The poet has used a number of poetic devices in the poem “I Know Why the Caged Bird Sings”.

Metaphor:
The poet uses metaphor (an indirect comparison) when she compares wind to water. The words ‘downstream’ and ‘current’ make us think of the tides in a sea or ocean.

and floats downstream
till the current ends

Again, she uses metaphors in the use of two birds — “free bird” and “caged bird”. The free bird represents the privileged section of the society whereas the caged one signifies the underprivileged. Maya Angelou was an active participant in the African American Freedom Movement. That is why this poem is seen as an autobiographical representation of the condition she and her community was in. The slavery and segregation of the African Americans are compared to the condition of the caged bird and the free bird refers to the freedom enjoyed by the White Americans.

Alliteration:
Alliteration (repetition of consonant sounds at the beginning of nearby words) is used in places like —
can seldom see through (repetition of ‘s’ sound)
and the fat worms waiting on a dawn bright lawn
his shadow shouts on a nightmare screams

End Rhyme and Internal Rhyme:
End rhyme is used in the second, fourth and sixth lines of the third stanza — ‘trill’, ‘still’ and ‘hill’.
Internal rhyme is used in the fourth stanza — and the fat worms waiting on a dawn bright lawn

Imagery:
Angelou has used vivid imageries. ‘Orange sun rays’, ‘distant hills’, fat worms’ etc are examples of visual imageries while ‘sighing trees’, ‘nightmare scream’ and ‘fearful trill’ are auditory imageries.

Personification:
The poet personifies (applies human characteristics) the two birds when she says —
‘dips his wing’, ‘dares to claim the sky’, ‘name the sky his own’, ‘opens his throat to sing’, ‘sings of freedom’ etc.

Repetition:
The poet has repeated the third stanza later in the poem to emphasize the distressed condition of the downtrodden people.

Moreover, the use of contrast in the form of two birds in completely opposite situation and the use of moods in ‘fearful trill’ ‘nightmare scream’, ‘bright lawn’, ‘grave of dreams’ etc. also form literary devices.