Four short lines, and they turn a small bird into something unsettling. The poem opens with a wren nesting, an ordinary sight, but the comparison that follows is strange and dark: it can nest "like a head full of evil." The image suggests that something harmless on the outside can hold something menacing within, the way a mind can hide thoughts no one else sees.
The last two lines add a sense of strategy. The wren is "now saying nothing / to save his place." Silence becomes a kind of protection, a way of keeping a spot safe by staying hidden and quiet. The title, "Versatile," fits this idea of adapting and blending in, whether that's a bird or a person.
The speaker's feeling isn't spelled out, but the tone is watchful and a little wry, even uneasy. The mood is tense and secretive, with a quiet menace sitting under a very small, domestic scene. The poem leaves it open whether the wren is truly sinister or whether the speaker is imagining it.