Situational irony manifests in “The Birds” through the subversion of expectations, particularly regarding the danger posed by the birds. Nat’s initial reports to his neighbors about the birds are met with disbelief and humor. Birds are perceived as delicate and nonthreatening in comparison to human technology.
The last time Nat sees Mr. Trigg alive, he's in a good mood, jovially declaring that he will "make the feathers fly" by shooting down the incoming gulls and that they are "in for some good fun." Nat thinks Trigg "must be crazy," but Trigg is convinced of his ability to easily dispatch the threat—so convinced, in fact, that he cheerfully says:
"See you in the morning. Give you a gull breakfast."
However, in the morning, Trigg is dead and the birds have feasted on his body. Trigg's expectation that his superior technology and intelligence will win the day has been completely subverted; Nat's paranoia proves to be correct. Earlier in the story, the cowman, Jim, suggests appeasing the birds by leaving them breadcrumbs, expecting them to "get tame" rather than "act savage." Used to either domesticated livestock or skittish wild animals, the human characters believe, until their very last moments, that humankind naturally has dominion over nature—but the opposite turns out to be true.