The poem follows a mother bird in a bad season. Seeds are scarce, the drought has pushed the earthworms far underground, and most of her nestlings have already died. The poem doesn't linger on this, but one detail lands hard: the dead chicks are "too pitiful / even for the crows." Only one baby is left, and she is desperate to keep it alive.
The last stanza shifts. Along the forest floor, between tall black trees, she finds "a trailing of coarse brown crumbs." The poem stops there, so we never learn what the crumbs are or who left them. The title and the fairy-tale feel of a trail through the woods may hint at a human hand, though that is our guess, not something the poem says.
The mood moves from bleak and anxious to a small, uncertain hope. The speaker keeps a cool, observing distance, which makes the suffering feel quiet but real, and the ending feels like a gift she can hardly believe.