At its essence, "The Birds" is a story about survival. The narrative and core themes center on Nat Hocken's attempts to withstand the bird onslaughts. Du Maurier initiates these attacks with a single bird pecking at Nat's bedroom window and culminates with a swarm surrounding the Hocken home, seemingly determined to reach the family sheltered inside. As a result, Nat's main concern throughout the tale is to protect himself and his family from this dangerous threat.

Nat remains composed and strategic in his efforts to ensure his family's survival. After the initial incident, he boards up the windows, understanding they are the birds' easiest entry point. He also secures the doors and seals the chimney. Even amidst the frightening attacks, Nat remains focused on survival, strategizing his next moves during the brief pauses. In each break, he musters the courage to step outside with minimal protection to repair the barricades or gather supplies and fuel in anticipation of the next assault.

Nat's determination to protect his children is stronger than his instinct for self-preservation. Early in the story, when his daughter screams, he rushes into their room to find it invaded by a swarm of gulls. His immediate focus is on his children's safety, so he quickly gets them out of the room before dealing with the birds. The following day, when he notices a large group of gulls moving inland, he hurries to his daughter's bus stop to ensure her safety. After securing her safe ride with a neighbor, he returns home, only to be attacked by another wave of birds at his doorstep.

Nat is also attentive to his children's emotional needs. Throughout the story, he works to ease their fears by distracting them from the bird attacks. He involves them in the family's daily routines and encourages his wife to make their favorite snacks. When the birds start to invade the upstairs bedrooms, he moves the family downstairs, presenting it as an exciting campout in the kitchen.

Amidst the family's struggle for survival, Nat and his wife conform to traditional gender roles. Some scholars, including Margaret Forster in her acclaimed biography of du Maurier, argue that this mirrors the author's intricate sexuality. Nat takes on the role of protector, while his wife, whom du Maurier leaves unnamed, often fades into the background with their children. Mrs. Hocken looks after the children by tending to Johnny's wound and preparing meals, but she often appears as frightened as the children.

After an attack subsides, Nat decides to go out in search of food and fuel. His wife is so terrified that she refuses to stay alone with the children. Her portrayal as submissive and frail is highlighted when Nat tells her to stay behind while he checks out the Trigg's farmhouse. At first, she attempts to follow him, but Nat's insistence makes her return to the children.

The first theme is human arrogance. When confronted with an incomprehensible situation, du Maurier's characters depend on their own experiences to try to exert control over their environment. According to du Maurier, people exhibit excessive pride, preventing them from admitting defeat or recognizing that events such as the mass killing of people by birds are beyond their comprehension. For example, Nat tries to rationalize the birds' behavior by citing their natural instincts. When a single bird initially attacks him, he attributes it to natural causes: "frightened, he supposed, and bewildered, the bird, seeking shelter, had stabbed at him in the darkness. Once more he settled himself to sleep." Nat can relax after justifying the bird's erratic behavior as a response to fear.

Even when these logical explanations become unreasonable, du Maurier's characters continue to cling to them. It seems that people can significantly deceive themselves when faced with impossible situations. As mentioned earlier, some characters blame the supernatural events on the sinister actions of the Soviet Union, searching for a social rationale. However, these explanations only emphasize the absurd lengths people will go to in order to assert their understanding of even the most perplexing situations.

As the characters give up trying to logically explain the crisis, they fall into the emotional chaos brought on by intense stress. Nat's family goes through a whirlwind of emotions—ranging from hysteria to contemplation and desperation—during the birds' relentless attack. After enduring the constant pounding of birds against their roofs and windows for an entire day and night, Nat's children find some relief from their anxiety by laughing at the situation: "This was the way to face up to it. This was the spirit. If they could keep up like this, hang on like this until seven, when the first news bulletin came through, they would not have done too badly."

The morning light and the familiar sound of the radio news can offer emotional relief similar to laughter. According to du Maurier, small comforts can ease the anxiety caused by impending danger. Nat understands this, so he assigns his wife and children small, seemingly insignificant tasks, hoping these chores will bring them a sense of normalcy. Nat considers this important for both his wife and children: "It kept his wife occupied, undressing the children before the fire, seeing to the bedding, one thing and another, while he went round the cottage again, making sure that nothing had worked loose." Routine domestic tasks can relieve the sense of dread just as effectively as laughter. Anything that distracts du Maurier’s characters from the threat outside their cottage walls helps them cope with their fear.

However, eventually, a dangerous situation can overwhelm those trying to withstand the anxiety it causes. This becomes clear in the final pages, when during a brief break from the birds' attack, Nat prepares to leave to gather supplies. Having relied on his calm demeanor throughout the night of terror, his wife succumbs to despair: "'Take us with you,' she begged, 'we can't stay here alone. I'd rather die than stay here alone.'" Du Maurier's characters experience a wide range of psychological states. They manage with minor familiarities or laughter. After maintaining their tension for so long, du Maurier ultimately depicts their spirit breaking and their acceptance of their fate.