Answer:
In her poem, "Caged Bird", Maya Angelou uses the symbol of the cage to develop the theme of lack of freedom.
If a bird is out of a cage, it is free to fly and do whatever it desires: it can even "claim the sky" and name it "his own." The flight of a bird symbolizes freedom. On the other hand, when in a cage, a bird is unable to fly, which means that it is not free. It is afraid and cannot use its wings. The bird sings because it wants freedom, but also because it is frightened.
A bird's cage is actually a metaphor for racism and slavery. It is a symbol for the lack of freedom which African American people experience. They are not free - both physically and psychologically. These people are chained and oppressed, and there is nothing they can do to escape that situation. The poem, therefore, does not only explore the theme of lack of freedom in general. It reminds us of the awful treatment of Black people, who are deprived of freedom to speak, move, love, etc.