By John Dodge

CHICAGO (CBS) — When viewing Becki Pikula’s time-lapse video, keep your eye on Diversey Harbor.

From her perch high above Lincoln Park, Pikula took one picture a day last year from her apartment and composed a short video, featured on Reddit and posted on You Tube, showing the seasonal changes.

There are many obvious seasonal moments, the trees, the melting snow and changing light. (There is even a brief glimpse of the Air and Water Show, around the 35-second mark.)

However, it is the migration of boats into–and out of–Diversey Harbor that perfectly mark the passing of time.

At the start, the harbor is snow-packed and barren–with the exception of what appears to be some ice fishermen.

As the thaw approaches a few early birds have docked their vessels. Then like spring blooms, the harbor explodes with activity and is quickly filled to capacity.

As the leaves change, slowly the boats disappear.

Then the emptiness of winter returns.