A walker moves through a winter wood and notices small signs of life and damage. First comes the sound of porcupines gnawing in an oak's crown, which the speaker compares to mistletoe, another thing that quietly feeds on a tree. The title, "Haustorial," points the same way: a haustorium is the organ a parasitic plant uses to draw nourishment from its host. Then the speaker sees deer tracks crossing and recrossing on the path, "braiding and unbraiding," a gentle image of movement and pattern.
The last stanza turns inward. Reaching into a coat pocket, the speaker finds a twig, as if the woods have already slipped inside them. "It's happening sooner than I thought" is left open, but it suggests something creeping in, perhaps aging, or the sense of belonging to nature and its cycles of taking and being taken. The mood is hushed, watchful, and a little uneasy, though not frightened. The speaker seems more struck than alarmed.