Three small moments from a snowy day sit side by side here, and the quiet connections between them are what make the poem work. First, a squirrel locates the exact spot where it buried a nut, even though everything around it looks the same. The landscape seems blank to us, but not to the animal, which knows its way by something we can't see.
The speaker then enters the scene, trudging along on snowshoes. The line "I choose to believe / I'm half-floating, not half-sinking" is the emotional center. It's wry and a little self-aware: the speaker admits that how the effort feels is partly a matter of attitude. Finally, snow falls from the trees and leaves scattered marks, almost like tracks with no animal to make them.
The mood is calm, attentive, and gently humorous. The speaker doesn't claim to understand the snowy world the way the squirrel does, but chooses a hopeful way of moving through it.