weather's role in the increasingly and uncharacteristic behavior of the birds. Disturbed by a tapping on his bedroom window as the wind blows outside, he goes to the window and opens it, surprising a bird that proceeds to peck his hand, drawing blood in the process. Consistent with his, and the farmer's earlier theory regarding the birds' behavior, Nat attributes this attack as the result of a frightened bird seeking shelter from the cold:
"Frightened, he supposed, bewildered, seeking shelter, the bird had stabbed at him in the darkness."
To the extent that this episode constitutes the birds' first attack, then the reason given for the bird's aggressive behavior is fear of the approaching winter.