What are three instances in "The Birds" in which a character behaves ignorantly or endangers themselves or others?

The first instance of ignorance in "The Birds" is when Nat makes the assumption that the birds attacked him and his family because they were looking for shelter. When Jill points that the birds pecked at them, and even drew blood, Nat dismisses it by saying, "fright made them do that . . . They didn't know where they were in the dark bedroom."
Mrs. Trigg is equally dismissive when Nat tries to explain to her about the attack. She tells him it was most likely a dream brought on by too much drinking.

"Sure they were real birds," she said, smiling, "with proper feathers and all? Not the funny-shaped kind that the men see after closing hours on a Saturday night?"

Finally, Mr. Trigg ignores the advice from the authorities, saying that "they like to scare you." He not only refuses to board up his house, but tries to take matters into his own hands and shoot the birds with his gun. It results in the deaths of Jim, and Mr. and Mrs. Trigg.

The news announcer is another character who behaves ignorantly in the story. Although reports have come in about tens of thousands of birds causing disturbances all across the country, the announcer reveals no urgency in his voice.
The main character, Nat, thinks that the news announcer is treating the entire affair as a sort of joke. The announcer's voice is "smooth and suave." It is the voice of someone who has never been forced to fight a swarm of violent birds in the dark. Earlier in the story, Nat experienced just this: he had to kill nearly 50 birds to save his children's lives.
That said, there is no telling how many lives were endangered or lost because of the announcer's nonchalance.
Yet another instance of a character behaving ignorantly is how the telephone operator treats Nat's message. When Nat implores the operator to warn others on the exchange about an impending gull invasion, she reacts with irritation.
We get the impression that she may not have relayed Nat's message to people on the exchange. The operator's careless attitude may have endangered the lives of others.

There are a number of instances likes this in "The Birds." One example is when Mrs Trigg dismisses Nat's story about the attack on his home. In fact, she goes as far as to mock him:

“Sure they were real birds,” she said, smiling, “with proper feathers and all?"

Her disbelief and ignorance towards the birds' attack on Nat and his family is significant because it foreshadows her own demise later in the story.
Secondly, Mr Trigg demonstrates his ignorance when he fails to board up his windows and doors, despite the advice on the wireless and the warnings from Nat. He thinks that these warnings are nothing more than scaremongering and he believes that he can protect himself with just a gun—another example of his ignorance.
Finally, while not strictly a character in the story, the BBC endangers people by not maintaining its emergency broadcasts. For much of the story, Nat and his family wait desperately by the wireless for news of what to do next and for updates on the situation across the country. By not updating people on the current situation and not giving further advice on what to do, the BBC leaves families, such as the Hockens, to battle the birds alone.