What evidence does the author present in support of her opinion in the poem you know why the caged birds sings?

The poem "Caged Bird" by Maya Angelou conveys its message through vivid imagery and metaphorical language. The author presents evidence of the caged bird's restricted freedom contrasted with the free bird's ability to soar and experience the world fully. Through these comparisons, the author conveys the theme of oppression, resilience, and the longing for freedom.