Morrison consistently uses bird and fowl imagery throughout the novel to represent freedom, and the ability to attain the American Dream.
Earlier in the passage, Morrison describes Pecola as "beating the air, a winged but grounded bird, intent on the blue void it could not reach—could not even see—but which filled the valleys of the mind," (204). In this passage, Morrison is suggesting that the ability to fly represents freedom, and social mobility, and provides stark imagery of Pecola struggling hopelessly to reach this goal. Morrison claims that Pecola has wings, alluding to the fact that all people should be able to reach the American Dream and freedom, yet African Americans are unable to do so.
By later referring to Pecola's motion as "birdlike," Morrison is suggesting that Pecola was so desperate to attain her beauty, the "blue void", that she drove herself insane and now the "gestures" have worn away. Morrison's use of the word gesture is intended to emphasize that, once again, that being upper-class was simply a performance.
By comparing the birdlike motions to a performance, Morrison is alluding to the fact that being upper-class is simply an act, not something that those are born into, or that white people deserve more than others.