The silent radio and the burning cigarette can also be interpreted as symbols of man's struggle to survive. The silent radio, for example, is a stark reminder that in the fight against the birds, man is alone and can only depend on himself. This is also reinforced by Nat's burning cigarette: it reminds him that he did not get more cigarettes when he went out for supplies and therefore illustrates that man is ultimately dependent on himself to obtain the things he needs, not on others.
Moreover, by using the cigarette and the radio as symbols, Du Maurier is suggesting that man cannot rely on modern inventions for self-preservation. As we see through Nat, protection against the birds comes from nature: the wood that he uses to barricade the windows and the changing of the tide, which lures the birds away. In short, protection does not come from cigarettes or radios.