Think of a filmstrip: a row of still frames that turns into movement only when light passes through it. Dave Bonta's poem is built the same way. It has three stanzas of three lines, each a single sentence, each a separate frame. First comes a wide shot of a valley, then a medium shot of someone on a ridge, then a close-up of a sign on a pole. The poem never explains the cuts between them. It leaves the reader to make the connections.
The opening image is the most startling. Clouds "pull their shadows / across the snow-filled valley / as if dragging for a drowned swimmer." Nothing in the scene is sad, since it is only weather moving over snow. But the simile turns the valley into a lake or riverbed and the shadows into nets or hooks sweeping slowly back and forth. Death enters the landscape without being announced. The verbs matter here: "pull" and "dragging" make the clouds labour, almost grimly, as if the sky had a job to do. The line break after "shadows" also lets the word hang for a moment before "across" drags the sentence onward, so the rhythm acts out the motion it describes.
In the second stanza a person appears: "I watch from the ridge." The vocabulary changes from physical effort to a kind of trance, and the key word is "mesmerized." The speaker is no longer searching, only watching, the way one watches a screen. "Alternation" is a long, abstract word that sits alone in the middle of its line and slows the reading down. Then the stanza closes on "gloom and glare," two short words that begin with the same sounds and mean opposite things. The sound pattern copies the flicker it describes, dark and bright in almost identical packages. At this point the title makes sense, because a filmstrip passing through a projector is exactly this alternation of shadow and light. The speaker is the audience and the valley is the screen.
In the last stanza the poem turns the camera around. It opens with the first sound we hear, "The No Hunting sign rattles," as if the film had been silent until now. The sign is a small human attempt to set rules on a wild place, and it hangs on an "electric pole," another human object. Yet the final line pulls the eye down to "the deep claw-marks of bears." Judging by the wording, the bears have scraped the pole, though the poem never says why and doesn't need to. The line also sounds heavy. "Deep claw-marks of bears" packs four strong stresses close together, a thud after the airy drifting of the first stanza.
The ending carries a quiet irony. The sign speaks to hunters, while the marks were left by animals that cannot read. Wildness here is not a pretty spectacle but a physical presence that leaves scars at about the height where human notices hang. The claw-marks also echo the drowned swimmer, since both are traces of bodies and of danger under a calm surface. The speaker's detached, almost cinematic view of the valley is interrupted by a rattle and a scratch, evidence that the landscape is not only something to be watched.
The form is plain. There is no rhyme and no regular metre, only short free-verse lines, everyday words and a full stop at the end of each stanza. That restraint gives the poem its power. It never says what the speaker feels about the drowned swimmer, the trance or the bears, and it trusts its images to carry the unease.
The poem is significant because it does so much in so little space. In nine lines it takes a pleasant winter view and shows how thin the pleasure of looking can be. Watching nature as though it were a film is easy and even soothing, but the last frame reminds us that the picture has teeth. Readers who finish it may look differently at the next scenic view they stop to admire.