Spectacled eider (Somateria fischeri) hen performs broken-wing display
If you’re a nesting bird, there is a lot of effort dedicated to raising your offspring: producing eggs is energetically costly, and then they have to be incubated, a task that means withstanding harsh conditions, day and night, while reducing your own food intake. Leaving the nest poses an immediate risk for a predator to devour the entire clutch, rendering all of that costly reproductive effort for naught.
One way that nesting birds reduce the chances that an enterprising nest predator might eat their eggs is by evolving clever behaviors. One of these is the common broken-wing display: when a predator comes near the nest, the parent will pretend to be injured, flopping around vulnerably in an attempt to draw the predator away from the nest.
The strategy must be effective, because it’s employed by dozens of bird species worldwide from many different groups! Key examples are shorebirds (like the familiar killdeer (Charadrius vociferus), famous for its broken-wing), waterfowl, and seabirds.