In literature, the mockingbird symbolizes innocence, purity, honesty, which I see in Edna’s accomplishing the duty which her mother and wife roles assume. Even if she is not the role model in her mothering, I think she is trying her best to raise her children and to give them wings to fly, wings she does not acknowledge she has as well.
By making a parallel between Edna and the mockingbird, I’d like to point out the fact that the author wanted us to see Edna’s changing, from the honest, innocent woman who is taking care of her family in the first part of the story, to the woman who loses interest in her mother and wife roles in the second part.
In her moment of uncertainty, after she learns to swim and lives her moment of awakening, bit by bit she starts to lose her honesty and her love towards her own family. Her awakening is sexual in part, but it is also a search for creativity, as suggested by her attempt to paint. She seeks the advice of the only artist she knows-Mademoiselle Reisz. She reads Emerson, the voice of individualism. From these sources, she gains the courage to challenge the authority of her husband.