Following poetic/literary devices have been used in the poem A Tiger in the Zoo:

1. Personification: In the poem the poet refers the tiger by the word “he” which is used for humans. So, the tiger has been personified as a human with emotions who can understand.
2. Metonymy: Metonymy is the substitution of the name of an attribute for that of the thing meant. In the poem, the poet calls body of the tiger as its strength (Stanza 4).
3. Metaphor: The poet compares the condition of tiger in the cage and in the forest. He tells how tiger feels in the cage and how it would have been feeling if it were free.
4. Alliteration: It is the the occurrence of the same letter or sound at the beginning of adjacent or closely connected words. e.g.  “should be lurking in shadow”, “where plump deer pass”, “in a concrete cell”.
5. Symbolism: it is the use of symbolic images and indirect suggestion to express mystical ideas. In the poet the poet describes eyes of the tiger and stars in the sky as brilliant. The eyes are bright either because of rage or because of its majestic look. On the other hand, the stars are brilliant because they twinkle in the sky.

Read summary of this poem.