The rhyme scheme in this poem is loose and somewhat erratic. In the first stanza, for example, there are no full end rhymes—although there is some assonance which creates a pattern of half-rhymes. For example, the last syllable of "downstream," ending line three, shares a vowel sound with the word "leaps" which ends the first line.
Likewise, lines two and five end with words ("wind" and "wing") which also share the same vowel sound. The assonance at the end of lines two and five is also compounded by the internal assonance, in line five, of the word "dips." The repetition of the breathy "i" vowel here could perhaps onomatopoeically echo the sound of the "free bird" riding up and down on the "back of the wind."
In the second stanza, the undulating assonance of the first stanza is nowhere to be found, reflecting the absence of flight and freedom endured by the caged bird. There is, however, a full (and somewhat harsh) rhyme in lines two and four, where "cage" follows "rage." The fact that this is the solitary end rhyme in the stanza emphasizes its impact. The rhyme also draws our attention to the negative connotations of "cage" and "rage," respectively.
In stanza three, when the caged bird decides to sing, there is plenty of assonance again, reflecting the freedom inherent in the act of singing. The assonance of the breathy "i" vowel is repeated several times, in, for example, "sings," "trill," "still" and "hill." The repetition of this vowel sound connects the act of the caged bird's singing with the flight of the free bird in stanza one. Both are expressions of freedom.
In stanza four, we almost have a pair of rhyming couplets. The first two lines, ending with "breeze" and "trees," form a rhyming couplet, and the third and fourth lines, ending with "lawn" and "own," form a half-rhyme.
The more consistent rhythm here reflects the fact that the focus has once more shifted back to the free bird. The long vowel sound of "breeze" and "trees" suggests the peaceful flight of the bird stretching its wings across the wind. The half-rhyme at the end of the stanza serves to arrest the rhythm set in motion by the first two lines and signals a return to the clipped wings of the caged bird in the following stanza.
In the fifth stanza, the first two lines again form a rhyming couplet, ending in "dreams" and "scream." The long vowel sound is very similar to the long vowel sound of the rhyming couplet in the previous stanza, but the "m" consonant at the end of the vowel sound serves to stifle the sound, whereas in the previous stanza the "z" and "s" consonants act to draw out the sound even further. The drawn out vowel sound echoes the flight of the free bird, and the stifled vowel sound echoes the restricted, stifled flight of the caged bird.
The sixth and final stanza is a repeat of the third stanza, and thus the pattern of the breathy, half-rhyme assonance of the "i" vowel is repeated again. The poem thus ends on the positive connotations of flight and freedom associated with the song that the caged bird defiantly sings. Although the caged bird is restrained and confined, it's soul, or spirit, yearns for the same freedom enjoyed by the free bird.
There’s no "scheme" to the rhyming pattern in Angelou's poem, at least in the conventional sense. Her use of rhyme underscores the contrast she is making between captivity and freedom, but also serves to emphasize the poem’s musical qualities. Angelou's meter is as irregular as her rhyming.
Take the first stanza about the free bird. While there are no rhymes, the first four lines are near rhymes—the vowel sound in "leaps" is repeated in "downstream," as is the case with wind/end. The meter is dominated by syncopated anapests ("on the back of the wind") but is broken up by unmetrical lines such as "in the orange sun rays." There is a music here, but rhyme and meter give it a spontaneous quality that evokes the theme of freedom.
A good contrasting stanza would be the third, which rhymes A-B-C-B-D-B-D-E. Here, the shortened line length suggests confinement, and the rhyming pattern, together with the dominant iambic meter, gives the language a kind of restless, repetitive energy. You can almost picture, from the rhythm of these words, someone pacing back and forth in a cage.
There is no set rhyme pattern in Maya Angelou’s poem “I Know Why the Caged Bird Sings.” Instead the poet uses the structure and rhyme of the poem to emphasize its metaphorical meaning.
In the first stanza, there is no set rhyme scheme which allows the reader to feel the freedom of the uncaged bird as it soars on the breeze.
In contrast, in the second stanza, the second and fourth lines rhyme ending with the words cage and rage. This brings emphasis to the feelings evoked by the bird being restrained in the barred cage. In stanzas three and six which form a refrain, she again writes of the caged bird. Lines two, four, and six are short, terse, rhyming lines that once again denote the plight of the bird. The use of a refrain brings emphasis and importance to the meaning of these two stanzas.
In stanzas four and five the first two lines of each form a couplet. The first stanza describes the free bird while the next one speaks to the caged bird. The pattern of these stanzas mirror each other to once again make the comparison between freedom and oppression.