What does the figurative language (used by the guard who arrests Antigone) reveal about how Antigone feels?

Simile was used as a figure of speech. 

According to the guard who arrests Antigone: She was wailing bitterly like the shrill voice of a bird who sees her empty nest, stripped of its nursling.

Antigone felt great pain and sorrow when she found that the body of Polynices was stripped off the dust that she buried him under.